Why GM should NOT build a DOHC V8

[regfootball]

the iron duke of old had about 100hp and 140 torque, and delivered solid mpg. The 2.5 even if it is detuned and the torque curve tuned down a bit, will achieve a combined EPA of 23-25 I would guess, and will as fast as a lot of sedans. It may not be best suited in 4WD, but even so it will probably outrun the colorado.

[Guest Patrick]

The most powerful engine Mercedes built ( bought ) for racing was a pushrod engine built by Illmore..1100 plus HP...Pushrods rule although a DOHC can rev a lot higher

[Guest Kyle]

This is total nonsense. Your chart clearly shows the Mercedes motor making more power and then you lie and say the LS made more power. And the BMW engine is 2.2L smaller and still barely falls behind in horsepower... Pushrods are ancient, if they were superior everyone would be using them, and GM would be using them in their 4 cylinder engines, get with the program GM.

[dwightlooi]

This is total nonsense. Your chart clearly shows the Mercedes motor making more power and then you lie and say the LS made more power. And the BMW engine is 2.2L smaller and still barely falls behind in horsepower... Pushrods are ancient, if they were superior everyone would be using them, and GM would be using them in their 4 cylinder engines, get with the program GM.

 

Pushrod engines were invented after single overhead cam engines and dual overhead cam engines, so historically this statement is untrue.

 

What's more important though is the merit of Pushrod designs today. Today, a modern pushrod engine with direct injection and variable timing provides higher power and torque output at a lower engine mass and external size than a DOHC engine of equivalent performance. It also offers better fuel economy despite having a larger displacement. A good example is the current generation of high performance small block V8s. The LT1 wth 460 hp / 465 lb-ft has lower mass and fits into a smaller engine bay than any mass produced DOHC engine (V6 turbo or V8). With At 17/29 mpg the pushrod 6.2 V8 is also arguably the most fuel efficient 460hp powerplant in service. A similar thing can be said of the 650hp / 650 lb-ft LT4 engine.

 

Having said that, the Pushrod configuration is not without it's disadvantages. In nations with misguided displacement tax laws -- which penalizes engine displacment and not actual fuel consumption -- larger displacement, lower specific output pushrod designs are at a tax disadvantage to extremely high reving or highly boosted DOHC alternatives. The Pushrod configuration is also optimized for reducing engine size and complexity on Vee type blocks. It essentially has no advatnages over a single overhead cam engine in inline-4s or any other inline engine.

[Guest Rick]

I know I'm late to the thread.  But Dwight is very knowledgable, EVERYTHING he said makes true from a scientific standpoint.  You cannot defeat the laws of physics, which is what everyone seems to be doing with DOHC and turbocharging, etc, etc.  

HP per liter is a useless standard in the real world.  Their are two places it is useful, as stated earlier, would be a country that has displacement taxes.  The other would be a racing class that is displacement limited.  

 

For maximum fuel efficiency, SOHC 2 valve inline 3's and 4's.  Or pushrod 2v v6 and v8 should be used.  Friction goes up with RPM, so a small DOHC engine that has to rev high to make the power needed is going to have more internal friction than a large displacement low rpm engine.  

 

The problem is most people don't bother to read into how engines actually work.  People hear 32 valve DOHC VVT engine and think it's the best thing on the planet.  When in fact, in reality, an engine will have a better Brake Specific Fuel Consumption, with a "simple"  OHV engine.  Dwight is the only other person that I've read that seems to understand all of these principles.   Small displacement doesn't mean small engine, lightweight, or fuel efficient : it simply means small displacement.  

 

With CAFE regulations I see OHV coming back, and SOHC engines.  All with lower specific output per liter, and better BSFC.  Toyota Prius is already doing it.  

[Guest willys4864]

Funny how alot of ppl hear are using horse power to gauge the prformance of an engine. While a smaller displacement dohc engine may produce more hp than a larger pushrod engine you also need to look at the more important torque ratings and power bands. While the ohc engines have to spin alot faster to get to their power bands most pushrod v8 start at lower rpms which is where its more useable. Again torque is what gets the job done, horse power is a number to brag about

[Guest M Power]

Anyone who has ever driven a real sportcar will know that torque isn't what you think about. It is the HP you seek, which is why you rev your engine to high rpms. This is what makes driving a M3 and GT3 fun. Revving out to get the Power you want. While having more torque might make your car effectively faster in normal driving around town or whatever, there is a reason F1 seeks high HP and doesnt care about torque. As an alternative, the best NA DOHC V8 engine I can think of is the speciale V8, which displaces 4.5 litres, produces 600 HP and 400 lbft, revving to 9k. This amount of torque is enough for normal driving, while the horsepower max at the top of the rev range, makes you want to rev the engine out, makes you want to hear the V8 scream. This makes the driving fun, I think. It isnt the torque which gives me a surplus of dopamine while driving. Of course I havent driven the speciale, but the M3 E92 with pretty 'low' torque at 300 lbft has been a blast to drive, way more fun than the torquey cars I have driven. I want to make the engine max itself out. Besides, Torque is easy to boost with turbos and electric motors, like in the laferrari, unlike HP which might be relatively simple to be upgraded with turbos but not with Electric motors. Another point about turbos is the obvious fact thaat there is one way of thr future for turbo V8s, and that is hot vee. This design where the exhaust and intake manifold locations are reversed and the turbochargers sit in the V of the V8, a good example is the BMW S63 or Mercedes M177/178. Not only is the turbo throttle response improved drastically due to the short exhaust tube distance to the turbos, but the engine is immensely more compact. A Hot Vee engine wouldnt be possible with a pushrod, but a DOHC, for the obvious reason of the cam inside the pushrod V. A hot vee DOHC turbo engine will be more compact than a similar normal located turbo pushrod. And turbos are the future, not the supercharger, you can be sure about that. Soon every engine will be turbocharged or electric, and the compact advantage of the pushrod will be gone, and therefore while the OHV engine might not be worse or might be better than a DOHC now (which I still dont believe), it is obvious that the future will be DOHC and Turbo. The Mercedes M177 4.0 biturbo V8 fits in the new C63 and is able to be boosted to easily 750 HP, if not more than 800. A 6.2 pushrod will fit in the C63, but the not with the Supercharger or turbochargers required to achieve similar power levels.

