Any possibility of introducing DOHC as against push rod technology in C6 ???

[Jack]

Gen IV C6 motor specs?

Hib:
Regarding the Gen IV C6 6.0L & 6.4L motors you referenced... do you have bore, stroke & rod length specs? Or are they readily available elsewhere?

Racer78:
Those cup cars' motors can spin over 9K for a few hours ... but do so at huge expense ... and the very things that make that happen are not practical for a platform marketed to general public ... even a performance-minded one. $2500-a-set Carillo rods running a tiny ID LEXUS rod bearing (that's right ... Honda bearings WERE the ticket ... but now it's Lexus) is but one example of the exotic nature of cup motors. Care to speculate what a finished cup crank costs:eek :eek :eek ? I didn't stay at the HI Express last night ... but ... Anybody care for a nice MSD HVC coil ... used a couple times ... only when Nadeau had to hit the backup system.

RE: OHC/DOHC:
I'll stick with pushrods & 2.1" journals for my daily-driver ... I can't afford not to! Pontiac made a few 250 ci L6 SOHC motors for Tempests & early 'birds ... 60's Ford made far-fewer race-only SOHC 427 ci V8. Though even it too has passed into history, I suspect the ZR-1 / LT-5 motor saw much greater production & acceptance than the Pontiac OHC. BTW, anyone seen what Harley's done in the OHC dept?? RE: V-Rod a la Porsche. And Willie G says it's a new concept ... I had a motorcycle rag back in '68 or '69 (where Honda 750's debuted) that had a two-page article about an experimental HD/AMF with a motor rumored to've been built by Porsche ... that's over 30 years ago! Now, I don't feel quite so guilty buying a Chinese-cast 388 crank (arrived today)!
JACK:gap

 

[Bullitt]

Aren't there "certified ZR-1" dealerships out there who have the mechanics who have the extra training to work on the ZR-1's?

While there are certified ZR1 mechanics, the amount of them is not great. Dealing with the problems of the motor on a constant basis is what makes some aftermarket tuners, like AutoMasters in California, stand out among the field. It's like anything in life. You may have the training, but the execution of that training can be entirely different. Only time and experience will get you through. The potential problems with a Super Corvette customer, is convincing them that not every Chevy dealer would be qualified to work on their vechile. A problem that occured with some ZR1 owners. Imagine that your Supercar has problems that most local Chevy dealers, whom you pass on the way to work, are unable to deal with or lack the mechanics to solve. I have an uncle who works for a Honda dealer and each year he attends classes to refresh his training and update him on new advancements. However, Honda doesn't make radical changes to their engine platforms. The question is, "How different would Chevy make their Supercar engine?" If it is too far off, you can bet that there will be angry customers when problems arise. Parts become another issue. ZR1 owners can attest that not only can parts be expensive, but they can also be a bit difficult to find. While GM did not develope the LT5 engine, I believe that they do have a responsibility to provide adequete parts and resources. The devaluated prices of ZR1s can be attributed to this fact, in part. I don't claim to have all the answers, but in order for a Super Corvette to prosper, GM needs to address the issues that caused the demise of the mighty ZR1. I do have a passion for Ferrari in part because it is a company that takes pride in passing down the knowledge and appreciation of all of it's past cars to each generation of mechanics. This is the advantage of being a specialized manufacturer. An advantage that GM will have to meet and incorporate if they plan on selling $100,000 Corvettes. Feel free to bring up anything I have overlooked. --Bullitt, tifiosi

 

[Rob]

Actually, remember that GM did develop the engine. It was a joint venture between GM and Lotus. GM engineers spent just as much time on trans-atlantic flights going to Hethel, England as Lotus engineers did coming to Detroit, MI. It would be unfair to omit GM's role in the development of the LT5.

