GM DI V8s

[Epitaph]

I've been looking around for something straight from GM, but I haven't come across anything. How about a summary on the Corvette team that's using it? Any problems so far?

Edit:
Post 14 was the start of a new thread.

[DGthe3]

No info that I've heard of. If you want to check up on Corvette Racing, here is their website:

http://www.corvetteracing.com/

But as I tell everyone that mentions the 5.5L ... don't expect the next gen V8's to be the same displacement as that race engine.

There is no way they will keep the same bore and stroke as the race engine (if they do, it would probably the most over-square engine in any production car ... and certainly for any pickup truck). So if they change the bore and stroke, why would they choose to keep the same final displacement? Afterall, there is nothing particularly magical that happens when you hit a displacement of 5.5L and clearly, the ALMS rules allow you to run a smaller engine in the race car than in its production counterpart (otherwise, the ZR1 would have a 5.5L engine already). So they'd have to change at least the stroke and probably reduce the bore and change the displacement in the process. Maybe they'll keep it at 6.2L for their main line of big V8 and then have smaller ones as the mainstay in trucks. Or perhaps as I've suspected, they'll downsize a bit from where they are now and resurrect the classic 5.7L displacement to fill in for the 6.2's they use now. In any event, all we can do now is speculate.

[Kyle2k]

Originally Posted by DGthe3

No info that I've heard of. If you want to check up on Corvette Racing, here is their website:

http://www.corvetteracing.com/

But as I tell everyone that mentions the 5.5L ... don't expect the next gen V8's to be the same displacement as that race engine.

There is no way they will keep the same bore and stroke as the race engine (if they do, it would probably the most over-square engine in any production car ... and certainly for any pickup truck). So if they change the bore and stroke, why would they choose to keep the same final displacement? Afterall, there is nothing particularly magical that happens when you hit a displacement of 5.5L and clearly, the ALMS rules allow you to run a smaller engine in the race car than in its production counterpart (otherwise, the ZR1 would have a 5.5L engine already). So they'd have to change at least the stroke and probably reduce the bore and change the displacement in the process. Maybe they'll keep it at 6.2L for their main line of big V8 and then have smaller ones as the mainstay in trucks. Or perhaps as I've suspected, they'll downsize a bit from where they are now and resurrect the classic 5.7L displacement to fill in for the 6.2's they use now. In any event, all we can do now is speculate.

Square engines are good for high revving racing applications because everything is in "balance" so to speak. However, an engine with more stroke would probably be good for a street car engine due to more torque...and the nostalgia of a "350" or whatever.

[FenwickHockey65]

Gen Vs will supposedly keep the current 5.3L/6.2L displacements.

[DGthe3]

Originally Posted by Kyle2k

Square engines are good for high revving racing applications because everything is in "balance" so to speak. However, an engine with more stroke would probably be good for a street car engine due to more torque...and the nostalgia of a "350" or whatever.

For racing you usually end up with way-the-heck-over-square because it allows for higher rpm's, which is about the only way to make more power once displacement is restricted and forced induction banned (which is how most race series are). Production small block V8's tend to be a bit over square (gen IV's have ranged from 1.03:1 to 1.13:1) allowing for a balance between torque and power. Strokers are somewhat rare these days, I'm not aware of too many under-square applications, maybe diesels?

[Russell James]

I just hope they get rid of AFM in the next gen V-8s. Everybody hates it, barely improves mpgs at all... If someone buys a V-8, it's because they want an 8 cyl, not 4. Ever see one L99 Camaro owner that really likes it when it kicks in and out of 4 cyl?

Shitcan AFM!

[Kyle2k]

Originally Posted by Russell James

I just hope they get rid of AFM in the next gen V-8s. Everybody hates it, barely improves mpgs at all... If someone buys a V-8, it's because they want an 8 cyl, not 4. Ever see one L99 Camaro owner that really likes it when it kicks in and out of 4 cyl?

Shitcan AFM!

If it helps GM stay within CAFE requirements and can be tuned out - I'm fine with it.

