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dwightlooi

Which engine for the C7 Corvette?

130 posts in this topic

I'd stick with the small block V8 for the Corvette. It just works so damn well and has for all of its existence. Plus, the fact that the V8 consumes less will keep the Corvette from becoming a CAFE casualty. We know the C7 is going on a diet. If they can get it to around 2800-3000 pounds, even if they use the 6.2Lc at its current spec, it will result in an al around much better performing car.

The V12 would be perfect for a supercar in the mold of the Cadillac Cien.

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v12s are for prancing horsey poony boys... besides, push rods are sexay hehehe

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i'd say the v8.

any chance the c7 will get "moderately lighter"? would a 350cuin motor making ~420hp be seen as a back step for corvette history.

i do realize if they used the current block it'd be heavier than need be, most likely. is the 5.3L able to be enlarged or is that set up for longer stroke?

is there any reason a new block should be made?

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The V12 would be perfect for a supercar in the mold of the Cadillac Cien.

yes, up the CR to make about another 30+hp....?

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It will be interesting to see how the Corvette evolves from here..the C6 is awfully good all around in all it's variations..

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Smaller and lighter is the way to go. Better MPG is important too in this car.

Also the key is which one would fit into the future Pick up truck line better.

V12 is a cool idea but not in todays market in a lower end sports car. When Pice is not an issue V12 when Cost and Price is an issue a shared V8 everytime.

The lighter engine will provide better balance anyway.

I would move some of the technology from the LNF turbo to this engine. If GM can get 145 HP per liter on the 2.0 liter LNF then imagine on a 6 liter V8.

Edited by hyperv6
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small block v8. but make it smaller and lighter. reduce displacement if need be.

add variable valve timing. direct injection.

bigger fish to fry is needing AWD. Nissan GTR and 911 have that.

Edited by regfootball
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A few things...

(1) A 5.3, 5.7 or 6.0 liter small block (the currently existing ones) are not lighter than the 6.2 and the 7.0 is not heavier either. They all hover around 198~212 kg. If you want to make the block lighter in general you want to make it smaller, that means you need to ditch the small block's 111.76 mm bore centers. Increasing or decreasing the stroke and bore do not change the weight tangibly, in fact it is accessories and the like which affects the model to model weight difference.

(2) A V-8 will be shared with trucks and other "muscle" cars like the Camaro. A V-12 will be shared with Caddy's STS replacement, etc. A V-12 is not particularly expensive if you use off-the shelf parts from the 3.0 V6 and simply mate two end to end. It'll may be add $3000~4000 more to the price of the car with the same profit margins. An S600 costs $120K not because the V-12 costs $40K more but because it's an S600 and they can charge $120K.

(3) In general, an in block cam V-8 has better power to weight or power to size ratio. A V-12 has higher power to displacement ratio, not to mention superior civility and prestige.

(4) Making the C7 slightly smaller and paying attention to mass will probably get it to ~3000 lbs (200 lighter than today). Adding DI and VVT to the LS3 will get you another 10% more output.

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There is no place for even a small V12 in the future.

Also GM needs to go at least 4 valve in the V8. The excuses they have used since they could not afford the change over will no longer work.

They have done well with 2 valves but like sticking with the 4 speed Automatics it is time to get up to date. At least even for their image as being a up to date advanced power plant.

The smaller displacement will need more RPM and even a turbo to meet mileage and still make power. DI thrives with Turbocharging. Like I said if GM can get 145 HP per liter out of the Ecotec then imagine what they could do with a modern V8. THe variable timing would also suit the trucks as the computer would be tuned for the application it is in.

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It will be the same engines they currently have. Although the 7.0 liter may die off in favor of a 6.2 with a small supercharger for the Z06, and big supercharger for the ZR1, assuming the ZR1 returns. The engines will get recycled to keep cost down, and they have no other V8 to use because they canceled work on a new V8.

Personally I'd rather see a 4.5-5.0 liter DOHC V8 making 500+ hp for the Z06, and a 400 hp "detuned" version for the base model. Ferrari has a 4.5 liter V8 that makes 562 hp.

