A Turbocharged V8 For The C7?

[William Maley]

A Turbocharged V8 For The C7?

William Maley - Editor/Reporter - CheersandGears.com

May 26, 2011

The rumor pile for the seventh generation Corvette has been growing over the past year. Rumors have ranged from the Corvette not being built in the Bowling Green plant to a mid-engine layout for the C7. Well, a new rumor has come in dealing with a possible new engine.

TheDetroitBureau.com is reporting that GM has approved a small displacement, turbocharged V8 engine for the Corvette. The engine is expected to be around three liters, use an overhead-cam setup, and dry sump oil system. Total horsepower is expected to be "in excess of 400 horsepower." The engine is also rumored to rev all the way up to 10,000 RPMs.

For those who think there is no replacement for displacement, the story says there will be a full lineup of engines, including the classic larger displacement engines.

We're not sure if this will come to fruition or if its just a rumor. The only things we know for sure is the C7 Corvette will aim at a different type of buyer and the C7 will be built in Bowling Green sometime within the next few years.

Source: TheDetroitBureau.com

[Robert Hall]

Cool...

[Northstar]

Wow, that would be really cool.

[Camino LS6]

I'd need to see the torque curve...

[hyperv6]

I'd need to see the torque curve...

Well if it is as good or better than my 2.0 Turbo you have no worries.

315 FT-LB from something like 2300-5100 RPM and 340 FT-LB in the Solstice. I would expect the V8 would be even greater torque and just as flat. Too many just don't understand most of todays Turbo DOHC engines have very flat torque curves with the advanced VVT and Scrolled turbos. I never has a V8 with as flat of a curve.

Here is the stock Eco Turbo curve. The upgrade is just the same just with more torque.

I am thinking this engine if proven true would provide Cadillac with just what they need. Technology is half the marketing in the performance Luxury market.

[dwightlooi]

Well, sparing the peculiarities of a specific motor, such a choice in lieu of a larger displacement Pushrod V8 will mean...

• More Weight
  
• Bigger Size
  
• Increased Complexity
  
• Higher Costs
  
• Inferior Performance
  
• No improvement in Fuel Economy
  

All in the name of appearing "high tech" to a subset of misinformed buyers.

Even if you baseline DOHC and 4-valves per cylinder, going to a very small V8 with turbocharging is dubious for two reasons... The first being that engines with small displacements and lots of cylinders are inefficient compared to one with fewer cylinders. The reason being that frictional losses are higher when you have 32 valves and 8 cylinders compared to 24 valves and 6 cylinders or 16 valves and 4 cylinders. This means they make less power and burn more fuel. The only reason racing engines are sometimes built that way is because of class regulations.

The second being that the main advantages of increased cylinder count with a small displacement is at odds with the basic tenets of turbocharging. The main advantage of a 8-cylinder 3.0 vs a 6-cylinder 3.0 is the ability to have each individual piston be smaller and lighter with each individual stroke being shorter. This allows for higher revs. A 3.0 V8 can reach 10,000~12,000 rpm. Sounds great if you like high reving engines, but when you throw turbos into the mix everything falls apart. Even the most advanced turbochargers of today can maintain a flat torque plateau of no more than 3500~4000 rpm. Hence, a very nice 2.0 turbo engine may reach maximum torque rating of say 250 lb-ft @ 1600~5600 rpm. The power peak usually arrives shortly there after... say 270hp @ 6000 rpm. If your engine revs to 10,000 rpm, you have a problem. For 10,000 rpms to be meaningful you'll probably want to have your powerpeak at 9,500~10,000 rpm. A turbocharger that supports flow rates that maintains your torque peak to 9000 rpm will not reach that peak until 5,000 rpm or so. This means that from idle to 4000 rpm you have no drivability to speak of. The compromise will be something like the McLaren MP4/12... 443 lb-ft @ 3000~7000, 592 hp @ 7000 rpm. If you do something like this it makes 10,000 rpm capability moot, which then makes the 3.0 V8 configuration moot.

[smk4565]

I like the turbo DOHC V8 idea, but I would go with something closer to 4 liters and not that high of a redline.

[Camino LS6]

I have serious reservations about the idea.

[Z-06]

Everything went fine till I saw a high revving V8 with a displacement of only 3 litres.

Another rumor wish-list for Corvette.

[William Maley]

Everything went fine till I saw a high revving V8 with a displacement of only 3 litres.

Another rumor wish-list for Corvette.

Yep..

[smk4565]

Those that have reservations can take comfort in the fact that an engine like this would be costly to develop and produce. Doing what is expensive and difficult isn't the way of GM. Plus Corvette sales are down, raising the price higher probably isn't going to help the Corvette recover, and the interior is the biggest short coming of the current car. To fix the interior and do an engine like this is going to drive the price up pretty high.

[riviera74]

Then GM should do an MCE and radically improve the interior. No need for a turbocharged 3L V8.

A 3L V8T is silly in that you could probably do better with a 4L V8. Remember the Oldsmobile Aurora 4L V8, which was a Northstar derivative? A Vette with a 4L V8 DOHC is fine for those who would want one instead of the traditional 350ci V8, if said DOHC was that good in getting 400HP and flat torque curves at the right levels.

[balthazar]

>>"Plus Corvette sales are down, raising the price higher probably isn't going to help the Corvette recover..."<<

Profit over volume.