Bullit did hit it on the nose pretty much. There are ZR-1 certified mechanics around the country, but they are few and far between. There are not a lot of them. In order for a dealership to have become ZR-1 certified, I believe they had to sell ZR-1s, and send one of their mechanics through several ZR-1/LT5 certification courses. Along with that, the dealership had to make a bit of an investement on a complete set of "J-tools" from Kent-Moore that were specific to working on the LT5 engine. Most Chevrolet dealership were (and I would be willing to say still are) foreign to selling a $60,000-$75,000 Chevrolet sportscar and supporting it for service.

Parts for the ZR-1 are not easy to find without connections. You can find them, but you either have to know someone, or you have to be willing to pay a small fortune for them. However, I would like to stress one issue here: I would be willing to bet, that a lot of the C4 interior components are just as rare and hard to come by as some of the LT5 engine components. You will be very surprised to find that next time you go to your local Chevy dealer to buy a new button, switch, trim panel, or whatever for the interior of your 1984 - 1996 Corvette, you may be told, "sorry, GM discontinued that part a while ago." Try finding a C4 sport seat leather covering.....good luck because if and when you do, you're going to hand over a small fortune.

There's one other problem that occurred with the introduction of the ZR-1. The car was so hyped up by the media to be the "Corvette From Hell", "King of the Hill" Corvette that was designed to take on the European Exotics, (and production was supposed to be very limited), most of the 1990's went into the hands of investors who paid in excess of $100,000 for the car and shoved away in a garage as a future investment. As a result, most of the 1990's didn't see steady road service, so mechanical problems and reliability feedback was not sent into GM right away. So....now, you have a bunch of 1990 ZR-1s sold and the mechanics that were trained didn't really get to use what they were trained for till later on and customer feedback to GM was rare.

This is why you still see 1990 ZR-1s coming out of garages with plastic still on the seats and steering wheel and under 30 miles on the odometer. Investors gradually come to the sad realization that an automobile is just as risky of an investment as the stock market is.

The original owner of mine, ordered it in late 1989 and bought it strictly as an investment. He shoved it into his enormous garage with other collectible Corvettes and sports cars and sat on it for a few years. After getting tired of seeing his investment losing money, he tried selling it on his own. He had only one bite. A guy flew all the way over here from Italy to buy the car for his son. (Imagine....a ZR-1 in Ferrari territory. ) They kept negotiating until finally the guy got so disgusted, he actually wrote a check out on the hood of the car and handed it to the owner. The owner didn't want to accept the offer. (so that's what that small scratch is.... ) He eventually sold it to a friend of his that owns a Ford dealership and it sat on the Ford lot for about a month. Someone came by, plunked down a deposit, but the financing fell through and he wasn't able to complete the transaction. Right around that time, I called Buds Chevrolet in Ohio, and they were negotiating with the Ford dealership to purchase the car. The rest is history.

This story is not uncommon among today's 1990 ZR-1 owners. The 1990s are gradually falling out of the hands of the investors and into the hands of the true enthusiasts who appreciate them and drive them on a daily basis. Unfortunately, now, they have to face the problems with trying to find reputable service and a good supply of parts.

 

[Edmond]

Those leather seat covers are indeed very expensive. I looked into those before on eBay I think and they were something like $1,000 or something like that.

IMHO, C4 parts are extremely expensive. I couldn't imagine what you ZR-1 and C5 guys have to go through. But fortunately, most of us here can do our own work. Imagine if you had to pay for parts and labor?:cry

But, I think there is really a huge "cult like" following for the 'Vette. Flip through any 'Vette magazine and you see a lot of used part junkyards dedicated to just used Corvette parts.

 

[JT ZR-Won]

Re: So Is ZR1 with OHC smoother than pushrod ??

I am just curious if the ZR1 is smoother than the pushrod engine and if so, can you tell the difference ?? I have read several mag articles going on and on about the 'easy breathing' and refinement of OHC motors and if anyone would know about this, it would be this forum.

My ZR-1 runs totally smooth all the way up to 7000RPM's. In fact, when most cars start to approach redline you can feel the car start to gasp for air and die out a little. Not the case with the LT5. All the way up to redline it has a bunch of pull........very smooth too.