[oldshurst442]

^^^

 

Anyone who has ever driven a real sportcar will know that torque isn't what you think about. It is the HP you seek, which is why you rev your engine to high rpms. This is what makes driving a M3 and GT3 fun. Revving out to get the Power you want. While having more torque might make your car effectively faster in normal driving around town or whatever, there is a reason F1 seeks high HP and doesnt care about torque. As an alternative, the best NA DOHC V8 engine I can think of is the speciale V8, which displaces 4.5 litres, produces 600 HP and 400 lbft, revving to 9k. This amount of torque is enough for normal driving, while the horsepower max at the top of the rev range, makes you want to rev the engine out, makes you want to hear the V8 scream. This makes the driving fun, I think. It isnt the torque which gives me a surplus of dopamine while driving. Of course I havent driven the speciale, but the M3 E92 with pretty 'low' torque at 300 lbft has been a blast to drive, way more fun than the torquey cars I have driven. I want to make the engine max itself out. Besides, Torque is easy to boost with turbos and electric motors, like in the laferrari, unlike HP which might be relatively simple to be upgraded with turbos but not with Electric motors. Another point about turbos is the obvious fact thaat there is one way of thr future for turbo V8s, and that is hot vee. This design where the exhaust and intake manifold locations are reversed and the turbochargers sit in the V of the V8, a good example is the BMW S63 or Mercedes M177/178. Not only is the turbo throttle response improved drastically due to the short exhaust tube distance to the turbos, but the engine is immensely more compact. A Hot Vee engine wouldnt be possible with a pushrod, but a DOHC, for the obvious reason of the cam inside the pushrod V. A hot vee DOHC turbo engine will be more compact than a similar normal located turbo pushrod. And turbos are the future, not the supercharger, you can be sure about that. Soon every engine will be turbocharged or electric, and the compact advantage of the pushrod will be gone, and therefore while the OHV engine might not be worse or might be better than a DOHC now (which I still dont believe), it is obvious that the future will be DOHC and Turbo. The Mercedes M177 4.0 biturbo V8 fits in the new C63 and is able to be boosted to easily 750 HP, if not more than 800. A 6.2 pushrod will fit in the C63, but the not with the Supercharger or turbochargers required to achieve similar power levels.

Did you just say it aint the torque that gives us the dopamine surplus we crave when driving?

 

Well...I could see by your style of driving enthusiasm....that may be true.

But...Im a muscle car guy...and what you just said sir, couldnt be farther from the truth....for me at least...

 

So...instead of judging somebody's taste in style of cars...one could have an open mind instead.

 

Because...I could easily say this:

 

Anyone who has ever driven a real muscle car...(and then I could go on a similar rant like yours defending and praising everything that makes muscle cars great while using examples of how a pushrod V8 is the best...yada yada yada...and using GM's vehicles...Corvettes, Camaros, Cadillac V Series and  and V8s as well asHemi Hellcats...yes...supercharged as proof....)

 

But you see...all that you said is just subjective BS...

What I do see though...is your love for V8s...DOHC or pushrods...

What I do see is your love for performance cars...

So...why must you push your philosophy and denounce another?

 

Ill never get that from people...

Edited August 8, 2015 by oldshurst442

[David]

^^^

 

Anyone who has ever driven a real sportcar will know that torque isn't what you think about. It is the HP you seek, which is why you rev your engine to high rpms. This is what makes driving a M3 and GT3 fun. Revving out to get the Power you want. While having more torque might make your car effectively faster in normal driving around town or whatever, there is a reason F1 seeks high HP and doesnt care about torque. As an alternative, the best NA DOHC V8 engine I can think of is the speciale V8, which displaces 4.5 litres, produces 600 HP and 400 lbft, revving to 9k. This amount of torque is enough for normal driving, while the horsepower max at the top of the rev range, makes you want to rev the engine out, makes you want to hear the V8 scream. This makes the driving fun, I think. It isnt the torque which gives me a surplus of dopamine while driving. Of course I havent driven the speciale, but the M3 E92 with pretty 'low' torque at 300 lbft has been a blast to drive, way more fun than the torquey cars I have driven. I want to make the engine max itself out. Besides, Torque is easy to boost with turbos and electric motors, like in the laferrari, unlike HP which might be relatively simple to be upgraded with turbos but not with Electric motors. Another point about turbos is the obvious fact thaat there is one way of thr future for turbo V8s, and that is hot vee. This design where the exhaust and intake manifold locations are reversed and the turbochargers sit in the V of the V8, a good example is the BMW S63 or Mercedes M177/178. Not only is the turbo throttle response improved drastically due to the short exhaust tube distance to the turbos, but the engine is immensely more compact. A Hot Vee engine wouldnt be possible with a pushrod, but a DOHC, for the obvious reason of the cam inside the pushrod V. A hot vee DOHC turbo engine will be more compact than a similar normal located turbo pushrod. And turbos are the future, not the supercharger, you can be sure about that. Soon every engine will be turbocharged or electric, and the compact advantage of the pushrod will be gone, and therefore while the OHV engine might not be worse or might be better than a DOHC now (which I still dont believe), it is obvious that the future will be DOHC and Turbo. The Mercedes M177 4.0 biturbo V8 fits in the new C63 and is able to be boosted to easily 750 HP, if not more than 800. A 6.2 pushrod will fit in the C63, but the not with the Supercharger or turbochargers required to achieve similar power levels.

Did you just say it aint the torque that gives us the dopamine surplus we crave when driving?

 

Well...I could see by your style of driving enthusiasm....that may be true.

But...Im a muscle car guy...and what you just said sir, couldnt be farther from the truth....for me at least...

 

So...instead of judging somebody's taste in style of cars...one could have an open mind instead.

 

Because...I could easily say this:

 

Anyone who has ever driven a real muscle car...(and then I could go on a similar rant like yours defending and praising everything that makes muscle cars great while using examples of how a pushrod V8 is the best...yada yada yada...and using GM's vehicles...Corvettes, Camaros, Cadillac V Series and  and V8s as well asHemi Hellcats...yes...supercharged as proof....)

 

But you see...all that you said is just subjective BS...

What I do see though...is your love for V8s...DOHC or pushrods...

What I do see is your love for performance cars...

So...why must you push your philosophy and denounce another?

 

Ill never get that from people...

Agreed and Since F1 cars are not street legal nor can they really do real world driving duties, I will take a V8 with a Flat Torque curve and HP equal to Torque. Without the Torque you will never have the push in the gut feel off the line nor that same feel when you are doing 60, 70 or more and stomp it to go even faster. Having driven a number of Italian sports cars, they are nice but a very different feel compared to a traditional USA Muscle Car. Both have their place but I have to agree with 442 that it is and always will be subjective to each individual. 

 

Love of V8's CHECK

Love of Performance Auto's CHECK

 

For me give me a proper big block with 500 hp 500 ft lbs of torque and I will be happy. Marketing has totally screwed up people to think that only HP counts, without Torque in the right places all that HP is a waste of fuel.

 

In regards to the Germans, glad you like to send your hard earned money to Germany, I will stay with supporting my fellow American keeping my profits here and buying the quality American Auto's that is way better than those that love their asian / european auto's know about and much cheaper to repair, maintain and drive.

 

Honestly, it amazes me how many people forget that when America was building the worlds best cars, Asia and Europe were trash, and in the late 70's to early 90's is all people here think about in regards to garbage american auto's and yet there were many awesome cars and trucks still built then.

 

Did the Asians bring 100K mile tune ups and pretty much trouble free driving for the 100K miles? YES, US was still stuck on 30K tune ups and many have proven to be LAZY about taking care of their ride so then the auto runs worse and they can only say nasty things about US auto's, but there is plenty of dirt to share as every auto maker has built their fair share of garbage.

