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

[Tom73]

Just my opinion here...most vette owners want torque. Big gobbs of torque. Everyday driving depends upon torque, not horsepower. The pushrod V8 is the best way to get that torque. DOHC engines can produce a lot of HP but they operate best at the upper rpm ranges. Torque comes early in the rpm ranges. So best choice is the OHV V8.

Also consider the package. DOHC adds several inches to the height and width of each cylinder head. That makes fitting the engine under a VERY low hood next to impossable. Would also require a redesign of the front suspension to allow clearnace for the extra width. If Chevy is going to do that redisgn, then I would rather they drop in a big block

tom...

 

[Bullitt]

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? These are not my words but facts, you make your own assumption.

First off, I didn't say either car was superior. The Vipers are running run-of-the-mill V8s, the Porsches don't have big money, as are the Corvettes. Want to see some advancement in customer C5s? Just take a look at how Justin Bell took on the Jaguars at the end of the Trans Am season. Also, the Acura still got beat by an Audi, that's a fact, too.

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.

...not sure where your going with this...

Does that answer your question? Let's make this simple, I know what high performance driving is, I know what racing is, therefore I was making something clear instead of assumptions about not driving certain cars.

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.

Jon, you brought up some V12 with 750hp. I'm just saying that the 'ol pushrod can still go like stink. That cannot be ignored. --Bullitt

 

[jon69]

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?

Great point, and yes this seems to be a great discussion. Well I'm not an engineer so I wouldn't know all the parameters to really judge the weight comparisons between the two styles of motors but I think if you look at it at a common sense point of view it may shed some light. Pushrods motors have exactly that pushrods and related hardware that DOHC motors don't, this adds weight on one respect. However, this would be offset by the fact that DOHC motors have extra cams (3 of them), mind you a OHC motor with 4 valves per cylinder is possible so that would be only one extra camshaft. I'm pretty sure weight would be negligible on this respect, at least we're not talking about anything significant that would increase a vehicles weight. Besides it all depends on the engineering of the motor itself, either or could be heavier depending on materials used in block, heads, intake, valve gear, con rods, etc, etc. As I've mentioned before the Northstar is GM's lightest/smallest production V8, advantage DOHC. And look at the XV8 prototype even lighter and more compact.
But what I think is the major advantage of DOHC motors is that they will produce the same power with less displacement. For instance you could have a sports car and drop in a 350hp Chevy V8 or put in a 330hp BMW inline 6. Now I'm not suggesting doing this to a vette, by no means at all, it would be criminal. But going back to the point for the same hp goal you can have a much smaller motor that is much lighter which means drive train can be lighter = car lighter = car faster = car handles and brakes better, so on and so forth. Take a look at the initial specs of the all new BMW Z5 that is in prototype testing. The car is said to weight in around 2000lbs and will have a front mounted 2.0 liter 4 cyclinder with 240hp. Weight will be brought down with extensive use of carbon fibre, aluminum, etc, even the wheels will be kevlar/aluminum construction and with a price that should be equal to vette or less (initial indications) 240hp does not sound like much and if you were to drive a car like that it would not feel too powerfull but assuredly would have amazing performance at the track. Lotus Elise weighs slightly more and has less power and if you see them at the track they already own it, walking around most other machinery Z06 included.
Fact is smaller everything = faster sports car, it would be nice to see if GM could go this route with the vette. Personally as I've stated before I'd still rather have a corvette be a cartoonish looking torque monster, something to make those Viper drivers scared of their throne. GM if your listening make me a 426ci monster that does 1.2 g's on the skid pad and smokes tires in 3rd gear on a whim. It may not be refined but if driving is about pleasure I can't think of anything better to make me smile.

 

[Bullitt]

In Defense of Bullwinkle

Maybe you didn't read the earlier posts...

As for you Bullit, I feel like our post are almost like a arguement and getting somewhat personal, not something I intended.