Jay

 

[danl72]

I think that the ZR-1 are just as unique cars as the Z06. Each one is special to its model year. I don't understand why people are comparing them. GM did not compare the Z06 to the ZR-1 when they built it, so why are we. They are both Corvettes are heart and lets leave it at that.

 

[Rob]

Actually, GM did compare the Z06 to the ZR-1 in some ways. Their goal was to reach the ZR-1's 405 hp. They succeeded in topping the 1st generation's ZR-1's 375 hp with the 2001 LS6's 385 hp, and then succeeded with meeting the 405 hp output of the second generation LT5 with the 2002 Z06. In some of the media literature distributed by Chevrolet with the introduction of the 2002 Z06, they do mention the ZR-1 as being a view point in the LS6's development.

 

[danl72]

OK, you are right Rob, but I don't think it is fair for people to compare both cars and say that one is better than the other because the were both built at different times and the Z06 has the 21st century technology.

 

[Hib Halverson]

Mmmmmmm.....yes and no. Actually the ZR-1's body work is unique starting with the doors back. From the middle part of the doors back to the rear quarters and bumper are slightly larger to accomodate the larger rear wheels. The exhaust is unique to the ZR-1 and I believe the suspension was a combination of base Corvette and Z07 suspension components. I'm not totally clear on this so Hib may be able to help clarify.
(snip)

The ZR1 exhausts were really only "partly" unique. The features that were different were pipe bends at the front where the system connects to the cats and on 90-91s, the outlets. Other than that, LT1/4/5 exhaust systems are the same.

ZR1 suspension for 90-92 was a mix of Z51 and base parts with unique stabilizer bars and selective ride control (FX3). 93-95 ZR1s used base springs, unique bars and SRC

Regarding the Gen IV C6 6.0L & 6.4L motors you referenced... do you have bore, stroke & rod length specs? Or are they readily available elsewhere?

I don't have any specs. I doubt you're going to find specs elsewhere on an engine that might not see the light of day until 2005.

 

[jon69]

i think the cost of the overhead cams out weigh the benefits. sure the acura nsx is a great car but it costs like $86,000 and gets out run by the corvette that is half the price. the one thing i notice about the zr-1 is the fact that other than the motor it has almost no change from a regluar c4 corvette but cost lots more. most of that extra cost is directly related to the engine alone. a new zo6 has slightly better performance and is cheaper than the zr1 was brand new and still cheaper than a real good used zr1. it just seems like a lot of cost for a marginal performance gain.

Double overhead cam is most definately the superior engine configuration and I'd love to see it on the next generation C6, although some good points have been made that a much cheaper pushrod engine can deliver intended performance, taking that into consideration the accountants will win every time. As for the NSX comments (me being an NSX owner/fan), it is untrue that a C5 will outrun it. There is many numbers posted out their for the NSX but typically an early generation NSX is a 5.2 0-60 and 13.2 1/4 mile car in stock form, with the newer 6 speed/3.2 engined cars running as low as 4.7 / 12.7 respectably. Not bad for a car that was introduced in 1989/1990 (sold as 1991 models)
and with only 270hp/221 torque (3.2's went up to 290) more than keeps up with current crop of sports cars for a car virtually unchanged.
Talk is that the next generation NSX may have a 4.0 liter 400-450hp engine, torque may not be max'd out in Z06 territory but expect fairly high number too with a much better spread of torque than any pushrod motor could muster. A V6 NSX only has 221 lbs but will produce that from 2000rpm all the way to it's 8000rpm redline. That is 6000rpm worth of full torque, more than most cars can spin off idle. Impressions from these types of motors are that they are less torquey becouse they are so much smoother but know that even though they may feel slower they will outperform. I have a C5 with slight mods and a NSX with nothing but some weight reduction and intake (so far), the C5 feels like it puts you in the seat MUCH harder but side by side the NSX will win every time, and with my new 6speed and gears , headers, exhaust the NSX should drop close to a second in the 1/4, well should now be in Z06/ZR1 territory.
Not trying to sell the NSX and put off the C5, I like both cars for their different traits, but my view is if chevy wants to be old school, then maybe give us a 427ci Viper killer, or even better a 350ci DOHC motor that revs to 7000rpm and gives us ferrari/NSX output per liter that should equal 500+hp.
JMHO