[hyperv6]

Misinformed buyers =$$$$$

If done as stated where is the down side. If they would offer both engines who loses? Let the market decide what they want. If GM can offer an engine like this and pick up buyers who would not buy a pushrod engine I see it only as a positive.

GM has done well with the LS but lets face it there are many good reasons most others no longer make them other wise they would be more common outside pickup trucks.

At this point before I can condem any such plan if one were to happen I would have to see what they would build. To condem the unknow is short sighted. Just like many did with the Malibu and other cars that are ok once you see them.

Right now I see this as a positive and will neither fully endorse or condem this idea till we know more about it if it even happens at all.

Even if GM did this I could see them sharing this with someone like Lotus etc. Infact someone like Lotus may be involved in the development like they were on the Ecotec.

Either way GM needs to move forward and give the market want it wants. Most sports cars today are DOHC and that is what many buyer expect. If you keep pandering to the same crowd you cars will end up like Buick did with the old people image. If GM had moved Buick forward a long time ago they would not have had to rebuild their image.

Of late GM has had few disapointments and I am sure if they could not do this engine at the right price and with as good or better performance they would not do this. The Vette team has done well and it is time to just let them do what they do best and see what they really offer. They have done a lot with so little for so long the new money being invested may make things interesting in many areas on the future models.

One thing is for sure the changes will not stop at the loss of the pop up headlamp. Tradtions are fine to a point but even the best cars have to move forward.

Edited May 27, 2011 by hyperv6

[Z-06]

Those that have reservations can take comfort in the fact that an engine like this would be costly to develop and produce. Doing what is expensive and difficult isn't the way of GM. Plus Corvette sales are down, raising the price higher probably isn't going to help the Corvette recover, and the interior is the biggest short coming of the current car. To fix the interior and do an engine like this is going to drive the price up pretty high.

No doing something which is inefficient, heavy while being costly shouldn't be the way for GM. Reread dwight's post if you believe that he knows better about the engine science than anyone else on this board.

Yes, Malibu's price skyrocketed tremendously by fixing the interior.

[Camino LS6]

DOHC is of dubious value at best.

Bending to the will of the buyers that insist on it (all three of them), just doesn't make any sense whatsoever.

[Northstar]

If nothing else, the DOHC V8 developed for the C7 would be a good engine for Cadillac to use in their vehicles as well (ATS-V?)

Of course this assumes that it's even true. There are always so many wild rumors when a new Corvette is about to debut.

[dwightlooi]

DOHC is of dubious value at best.

Bending to the will of the buyers that insist on it (all three of them), just doesn't make any sense whatsoever.

I won't say that. The value of DOHC is substantial if the objective is to achieve the highest output from a given displacement. It does so in two ways... by allowing a larger valve-to-bore area ratio which improves breathing and by reducing the actuated valvetrain mass which permits higher RPMs allowing more power to be had from the same torque output. These are important attributes if you are governed by a certain displacement limit -- either by government tax regulations or by racing class rules. An additional benefit of getting the same power out of a smaller displacement engine -- assuming you have the same cylinder count -- is that the reciprocating mass is lower. This tend to result in better refinement in designs that are not completely balanced (eg. I3, I4, I5, V6 or V8), even if they make little or no difference in balanced layouts (eg. H4, H6, I6, V12).

Many common assumptions surrounding DOHC, however, simply aren't true. The most common being that DOHC engines being freer breathing have better fuel economy. This is largely false because DOHC engines actually have higher frictional losses due to their more numerous valve train parts, and volumetric efficiency (freer breathing) at cruise is an oxymoron because the engine is being artificially choked by the throttle body no matter how free breathing it otherwise is! Another common misconception is that DOHC is "higher" tech. This is incorrect both in today's technical reality and from a historical perspective. technically features like an aluminum or magnesium block, variable timing (independent or not), direct injection, cylinder shutoff, coil-per-plug ignition, returnless fuel systems, ionic knock sensing, hypereutectic pistons, you name it, can be implemented on both Pushrod and DOHC designs. Their incorporation or lack thereof makes an engine high tech or low tech, the Pushrod or DOHC layout has nothing to do with it. Historically, Pushrod designs were invented after DOHC designs, period. And of course there is the seemingly logical, but erroneous, assumption that because DOHC engines allow the same output to be attained with less displacement, they lead to smaller and lighter engines, when in fact the reverse is true and a 4 liter class DOHC V8 is typically just as heavy and sometimes heavier than a 6 liter class pushrod engine! DOHC engines are bulky and heavy because of their significantly fatter and taller DOHC heads, along with the packing of four times as many camshafts, sprockets and bearings, as well as twice as many valves and springs.

Edited May 27, 2011 by dwightlooi

[Camino LS6]

Like I said, dubious at best.

In the absence of artificial factors such as government regs or race rules, there is no advantage in the real world.

In the case of GM doing this, it would be nothing more than an example of "See, we can build one too".

What the hell is the use in that?

[dwightlooi]

If nothing else, the DOHC V8 developed for the C7 would be a good engine for Cadillac to use in their vehicles as well (ATS-V?)

Of course this assumes that it's even true. There are always so many wild rumors when a new Corvette is about to debut.