The saying goes, "the road to hell is paved with good intentions." First off, Bullwinkle was on this subject before either of us, trying to find out more information and just asking questions. To suggest that he just jumps in without reading the posts is insulting to all of us who know and like Bullwinkle. In the time that I have read his posts and have been here at the CACC, I have never found him to be one to jump on the bandwagon. He's a good guy in my opinion. --Bullitt

 

[jon69]

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?

I completely agree with you, I've never said that a change is so important, in fact I have said on more than one occasion I much rather the vette be a big cubed V8 monster. Yes the chevy small block has evolved into a great option for GM, but my point is that DOHC has far superior performance potential, this cannot be contested as you cannot change physics.

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

I'm not asking you to agree with me, but look at these figures from my view point, really have an open mind about it. The motor above that you mentioned makes full torque from 2000 to 4750, that is a 2750 rpm spread. Now take into consideration a DOHC NSX V6, it makes full torque from 2000 to 8000 rpm that is 6000 rpm worth of full torque. What do you think is more favorable? Yes the hp or torque figures between the two motors are far off but you can take any motor and make any power you want for the most part, shoot Oldsmobile had 1000hp 2.0 liter quad 4's, big deal. We could sit here and write about this mod'd motor and that one forever. Why do you think a NSX with only 270hp/221 lbs of torque is about the same speed in the 1/4 as a C5 with almost 350hp / 350 lbs torque. First glance would give the advantage to the vette by far right? Well these cars that have relatively the same weight have the playing field leveled becouse the NSX has a much better power and torque curve, this mainly becouse of it's vtec and DOHC architecture (plus it has much less drive train losses, but that is another book altogether).

 

[Rob]

In terms of refinement, what would you want to see in the C6? Obviously, a common complaint from C5 owners is the quality of the interior.

Admittedly, I have to agree with them. I sat in a '98 coupe recently and although I thought the layout, and overall ergonomics were good, I wasn't impressed with the heavy use of plastic in the interior.

However, refinement can cover several areas of a car. Many owners feel that the C5 is too refined in ride and exhaust sound. What areas would you like to see further refinement?

 

[Bullitt]

I underestimated...

... the torque of that LT1, was 528 lbs.-ft at 4750 rpm. From 2250 to 6000, it made over 450 lbs.-ft. This is but one example of pushrod power, as many people all over have created their own torque monsters. Again, this is one example I was pointing out. Also, you ignore the mid engine layout of the NSX versus the Corvette. Hence, the balance issue I brought up earlier. --Bullitt

 

[jon69]

First off, I didn't say either car was superior. The Vipers are runnin run-of the mill V8's, the Porsches don't have big money, as are the Corvettes. Want to see some advancement in customer C5's? Just take a look at how Justin Bell took on the Jaguars at the end of the Trans Am season. Also, the Acura still got beat by Audi, that's a fact too.

First off, your exact words "despite an equal effort, shows that this cars isn't that superior" know you didn't say any car was superior that is true you definately implied the NSX was not. But here again why don't you look at facts first before making statements. Vipers one don't run run of the mill V8's, they run slightly mod'd V10's which start off stock at 450hp. Porshe's and Corvettes don't run with big money, well neither does the NSX. The only car in that entire series that has serious money are the two FACTORY sponsored Audi's. The only car that could compete was the NSX which won more poles and races than any other car, remember a one car NSX effort came one point out of first for manufacturers championship. This in a class with multiple Vipers, Vettes, Porshe's and of course the factory backed Audi's. Also your comments suggest equality "despite an equal effort", this is completely wrong, Audi's were factory backed with big money and the NSX had a 650lb weight penalty, two huge hurdles to overcome, which it almost did.

Jon, you brought up some V12 with 750hp. I'm just saying that the ol' pushrod can still go like stink. That cannot be ignored. --Bullitt

I've never contested that fact, yes the LS1 is a good motor and it has the torque and power and as you said goes like stink, better yet it does it for cheap. I never ignored those points I embrace them, maybe your not reading my messages close enough, numorous times I did say that a big displacement V8 should be in the vettes future. I'm just trying to discount the points that your trying to make about pushrod vs. DOHC in the purely all out performance potential. DOHC will make more outright power, it will be better at gas consumption, and emisions. Pricing and packaging is stricly and engineering achievement, either configuration can be made expensive or cheap or either can be engineered to be ultra compact or not. NUFF SAID.