 

[Bullitt]

I don't think trying to shoot for a power to liter ratio, is really worthy. The reason why Ferrari ends up at a similar configuration has more to do with engine compactness and the gearbox that is used, than anything else.Porsche realized the potential of more displacement when they created the 917. They took advantage of a rule by creating 25 examples of the 917, thereby increasing it's capacity from 3.0 liters to 5.0 liters. Instead of just competeing, they were able to dominate racing with this bigger engine and it's Flat-12 design configuration. The Flat-12 can make tremendous power that is superior to most designs, but suffers from it's large exterior size.

...even better a 350ci DOHC motor that revs to 7000rpm and gives us ferrari/NSX output per liter that should equal 500+hp.

Whether it's a better design or not, is a case for disagreement and opinion, when concerning the OHC. A more balanced evolution is what all car makers usually strive for and this should be put, first. Lighter weight should be more of a focus, instead of higher revlines. The pushrod engine is alive and well, and as many of us "old schoolers" will testify, can't be beat in a bang-for-buck comparison. Developing a whole new engine that is only marginally better than a pushrod may not be the best way to spend money and resources. Witness Ford's problems with the Mustang Cobra and the lack of aftermarket support. You can have 221 lbs.-ft through 6000rpm, but any well tuned Chevy can produce 300lbs.-ft from low to redline, for sure. And at a cheaper price. The problem does not arise with pushing the small block to it's limits, the C5R program is proving that, it's developing a mass produced engine with the ability to pass stricter emissions testing. Testing which caused the demise of the Nissan 300ZX, Mazda RX7 and the original Acura NSX. Those manufacturers could not afford to put more money into developing cars that were not profitable. They opted instead to wait for technology in fuel atomization to catch up, before taking the task again. The Corvette cannot and should not endanger itself by trying to reach some unjustified goals, that can be attained with the current engine configuration at hand. As stated with the discussion of the ZR1 and any future Super Corvette, every dealership will have to invest in money, training and time to get their mechanics up to snuff with a drastic engine change. These issues and others mentioned before must be overcome, if the Corvette wants to stay in the forefront of GT based cars. The Pushrod V8 is a legendary and historic engine. I think it's constant evolution will show that it still has more power potential to unleash. --Bullitt

 

[jon69]

I don't think trying to shoot for a power to liter ratio, is really worthy. The reason why Ferrari ends up at a similar configuration has more to do with engine compactness and the gearbox that is used, than anything else.

Power to liter ratio is of course something to shoot for, it tells much about and engine makers ability and engineering wit. Ferrari, Porsche, Honda, BMW are great engine builders that can build reliable hp at extreme power to liter ratios 100+ normally aspirated. Just look at a S2000 and it's 120hp per liter, the engine is economical and will last for houndreds of thousands of miles no problem, even if your at its 9000rpm redline. The arguement of power to liter ratio not being important usually comes from those who cannot compete in this area...our beloved 2002 Z06 only gets 71 hp per liter! And as for Ferrari of course their high output per liter has to do with compact lightness, the less weight and more power you can get = better sports car, not sure I understand your point?

A more balanced evolution is what all car makers usually strive for and this should be put, first. Lighter weight should be more of a focus, instead of higher revlines.

for any given hp goal DOHC motors will allways attain them at a lighter weight than pushrod engines. Look at a northstar V8, sure they only make 300hp in a cadillac but that motor could easily push 400 hp at 4.6 liters with revised head and cam work and better yet it is GM's lightest engine (excluding the xv8), and the motor is very durable, I've know of 600+hp turbo charged northstars with no internal mods that run all day long. Fact is pushrods only advantage is cheaper construction their good performance stem from decades of development time. Imagine 50 years of evolution of a norsthstar!

