GM DOHC plans, shelved in '08

[tpepmeie]

Picked this up on another forum. I have no way to confirm it, but if anybody else has contacts in GM it would be interesting to ask them...It would appear the "LT5" designation was set for a comeback. Too bad the economy tanked and GM went bankrupt. Maybe someday.


2012/2013 DOHC plans that were cancelled/shelved in late 2008.


LT5 was to replace LS3
6.2L DOHC
500HP @ 6500RPM
500lb-ft @ 4400RPM
Direct Injection
Displacement on Demand hardware
Cam Phaser
376 cu/in
11.0:1 C/R
11mm Intake valve lift
41mm Intake valves
Steel Crank.


LT6 was to replace LS7
6.2L DOHC
600HP @ 7500RPM
550lb-ft @ 5000RPM
Direct Injection
Cam Phaser
376 cu/in
11.0:1 C/R
13mm Intake valve lift
41mm Intake valves
Steel Crank.


LTC was to replace LS9
6.2L DOHC
700HP @ 6500RPM
700lb-ft @ 4400RPM
Direct Injection
Cam Phaser
376 cu/in
9.0:1 C/R
Supercharged + Intercooled
13mm Intake valve lift
41mm Intake valves
Steel Crank.

[USAFPILOT]

That would be cool...but it is just a dream

[Aurora40]

There was definitely a plan for a Northstar replacement, and they did shelve it around 2008. I believe the target was more Cadillac than Corvette

[Ccmano]

Direct injection, generally with DOHC, is the latest generation of production engines. Great fuel economy, power and low emissions. Just look at the Hyundai 4cyl in the new Sonata doing 30+ mpg and 200 hp or the Ford and GM 6cyl @ 30mpg and 305hp. Currently only Mercedes, BMW, Ferrari and Jaguar have DI V8's, with power in the 450 to 600 hp range. 500hp should be the benchmark. GM will make the move, it will just take a little longer. Heck, I can still remember when Corvettes barely had 200hp. (yes I'm old:rolleyes:)
H
:cheers:

[Paul Workman]

Direct injection, generally with DOHC, is the latest generation of production engines. Great fuel economy, power and low emissions. Just look at the Hyundai 4cyl in the new Sonata doing 30+ mpg and 200 hp or the Ford and GM 6cyl @ 30mpg and 305hp. Currently only Mercedes, BMW, Ferrari and Jaguar have DI V8's, with power in the 450 to 600 hp range. 500hp should be the benchmark. GM will make the move, it will just take a little longer. Heck, I can still remember when Corvettes barely had 200hp. (yes I'm old:rolleyes:)
H
:cheers:

At the round table discussion at the end of the GTG at Bowling Green, our Dominic told me he asked them why after spending the money to develop the LT5 (which was at the heart of the celebration) did they go back to a 50-YO technology?

Dom told me one of the GM people got flippant and responded with (in effect), "If I can beat you, I don't care how many cams I have!"

I wasn't there, and maybe that's a good thing. That comment pissed me off!!. I've long harbored the feeling that it may have been expedient and cheaper to go with the LS, but in the long run, it was a mistake to shelve further development of the DOHC design. GM my find themselves in a game of "catch up" when they had the gold ring in there hand and talked themselves into giving it up!? Case in point: Look a the performance of the new 5.0L 4-valve, DOHC Coyote. They're at 412 hp N/A and haven't even begun wringing out the performance software yet. Do we have to discuss the Hondas?

In the future, it is going to require even greater performance - in spite of tighter fuel efficiency and emissions standards to keep Corvette in the hunt. I just hope GM/Corvette has not squandered the opportunity to have been further developing the DOHC by being distracted with 50 year old push-rod designs. Sooner or later going to the CID well is not going to be the answer, methinks. Others seem to have taken the hint...Just not GM, apparently! (I hope GM has a garage similar to Pete's Skunkworks where super secret-squirrel stuff goes on out of the glaring eyes of the masses!:mrgreen: (Big inch LT5s anyone?)

Rant off (sorry)

P.

[Polo-1]

I was there for that "If I can beat you, I don't care how many cams I have!"

They were very touchy about their ohv motor. :rolleyes:

:worship: the LS motor. whatever

[XfireZ51]

I was there for that "If I can beat you, I don't care how many cams I have!"

They were very touchy about their ohv motor. :rolleyes:

:worship: the LS motor. whatever

Well based on Todd's posting maybe now I can understand why!

[FU]

The renewal of the DOHC LTX platform would have been a nice booster shot for us , no doubt.

GM = :sleepy1:

[ZR1Vette]

Neither condemning nor defending GM...I too was at the session where the question/reply comment was said. Yes, GM/Corvette are strong advocates of the LS series engine and I can understand why. For the size of the engine package it produces more HP (LS2/3/7/9) that anything out there. It is a tried and true engineered design, allows for low profile cars (thus helps in the Cd area), is lighter than its DOHC counterparts (look at the LT5 and the Ford V8s for size, mass and height...thus why the Mustang looks like a brick compared to the C6) To wit>>
http://i17.photobucket.com/albums/b79/MRBLU/C6GT500Frontal.jpg

LS engines have technological growth potential... direct injection, variable cam timing, DOD, etc. So for now the LS family (and its future variants) makes sense to me...but they too will go the way of the dinosaur as the V8 becomes history and high performance V6s begin to reign.