I think that if GM really wants a DOHC V8, the best avenue will we a 60 deg V8 created from addding two cylinders and a balance shaft to the 3.6 liter LFX DI V6 engine. Such an engine has numerous benefits over a new 90 deg DOHC V8 design. It will be considerably narrower, allowing it to fit into engine bays designed for the V6 or the Pushrod V8s (which may not accommodate a wide DOHC 90 deg V8. It can also be manufactured on the same production lines sharing most of the tooling with the high volume V6 engines. The 4.8 liter displacement is just about right and the projected output of 430 hp / 370 lb-ft on Regular 87 Octane is also plenty decent.

[regfootball]

perhaps this small v8 will help the corvette become more accepted in europe, and perhaps the motor can be shared with Lotus, etc. as you say.

there would be a good chance then that corvette may not even sell in some countries with a huge pushrod motor.

a tiny v8 as such would be quite compact. even with its DOHC headgear. perhaps a 3.0 displacement could avoid some taxes in some places.

Misinformed buyers =$$$

If done as stated where is the down side. If they would offer both engines who loses? Let the market decide what they want. If GM can offer an engine like this and pick up buyers who would not buy a pushrod engine I see it only as a positive.

GM has done well with the LS but lets face it there are many good reasons most others no longer make them other wise they would be more common outside pickup trucks.

At this point before I can condem any such plan if one were to happen I would have to see what they would build. To condem the unknow is short sighted. Just like many did with the Malibu and other cars that are ok once you see them.

Right now I see this as a positive and will neither fully endorse or condem this idea till we know more about it if it even happens at all.

Even if GM did this I could see them sharing this with someone like Lotus etc. Infact someone like Lotus may be involved in the development like they were on the Ecotec.

Either way GM needs to move forward and give the market want it wants. Most sports cars today are DOHC and that is what many buyer expect. If you keep pandering to the same crowd you cars will end up like Buick did with the old people image. If GM had moved Buick forward a long time ago they would not have had to rebuild their image.

Of late GM has had few disapointments and I am sure if they could not do this engine at the right price and with as good or better performance they would not do this. The Vette team has done well and it is time to just let them do what they do best and see what they really offer. They have done a lot with so little for so long the new money being invested may make things interesting in many areas on the future models.

One thing is for sure the changes will not stop at the loss of the pop up headlamp. Tradtions are fine to a point but even the best cars have to move forward.

[hyperv6]

perhaps this small v8 will help the corvette become more accepted in europe, and perhaps the motor can be shared with Lotus, etc. as you say.

there would be a good chance then that corvette may not even sell in some countries with a huge pushrod motor.

a tiny v8 as such would be quite compact. even with its DOHC headgear. perhaps a 3.0 displacement could avoid some taxes in some places.

Misinformed buyers =$$$

If done as stated where is the down side. If they would offer both engines who loses? Let the market decide what they want. If GM can offer an engine like this and pick up buyers who would not buy a pushrod engine I see it only as a positive.

GM has done well with the LS but lets face it there are many good reasons most others no longer make them other wise they would be more common outside pickup trucks.

At this point before I can condem any such plan if one were to happen I would have to see what they would build. To condem the unknow is short sighted. Just like many did with the Malibu and other cars that are ok once you see them.

Right now I see this as a positive and will neither fully endorse or condem this idea till we know more about it if it even happens at all.

Even if GM did this I could see them sharing this with someone like Lotus etc. Infact someone like Lotus may be involved in the development like they were on the Ecotec.

Either way GM needs to move forward and give the market want it wants. Most sports cars today are DOHC and that is what many buyer expect. If you keep pandering to the same crowd you cars will end up like Buick did with the old people image. If GM had moved Buick forward a long time ago they would not have had to rebuild their image.

Of late GM has had few disapointments and I am sure if they could not do this engine at the right price and with as good or better performance they would not do this. The Vette team has done well and it is time to just let them do what they do best and see what they really offer. They have done a lot with so little for so long the new money being invested may make things interesting in many areas on the future models.

One thing is for sure the changes will not stop at the loss of the pop up headlamp. Tradtions are fine to a point but even the best cars have to move forward.

My first thoughts were of Europe. This is just the kind of engine they love. While the Push Rod Vette has its fans in Europe it still has never sold as well as it could or should. To many over there it is still the plastic car made by fat men in Kentucky. They like their F1 and High Tech Engines.

Even in this country more and more of the younger generations grew up with higher tech engines. Most were smaller but that is what they are interested in. I deal with this at work and know there are a lot of people out there that feel the same about push rods as Camino feels about DOHC.

The Auto market has always been about adapt or die to what the market wants. That is part of what got GM in trouble as they tried to force what they wanted at times and not give what the customers wanted.

I see no issue on offering both engines and give all buyers what they want. Some act as if they do a DOHC that it is a threat to the Pushrod? I don't see that as it will be around in DI form for forseen future. Either way if there is a chance to offer an option on the Vetter of this engine and also offer it thorugh Cadillac it will only help sales and makreting with the younger buyers and Europe.

No matter number anyone can post and any claims of no need of DOHC these new engine are very able and are part of what will keep performance alive in the future. The new Mclaren M838T is putting out 600 HP with 80% of the torque available at 2,000 RPM with only 3.8 liters. It is enough to to give 0-60 times under 3 seconds and 0-124 in under 10 seconds. The Mclaren weighs in at 2866 pounds not alot less than the Vette and I would also expect the C7 and C8 to shed some pound too. The next two C 7-8 will only be better than what we have now.

If they were killing the Pushrod I could understand the crys but they saying here if true they both will be around. You would have your engine and others will have theirs what could be better?