Actually, what I would like to see most is for Duesenberg to come back and blow all these cars away so America has the best car in the world again. The 1932 Duesenberg SJ has more torque (425 vs 424 lb-ft) than a 2009 Corvette. Why did Duesenberg 77 years ago have an engine as good as the Vette has now, oh right, they started using DOHC in 1929, the Vette isn't there yet.

Edited by smk4565
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Dwight, any knowledge of GM moving to 3 valve in the near future? that should add another 3-7% or so, right?

i think DOHC has it's place, but many here would like the simpler design for larger displacement and power....other than a few vette's, if it's a vette it needs CIB.

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Where did these numbers come from? The HP estimate for a 6.2L gen 4 or gen 5 v8 with direct injection is way too low, that thing will easily pass 500 hp.

One of the disadvantages for the v8 is 'less output per liter'? Come on man, this is an enthusiast site, we all know that the small block chevy has one of best ratios of hp per external displacement. That v12 dohc monstrosity is going to take up a whole bunch of space.

Edited by Chevy Nick
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That v12 dohc monstrosity is going to take up a whole bunch of space.

They could fit a V12. The Mercedes SL and Aston Martin Vantage have V12s and they are similar size to the Vette. Although we all know there is about zero chance of GM making a V12.

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They could fit a V12. The Mercedes SL and Aston Martin Vantage have V12s and they are similar size to the Vette. Although we all know there is about zero chance of GM making a V12.

with the v12 comes more complex repairs... i think we all remember the first generation zr-1. i recall hearing that there was a service bulletin that came out stating if a zr-1 came in for engine related service, it had to be boxed up and sent to mercury marine for repairs.

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Dwight, any knowledge of GM moving to 3 valve in the near future? that should add another 3-7% or so, right?

i think DOHC has it's place, but many here would like the simpler design for larger displacement and power....other than a few vette's, if it's a vette it needs CIB.

Not sure, but the 3-valve Single In-Block Cam design was actually tested but rejected for the LS3. The reason being that the increase in performance is not significant and not worth the additional complexity. The added valvetrain mass also lowered the redline.

More valves do not necessarily add power. It is increased airflow that makes more power and more valves simply facilitate that at high rpms. The problem is that a 2-valve head with lift at LS3 levels is adequate in supplying air at 6000~6300 rpms (which is where the power peaks in the LS engines). Going to a 4-valve or 3-valve head doesn't do much good unless you also optimise the cam profile for higher rpms. Herein lies the problem... the 6L80 transmission (which can handle 468hp/439 lb-ft) has a maximum shift speed of 6500 rpm. The 6L90 is even lower at 6000 rpm. Hence, if you want to have an engine which makes proper use of the advantages of a 4-valve head you need to develop a new tranny to allow it to rev to 7000 rpm or higher -- like GM's own LF1 3.0 liter V6 which makes 270hp @ 7000 rpm (90 hp / liter). Otherwise, a 4-valve head is just more bulk, more weight and more costs for very little benefit.

Think about it for a second a Camry V6 makes 268 hp out of 3.5 liters at 6200 rpm. That's 76.5 bhp/liter and not worth while using a DOHC-4v design for! An LS7 is already at 505 hp @ 6300 rpm out of 7 liters. That's 72 hp per liter. With DI we can probably get to about 75 hp/liter. Close enough. And not using DOHC saves globs of mass by eliminating the big DOHC heads, and three camshafts. You also make the engine smaller dimensionally so you can fit it into a smaller bay.

Edited by dwightlooi
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The Mercedes AMG 6.2 liter V8 weighs 438 pounds and puts out 493-525 hp depending on the car. The LS7 weighs 458 pounds and makes 500 hp, of course it is 7 liters. But the LS2 6.0 liter engine still weighed 448 pounds. The DOHC design isn't adding weight to the car, the Z06 would actually weigh less if they used Mercedes DOHC engine.

The Mercedes S65 V12 weighs 486 pounds, only 28 more than the Z06's engine, but look at the power the V12 makes. The S65 makes 738 lb-ft of torque only because they had to electronically limit it to prevent it from tearing the transmission apart. Without a limiter that engine makes 885 lb-ft of torque.

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The reason I want the DOHC is efficiency.

The new engines will grow smaller in time We may still have a V8 but it will not be as large as it is today. By going to the DOHC it will improve the power per liter. Add to that a twin turbo with DI and VVT and you would have a power plant worty of a Ferrari. Base a truck engine on this design as well as a engine for Cadillac they could all support the cost and have a world class engine.