[Guest MPower]

@oldshurst442 @dfelt

I can see why it might upset you that I expresses my opinion so vividly, I can see that you have a certain passion for equal torque and hp, but IMO it is not the torque I really feel when driving fast. Like I said, the E92 is a lot more fun than the F80 M3, while the F80 is WAAY faster than the E92 V8. I still miss revving the engine out. You must at least undertand what Im talking about when mentioning HP and torque. I want my torque to come late in the rev range, which by then the torque is irrelevant as it isnt lower in rev range and doesnt have a flat torque curve. It is the low torque which makes me want to rev the engine. Well, but at least give me an opinion about my second part of the post, about the future of OHV and DOHC V8s. Do you agree that the future will have to implement DOHC with the turbocharging technology which makes the engine compact in comparison to a turbo OHV?

[oldshurst442]

MR. DFELT

 

Ive used your above post on another site to prove a point.

I feel like you expressed the feelings that I have excellently about a similar subject regarding self loathing Americans that prefer to see the American car industry destroyed over foreign ones.

I hope you dont mind?

[David]

@oldshurst442 @dfelt

I can see why it might upset you that I expresses my opinion so vividly, I can see that you have a certain passion for equal torque and hp, but IMO it is not the torque I really feel when driving fast. Like I said, the E92 is a lot more fun than the F80 M3, while the F80 is WAAY faster than the E92 V8. I still miss revving the engine out. You must at least undertand what Im talking about when mentioning HP and torque. I want my torque to come late in the rev range, which by then the torque is irrelevant as it isnt lower in rev range and doesnt have a flat torque curve. It is the low torque which makes me want to rev the engine. Well, but at least give me an opinion about my second part of the post, about the future of OHV and DOHC V8s. Do you agree that the future will have to implement DOHC with the turbocharging technology which makes the engine compact in comparison to a turbo OHV?

MPower, I have no problem with you expressing you opinion so vividly. I welcome all who want to share their passion and respect each other here.

 

I just have a difference of opinion in regards to reving, HP and Torque. I understand the rev thing as I have two Yamaha Wave Runners SVHO that are a blast to run though I do find it crazy that I have to rev to 12,000 RPM to go 65MPH on the water. I have seen plenty of quality engines in boats that only have to rev to 4k to 5k RPM to go just as fast.

 

Torque = Motion

HP = Sustaining that Motion

 

Without proper Torque to get moving it does not matter how much HP you have if you cannot get moving quickly, but like I said, having driven my share of Italin auto's I also respect people who like to rev the engine and hear it before actually moving.

 

In response to your OHV versus DOHC V8's, I am NOT a fan of DOHC engines in any size. They are Bloated Fat Pigs that make HP with little Torque. Did Cadillac build a DOHC engine? Yes the Northstar and while a nice engine it was far heavier than needed and no real gains over a quality built DI Pushrod V8.

 

Plenty of Evidence has been given to show that we do not have to build Bloated Fat 4, 6, 8 or any size engines and Turbo's have their pro's and con's.

 

Dwightlooi who started this thread has intelligently shown that we can achieve all the same things in traditional Pushrod engines, yet marketing has twisted the public's perception as such, DOHC Turbo engines will become more common, but not because they are a superior engine.  IMHO

 

Hope you all have a great weekend.

MR. DFELT

 

Ive used your above post on another site to prove a point.

I feel like you expressed the feelings that I have excellently about a similar subject regarding self loathing Americans that prefer to see the American car industry destroyed over foreign ones.

I hope you dont mind?

No problem, thank you for checking with me.

[oldshurst442]

at  MPOWER

 

Im not upset. Its is you that is upset because it is you that has taken the time to denounce pushrod engines. It seems it is you that  wants to eradicate pushrods from the face of the earth just because you have a certain driving style and pushrods and loads of torque is against all that you believe in. It seems like you are the intolerant one.

 

Have you noticed that I never said a word about DOHC engines?

You have no idea how I feel about DOHC engines....just your preconcieved notions and biases against muscle cars and muscle car type guys...

 

You know what is great about engineering?

Its because there is ALWAYS more than one way to solve a problem.

 

You knoiw what is great about engineers?

Its that engineers are a tenacious bunch. They WILL find the solutions necessary...

 

And you know what is great about being a car guy?

Is that you RESPECT all car philosophies and how engineers answer the same performance equation while getting the same answer using a different solution...

 

About superchargers and pushrod OHV engines and them being big and cumbersome compared to DOCH turbo V8s...

 

Dont tell that to Chevy engineers  with their LS-9...

Dont tell that to the thousands of hot rodders who swap the original engines of different cars...Porsche 911s, Nissan Sylvias, even Miatas and Toyobaru FRS-BRZs with Chevy`s LS engines...and some of these are supercharged...

 

More détails then this..I cant give you...as I aint an engineer....but I do know one thing...that Chevy`s LS V8 engines... are just about as compact as one could get for V8s...and as for turbos...when you already start with a compact package...as compared to a hugely displaced DOCH V8 which ois bigger in every way as compared to a Chevy LS V8...and DOCH V8 from any manufacturer...your assumptions might be just that...assumptions...

 

PS:

You still dont know how I feel about DOCH V8s....I wouldnt make an opinion about how I feel about them if I were you...because stating that Chevy LS V8s are a smaller package thyan DOCH V8s is just facts...

Edited August 8, 2015 by oldshurst442

[oldshurst442]

at MR. DFELT.

Thank-you for thanking me.

 

[Guest Wings4Life(BANNED)]

Pushrod engines have their limitations, and their advantages.  There are engineered trade-offs like anything else. One of the key advantages that GM has shown repeatedly, is package space.  GM has taken their latest V8 engine and utilized more displacement in the same space as smaller DOHC engines.  Absolutely nothing wrong with that.  Additionally, that small package allows for even more power through supercharging.  So speaking in terms of efficiency as an air pump, yes, 1 valve will never have the same amount of airflow as 2.  Simple physics. But if you up size the bore, hence allowing a bigger valve, you quickly make up SOME lost ground. And in terms of BSFC, bigger displacement will ALWAYS require more fuel, all else being equal.  Pushrod allows you easy cyl deactivation to make up some of that larger displacement inefficiency, but I have been actively involved with several technologies that will bring deactivation to DOHC engines very, very soon.  Stay tuned on that.

 

 

A friend I know on a first name basis in Michigan, builds mopar engines exclusively and is well respected in the mopar community. His link is below.  His latest generation of small block mopars are built to make huge gains in power, but more importantly, in a very street friendly level that maintains good vacuum and driving manners. And of course with pushrod technology.  He will take your 340ci engine and produce 450 hp and similar torque.  He will stroke it to about 408ci and make 560 plus hp with even more torque.  These engines cost about $8-10K and are far less than a modern crate motor costing far more.  