We will get a better interior no matter the engine so that excuse is out.

[Z-06]

perhaps this small v8 will help the corvette become more accepted in europe, and perhaps the motor can be shared with Lotus, etc. as you say.

there would be a good chance then that corvette may not even sell in some countries with a huge pushrod motor.

a tiny v8 as such would be quite compact. even with its DOHC headgear. perhaps a 3.0 displacement could avoid some taxes in some places.

Do you actually read the other posts?

Well, sparing the peculiarities of a specific motor, such a choice in lieu of a larger displacement Pushrod V8 will mean...

• More Weight
  
• Bigger Size
  
• Increased Complexity
• Higher Costs
• Inferior Performance
• No improvement in Fuel Economy

All in the name of appearing "high tech" to a subset of misinformed buyers.

Even if you baseline DOHC and 4-valves per cylinder, going to a very small V8 with turbocharging is dubious for two reasons... The first being that engines with small displacements and lots of cylinders are inefficient compared to one with fewer cylinders. The reason being that frictional losses are higher when you have 32 valves and 8 cylinders compared to 24 valves and 6 cylinders or 16 valves and 4 cylinders. This means they make less power and burn more fuel. The only reason racing engines are sometimes built that way is because of class regulations.

The second being that the main advantages of increased cylinder count with a small displacement is at odds with the basic tenets of turbocharging. The main advantage of a 8-cylinder 3.0 vs a 6-cylinder 3.0 is the ability to have each individual piston be smaller and lighter with each individual stroke being shorter. This allows for higher revs. A 3.0 V8 can reach 10,000~12,000 rpm. Sounds great if you like high reving engines, but when you throw turbos into the mix everything falls apart. Even the most advanced turbochargers of today can maintain a flat torque plateau of no more than 3500~4000 rpm. Hence, a very nice 2.0 turbo engine may reach maximum torque rating of say 250 lb-ft @ 1600~5600 rpm. The power peak usually arrives shortly there after... say 270hp @ 6000 rpm. If your engine revs to 10,000 rpm, you have a problem. For 10,000 rpms to be meaningful you'll probably want to have your powerpeak at 9,500~10,000 rpm. A turbocharger that supports flow rates that maintains your torque peak to 9000 rpm will not reach that peak until 5,000 rpm or so. This means that from idle to 4000 rpm you have no drivability to speak of. The compromise will be something like the McLaren MP4/12... 443 lb-ft @ 3000~7000, 592 hp @ 7000 rpm. If you do something like this it makes 10,000 rpm capability moot, which then makes the 3.0 V8 configuration moot.

[regfootball]

just because dwight says so? i am sure some engineers out there are quite capable of making a tiny engine like a 3.0 v8 that is smaller than a huge pushrod mill.

the 1.4 turbo is quite small, a 3 litre v8 is basically that plus a cylinder bank. perhaps GM has some tricks up their sleeve. maybe the future cruze performance engine is a 1.5 turbo and so maybe GM can afford to co-develop something like that together.

if the euros need a small displacement motor, and GM thinks it nice to be tightly wound in order to do it, hey why not? GM cannot exist in a north american vacuum anymore. Corvette is dead if they don't make it world appeal. Lotus might want it for the Evora.

Corvette's current fan base is practically all residing in a nursing home right now anyways. GM sees they gotta move on some.

Hey, maybe eAssist is on the corvette future list also.

Edited May 28, 2011 by regfootball

[Camino LS6]

just because dwight says so? i am sure some engineers out there are quite capable of making a tiny engine like a 3.0 v8 that is smaller than a huge pushrod mill.

LSx engines are not "huge" physically, they are compact and lightweight.

the 1.4 turbo is quite small, a 3 litre v8 is basically that plus a cylinder bank. perhaps GM has some tricks up their sleeve. maybe the future cruze performance engine is a 1.5 turbo and so maybe GM can afford to co-develop something like that together.

if the euros need a small displacement motor, and GM thinks it nice to be tightly wound in order to do it, hey why not? GM cannot exist in a north american vacuum anymore. Corvette is dead if they don't make it world appeal. Lotus might want it for the Evora.

Corvette never has, and doesn't now, need to sell anywhere else to be profitable - which it is. It would be nice, yes, but not necessary.

Corvette's current fan base is practically all residing in a nursing home right now anyways. GM sees they gotta move on some.

Ummm, not even close to true.

Hey, maybe eAssist is on the corvette future list also.

Possible.

If the case is to be made for such an engine, it won't rely on use in the Corvette to justify it. If such an engine finds its way into a Vette, I suspect it will not be there very long, nor pay for itself. It very well could be an expensive experiment without any positive return.

In short, there is no need to do this.

[hyperv6]

Ok let get this out first I am not a pushrod hater. I like and have built pushrod engines for years.

But I also appreciate the new engines and what all they can do now that the electronics and technology has given them performance and torque at the low end.

The fact is in the future engines will have to get smaller and there is no choice on this. The goverment is pushing for 60 MPG and while they may not get there next week they will get there. The Vette team needs to look ahead and try to bring in this new technology as the engines get smaller in displacment they will have to make up the performance with Turbo's and better breathing.

As for size and weight that is not a great issue. All the other great sports cars can fit them in and the weight is lost else where. We already know they want to cut the weight in the C7 and even more in the C8.

As in cost yes they do cost more and there is no way around it. But that is just going to be the cost of doing business in the Future.