 

[jon69]

Re: In Defense of Bullwinkle

The saying goes, "the road to hell is paved with good intentions." First off, Bullwinkle was on this subject before either of us, trying to find out more information and just asking questions. To suggest that he just jumps in without reading the posts is insulting to all of us who know and like Bullwinkle. In the time that I have read his posts and have been here at the CACC, I have never found him to be one to jump on the bandwagon. He's a good guy in my opinion. --Bullitt

Misinterpratation, I was never suggesting anything to bullwinkle? Everybody has opinions and that's fine with me, I was just trying to be carefull that the posts between you (BULLITT) and I didn't get into a ****ing match, nothing personal buddy just wanted to try to keep it about opinions on cars not each other. It's all good, in any case this has been fun. Sorry if I offended anybody, not my intention.

 

[jon69]

In terms of refinement, what would you want to see in the C6? Obviously, a common complaint from C5 owners is the quality of the interior.

Admittedly, I have to agree with them. I sat in a '98 coupe recently and although I thought the layout, and overall ergonomics were good, I wasn't impressed with the heavy use of plastic in the interior.

However, refinement can cover several areas of a car. Many owners feel that the C5 is too refined in ride and exhaust sound. What areas would you like to see further refinement?

Your right refinement can cover many areas, ride and exhaust can be easily adjusted with aftermarket suspension and mufflers. If chevy wants to have a refined car they really have to look at everything else. From the shifting feel, quality of materials, as well as all the little things, like ashtrays or the way a door opens and closes. The easiest way to see a vettes shortcomings is to go to a porsche or BMW dealership. Sit in a X5 4.4, or a 911, drive it spend a bit of time with it, play with all the controls, windows, doors, etc. Then jump into a C5, I need to speak no further as you will immediately see the difference, it will be plain as day.

 

[Rob]

My next question is, would you be willing to sacrifice further refinement, and in some cases, current production options such as AC, power seats, PKE etc., for all out performance?

What comes to mind is the Viper. I rode in a '95 Viper. The acceleration was awe inspiring. The overall look of the car, was IMHO, awesome. It looks mean and aggressive and definitely calls attention to itself, although I do find the car a little too big.

However, overall refinement of the car was poor. Interior quality was worse than on some cars that cost 1/4 of what the Viper cost. If Corvette Engineers were to develop a similar beast....refinement and interior quality were thrown to the wind in interest of developing an all out high performance Corvette, is this something you would consider for possible purchase?

 

[Bullitt]

I admit, I was thinking of Trans Am racing instead of Grand Am on the Vipers. My bag, I accept that. I'm not the one harping on the NSX, so we know I don't think it's superior. The Audi isn't either, and you can talk about this or that excuse, but when the season was over the Audis took home the championship. That's racing, pure and simple. This has happened before in racing, no news there. To think that the Acura team did not benefit from better sponsorship is folly, though. I look at the DOHC design from a cost comparison, I never said that OHC or DOHC are inferior, but from a practical standpoint don't make huge sense with the current Corvette LS1 power and potential power. Read again. Hib once commented on the "offense rule," and having been a member here for quite some time, I don't think I need to go over it. Personal against me? Please, you're not that high on my list. Don't worry about me, I'm a big boy. --Bullitt

 

[Rob]

This discussion really brings me back to what I've desired from Corvette all along: a similar platform structure similar to what Ferrari and Porsche have evolved into.

They offer a few different models to satisfy the driving desires of a wide range of drivers and incomes rather than a select few.

With Ferrari, you have the 360 Modena on the low end of the spectrum, and on the opposite end, you have the 550 Maranello and soon to be F50 successor.

Same with Porsche. You have the Boxster on one end and the high performance twin turbo 911 on the other.