[DGthe3]

Originally Posted by Russell James

I just hope they get rid of AFM in the next gen V-8s. Everybody hates it, barely improves mpgs at all... If someone buys a V-8, it's because they want an 8 cyl, not 4. Ever see one L99 Camaro owner that really likes it when it kicks in and out of 4 cyl?

Shitcan AFM!

Proof that it doesn't help fuel economy? Logically, I don't see how a 3.1L V4 can not be more efficient than a 6.2L V8 when cruising at a roughly steady speed? And it seems the EPA sides with GM, since they rate the L99 Camaro at 25 mpg highway vs 24 for the LS3. Same deal with Dodge on the 5.7L Challengers. And GM is doing it for the EPA ratings because they figure into their corporate CAFE score. So despite what people may claim when they tune out AFM, none of that really matters to GM.

Lastly, of the hundreds of thousands (possibly millions) of engines that have been built with cylinder deactivation over the last few years, spread across GM's lineup, the complaint rate seems to be pretty low and most of what I've heard has been limited to people who have installed an aftermarket exhaust on their Camaro or G8 and complained about the odd sound. Much more common are complaints about CAGS aka Skip Shift on manual performance cars, and that has been around for what ... 15 years? GM isn't going to abandon that either, for the exact same reason they're not ditching AFM.

[Mr Twisty]

Took a Northstar Caddy with AFM on a 90 mile jaunt, figured I'd see what I could get out of it..... 32MPG!!! And that was in the big sedan. Of course, I did drive between 55 and 60 with a feather foot.... But still, that's amazing!

[ljstella]

Last I had heard the new generation of V8s would include multiple displacements ranging from 6.2 or so down to 5.0 or so. I think I had read that on here awhile back, in an article.

[THE EVIL TW1N]

Originally Posted by DGthe3

....Production small block V8's tend to be a bit over square (gen IV's have ranged from 1.03:1 to 1.13:1) allowing for a balance between torque and power. Strokers are somewhat rare these days, I'm not aware of too many under-square applications, maybe diesels?

the new 5.0 is undersquare and the 5.4 found in the Ford GT and GT500 (and any Ford 5.4 for that matter) are WAY undersquare but rev pretty damned well.

on the other end of the spectrum the big lazy 460 Ford was way oversquare with its 4.36x3.85 (1.13:1) but is known more for tq than its revving capabilities

[Russell James]

Originally Posted by DGthe3

Proof that it doesn't help fuel economy?

My '09 Silverado 5.3 was averaging in the mid 15's mpg. I turned off the AFM with a hand held tuner, no other changes. DIC still said mid 15's months later with the same driving habits. Only no more annoying kicking in and out of AFM.

Proof that it is problematic - bulletin 10-06-01-007C. It covers 5 model years, 26 models, and 10 engines. I've seen many people on here having to go through a lifter replacement on their L99's. Not a happy sight to see your new car tore down to the block in the service dept.

[aldaron327]

Originally Posted by Russell James

My '09 Silverado 5.3 was averaging in the mid 15's mpg. I turned off the AFM with a hand held tuner, no other changes. DIC still said mid 15's months later with the same driving habits. Only no more annoying kicking in and out of AFM.

Proof that it is problematic - bulletin 10-06-01-007C. It covers 5 model years, 26 models, and 10 engines. I've seen many people on here having to go through a lifter replacement on their L99's. Not a happy sight to see your new car tore down to the block in the service dept.

I've been there. I've had my lifters replaced twice and my cam once on my 5.3L '09 Silverado. It only has 45,000 miles on it (99.9% highway). If it happens again, I'm getting rid of the truck. I know I'll take a loss on it, but I'm tired of having to let it sit in the service department for several days at a time.

[LostInMoscow]

Anybody have any "solid" information on how the GM DI V8 program is developing? I can't find anything other than speculation on the web. That program is going to be the key to GM's future. I'm really looking forward to seeing the numbers on the production engines CI, HP, Tq, weight, etc.