The fact is you can toss all the numbers out you like but the DOHC cam is much more lower emissions too. That is what got all this rush to DOHC started in the first place. Emissions are tough everywhere different but tough. They will only get tougher as time goes on. GM stated that they do not want to do a hybrid Vette. To their credit they are looking for ways to meet the future demands to keep it a full true gas powered sports car.

As for sales Yes they are doing ok right now but never sit back and just let growth get away. Those sales and younger buyers need to be brought in all the time. Otherwise the Vette could become the new Le Sabre. The youth market is not in love with the Chevy V8 like they used to be. In the past it was the only thing to have and today it is being passed over for many other engines with more cams and often less cylinders. Often these guys are paying twice as much to build these engines and do not care. I see it daily with the sales where I work. We used to be just Chevy, Ford and Dodge V8's and today the the Pushrod is king but not like it used to be.

I thing the entire market has shown how to go. If Pushrods were the answer for the future they all would have one in production. Might note Chrysler and GM are the ones with pushrods, might also note they are also the two who were cash strapped and got bailed out too. They even had to kill the N star update for lack of funds.

So to say the Pushrod is not a good engine is short sighted as it is still viable and the DI engine will help it at least another 10 years. But to take a look at a DOHC will leave them out to dry later when the stricter regs come in and also as the youth market gets to the point they want higher tech Vettes.

GM needs a now as it will have to have it sooner or later. Better to get a start on it now while the pushrod engine is viable and get it right when they will need it.

IF there is anything to this whole deal the Vette team has standards and if the DOHC does not meet them they will not do it. I expect the new engine if done would be as good or better than the present engine. If not we will not see it anyways.

As long as you have a pushrod engine this option for a DOHC is a no brainer and no risk. This is the kind of plan that should keep all happy. Those who what pushrods will have it and the DOHC will have a chance to sell itself. If it is not as good or better it would not make it anyways.

SO lets just look forward to the DI pushrod and see if they bait the hook on the DOHC and see what they catch.

I think if you look at the engines and names of the companies with great DOHC engines GM should do well. They can if funded well make a engine with great power and low torque with little to no lag.

[Camino LS6]

GM makes great engines - and I'm certain that if they built a DOHC V8 that it would be a great DOHC V8.

I just see no benefit, nor justification, for it.

The technical advances apply to pushrod engines just like they do to DOHC engines. And, the myth of DOHC superiority has been soundly debunked here many times. So, I see it as a "why bother" idea.

Producing a new powerplant with just on par power, at greater expense,with greater weight and complication just doesn't make much of a business case.

[regfootball]

corvette will be competing globally with the likes of R8, GTR, etc. in certain markets a small displacement mill will be an advantage.....

[hyperv6]

GM makes great engines - and I'm certain that if they built a DOHC V8 that it would be a great DOHC V8.

I just see no benefit, nor justification, for it.

The technical advances apply to pushrod engines just like they do to DOHC engines. And, the myth of DOHC superiority has been soundly debunked here many times. So, I see it as a "why bother" idea.

Producing a new powerplant with just on par power, at greater expense,with greater weight and complication just doesn't make much of a business case.

It is a shame how so many engineers and companies are spending Billions on these engines. Too bad these highly trained engineers don't have your facts it would save them all this money.

Funny too how many companies leaders have approved business cases on how many DOHC engines. They too must have missed the facts to.

I get the feeling they know something you may have missed somewhere?

[z28luvr01]

Like I said, dubious at best.

In the absence of artificial factors such as government regs or race rules, there is no advantage in the real world.

In the case of GM doing this, it would be nothing more than an example of "See, we can build one too".

What the hell is the use in that?

As long as they still offer the small block V8, I think it could be a good thing. A smaller, high-strung low-displacement V8 would certainly give the Corvette a different personality than its LS-based siblings. The car would pretty much be a street legal Indy car with a Corvette body, especially if GM does end up putting the car on a crash diet. And it would be a modern interpretation of the original ZR-1 with the high-revving LT-1 350.

[FAPTurbo]

Well it says that GM will offer a full line, so people who want a big stonking OHV engine can have one too! Giving the Corvette a high-winding mill may actually be helpful to lure away potential GT-R buyers, and give the car a totally different personality. This could be exciting!

[smk4565]

The Ferrari F40 had a 2.9 liter turbo V8 and it did okay. Koenigsegg has 900 hp and 250 mph out of a 4.7 liter V8. The Corvette can learn from those two, although I still think that cost of an engine like that will make it not feasible.

[hyperv6]

The Ferrari F40 had a 2.9 liter turbo V8 and it did okay. Koenigsegg has 900 hp and 250 mph out of a 4.7 liter V8. The Corvette can learn from those two, although I still think that cost of an engine like that will make it not feasible.

Best to look at the 458 Italia and Mclaren MP4 as better modern examples. The F40 while leading edges back 25 years ago still had many of the issues the older turbo cars had.

The fact is with both engines available it is a win win. Let me add a third win if they could share with Cadillac.

The Pushrod is like NASCAR a good and entertaining racing series but still people world wide love F1 for the techinical aspect. It makes neither wrong or bad just different and that is why people support both. Some people are happy with Checkers and some like Chess, people like choice.

Most MFG have figured out how to build these engines cost wise I am sure GM will soon figure it out too.