In some ways, Corvette achieved this in the '60s with the various engine and high performance otions ('63 Z06, L88 etc.) and made a similar move back in the early 1990s with the introduction of the ZR-1 and now in 2001-2002 with the Z06, but do you think Corvette should take it even further along the same lines as what Porsche and Ferrari have done?

P.S. Just a friendly reminder....let's remember to be respectful of one another and remain civil.

 

[jon69]

My next question is, would you be willing to sacrifice further refinement, and in some cases, current production options such as AC, power seats, PKE etc., for all out performance?

What comes to mind is the Viper. I rode in a '95 Viper. The acceleration was awe inspiring. The overall look of the car, was IMHO, awesome. It looks mean and aggressive and definitely calls attention to itself, although I do find the car a little too big.

However, overall refinement of the car was poor. Interior quality was worse than on some cars that cost 1/4 of what the Viper cost. If Corvette Engineers were to develop a similar beast....refinement and interior quality were thrown to the wind in interest of developing an all out high performance Corvette, is this something you would consider for possible purchase?

I think refinement and quality need to be important on any car that is built. But cutting corners on creature comforts is fine with me, I don't need satellite navigation, power everyting, heads up display, etc, etc, just power locks and windows, a decent radio and a big tach. Make the car fast and powerfull and entertaining on the race track, you'll be too busy controlling oversteer to worry about a heated seat.

 

[zurmagus]

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.

How much weight are you ditching on your NSX and what do you mean it will win every time "side by side"?

The Corvette's 0-60 4.6s vs the NSX's 5.0s?
Compared to a z06, there is absolutely no contest - 2002 z06 hits 60 in less than 4.0s (I read one review that said they hit 60 as fast as 3.85s and the finished 1/4 mile in 12.4s @ 118, no mods)

So explain "side by side the NSX wins every time" please.

 

[Rob]

How much weight are you ditching on your NSX and what do you mean it will win every time "side by side"?

The Corvette's 0-60 4.6s vs the NSX's 5.0s?
Compared to a z06, there is absolutely no contest - 2002 z06 hits 60 in less than 4.0s (I read one review that said they hit 60 as fast as 3.85s and the finished 1/4 mile in 12.4s @ 118, no mods)

So explain "side by side the NSX wins every time" please.

Where did you read that a 2002 Z06 was tested at 3.85 0-60? The lowest I've seen published is 4.0.

 

[Tom73]

Where did you read that a 2002 Z06 was tested at 3.85 0-60? The lowest I've seen published is 4.0.

I did some snooping and found this, 3.9 0-60: http://www.supercarsite.net/corvette_z06.htm

tom...

 

[jon69]

How much weight are you ditching on your NSX and what do you mean it will win every time "side by side"?

The Corvette's 0-60 4.6s vs the NSX's 5.0s?
Compared to a z06, there is absolutely no contest - 2002 z06 hits 60 in less than 4.0s (I read one review that said they hit 60 as fast as 3.85s and the finished 1/4 mile in 12.4s @ 118, no mods)

So explain "side by side the NSX wins every time" please.

I've probably ditched close to 200 lbs so far, and my car is one of the earlier "lighter" models to start off with. Still have another 200 lbs to go, on this car it makes a HUGE difference. "side by side" well I often take both cars out with a friend and race them, basically it goes like this 1st, 2nd gear depends on who gets the better launch, but basically even, by the time the NSX hits 3rd gear it will pull on the vette strong, not blow it away just pull. I have yet to install headers, exhaust, and gears but that should bring the NSX into low 4's easy and low 12's in the 1/4. It takes the right mods and light weight to make the NSX faster, too many guys out their have big hp supercharged NSX's but they are barely faster than stock as they add weight with big wheels, body kits, stereos, etc, etc.
Stock 0-60 and 1/4 mile times vary lots on driver, conditions, the car itself. Best time I've seen on a magazine tested NSX is 4.7
0-60 and 12.7 in the 1/4mile. Which depending on what publication you use is either quicker or as quick as the C5's out there. Z06, granted, different puppy, that thing rocks... Chevy claims 0-60 in 3.9 but most tests I've read are low 4's, mind you that 3.85 is certainly possible I guess in the right conditions. I'd be curious to see what would be faster around a track, either a Z06 or a NSX-R which is the Japanese factory hotrod NSX? I know my stock NSX corners circles around my C5, but the Z06 is a monster from what I've heard.