The problem does not arise with pushing the small block to it's limits, the C5R program is proving that, it's developing a mass produced engine with the ability to pass stricter emissions testing. Testing which caused the demise of the Nissan 300ZX, Mazda RX7 and the original Acura NSX. Those manufacturers could not afford to put more money into developing cars that were not profitable. They opted instead to wait for technology in fuel atomization to catch up, before taking the task again.

I think you may want to get your facts straight on this.
1) Emissions testing was not the demise of the Nissan 300ZX, and RX7, in fact the 300Z was only recently discontinued in Japan, and the RX7 still lives. The problem in North America was that these cars were introduced just before the decline of sports car sales during the start of the last recession. That is the only fact, Initial demand was high and then when recession brought much less demand it rose the cost of the product that priced it out of North American markets, given even less sales. Those are the commonly known fates of these cars, in fact at that time the Corvette was inches from being canceled by GM as well. What fuel atomization technology has to do with it is completely irrelavent! Besides DOHC motors inherently have much better economy and emissions than any pushrod motor, as they operate much more efficiently.
2) NSX, you talk about the original NSX, If you go to Acura and pick up a 2001 NSX it is virtually identical to the first NSX, only difference being a slight bore and stroke to 3.2 liters, and extra gear, bigger wheels, and power steering. No demise here, except maybe in sales as the mid-90's sports car market brought down demand and raised prices for a car that by the time the market picked up was priced much higher and was virtually unchanged.

The Corvette cannot and should not endanger itself by trying to reach some unjustified goals, that can be attained with the current engine configuration at hand. As stated with the discussion of the ZR1 and any future Super Corvette, every dealership will have to invest in money, training and time to get their mechanics up to snuff with a drastic engine change. These issues and others mentioned before must be overcome, if the Corvette wants to stay in the forefront of GT based cars. The Pushrod V8 is a legendary and historic engine. I think it's constant evolution will show that it still has more power potential to unleash. --Bullitt

I agree with you to some extent, granted the pushrod motor will more than be able to reach the performance goals for the corvette as it has lots of go fast torque and power as well as untapped potential and although I can't quote actual costs figures I assume it is cheaper to make being a simplier design with less parts. The bottom line is what type of car is GM intent on building. No doubt the C5 is a hit, it looks good and it's performance numbers are very impressive and if that's their goal with the C6 then fine pushrod works for me. As I mentioned on my earlier thread I'd love to see an all out good ol' American muscle car with a 427ci tire shredding motor capable of 500+hp that will blister around a track faster than any viper or ferrari, I'm all for that
But I'd also be for a 5.7 liter DOHC engined car that would have a flatter torque curve, rev much higher and should easily be able to attain 96+ hp per liter = 541.5+ hp and torque just under that. Or if "only" 400hp was a goal, then a 4.0 liter DOHC V8 should be no problem (based on 95hp per liter), base it on a northstar then it should be fairly economical as you wouldn't have to develop a new engine and we already know it's lighter than any othe GM v8. 400hp and bring the weight down under 2800 lbs, give it a interior and quaility to rival Audi and good track manners and you'd have one amazing car. Take an NSX for a drive and you'll know what I'm talking about, cars like that are on a different realm with driver interaction and for most true enthusiasts that is what it is about, the joy a car gives you whilst driving.

 

[Edmond]

I don't think GM needs a 426 ci to get 500 HP, they could probably do that with a 350. I think that American engineering is totally different from the European/Japanese. The Americans are all about muscle while the Europeans and Japanese are more about refinement and packing a lot of punch in a small package. The Europeans seem to have absolutely no regard for cost, but it shows by the great cars they produce. I think American car makers are more value minded.

If I had a car that had 500 HP, I would want a bigger engine doing the work because it would be less strain on the engine. I don't really like the high revs myself.

I'm a small guy, 5'5" and 125 pounds, but I can lift with guys much bigger than me. The only difference is that my body will break down before their's because I have less to work with. I think it's the same way with a car engine.

If it were up to me, I'd make a sportscar that you could drive in rain, sleet, snow or hale. Does 0-60 in 3.8 seconds and could cover the 1/4 mile in less than 12 seconds all for under $25,000.

