GM DOHC plans, shelved in '08

[1989ZR1#74]

Originally Posted by Aurora40

Hmm, sounds like the guy deserved to get some flak if he was doing that at a ZR-1 event. That seems typical though... Incapable of giving credit to some older approach, all they can do is tout the latest and greatest.

Please, in no way was he putting down the LT5. There was no attempt to offend the ZR-1. They were just answering questions about the new LS(X) -vs- the DOHC Ford platforms. They gave plenty of credit to the "older" approach. The whole weekend was filled with that including some of those guys almost in tears talking about our Zs. Do not read more into this one single 2 minute span of time then need be.

[XfireZ51]

Originally Posted by 1989ZR1#74

Please, in no way was he putting down the LT5. There was no attempt to offend the ZR-1. They were just answering questions about the new LS(X) -vs- the DOHC Ford platforms. They gave plenty of credit to the "older" approach. The whole weekend was filled with that including some of those guys almost in tears talking about our Zs. Do not read more into this one single 2 minute span of time then need be.

Have to agree with Eric. The Gathering was clearly an event commemorating a truly unique car and powertrain. I think the ZR-1 legend will gain momentum from this point IMO as we view it from an expanding historical perspective. A brave band of people took on a corporate structure in order to build a truly marvelous car. The Gathering was as much a tribute to them and their effort as it was a tribute to the car.
Sometimes I wonder if they are surprised at how these motors and cars have been modified over the years to levels maybe even they hadn't anticipated.
I gotta think that they must view the strides Ford and others have made with the DOHC config with a touch of sadness. After all, this could have been them and they were there 20 years ago. So the Gathering must have provided them with both a rush of pride but also some slight bitterness. That would help explain some of the "defensiveness" re: the move towards the LS OHV config.

[Aurora40]

Cool, glad to hear that wasn't the tone the corporate guys were using.

I don't quite get the Ford thing, though? Ford hit 400+hp N/A in 2011. GM did it in 2002 with pushrods (and 1993 with cams). Ford isn't setting any bars, though they have improved a lot with the 2011 model.

Their V6 is no more impressive than GM's, but the Mustang is much lighter than the portly Camaro, so it gets better economy numbers. The Mustang GT isn't showing the 'vette how to make power and economy.

[Meanmyz]

Originally Posted by 1989ZR1#74

Please, in no way was he putting down the LT5. There was no attempt to offend the ZR-1. They were just answering questions about the new LS(X) -vs- the DOHC Ford platforms. They gave plenty of credit to the "older" approach. The whole weekend was filled with that including some of those guys almost in tears talking about our Zs. Do not read more into this one single 2 minute span of time then need be.

I was right there in line with most of you guys, and I have to agree with Eric. I don't think there was any attempt to offend us ZR-1 guys. Inherently, there are advantages to both designs. We know that. The "marketing guy" who made this comment is first and foremost a Corvette guy and I don't think he is anti-LT5. His answer was moreso as to after LT5, why LSX and pushrods was the direction taken.

For the cost, simplicity, and volume of Corvettes and other cars that have shared the LS engines since LT5, I think he was expressing his "strong" opinion on why that was the way to go. Also the ability of "Joe Public" to be able to afford and service the car is another reason.

Can you imagine if every car beginning with C5 was DOHC? Our cars might not be so special or unique. It is kind of nice having something like that. And if GM started building it again, I think it would be kind of nice if it was for the "Z" orientated Corvette crowd.

Yes, I can only imagine what kind of DOHC Corvette engine we might have if GM continued to develop it. To me, the LT5 is "the crown jewel", the "Rolex" of Corvette engines. Knowing that our stock 20 year old 350 ci. LT5's can make 500 HP with only porting, I can only imagine what we could have done with today's engine management software technology and "state of the art" DOHC design.

I'll tell you this, I am sure the new ZR-1 would have more HP and wouldn't need a super charger!!!

But in the end, why would there have been the need when they have much more cheaply been able to offer 400, 505, and 638 HP? In 1985, DOHC was exactly what it was going to take to advance on 230 HP. If we had never had the LT5, I wonder if we would be as far as we are now?

From an earlier comment, I hope Corvette isn't ever saddled with a V6, but if Corvette is ever forced into smaller displacement, then a DOHC may still end up on the table in the future, if we are to hold onto higher HP. ??

[rkreigh]

from a cost, efficiency, and power to weight, it's pretty hard to beat the LSx platform. it's small, light, torquey, and most of all CHEAP (read profit margin) to produce

but there is an engineering limit to how much more they can go

don't get me wrong, I've got a nice LPE LSV ZR-1, and a TT 203 Z06 so I support all corvettes, and love the old BB and LT1 cars too

but here goes,

the advantages of DOHC and variable valve timing are clear. the new ford engine competes very favorably from a cost, weight, HP (clearly more per liter) with the LS3

the 5.0 engine isn't "heavy or inefficient" and I agree that the GM marketing guy needs to tout the advantages I listed above

the future however (as shown by most manufacturers, all those engineers can't be wrong) is likely to go DOHC, direct injection, smaller more efficient displacements, and higher tech to meet the emissions, mileage and emissions challenges of the future CAFE

GM needs to go back and "dust off" those designs that shelved due to the bankrupcy thing, and bring them forward into production to remain competative

nascar has pushrods because of the rules, not many other race cars do

the advantages of DOHC are there, they just don't come cheap

I happen to like a torq monster with a very broad power band, and a variable valve timing DOHC cam engine makes that a bit more realistic IMHO

the LT5 was about to roll out that technology, and pick apart that new 5.0 DOHC ford, it's not bad

[Paul Workman]

Originally Posted by Aurora40

Cool, glad to hear that wasn't the tone the corporate guys were using.

I don't quite get the Ford thing, though? Ford hit 400+hp N/A in 2011. GM did it in 2002 with pushrods (and 1993 with cams). Ford isn't setting any bars, though they have improved a lot with the 2011 model.

Their V6 is no more impressive than GM's, but the Mustang is much lighter than the portly Camaro, so it gets better economy numbers. The Mustang GT isn't showing the 'vette how to make power and economy.

I think the point is the power per cubic inch...is more to the point and an example held up for comparison. As fuel economy standards increase, and should cubic inches have to be reduced, then more output per displacement is a requirement or at least very desirable.

Using the 5L Coyote as an example, it is making 412 hp or approx 82.4hp/L. The 5.7L LS6 makes only 86% of that per liter, the 6.2 LS2 makes 78% per liter, and the 6.xL LS3 makes 84% of that made by the 5L DOHC Coyote.

And, we often get hung up on "peak horsepower" numbers and disregard the "power under the curve". As anyone that has hammered the red line of an LT5 knows, the power curve is sooo much wider and flatter than those others - LT5s making significantly more power "under the curve" than characteristic of (past at least) 2-valve push rod motors.

Plus, there is the "gee wizz" factor of the DOHC that intrigues "some" of us as well. Something different. I just don't see me buying any supercharged ohv V6 Corvettes...ever. But that's just me.

P.