 

[Bullitt]

The Focus

I think that magazine tests leave alot out to account for when evaluating several cars in a comparision. See the thread in the Off-Road section. To believe that they mags are not getting "ringers" is a mistake. This goes for most magazine tests. Does anyone really believe the early '60s scenario involving the Ferrari GTO vs. the Pontac GTO? I don't put much real-world faith in most of these tests.

Second, the 12.9 1/4mile that the Acura NSX, 3.2L @ 290hp pulled was the absolute best of the day, done by pros who drive test cars for a living, under a system that was originally created in a parking lot. This figure was published in Car & Driver in 1998. The average for this car is around a 13.3 in the 1/4 mile. You're talking about a mid-engine design that incorporates an aluminum body with a weight in the low 3,000s. If I'm not mistaken the 3.2L version comes in around 3100 lbs. in manual transmission form. In '97 the NSX received more weight cutting measures in stronger aluminum panels that also increased rigidity, as well as emission reduction practices. It's a car that comes standard with traction control. It also received updates in cylinder liner materials in reinforced fiber (FRM). The throttle computer software has been updated, including different software and acheived LEV staus in 2000.

What I'm trying to say here, is that comparing a $80,000 NSX to a $40,000 Corvette is really not a good practice. A mid-engine car is naturally a better handling car, (I don't really like the Acura by the way, but it's not terrible) which incorporates a lower polar of inertia resulting in better twisting capabilities. By keeping the weight in the middle it will have a better distribution of weight and center of gravity aroung an axis.

We can argue till the cows go home and out to the field again, but no one will be satisfied. The original question has been lost in this muddle. Will a DOHC cam configuration return to the Corvette platform? I think the money would be best laid on a "No." Is a mid-engine design a superior design? Yes. Does that mean that a mid-engine car will outclass a other type of car? Not nessecarily. It goes down to execution and I feel that only a small group of cars have acheived the highest standard. Do I think the Acura is one of them? No, but that is my opinion. Is the Corvette one of them? No, but again, that's my opinion. Does the Corvette need OHC or a derivative of this configuration to be world-class? No. It has been proven over and over that pushrod power is still a powerful engine whose capabilities have yet to be limited.

Another question that arises is whether all the "fluff" in higher end automobiles is necessary. There is a strong consensus among performance drivers that these are not needed and only detact from the driving experience. Is GM willing to build this car? Well, with Bob Lutz at the helm, anything is possible. However, GM has abandoned this idea before. Rob commented about the '60 enviroment in which the Corvette could be all things to all people as far as performance need were concerned. If the liability lawyers could be kept at bay, I would like to see a better over-the-counter program wherein, customers are encouraged to buy performance parts that won't void the warranty. Mopar and Ford have excellant counter programs, that I hope GM would incorporate. I've been into many Ford Part Counters where the guy behind the counter knows what you want and can give good advice for perfromance gains. I see this more of a normal thing at Ford than GM. What must be kept in mind is that the prices must be competitve with the aftermarket or buyer support won't be there. This can happen and will flourish if GM and the Chevrolet division get really serious about their racing image.

I'm sorry about the length, but hopefully it clears up the discussion some. I want to be constructive as possible when broaching the subject of the next Corvette. Hopefully, the Corvette team will hear these concerns and take them into account when considering the future of one of the greatest automotive legends in existence. --Bullitt

 

[Rob]

I did some snooping and found this, 3.9 0-60: http://www.supercarsite.net/corvette_z06.htm

tom...

Right. 3.9 0-60 is Chevrolet's official 0-60 established time, but I'd like to know where that review was published that states a 0-60 time of 3.85 seconds was acquired.

-Rob