 

http://www.mrlperformance.com/

[oldshurst442]

Pushrod engines have their limitations, and their advantages.  There are engineered trade-offs like anything else. One of the key advantages that GM has shown repeatedly, is package space.  GM has taken their latest V8 engine and utilized more displacement in the same space as smaller DOHC engines.  Absolutely nothing wrong with that.  Additionally, that small package allows for even more power through supercharging.  So speaking in terms of efficiency as an air pump, yes, 1 valve will never have the same amount of airflow as 2.  Simple physics. But if you up size the bore, hence allowing a bigger valve, you quickly make up SOME lost ground. And in terms of BSFC, bigger displacement will ALWAYS require more fuel, all else being equal.  Pushrod allows you easy cyl deactivation to make up some of that larger displacement inefficiency, but I have been actively involved with several technologies that will bring deactivation to DOHC engines very, very soon.  Stay tuned on that.

 

 

A friend I know on a first name basis in Michigan, builds mopar engines exclusively and is well respected in the mopar community. His link is below.  His latest generation of small block mopars are built to make huge gains in power, but more importantly, in a very street friendly level that maintains good vacuum and driving manners. And of course with pushrod technology.  He will take your 340ci engine and produce 450 hp and similar torque.  He will stroke it to about 408ci and make 560 plus hp with even more torque.  These engines cost about $8-10K and are far less than a modern crate motor costing far more.  

 

http://www.mrlperformance.com/

Thanx Wings for that post.

This is what I enjoy.

Not the lame fanboyism.

 

This is what I always knew about you.

That you are quite knowledgeable about automobiles, engines and stuff.

This is what I want to read from you.

Again. Thanx. I appreciated your input.

[Guest Wings4Life(BANNED)]

You are welcome olds.  I love talking shop, and happy to do it all day long.

[Drew Dowdell]

You say you're not feeling torque when you drive, you're feeling horsepower...... that makes zero sense.

 

 

Horsepower is just a measurement of torque.

(torque * RPM)/5252.  

 

An engine capable of producing 300 lb-ft at 1500 RPM is delivering just 85 horsepower at that same RPM

An engine that must turn 3,000 rpm to produce that same 300 lb-ft is delivering 171 horsepower at 3,000 rpm.

 

So which one delivered more power at their respective RPM?  Neither, they both produce the same 300 lb-ft.  One engine just takes twice the number of revolutions to do it and made a bunch more noise.

 

I rarely ever look at horsepower numbers anymore because they are too subject to manipulation (see the 3.0DOHC V6 from GM that only produced its stated maximum horsepower at red-line, which was never reached due to the transmission shifting before that point).

 

Give me as much torque as possible, as far down in the RPM band as possible (or over a range that begins low in the RPM band, such as in Turbo-DI engines). 

[Guest Wings4Life(BANNED)]

Well, to a point Drew.  Torque is good, but torque and hp is really what you want.  

 

Drive any 3.8L around town and it feels like a big motor pulling you from stand still.  Another advantage of OHV engines.  But on the highway, it feels flat and under powered, due to it's low hp peak. It was a relatively large V6 engine with a cam biased down low for torque.  There are aftermarket cams that bring it to life higher in the rpm range.  

[El Kabong]

You say you're not feeling torque when you drive, you're feeling horsepower...... that makes zero sense.

 

 

Horsepower is just a measurement of torque.

(torque * RPM)/5252.  

 

An engine capable of producing 300 lb-ft at 1500 RPM is delivering just 85 horsepower at that same RPM

An engine that must turn 3,000 rpm to produce that same 300 lb-ft is delivering 171 horsepower at 3,000 rpm.

 

So which one delivered more power at their respective RPM?  Neither, they both produce the same 300 lb-ft.  One engine just takes twice the number of revolutions to do it and made a bunch more noise.

 

I rarely ever look at horsepower numbers anymore because they are too subject to manipulation (see the 3.0DOHC V6 from GM that only produced its stated maximum horsepower at red-line, which was never reached due to the transmission shifting before that point).

 

Give me as much torque as possible, as far down in the RPM band as possible (or over a range that begins low in the RPM band, such as in Turbo-DI engines).

Indeed.

Just did a 2,000km-range run in the Ram. Through mountains, cities, and highways, it averaged 25.6mpg.

[Drew Dowdell]

Well, to a point Drew.  Torque is good, but torque and hp is really what you want.  

 

Drive any 3.8L around town and it feels like a big motor pulling you from stand still.  Another advantage of OHV engines.  But on the highway, it feels flat and under powered, due to it's low hp peak. It was a relatively large V6 engine with a cam biased down low for torque.  There are aftermarket cams that bring it to life higher in the rpm range.  

 

That was at least partially the result of the gearing. Off the top of my head, I don't think the 3800 was paired with anything but a GM 4-speed automatic. 4th gear was too tall and 3rd gear was too short... when you needed more power and a downshift, the transmission was forced to take the engine out of its comfort zone.

 

The 3900s paired with a 6-speed manual wouldn't feel the same..... so it's not a matter of just the valvetrain layout. 

[Guest Wings4Life(BANNED)]

 

Well, to a point Drew.  Torque is good, but torque and hp is really what you want.  

 

Drive any 3.8L around town and it feels like a big motor pulling you from stand still.  Another advantage of OHV engines.  But on the highway, it feels flat and under powered, due to it's low hp peak. It was a relatively large V6 engine with a cam biased down low for torque.  There are aftermarket cams that bring it to life higher in the rpm range.  

 

That was at least partially the result of the gearing. Off the top of my head, I don't think the 3800 was paired with anything but a GM 4-speed automatic. 4th gear was too tall and 3rd gear was too short... when you needed more power and a downshift, the transmission was forced to take the engine out of its comfort zone.

 

The 3900s paired with a 6-speed manual wouldn't feel the same..... so it's not a matter of just the valvetrain layout. 

 

 

Well, they did make a lot of improvements to the 3.9L.  But at dang near 4.0L, it was still low in HP and although I have not driven one, I would bet it still feels a bit lacking at highway speeds, regardless of gear count, because of the low hp. Especially when compared to GM's own smaller 3.6L, at far more hp.

 

My point again, adequate hp and torque is what would satisfy most, not just torque.  

Edited August 10, 2015 by Wings4Life

[El Kabong]

Sales numbers in certain segments where torque is of utmost importance would not tend to back up your claim.

The demands of customers are not always objective and in many cases where they are, the objectivity tends to be in unexpected areas, and thus manifest itself in unexpected ways.

If life were always a racing grid, then most road cars would be endurance racers. Today, the most successful of those offer big torque, often through hybrid or diesel power. Even Formula 1 racers are (high-strung, granted) hybrids these days. So even for the enthusiast, torque typically looms large in their preferences. Hence, the popularity of GM and Mopar V8 engines.

Edited August 10, 2015 by El Kabong

[Drew Dowdell]

 

 

Well, to a point Drew.  Torque is good, but torque and hp is really what you want.  

 

Drive any 3.8L around town and it feels like a big motor pulling you from stand still.  Another advantage of OHV engines.  But on the highway, it feels flat and under powered, due to it's low hp peak. It was a relatively large V6 engine with a cam biased down low for torque.  There are aftermarket cams that bring it to life higher in the rpm range.  