Oh...there were several comments by the GM folks beyond "If I can beat you..." talking about several of the items I note above...particularly overall package size and weight considerations. Of course just my opinion...

[1989ZR1#74]

Well before you throw the Powertrain guys under the bus it was a bit of an affront to them. The tenor of that comment was basically

"How could you let the blue oval beat you in tech?"
"They have a cool DOHC motor and you have push rods?"
"Don't you think your design is behind the times?"

Then the "don't car how many CAMs comment." THen they went on to explain packaging and how the OHV engine is not by any means low tech.

Basically the their right. They will blow the doors off the DOHC ford...

[scholtmj]

Well before you throw the Powertrain guys under the bus it was a bit of an affront to them. The tenor of that comment was basically

"How could you let the blue oval beat you in tech?"
"They have a cool DOHC motor and you have push rods?"
"Don't you think your design is behind the times?"

Then the "don't car how many CAMs comment." THen they went on to explain packaging and how the OHV engine is not by any means low tech.

Basically the their right. They will blow the doors off the DOHC ford...

True, they might have felt the cold shoulder but they were stepping into the lion's den of DOHC Chevy guys. They should expect passionate defense of a motor GM stopped supporting.

[jimmac28]

Where is the best push-rod technology, just have to look to NASCAR, 850-900 hp @ 9500 RPM from a carbureted 358 cubic inch motor. So there is some room, but to get the SB to 500 hp they had to throw cubic inches at it and that?s what Corvette has been doing, nothing special they are doing what Hot Roders have been doing for years.

Where should the 350 cu LT-5 be if left in production, easily 475-500 hp that fit?s in a C4 an is as dossal as Buick. I don?t think engineering had any thing to do with the end of this engine. It had to be all marketing and the bottom line boys, why should we spend on engineering when we can BS everyone.

And remember the LT-5 is late 1980?s technology just think where we would be 20 years later.

[DMark]

.... And remember the LT-5 is late 1980?s technology just think where we would be 20 years later....
Where Ford is with the 2011 Mustang - - - 5.0 DOHC with 412 hp. ;)

[DaveK]

I think it was pretty hilarious when the guy made his "if I can beat you" comment. Yeah, you can beat us, by adding considerable eaxtra cubic inches and having 20 years of technology and engineering refinement.. yep, you can really beat us...

Also at the JVD BBQ, didn't the last speaker say in his slideshow that they had already done the engineering on how to fit the LT5 in to the C5 package?

It was the bean counters winning yet again. Dave M as much as said so. The LS series was cheaper because they could share it with the trucks, standard cars and other assorted farm vehicles... which is why they never achieve the legendary status that the LT5 has.

You don't see Ferrari putting truck engines in their cars, or Porsche or any of those other super cars!

[Aurora40]

You don't see Ferrari putting truck engines in their cars, or Porsche or any of those other super cars!

You do see both Porsche, and especially Ferrari, going to the same displacement well, though.

The performance of LS equipped Corvettes has been impressive. And it was suitable for cheaper cars like the G8 and even Impala.

Would it have been interesting to see where the lt5 program would have gone? Hell yeah. But was going LS the wrong move? I'm not sure how anyonecan look at the cars to date and say so.

Abandoning the DOHC V8 altogether though, yeah I too think that will bite them. I don't see how Cadillac can hope to run with the big boys without one.

[Aurora40]

http://www.insideline.com/car-news/gm-drops-plans-for-new-dohc-v8-engine-in-2009.html

[LGAFF]

Well, dumping the program keeps our cars unique to the breed.

[Locobob]

The guy on stage who was most vocal about touting the LS motors was not an engineer but a marketing guy, I can't think of his name off hand. I talked to him a bit more while waiting in line for a poster and he was rather adamant in his support of the choice to go with pushrods instead of DOHC.

[XfireZ51]

BTW, we were all there to celebrate an historical event which involved Chevrolet, Lotus and a DOHC motor. I didn't hear guys like Graham Behan rushing to the defense of the OHV technology. My question was prefaced by an observation about how young people KNOW about the LT-5. They know about it more than most other Vette guys. They are the future of Corvette and they have grown up on OHC configuration. What I asked is what do the guys in Dearborn know that the Warren guys don't or vice versa. Frankly the story of the LT-5 isn't much different than some other firsts by GM. We've seen them abandon efforts just as they were getting it right. Then somebody else comes
along and picks it up making it their own. The LS series is a marvelous piece of engineering and packaging. But let's not kid ourselves. It was built to power trucks and not high horse high speed supercars. It's the formula that makes Corvette a great bang for the buck BUT, it won't capture the next generation which it needs to do in order to continue on. That was my point. I've worked in
marketing most of my life. I have done strategic
and product planning. You're either a leader like Apple or end up with Zune.

[Aurora40]

The guy on stage who was most vocal about touting the LS motors was not an engineer but a marketing guy, I can't think of his name off hand. I talked to him a bit more while waiting in line for a poster and he was rather adamant in his support of the choice to go with pushrods instead of DOHC.

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.

[1989ZR1#74]

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]

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]

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]

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.