 

[Edmond]

Oh, and we haven't even mentioned the millions of dollars it would take for GM to develop a DOHC engine. It would also take years to make it up to Corvette standard. Not to mention the amount of money GM would have to spend in training more technicians to be certified. I don't think they could take that chance for the Corvette. A good idea would be to make that revision to the Camaro if it were ever brought back.

 

[Bullitt]

Just look at a S2000 and it's 120hp per liter, the engine is economical and will last for houndreds of thousands of miles no problem, even if your at its 9000rpm redline.

I know that Honda engines are very relaible, but until the S2000 starts hitting these mileage figures and at that sustained rpm in real world driving, I think that claim is premature. While I do love Ferrari's, I also know how much they cost. And that is a very relevant issue that is very easy to understand. That's what I'm talking about. What's the sense of creating a Supercar with the economic downturn at hand, that will not prove profitable in this climate? Again, this road has been already traveled by the ZR1. That point has already been made.

I've know of 600+hp turbo charged northstars with no internal mods that run all day long. Fact is pushrods only advantage is cheaper construction their good performance stem from decades of development time. Imagine 50 years of evolution of a norsthstar!

Once again, the relevant issue of cost is brought up. There must be an affordable Corvette, not stuck with prices that will spell it's demise. Again, the ZR1 has been down this road. Surely you have not visited John Lingenfelter's website. See the Twin Turbo charged C5 pull a 9sec 1/4 mile. Pushrods can make Turbo power, too. Also, look into the Tiger Shark rendition of the C5. 742hp, anyone?

Emissions testing was not the demise of the Nissan 300ZX, and RX7, in fact the 300Z was only recently discontinued in Japan, and the RX7 still lives.

Japan has more lenient emissions laws, that's why those cars still make it there. Have you ever been to Tokoyo? Notice the people wearing respirator masks? Emission was a determining factor is these cars from being imported to the U.S. The passing of stricter emissons laws (especially in the early "90s) has killed motors and performance before. Contrary to believe, the Japanese are not immune to this. Engine mapping and other engine management operations were changed to meet the required tests for importing. In the past seven years, technology in this area has grown tremendously, which was also adapted by the Japanese manufacturers. All of the Japanese motorcycle manufacturers have gone to fuel injection to clean up the motors and make more power. This facet cannot be ignored.

Take an NSX for a drive and you'll know what I'm talking about, cars like that are on a different realm with driver interaction and for most true enthusiasts that is what it is about, the joy a car gives you whilst driving.

You assume that I have not done this, when to the contrary I have. I've also driven RX7s and the 3000GTs, to boot. While some do have a better balance than a C4, the Acura suffers in the power department at high speeds. Losing to an Audi in Grand Am Racing this past year, despite an equal effort, shows that this car isn't that superior. I've also raced competition 750 GSX-Rs, Ducatis, 600 Hondas and the like, so I'm very much aware of driver/rider interaction and power to weight ratios. Try 160hp in a 380lb. bike. I've raced at tracks like Laguna Seca, Road America and Sears Point. I was kicked off a historic race for exceeding the 7/10ths rule. In other words, I'm speaking from experience and not just talking out of my ***. Higher revlines are needed in racing to use the power there. Personally, there are some things that should just be in a Corvette. I believe that big bad motors are one of them. Until it becomes cost beneficial for DOHC in regular production Corvettes, I'll support the pushrod motor. My torque curve in my 454 BB in very healthy and will dust virtually any engine, OHC or not. Since there are no Ferraris, Porsche TTs or Lambos out here, I can't say all of them. A modern Corvette doesn't need a OHC or DOHC, it just needs more cubes . --Bullitt

 

[Bullitt]

Oops!