 

That was at least partially the result of the gearing. Off the top of my head, I don't think the 3800 was paired with anything but a GM 4-speed automatic. 4th gear was too tall and 3rd gear was too short... when you needed more power and a downshift, the transmission was forced to take the engine out of its comfort zone.

 

The 3900s paired with a 6-speed manual wouldn't feel the same..... so it's not a matter of just the valvetrain layout. 

 

 

Well, they did make a lot of improvements to the 3.9L.  But at dang near 4.0L, it was still low in HP and although I have not driven one, I would bet it still feels a bit lacking at highway speeds, regardless of gear count, because of the low hp. Especially when compared to GM's own smaller 3.6L, at far more hp.

 

My point again, adequate hp and torque is what would satisfy most, not just torque.  

 

 

 

No. You're getting into Horsepower Per Liter which is a false metric... and is in fact the very opposite of the ideal.  

 

The 3.9 liter is physically much smaller and lighter than the 3.6 DOHC.  Also, in 2006 when the 3.9 came out, the 3.6 was not producing vastly more horsepower.  It was rated at 255hp and 252 ft-lb at 3100 rpm.  The 3.9 liter produced 240 horsepower and 240 lb-ft of torque with at least 90% of the torque available from 1500 rpm to 5500 rpm.  So the 3.6 was not "vastly more powerful", though it was later capable of it.

 

The 3900 was more of a replacement for smaller, peakier, DOHC V6es of the day.  Basically, a 3900 from GM was roughly equivalent to a 3.0 DOHC from Toyota or a 3.2 liter SOHC from Honda from the same era in output, yet it was lighter, less complex, and had a broader torque curve.

 

 I've had 3900s on long trips and they could return fantastic fuel economy. They were also incredibly smooth.... one time I had left the shifter in 3rd gear by accident (a quirk of the Lucerne's shifter gate) and drove for 20 miles before realizing anything was amiss.  The Malibu with a 3500 could get better highway MPG than a Toyota 4-cylinder simply because the 3500 didn't have to work as hard to maintain speed. 

 

But people looking at horsepower per liter as if it mattered killed those excellent pushrod V6s. 

 

All of this changed with small displacement, turbo-charged, direct injected engines like the Ecoboost... but back then, there was only one in the mainstream market - The GM LNF 2.0T.

 

 

 

My point again, adequate hp and torque is what would satisfy most, not just torque.  

 

My point again... HP is just a measurement of torque at a certain RPM..... HP cannot exist without torque, so just skip a step and measure the torque.   If the car has satisfying torque, HP is irrelevant. 

[Guest Wings4Life(BANNED)]

Drew,

We really are saying the same thing in total.  I have already discussed the benefits of package space earlier with OHV and how they use it to their benefit in their V8 line.  But GM chose a path for their car/CUV V6 engine line that uses DOHC, and they chose it wisely.  Because the OVERALL trade-offs directed them that way.  Better emissions, fuel economy, horsepower, NVH, etc.  We can debate all day about individual metrics for either case, but again, overall is the keyword.  Yeah, there are many great things to say about the 3.8L and 3.9L.  But the segment could not benefit overall.  Trucks is a different matter, that loves the torque, sure.  That is why they stayed with big displacement OHV V6 engines. 

 

And although GM should not switch all V8’s to DOHC, it certainly would not hurt them to offer one.  They really are at or near a brick wall when it comes to V8 hp for NA engines.  Their latest LT1 is a marvelous engine producing great torque and hp.  But take away the exotic CNC machining  for their entire head, and the costly components to handle more rpms to get to that 460hp, and you are left with a pretty good V8 for its displacement.  This engine is not cheap to make or sell.  So what is left?  Where else can they go?  Torque is good, but hp is what it is.  To get more hp, you need that rpm factor, combined with more airflow.  IT’s that simple, no way around it in an NA engine.  And with only one valve doing it’s best flow ever in the history of GM V8 engines, will fall short of 2 valves with more area, pushing another 1000rpm’s.  That is where DOHC engines shine, plain and simple.  Oh, and NVH is pretty darn good too.

[El Kabong]

Nice font doesn't improve your argument.

[Drew Dowdell]

I have never had an issue with the NVH in the modern pushrod engines.  As I mentioned, I drove for 20 miles with one in 3rd gear and never noticed anything until the fuel economy instant readout seemed relatively low.

 

The OHV V6s could out-MPG 4-cylinder DOHC units from Toyota... and in 2007 the 3900 could produce highway fuel economy with a 4-speed auto nearly equal to the current PentaStar + 8-Speed of today.  The 3800 was the first V6 to be ULEV certified and the 3500/3900 engines had VVT to improve emissions further.

 

GM is not anywhere near a brick wall on their V8s.  Due to the relatively small packaging of the pushrod V8s, they can simply increase the displacement. That's what the 6.3 is for... and they can go all the way to at least 7.0 if they need to.   And that 7.0 will fit in the same or less space than a 5.0 DOHC.    

 

Probably the best comparison to make is the new GM 4.3 Ecotec3 V6 Silverado verse the GM 3.6 DOHC Colorado.  Fuel economy is roughly the same (when adjusting for the heavier, squarer vehicle the Silverado is), Torque in the 4.3 is a good bit higher, but that is mostly tuning.  And yet the 4.3 is physically smaller and lighter than the 3.6. 

 

Wherever you can put a DOHC engine, I can fit a pushrod engine with 50% more displacement.   Every time I see a car with a 3.6 liter DOHC V6 in it... there is a little voice in the back of my head saying "You know, a 5.3 V8 would fit there with space left over...."

 

GM has already done it.

 

[Guest Wings4Life(BANNED)]

Nice font doesn't improve your argument.

 

Any thoughts on the subject matter, by the font police?

Did not think so.

[Guest Wings4Life(BANNED)]

I have never had an issue with the NVH in the modern pushrod engines.  As I mentioned, I drove for 20 miles with one in 3rd gear and never noticed anything until the fuel economy instant readout seemed relatively low.

 

The OHV V6s could out-MPG 4-cylinder DOHC units from Toyota... and in 2007 the 3900 could produce highway fuel economy with a 4-speed auto nearly equal to the current PentaStar + 8-Speed of today.  The 3800 was the first V6 to be ULEV certified and the 3500/3900 engines had VVT to improve emissions further.

 

GM is not anywhere near a brick wall on their V8s.  Due to the relatively small packaging of the pushrod V8s, they can simply increase the displacement. That's what the 6.3 is for... and they can go all the way to at least 7.0 if they need to.   And that 7.0 will fit in the same or less space than a 5.0 DOHC.    

 

Probably the best comparison to make is the new GM 4.3 Ecotec3 V6 Silverado verse the GM 3.6 DOHC Colorado.  Fuel economy is roughly the same (when adjusting for the heavier, squarer vehicle the Silverado is), Torque in the 4.3 is a good bit higher, but that is mostly tuning.  And yet the 4.3 is physically smaller and lighter than the 3.6. 