[smk4565]

Hart to do choice on a low volume car. I think the Corvette should stay front engine, rear drive as it always has. I like DOHC more, but if they want to keep the Corvette cheap (lower MSRP) than today's model, they can stick a pushrod in there. But then again, the Camaro offers that for people, unless the next generation Camaro is losing the V8.

There is always the option of doing a mid-engine Cadillac supercar with a DOHC, twin-turbo V8. Mercedes had the SLR, now has the SLS AMG, Audi has the R8, and Lexus the LF-A, perhaps Cadillac wants a supercar too. The the Corvette can appeal to it's base, while the Cadillac appeals to the global crowd.

[Camino LS6]

There is always the option of doing a mid-engine Cadillac supercar with a DOHC, twin-turbo V8. Mercedes had the SLR, now has the SLS AMG, Audi has the R8, and Lexus the LF-A, perhaps Cadillac wants a supercar too. The the Corvette can appeal to it's base, while the Cadillac appeals to the global crowd.

This is actually a lucid look at the issue.

I would call it all but certain that such an engine, if produced, would be primarily a Cadillac property. A Vette using it would be simply an experiment.

[Camino LS6]

GM makes great engines - and I'm certain that if they built a DOHC V8 that it would be a great DOHC V8.

I just see no benefit, nor justification, for it.

The technical advances apply to pushrod engines just like they do to DOHC engines. And, the myth of DOHC superiority has been soundly debunked here many times. So, I see it as a "why bother" idea.

Producing a new powerplant with just on par power, at greater expense,with greater weight and complication just doesn't make much of a business case.

It is a shame how so many engineers and companies are spending Billions on these engines. Too bad these highly trained engineers don't have your facts it would save them all this money.

Funny too how many companies leaders have approved business cases on how many DOHC engines. They too must have missed the facts to.

I get the feeling they know something you may have missed somewhere?

Yes, they know how it feels to get trounced by a pushrod Corvette.

One that costs less, and delivers more, all while being more fuel-efficient.

Edited May 29, 2011 by Camino LS6

[Camino LS6]

These are the questions that need to be asked about this:

Does this engine dramatically increase performance?

Does this engine dramatically increase fuel-efficiency?

Will this engine positively affect the profitability of the Corvette?

Today, the answer to all three questions really needs to be yes for this to make sense.

Do any of you really think that is the case?

It appears at this point not to be.

[smk4565]

Yes, they know how it feels to get trounced by a pushrod Corvette.

One that costs less, and delivers more, all while being more fuel-efficient.

Right now, the ZR-1 gets beat by a $30,000 cheaper Nissan with a V6 (that is also more efficient). The Corvette formula still appeals to Corvette fans, but that is an aging bunch and the current car isn't appealing to non-Corvette drivers. I still like front engine, rear drive, I would go with a boosted V6 and a V8, make the car not so wide, with a better interior, and I think they can get more appeal.

The potential risk I see here is the Corvette going after the Audi R8, Porsche 911, Ferrari California, Aston Martins, etc, and the Corvette isn't a mid-engine super car, nor is it a luxurious grand tourer. If they aim too high and try to sell Corvettes to people that are driving European exotics, the C7 will be a bust.

Current price point is mostly good, I think the Corvette could even drop a little in price (unless way more content is standard). Interior and width hurt the current car. I think Chevy needs to stay close to the current formula, but with something new and different to pull new buyers in. The Corvette has basically been the same car for the past 10-15 years, save for a couple power increases and interior tweaks. The car is dated, why spend $60k on a new one, when a used one for half that price or less is basically the same. Chevy has to give people a reason to buy a new Corvette, while at the same time staying loyal to he fans.

[hyperv6]

These are the questions that need to be asked about this:

Does this engine dramatically increase performance?

Does this engine dramatically increase fuel-efficiency?

Will this engine positively affect the profitability of the Corvette?

Today, the answer to all three questions really needs to be yes for this to make sense.

Do any of you really think that is the case?

It appears at this point not to be.

Answer this question first. If all you claim is really true then why do so many great MFG's and most of the top engineers all disagree?

While you make a good argument I think I will have to side with where they are going under the conditions they have to face in the future.

Keep in mind you appear to be behind too on you precepsion of a DOHC engine. When you voice concern over low end torque it sends a signal you have not kept up with what really is going on with the engine today. That kind of concern is no longer in play as is many other issues.

Like price Ford seems to know how to make a low cost DOHC and still show profits. Also they are giving what people seek. Wise or not it is bet to serve the customer what he wants or they will find it else where. Times and buyers are changing.

Much of the same arguments were made when companies went from valve in block to in head. Many Flat Head Ford guys used a similar arguemt.

[Camino LS6]

These are the questions that need to be asked about this:

Does this engine dramatically increase performance?

Does this engine dramatically increase fuel-efficiency?

Will this engine positively affect the profitability of the Corvette?

Today, the answer to all three questions really needs to be yes for this to make sense.

Do any of you really think that is the case?

It appears at this point not to be.

Answer this question first. If all you claim is really true then why do so many great MFG's and most of the top engineers all disagree?

While you make a good argument I think I will have to side with where they are going under the conditions they have to face in the future.

Keep in mind you appear to be behind too on you precepsion of a DOHC engine. When you voice concern over low end torque it sends a signal you have not kept up with what really is going on with the engine today. That kind of concern is no longer in play as is many other issues.