I accidently erased the first paragraph in my post before last. Here it is, as to not confuse anyone. From what I remember:

Originally posted by Bullitt
I don't think trying to shoot for a power to liter ratio, is really worthy. The reason why Ferrari ends up at a similar configuration has more to do with engine compactness and the gearbox that is used, than anything else.Porsche realized the potential of more displacement when they created the 917. They took advantage of a rule by creating 25 examples of the 917, thereby increasing it's capacity from 3.0 liters to 5.0 liters. Instead of just competeing, they were able to dominate racing with this bigger engine and it's Flat-12 design configuration. The Flat-12 can make tremendous power that is superior to most designs, but suffers from it's large exterior size.

That's pretty close to what I said. --Bullitt

 

[jon69]

Oh, and we haven't even mentioned the millions of dollars it would take for GM to develop a DOHC engine. It would also take years to make it up to Corvette standard. Not to mention the amount of money GM would have to spend in training more technicians to be certified. I don't think they could take that chance for the Corvette. A good idea would be to make that revision to the Camaro if it were ever brought back.

Maybe you didn't read the earlier posts but GM does not have to develop any new DOHC engines, they have one in the Northstar that has been in cadilacs for years, remember the 100,000 mile no tune up engines that can even run without coolant for a short period of time? How much money would they have to spend for training, almost nothing, as these engines have been worked on by GM technicians as long as they have been around. I know this motor well, it is a jewel and capable of huge horsepower, heads and cams alone are good for near 100hp and that's aftermarket, with GM's engineers they could sure do better, 100hp per liter shouldn't be a problem. Just look at the Cien it's a northstar with 4 extra cylinders and 750hp with gas mileage and emisions on par with an LS1 (normal driving). As for taking a chance on the Corvette, you should all be aware that the northstar was under serious consideration on the C5. By the way that V12 northstar is very likely going to find it's way into the STS, most likely with less hp but to do battle with the next generation 500hp V-10 BMW M5. However, I will agree that the marketing of a DOHC corvette may take some getting used to, it was just like when fuel injection first arrived in cars, most laymen hated the idea as they were unfamiliar with it, thinking carbs are more easily tuned and created great hp, well how many carbs do you see around today? Fuel injection has proved to be far superior. Same thing I think with the Corvette, you have a mystic and past that has developed a image that all corvettes must be small block pushrod V-8's... when in reality the car would be so much better with a DOHC of equal displacement or less.

 

[Rob]

This is awesome! This has definitely turned out to be an excellent discussion.

One thing that I haven't really seen mentioned, and maybe I've missed it is: DOHC motors are inherently heavier due to more moving internal parts. What do you think the effects might be on handling and overall curb weight of a C6 equipped with a DOHC motor?

Remember one thing: since the introduction of the C5, Corvette engineers have been working hard at shaving pounds off of the Corvette which it has always been criticized for. I believe I read somewhere that one of the goals for the C6 is a curb weight under 3,000lbs. Don't you think that the the DOHC would be counterproductive to this goal?

 

[Bullitt]

know this motor well, it is a jewel and capable of huge horsepower, heads and cams alone are good for near 100hp and that's aftermarket

Errr.. most small and big block Chevys can reach these goals too, with the same modifcations.

Just look at the Cien it's a northstar with 4 extra cylinders and 750hp with gas mileage and emisions on par with an LS1 (normal driving).

Oh yeah, that's real similar! Those extra cylinders cost how much to graph on and develope for mass production, not to mention every other component that is made for compatibility? That should only add what, $500? :eyerole

..you have a mystic and past that has developed a image that all corvettes must be small block pushrod V-8's... when in reality the car would be so much better with a DOHC of equal displacement or less.

The key word here is :REALITY!!! Again, the "old" pushrod motors still make a ton of power and have been around for ages because of the relaible design. It hasn't been sitting around for 50 years, as you pointed out before, Jon. It just plain works! With the current LS1 Z06 putting out 405hp and the realiziation that there is more to be found, what makes the DOHC change so important? Another thing that I first posted for Ken, was a LT-1 engine that made 360lbs.-ft starting a a measely 2000rpm and topped at 508 @ 4750, which then dropped to 454 at 6000rpm. Sure, it had a better intake and cylinder head work, but that only goes to show what "wit" can do to a 350 SMALL BLOCK CHEVY! The LS1 can probably benefit from the same work, but if it had more cubes, it would be unstoppable. The 'ol pushrod to the rescue! --Bullitt

 

[jon69]

You assume that I have not done this, when to the contrary I have. I've also driven RX7s and the 3000GTs, to boot. While some do have a better balance than a C4, the Acura suffers in the power department at high speeds. Losing to an Audi in Grand Am Racing this past year, despite an equal effort, shows that this car isn't that superior.