 

Wherever you can put a DOHC engine, I can fit a pushrod engine with 50% more displacement.   Every time I see a car with a 3.6 liter DOHC V6 in it... there is a little voice in the back of my head saying "You know, a 5.3 V8 would fit there with space left over...."

 

GM has already done it.

 

2008_chevrolet_impala_ss-pic-7483606246714910937.jpeg

 

 

So then GM made a mistake by switching to DOHC for their sedan/CUV line?

 

Anyway, more displacement can be had by anyone, but in terms of making the air pump more efficient, they are pretty tight against that wall.  We know this because of how hard they worked for to get more power out of the LT1, mostly using old hot rodders tricks for more airflow (CNC'n ports and chamber) and a stout bottom end that can handle a few hundred more rpms.  And there is little by way of technology to change that any time soon.   I am in the business deep enough, and an avid hot rodder, to know this mjuch anyway.

 

And yeah, Ford was able to get a heck of a lot of power out of only 5.2L, but you will never see an OHV engine with a FP crank, because OHV is restricted to much fewer rpms.

Edited August 10, 2015 by Wings4Life

[Drew Dowdell]

And GM chose the DOHC route to silence critics like yourself and SMK who think HP per Liter is important.  

 

It is all marketing and all of the manufacturers doing it.  Horsepower is an easy number to fudge since it is only measured at the peak. In the case of naturally aspirated engines, simply spin the engine fast enough and you'll make the horsepower the marketing department wants.... but us end-users rarely see that horsepower because it is so high up in the RPM band.

 

Ford 3.7 liter DOHC - 305 hp at 6500 rpm (F-150)

GM 3.6 liter DOHC - 305 hp at 6800 rpm (Colorado)

Chrysler 3.6 liter Pentastar - 305 hp at 6350 rpm (Ram 1500)

 

In all of the above cases, you'll never see that horsepower because the transmission will shift before you even get there. 

 

Now in that same space, if I'm not at all concerned about valvetrain layout.... I can fit a pushrod V8.

 

GM 5.3 liter Ecotec3 - 355 hp at 5600 rpm (Silverado)  OR 376 hp at 5600 rpm if running E85

Chrysler 5.7 liter Hemi - 395 hp at 5600 rpm (Ram 1500)

 

So if you only have so much engine bay to fill... would you pick from the 3.6 liters or the 5.x liters above?

 

What if you're looking for a small, lightweight engine for a sedan?  Perhaps a Buick Lacross or Cadillac XTS... both of which have received complaints about soft low end torque..

 

GM 4.3 V6 Ecotec3 - 305 lb-ft @ 5300rpm 

 

GM 3.6 V6 DOHC - 264 lb-ft @ 5200 rpm 

 

 

Between these two engines, at no point in the RPM band does the 3.6 exceed the 4.3 in torque.  Given that the 4.3 is physically smaller than the 3.6, which of these would you choose?

 

Turbo charging brings in a new variable, but we haven't seen a turbo-pushrod since the 1990 Pontiac Grand Prix McLaren.  A turbo-DI 4.3 V6 would be awesome.

[El Kabong]

Nice font doesn't improve your argument.

 

Any thoughts on the subject matter, by the font police?

Did not think so.

No, Drew is doing a great job. Im just reading this because it's entertaining, not a clandestine PR war.

Sorry to burst you bubble on that and all

[Guest Wings4Life(BANNED)]

Yup, did not think so.

 

 

If and when you have something to add to the subject, rather than one of the commentors, we would love to hear it.

Edited August 10, 2015 by Wings4Life

[Drew Dowdell]

 

I have never had an issue with the NVH in the modern pushrod engines.  As I mentioned, I drove for 20 miles with one in 3rd gear and never noticed anything until the fuel economy instant readout seemed relatively low.

 

The OHV V6s could out-MPG 4-cylinder DOHC units from Toyota... and in 2007 the 3900 could produce highway fuel economy with a 4-speed auto nearly equal to the current PentaStar + 8-Speed of today.  The 3800 was the first V6 to be ULEV certified and the 3500/3900 engines had VVT to improve emissions further.

 

GM is not anywhere near a brick wall on their V8s.  Due to the relatively small packaging of the pushrod V8s, they can simply increase the displacement. That's what the 6.3 is for... and they can go all the way to at least 7.0 if they need to.   And that 7.0 will fit in the same or less space than a 5.0 DOHC.    

 

Probably the best comparison to make is the new GM 4.3 Ecotec3 V6 Silverado verse the GM 3.6 DOHC Colorado.  Fuel economy is roughly the same (when adjusting for the heavier, squarer vehicle the Silverado is), Torque in the 4.3 is a good bit higher, but that is mostly tuning.  And yet the 4.3 is physically smaller and lighter than the 3.6. 

 

Wherever you can put a DOHC engine, I can fit a pushrod engine with 50% more displacement.   Every time I see a car with a 3.6 liter DOHC V6 in it... there is a little voice in the back of my head saying "You know, a 5.3 V8 would fit there with space left over...."

 

GM has already done it.

 

2008_chevrolet_impala_ss-pic-7483606246714910937.jpeg

 

 

So then GM made a mistake by switching to DOHC for their sedan/CUV line?

 

Anyway, more displacement can be had by anyone, but in terms of making the air pump more efficient, they are pretty tight against that wall.  We know this because of how hard they worked for to get more power out of the LT1, mostly using old hot rodders tricks for more airflow (CNC'n ports and chamber) and a stout bottom end that can handle a few hundred more rpms.  And there is little by way of technology to change that any time soon.   I am in the business deep enough, and an avid hot rodder, to know this mjuch anyway.

 

And yeah, Ford was able to get a heck of a lot of power out of only 5.2L, but you will never see an OHV engine with a FP crank, because OHV is restricted to much fewer rpms.

 

 

The limit of flow is a design choice.  Multi-valve pushrod engine designs do exist and there is no reason they could not be included in modern engine designs.

 

But the point that I'm apparently failing to make is that pushrod engines offer more usable power rather than the marketed power of DOHC designs.   Who cares if your DOHC engine is rated to 300 horsepower if the transmission will never let you see that RPM?

 

I have 160hp in my Honda CR-V, but I only get that if I rev the thing up to 6,000 rpm.... and trust me, it really doesn't like it.  My Buick Encore has 138hp at 4900 rpm, but I also have 148 lb-ft of torque at 1800 rpm to 5,000 rpm.  Though it has lower horsepower, the Encore actually feels quicker. 

[El Kabong]

Yup, did not think so.

 

 

If and when you have something to add to the subject, rather than one of the commentors, we would love to hear it.

I already posted my thoughts on he issue. I cannot help it you lack the cojones to respond to them.

[David]

It is freakin amazing the info on the new LT4 V8 engine. Superior to just about anything I have seen that is V8 DOHC.

 

http://media.chevrolet.com/media/us/en/chevrolet/news.detail.html/content/Pages/news/us/en/2014/Aug/0820-8speed/0820-compact-powerhouse.html

 

 

Interesting to see this comparison to other supercars.