The LS line is amazing to make the power it does with a very inefficent engine as well as an engine that has yet to take advantage of VVT or DI yet.

GM threw tech into the Ecotech or 3.6 DI and it has paid off with a great little engines that can. Just put that effort into a V8 and it will make it viable for many vehicles even with the tougher goverment standards.

Besides how much longer will the lie that the 2 valve engine abd 4 speed autos are enough. GM bought time buy saying they were good enough but the truth was they just could not afford to go with the better technolgy.

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GM's pushrod v6's were universally panned for being too heavy (iron block), not as smooth at higher rpm as OHC mills, not producing as much hp/litre, not revving at quickly, and only limited to best power delivery at lower rpms.

now the vette and CTSv make great cases for v8 applications of pushrod power.

GM never opened the floodgates for pushrod tech and all the other goodies on a v6.

On an inline 4, its easy to do DOHC, you have only 2 cams, but then you don't have all the other pushrod gear that the PR engine has. Its prob a wash on the 4 but everything is overhead.

i think it would make sense for the corvette to have a DOHC v8 mill at some point. although, i think it would be like the CTSv, make the LS whatever the rare high perf version. the time may be soon where the corvette might function better to have a high strung 4.5 litre DOHC v8 instead of a big pushrod. But GM knows the pushrod v8 and it packages well into the corvette.

at some point the corvette will be perceived as stale with the character of its running gear. its brash and brute. but ultimately the rags will pass it of as old school etc. that point isn't here yet i don't think but it may come sooner than you think.

rather than examining the engine of the vette i think the more proper question is to question the character and capabilities of what corvette means. should corvette be this big wide gaudy huge car with a big v8? Or is something like the Lotus Evora or the size of a solstice or crossfire with a few more inches of leg room be more appropriate for the next decades of corvette existence?

For example, a stretched Kappa with a twin turbo 3.6DI that could do say 425 hp......assuming weight could be kept reasonable i wonder if they could make that work.

I do like the current corvette quite a lot and would gladly take one as an everyday rig. A base coupe with removable panel roof, and 6 speed manual, maybe with the upgraded suspension. I would love to travel cross country in one.

Edited by regfootball
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once GM can right itself from all the ch 11 stuff i think the corvette will find itself in 1982, staring 1983 down with a reinvention a la 1984. i mean that was a huge leap going from a nearly 15yr old design

NSN-BB82.jpg

to

1984corvette070608.jpg

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The Mercedes AMG 6.2 liter V8 weighs 438 pounds and puts out 493-525 hp depending on the car. The LS7 weighs 458 pounds and makes 500 hp, of course it is 7 liters. But the LS2 6.0 liter engine still weighed 448 pounds. The DOHC design isn't adding weight to the car, the Z06 would actually weigh less if they used Mercedes DOHC engine.

The Mercedes S65 V12 weighs 486 pounds, only 28 more than the Z06's engine, but look at the power the V12 makes. The S65 makes 738 lb-ft of torque only because they had to electronically limit it to prevent it from tearing the transmission apart. Without a limiter that engine makes 885 lb-ft of torque.

... i would tend to want to leave the Z06 out of this fight purely for the fact that most magazines say unless your name starts with "Ron" and ends like "Fellows" you will probably never have the skill for the Z06 to realize its full potential. the Z06 is a finicky track beast, and most will say that for the average joe a Z51 and for sure the ZR1 will serve the owner better due to the Z06's handling traits. with the new GS vettes... i'd say the days of the 7.0 Z06 are already numbered.

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GM's pushrod 4's died because they were uncompetitive and the imports had DOHC 4's in the 1980s that were better. Then GM's pushrod V6s died (except on the Impala/Lucerne) because the Imports have DOHC V6s through the 1990s and 2000s that are better. The pushrod V8 will die also, because right now, the imports have DOHC V8s that are better. GM uses the pushrods so they don't have to develop a new engine and because it is cheaper to make, they don't use it because it is a superior engine. But that is what led to GM's demise and bankruptcy. 20-30 years of being a step or 2 behind the competition and trying to pass off their mediocre product as being "good enough".

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