Like price Ford seems to know how to make a low cost DOHC and still show profits. Also they are giving what people seek. Wise or not it is bet to serve the customer what he wants or they will find it else where. Times and buyers are changing.

Much of the same arguments were made when companies went from valve in block to in head. Many Flat Head Ford guys used a similar arguemt.

Manufacturers have each followed their own paths to DOHC (and GM has been there as well), but what they have done is not determinative of what GM should do. Arguably, GM has proven to be the most talented builder of OHV V8s. They have carried them further into the future than anyone else, and no one does it better. The sheer quantity of those building DOHC engines is not evidence of the superiority of that configuration.

And evidence is what is required, anything else is supposition.

My three questions remain valid and critical. No amount of opinion changes the fact that they have not been answered.

My concerns about torque likewise remain until we have numbers and the shape of a curve to go by. However, you do me a disservice by intimating that my objections rest on that aspect of this.

A cost/benefit analysis is where my objections lie as enumerated throughout this thread.

When and if the answers to my three critical questions become affirmative, I am prepared to lay aside my concerns.

But not before.

[hyperv6]

The bottom line come down to the fact that DOHC is being done with the intent on higher emission levels. They can get better burn and cleaner engines with them. It will be interesting to see what they can do with the DI on the Chevy V8.

To this point VVT is something that has been used not only improve performance but also improve the emissions on the engine. It for the most tunes the car in ways you could not do otherwise. Also with two cams per head they can work with the extra valves for more control of what the engine is doing.

Chrysler has the Cam in Cam deal but it is not common. Word is the new Chevy will have some form of this.

As things get tought to meet performance levels and most companies are investing for the future to meet what is expected to happen.

The other reason right or not is marketing. People today informed or not like these engines and want these engines. Technology sells today and will sell even more in the future. The youth of today are very tech driven.

But no matter what they are here to stay. Companies see enough benefits to spend the kind of money needed to make these. They also are not having issues with fitting them underhoods or making a profit by installing them. For the most many are making more money with them than without as people want them. If they are willing to pay more profits are there for the taking.

But in the eyes of the engineers they are looking and emissions and control of the engine. Cam phasing is being used to many things today. I can watch on my scan meter on my 2.0 and see how they have thing phased and what they are doing.

It is kind of like Direct Injection on the new engines. Carbs are cheap and work but you have much more control. DI is more expensive and more complicated with a high pressure pump that is cam driven and fuel pressure that are off the chart. My fuel presusre guage reads in thousands not hundreds of pounds and they have to use better and more expensive lines and injectors. But they get more performance and cleaner engines with it.

[Camino LS6]

So now you are saying that DOHC has lower emission levels?

Got any stats to back that up? If so, then at least you've found one real advantage for what it's worth.

Meeting emission standards hasn't really been too tough for most engines lately it seems to me.

I'd like to hear more about how various engines do compare in this regard currently.

Dwight?

[smk4565]

This isn't just DOHC vs Pushrod. Because they aren't proposing a 4.8 liter DOHC V8 with 420 hp vs a 6.2 liter pushrod with 420 hp. That is sort of Mustang V8 vs Camaro V8 and which is preferred. This is considering a super high tech, high revving V8, and doing an engine like you'd find in a McLaren, Lexus LF-A or Koenigsegg.

If they make the Corvette mid-engined, that is another drastic change. So really the debate is whether or not the Corvette's time has come. Can C7 be a front engine, rear drive, big V8 car, or does it become a mid-engine, 3 liter, 9,000 rpm car.

[Drew Dowdell]

If the quantity of something being built is an indicator of the quality of it's performance, how do you explain all of the 4-cylinder 4-speed automatic Corollas running around?

The Nissan GT-R is just a car racing game with really good graphics. The computer does all of the work for you.

[Drew Dowdell]

DOHC getting better emissions has nothing do to with it's valvetrain layout and everything to do with the extra technology added to the engines. VVT and Direct Injection are the two biggest contributers to cleaner high powered engines.

As far as I know, there isn't a DI CIB engine out there yet and only the V6 CIB engines have VVT so far (and the V10 Viper)

[hyperv6]

DOHC heads have better valve placment and plug location to take advantage of better burn. This is step one for better emissions. CIB have improved their heads too but it is hard to get the same flow and central spark plug location. The company I work for has two head companied and they both have engineered better CIB heads but they have limits on location and also on size of valves.

As Olds has pointed out VVT or even cam phasing like they used to do would help improved efficency of the engine and emissions. Smaller engines making a lot of power often make less emissions.

Finally DI is the real gain. It will be interesting to see what effect it will have on the new Chevy engine as will the VVT. It should help them make a smaller engine and not lose power.

Finally marketing is a real big issue too. People want techinolgy and if that is what they want you need to give it to them. Henry Ford may have had the right idea on making all Model T's black but people wanted other colors they also wanted an affordable 6 cylinder, Chevy gave them that and took the lead in the market for years. Henry used logic to sell cars when people wanted something else.

The bottom line is a good company will give the people what they want and not force their will on them. If not they will go else where. This is where the DOHC and CIB engines both being offered is a good idea. let the people choose if they are willing to pay the extra hell take their money. You really underestimate what these people will want and do.

No matter how logical your argument the fact is people are wanting and buying these engines. The companies all have found the investment in these engines has also paid off. In many cases they can charge more money and for the most make more profit. It is not like they are giving these away.