 

 

Weird but hard to find a comparison chart to Ferrari's. This is the only one I could find for a 2000 F1

 

[El Kabong]

Yup. Superior engineering. It's little wonder GM is riding high in Detroit these days.

[Guest Wings4Life(BANNED)]

Sorry drew, I am not a critic of OHV, and in fact highlighted it's benefits here.  But I can speak openly and honestly about the pro/cons having designed both myself. 

 

But, these valve train architecture benefits/downsides can be very application specific.  A NA DOHC V6 will in fact offer more overall benefits than an OHV, as  I mentioned earlier -  and like I also mentioned, several noted metrics or benefits of one or two does not equal OVERALL.  And I sure hope GM is smart enough to have learned this, rather than just made some mistake and cave in to critics.  If not, they are doomed as an organization.

[Drew Dowdell]

Sorry drew, I am not a critic of OHV, and in fact highlighted it's benefits here.  But I can speak openly and honestly about the pro/cons having designed both myself. 

 

But, these valve train architecture benefits/downsides can be very application specific.  A NA DOHC V6 will in fact offer more overall benefits than an OHV, as  I mentioned earlier -  and like I also mentioned, several noted metrics or benefits of one or two does not equal OVERALL.  And I sure hope GM is smart enough to have learned this, rather than just made some mistake and cave in to critics.  If not, they are doomed as an organization.

 

At the same displacement, yes.  However, a NA OHV engine can be much larger and deliver more usable power than a DOHC engine of the same exterior packaging. 

 

It has been shown over and over again that marketing is more important than performance results.   If moving to DOHC gets GM more sales due to marketability, then of course they should make that move... even if OHV engines would actually serve the customer better.  GM is in the business to make money, and unfortunately, that means keeping HP/L whiners happy.  (sometimes I really hate the automotive media, they have the majority of the responsibility on this issue)

[El Kabong]

an additional thing to consider in the pushrod debate is the age of the pushrod designs in question. In GM's case their pushrod V6 engines are very old designs, and they certainly didn't have development cash spent on them like the smallblock did (with the possible exception of the current EcoTec3 4.3). Doubtless a stricter NVH regimen would produce a more refined cam-in-block design.

For passenger vehicles, external displacement trumps internal displacement, especially for packaging purposes. The LT4 is essentially a 650hp cube. Short of a battery pack it's about as user-friendly a shape as you can give a designer or engineer to plunk in a vehicle.

And yes: PR fluff can be evil.

[Guest Wings4Life(BANNED)]

 

Sorry drew, I am not a critic of OHV, and in fact highlighted it's benefits here.  But I can speak openly and honestly about the pro/cons having designed both myself. 

 

But, these valve train architecture benefits/downsides can be very application specific.  A NA DOHC V6 will in fact offer more overall benefits than an OHV, as  I mentioned earlier -  and like I also mentioned, several noted metrics or benefits of one or two does not equal OVERALL.  And I sure hope GM is smart enough to have learned this, rather than just made some mistake and cave in to critics.  If not, they are doomed as an organization.

 

At the same displacement, yes.  However, a NA OHV engine can be much larger and deliver more usable power than a DOHC engine of the same exterior packaging. 

 

It has been shown over and over again that marketing is more important than performance results.   If moving to DOHC gets GM more sales due to marketability, then of course they should make that move... even if OHV engines would actually serve the customer better.  GM is in the business to make money, and unfortunately, that means keeping HP/L whiners happy.  (sometimes I really hate the automotive media, they have the majority of the responsibility on this issue)

 

 

 

usable power is a subjective metric, or at least, an application specific one.

 

And upsizing can be done by anyone.

There is no reason why a 5.0L coyote valve train can't fit on a 6.0L.

[El Kabong]

If usable power is a subjective measure, then why the concern over hp/L, which is objective?

[Drew Dowdell]

an additional thing to consider in the pushrod debate is the age of the pushrod designs in question. In GM's case their pushrod V6 engines are very old designs, and they certainly didn't have development cash spent on them like the smallblock did (with the possible exception of the current EcoTec3 4.3). Doubtless a stricter NVH regimen would produce a more refined cam-in-block design.

For passenger vehicles, external displacement trumps internal displacement, especially for packaging purposes. The LT4 is essentially a 650hp cube. Short of a battery pack it's about as user-friendly a shape as you can give a designer or engineer to plunk in a vehicle.

And yes: PR fluff can be evil.

 

You may be thinking of the 3800 as an old design.  The 3500/3900 were not and they didn't have NVH issues like was said about the 3800.   

 

The 3800 was a 90 degree V6 and always had a bit of a balance issue.

The 3500/3900 were new 60 degree V6es with variable valve timing, variable intake manifold runners, variable displacement (Impala only)

[El Kabong]

an additional thing to consider in the pushrod debate is the age of the pushrod designs in question. In GM's case their pushrod V6 engines are very old designs, and they certainly didn't have development cash spent on them like the smallblock did (with the possible exception of the current EcoTec3 4.3). Doubtless a stricter NVH regimen would produce a more refined cam-in-block design.

For passenger vehicles, external displacement trumps internal displacement, especially for packaging purposes. The LT4 is essentially a 650hp cube. Short of a battery pack it's about as user-friendly a shape as you can give a designer or engineer to plunk in a vehicle.

And yes: PR fluff can be evil.

 

You may be thinking of the 3800 as an old design.  The 3500/3900 were not and they didn't have NVH issues like was said about the 3800.   

 

The 3800 was a 90 degree V6 and always had a bit of a balance issue.

The 3500/3900 were new 60 degree V6es with variable valve timing, variable intake manifold runners, variable displacement (Impala only)

Having owned a 3500 in my G6 and helped bolt a goodly number of 3800s and 3900s in Impalas, there was still enough of the old 2.8 in there to make me nervous. Despite the NVH issues apparent in a 90-degree V6, I still preferred the old 3.8.

Ultimately, the clean-sheet 3.6 was the better way to go, but primarily because it was a clean sheet, not necessarily because of the valvetrain.

[Drew Dowdell]

 

 

Sorry drew, I am not a critic of OHV, and in fact highlighted it's benefits here.  But I can speak openly and honestly about the pro/cons having designed both myself. 

 

But, these valve train architecture benefits/downsides can be very application specific.  A NA DOHC V6 will in fact offer more overall benefits than an OHV, as  I mentioned earlier -  and like I also mentioned, several noted metrics or benefits of one or two does not equal OVERALL.  And I sure hope GM is smart enough to have learned this, rather than just made some mistake and cave in to critics.  If not, they are doomed as an organization.

 

At the same displacement, yes.  However, a NA OHV engine can be much larger and deliver more usable power than a DOHC engine of the same exterior packaging. 

 

It has been shown over and over again that marketing is more important than performance results.   If moving to DOHC gets GM more sales due to marketability, then of course they should make that move... even if OHV engines would actually serve the customer better.  GM is in the business to make money, and unfortunately, that means keeping HP/L whiners happy.  (sometimes I really hate the automotive media, they have the majority of the responsibility on this issue)

 

 

 

usable power is a subjective metric, or at least, an application specific one.