RX7, amazing handling car, 3000GT is a pig but AWD makes up in that what it looses in dynamics it gains in point and shoot cornering. The NSX may not have huge HP, but how does it suffer at high speeds for a 290hp car it may not have an all out top end but it will get there faster than a C5 for sure, does that mean the C5 suffers too? As for the speedvision cup, maybe you should look into the facts first, only one NSX realtime NSX was entered, this is the car that with a 650lbs weight penalty won the most amount of races, received the most amount of pole position starts and finished few points out of first place to an audi S4. Not to mention that Acura finished one point out of first in the manufacturers standings to Audi that had two full factory backed cars vs. one realtime racing supported NSX, all the while keep in mind the 650 lbs penalty of weight. How you can't view this car as superior is beyond me, what did they need to do to sway your opinion win every race? By the way speaking of apples to apples what happened to all the Vipers, 911's and C5 corvettes that rittled the field? That's right they weren't a factor being outclassed by the NSX and Audi. These are all factory cars with factory engines with roll cages and suspension/brake upgrades but all in all dynamically the same as what you drive on the street. These are not my words but facts, you make your own assumption.

and having said that I've also raced competition 750 GSX-Rs, Ducatis, 600 Hondas and the like, so I'm very much aware of driver/rider interaction and power to weight ratios. Try 160hp in a 380lb. bike. I've raced at tracks like Laguna Seca, Road America and Sears Point. I was kicked off a historic race for exceeding the 7/10ths rule. In other words, I'm speaking from experience and not just talking out of my ***. Higher revlines are needed in racing to use the power there.

Great you race bikes too, so do I what does that have to do with the price of tea in china? 160hp 380 lbs GSXR1000's and R1's lots of fun yes and I've raced them myself, OK good. And yes higher revs on the track are the goal as your running 100% most the entire time, not sure where your going with this, I thought we were talking about factory equipted sports cars? That is what is so good about DOHC, from the factory (especially if equipted with vtec which many manufacturers use, and soon we may even see infinitaly adjustable valves that BMW, and even Ducati are working on) you get a powerplant that can have all the down low torque and all top end power all in one engine. Look at a 3liter M3 with full torque from just over idle to redline, and this is a factory motor not a modified chevy small block.

Personally, there are some things that should just be in a Corvette. I believe that big bad motors are one of them. Until it becomes cost beneficial for DOHC in regular production Corvettes, I'll support the pushrod motor. My torque curve in my 454 BB in very healthy and will dust virtually any engine, OHC or not. Since there are no Ferraris, Porsche TTs or Lambos out here, I can't say all of them. A modern Corvette doesn't need a OHC or DOHC, it just needs more cubes . --Bullitt

Couldn't agree with you more, I personally feel that the corvette shouldn't stay with it's current configuration. It partially tries to be a good ol american hot rod at the same time trying to be high tech and refined and gets beat on on both ends. For all out american muscle the Viper kills it dead and refinement well no need to say anything there, fact is it falls far short of any European or Japanese sports cars in its class. It does though do a great job of capturing old corvette heritage and has great bang for the buck. But my whole point is Chevy should just choose, if you want to be a hot rod build a Viper killer, please I would buy one in a second, or if your gonna try to be refined then do it right and build a "true" sports car worthy of praise from the most discriminate enthusiast. As for you Bullit, I feel like our post are almost like a arguement and getting somewhat personal, not something I intended. I value your opinion even though we may have some phylisophical differences but in the end we are both Vette and sports car fans so let's just leave it at that.