When the dust settles I see no problem keeping the regular engine around but I can see no reason GM should not have a top class DOHC to offer in Cadilacs and as an option in the Vette. While the Chevy engine is a good engine it is a markting nightmare in the Cadillac vs the other cars in its class. You know and I know that it is a fine engne as shown by the CTSV. But in the unwashed market of luxury cars people want the latest and most trick toys and will pay much more for them. Too many just see the Chevy engine as a pick up engine. Yes they underestimate it but too often to the point they don't even consider a GM car because of it.

[balthazar]

>>"People want techinolgy and if that is what they want you need to give it to them. Henry Ford may have had the right idea on making all Model T's black but people wanted other colors they also wanted an affordable 6 cylinder, Chevy gave them that and took the lead in the market for years. Henry used logic to sell cars when people wanted something else."<<

Chevy went to a 6 in '29, while Ford continued with it's 4 (thru '31). Ford's 4 outsold Chevy's 6 in '30 almost 2:1 (1,140,xxx vs. 640,xxx). Your conclusion based on cylinder count is a very large leap, and Chevy did not 'take the lead for years', either. Chevy eclipsed Ford in '32-34, but Ford eclipsed Chevy '35-37. In many years, they were nearly dead even (1931: 619K vs. 615K). The market, even then, is too complicated to make singular-cause arguments.

[dwightlooi]

So now you are saying that DOHC has lower emission levels?

Got any stats to back that up? If so, then at least you've found one real advantage for what it's worth.

Meeting emission standards hasn't really been too tough for most engines lately it seems to me.

I'd like to hear more about how various engines do compare in this regard currently.

Dwight?

In general it is true that DOHC engines -- on the average -- have better emissions than Pushrod engines. However, this has nothing to do with the valve train layout. Rather, it is the result of a technologies that are commonn in DOHC designs, but not traditionally incoporated into Pushrod designs. The first being that DOHC engines frequently have independent cam phasers, whereas Pushrod designs either do not have cam phasers or have synchronous phasing for the intake and exhaust valves. Independent phasing allows EGR to be continuously and effectively managed to control Hydro-Carbon and NOx levels in the exhaust. However, this is a cost decision rather than one which is limited by the valvetrain layout. A pushrod design can have independent timing control -- the Viper 8.4 V10 does that with concentric cams. Other technologies like Direct Injection and wide range oxygen sensing are also more not traditionally found on pushrod designs. These too help with emissions.

The important thing to understand is that none of these features cannot be implemented in a Pushrod design. In fact, it looks like the Gen V small block will have them all.

[dwightlooi]

When the dust settles I see no problem keeping the regular engine around but I can see no reason GM should not have a top class DOHC to offer in Cadilacs and as an option in the Vette. While the Chevy engine is a good engine it is a markting nightmare in the Cadillac vs the other cars in its class. You know and I know that it is a fine engne as shown by the CTSV. But in the unwashed market of luxury cars people want the latest and most trick toys and will pay much more for them. Too many just see the Chevy engine as a pick up engine. Yes they underestimate it but too often to the point they don't even consider a GM car because of it.

Actually, I don't see anyone complaining about the CTS-V engines. Not the American journalists, not even the European ones.

[hyperv6]

When the dust settles I see no problem keeping the regular engine around but I can see no reason GM should not have a top class DOHC to offer in Cadilacs and as an option in the Vette. While the Chevy engine is a good engine it is a markting nightmare in the Cadillac vs the other cars in its class. You know and I know that it is a fine engne as shown by the CTSV. But in the unwashed market of luxury cars people want the latest and most trick toys and will pay much more for them. Too many just see the Chevy engine as a pick up engine. Yes they underestimate it but too often to the point they don't even consider a GM car because of it.

Actually, I don't see anyone complaining about the CTS-V engines. Not the American journalists, not even the European ones.

It is not that people complain so much but how many pass it over for the more technical hardware? Preception is one of the largest factors in marketing. There is no logic to it and never will be but that is a large part of image and sales in these higher priced models. It may be the brag factor at the golf course.

Buyers of these cars seldom do any modifications on their cars either a tuner does it or it remains stock. Theses guys are not Mustang guys or Camaro guys who will do their own work. So often what buy is what they get.

Example Benz may be offering a special edition engine from AMG that was done just for the model where as Cadillac offers an engine that is pimarily used in a truck. To you or I we understand and know that there is nothing wrong with that, infact we being GM fans we can overlook this very easily. But on the other hand to win a guy away from another brand who really has no love for GM but does like the styling on the new CTS coupe you need to offer what he wants logical or now. If he is willing to pay for it you need to offer it. Like I stated Marketing is a big part of this. Preceved value for what you pay also is a big part of the deal. The more complicated or advance the more precieved value.

Case in point. I had a Ford engineer in collage who came in and had a very frank presentation on customer. He covered topics like idiot proofing a car not fool poofing etc. One point he said many people would look at the orange peel on a Benz years ago and said many people felt it was there because Benz used more paint on their cars. He said it was an odd case where a flaw in the car was naturally look upon as a benefit. He said it was sad that people back then had no idea that the poor pain was really not the best paint job. Like he stated then that preception is a big part of selling cars. Most times a understood advancement is what does it other times it is a misunderstood concept.

Also as time goes on the pushrod engines will get more expensive too. They will always have a size and weight advantage but the aditition of DI and VVT will add to their cost. They will make a lot of gains with these two items so it will be well worth the investment.