 

And upsizing can be done by anyone.

There is no reason why a 5.0L coyote valve train can't fit on a 6.0L.

 

 

No it isn't.  If the transmission forces an upshift at 6,000 rpm but the engine peak horsepower isn't until 6500 rpm.... you are OBJECTIVELY not getting the horsepower that the car is marketed at.

 

But if I get my peak horsepower and torque down low, say around 4000 rpm, and the transmission still doesn't shift until 6,000 rpm, I get everything I paid for.

 

 

You realize that if usable power was purely subjective there would be no reason for Ecoboost to exist. Ecoboost only exists as a replacement for displacement now that pushrod V6es are out of fashion. Ecoboost allows the feel of a big displacement V6 out of a small displacement I4, or a big displacement V8 out of a small displacement V6.   The very existence of Ecoboost crushes your argument that horsepower is more important than low end torque.

 

Anywhere you can put a 6.0 DOHC, I can fit a 9 liter pushrod.. or an 8.5 liter with a super charger on top.  You can't get around the fact that DOHC engine just take up way more space than pushrod engines.

[El Kabong]

Drew... you're wasting your time.

Really. He's explicitly said that he's here for PR. It's sad, but it is what it is.

[Guest Wings4Life(BANNED)]

 

 

 

Sorry drew, I am not a critic of OHV, and in fact highlighted it's benefits here.  But I can speak openly and honestly about the pro/cons having designed both myself. 

 

But, these valve train architecture benefits/downsides can be very application specific.  A NA DOHC V6 will in fact offer more overall benefits than an OHV, as  I mentioned earlier -  and like I also mentioned, several noted metrics or benefits of one or two does not equal OVERALL.  And I sure hope GM is smart enough to have learned this, rather than just made some mistake and cave in to critics.  If not, they are doomed as an organization.

 

At the same displacement, yes.  However, a NA OHV engine can be much larger and deliver more usable power than a DOHC engine of the same exterior packaging. 

 

It has been shown over and over again that marketing is more important than performance results.   If moving to DOHC gets GM more sales due to marketability, then of course they should make that move... even if OHV engines would actually serve the customer better.  GM is in the business to make money, and unfortunately, that means keeping HP/L whiners happy.  (sometimes I really hate the automotive media, they have the majority of the responsibility on this issue)

 

 

 

usable power is a subjective metric, or at least, an application specific one.

 

And upsizing can be done by anyone.

There is no reason why a 5.0L coyote valve train can't fit on a 6.0L.

 

 

No it isn't.  If the transmission forces an upshift at 6,000 rpm but the engine peak horsepower isn't until 6500 rpm.... you are OBJECTIVELY not getting the horsepower that the car is marketed at.

 

But if I get my peak horsepower and torque down low, say around 4000 rpm, and the transmission still doesn't shift until 6,000 rpm, I get everything I paid for.

 

 

You realize that if usable power was purely subjective there would be no reason for Ecoboost to exist. Ecoboost only exists as a replacement for displacement now that pushrod V6es are out of fashion. Ecoboost allows the feel of a big displacement V6 out of a small displacement I4, or a big displacement V8 out of a small displacement V6.   The very existence of Ecoboost crushes your argument that horsepower is more important than low end torque.

 

Anywhere you can put a 6.0 DOHC, I can fit a 9 liter pushrod.. or an 8.5 liter with a super charger on top.  You can't get around the fact that DOHC engine just take up way more space than pushrod engines.

 

 

 

You keep missing my point entirely.

 

First of all, nobody is arguing that OHV packages more cubes than DOHC in the same space. I am just continueally remarking that both can be upsized. Please don'r revisit this argument.  And there is nothing wrong with an hp/displacement debate vs a hp/package displacement debate.  But more bore diameter carries with it disadvantages that need to be worked around, like increased BSFC and emissions....hence the need for more spark plugs etc.  All else being equal.  This is not an opinion, but engineered fact.  And I fully recognize that GM has evolved it to minimize the negatives, but the fact remains.

 

And yes, sorry, where your usable power is in the power band is very, very subjective, and even more so....application specific.  Think torque down low for a truck, and high rpm power for a race car - and verying degrees in between, based on where a customer wants his car to come to life.. Forget shift points, those are merely calibrated to the cam, not the other way around. And yes, I recognize that both should be ideally calibrated together, in a perfect world.

Edited August 10, 2015 by Wings4Life

[Guest Wings4Life(BANNED)]

Drew... you're wasting your time.

Really. He's explicitly said that he's here for PR. It's sad, but it is what it is.

Dude, STFU!!!

You contribute nothing but anger and trolling and NPR.

 

Let the big boys talk about this classic engine discussion please.

[Drew Dowdell]

"First of all, nobody is arguing that OHV packages more cubes than DOHC in the same space. I am just continueally remarking that both can be upsized. Please don'r revisit this argument. "

 

 

Not if there is no more room to upsize.  In sedans, 3.6/3.7/3.8 seems to be the upper limit for DOHC engines.

 

We're not talking about race cars here.  We're talking about the every day cars that people drive.... the Ford Fusions, the Jeep Cherokees, the Honda Civics.  All of the cars that rarely crest 4,500 rpm on any given day.  Cars that are being sold with 250hp in big numbers and @ 6500rpm in tiny print at the bottom.   It's the Honda Civics that you have to wind up to get them to go. 

 

Everyone (except race car drivers, which we aren't talking about anyway) would do better with engines that made their torque at low RPM.  If that wasn't the case, Ecoboost wouldn't have a reason to exist.

[El Kabong]

Drew... you're wasting your time.

Really. He's explicitly said that he's here for PR. It's sad, but it is what it is.

Dude, STFU!!!

You contribute nothing but anger and trolling and NPR.

 

Let the big boys talk about this classic engine discussion please.

Drew is trying to reason with you. Everyone who is reading this knows it's you who's not getting it.

Seriously. You have made an absolute travesty of yourself today. Stop with the self-inflicted damage.

[El Kabong]

"First of all, nobody is arguing that OHV packages more cubes than DOHC in the same space. I am just continueally remarking that both can be upsized. Please don'r revisit this argument. "

 

Not if there is no more room to upsize.  In sedans, 3.6/3.7/3.8 seems to be the upper limit for DOHC engines.

 

We're not talking about race cars here.  We're talking about the every day cars that people drive.... the Ford Fusions, the Jeep Cherokees, the Honda Civics.  All of the cars that rarely crest 4,500 rpm on any given day.  Cars that are being sold with 250hp in big numbers and @ 6500rpm in tiny print at the bottom.   It's the Honda Civics that you have to wind up to get them to go. 

 

Everyone (except race car drivers, which we aren't talking about anyway) would do better with engines that made their torque at low RPM.  If that wasn't the case, Ecoboost wouldn't have a reason to exist.

Indeed. And even with Honda the message is sinking in. The Euro-Spec Civic now offers turbocharging in its top offering. VTEC just kicked out yo. Torque is where it's at, and pushrods are a great way to get it.