RapidC84B

The latest batch of rumors is that the C8 is having frame twist issues with the "1000 horsepower variant". Where is this car? Everything we've seen testing has sounded like an updated LT probably a new LT2 as many assume. I would assume the 1000 horse variant would be a twin turbo Blackwing derived motor with electric assist front drive. Does this car exist already? Also, everything we've seen has had relatively mundane wheels/tires/brakes. I would expect this monster "Zora" model to have a widebody, large tires, and fancy brakes. Hard to do powertrain testing on the 1000 HP model if you don't use the correct sized tires to test chassis loading.

Any production engineers or powertrain engineers have any insight on how they might be testing the hi-po variant at this point? Is this real-world torture testing or theoretical computer modeling stuff?

84 4+3

We do lab testing for 1-3 years before real world testing so... it is possible they are just modeling it on a computer at the moment. If 1000 hp can infact cause problems like they claim... I'm curious what jacking the car up could do as well. I'd guess the problem is more along the lines of harmonics than actually physical bending of the frame though. Sort of like the C4. The frame isn't inherently weak, the problem is more that the presented loads hit frequencies where the frame bounces. I'm not a mechanical engineer so that is roughly the limit of my physical properties knowledge. It has also been a while since I've needed to discuss those things so bear with me. The most I deal with is stress strain and yield so.... that there is my theory.

Edit: stiffness. That's what I'm getting at. The frame may not be as stiff as what we are used to over the last few generations.

68RPOL71

perhaps that's a reference to the "C8-R" we have briefly seen testing? I doubt any of the "mules" on the road are this, as you mentioned, Wheels and Tires don't fit.

RapidC84B

The C8R is just that... the C8R... built by Prat & Miller and being tested for the 2020 IMSA season. Doug Fehan talked about the car at the bash last year much to the annoyance of Harlan Charles. He issued a statement after the bash walking back his comments and talking up racing the C7 again for 2019. Plus, those cars have under 500 horse.

Mikec7z

1000hp with turbos makes less noise than a stock c7, via its exhaust note. Turbo whistle is nothing overly pronounced with small twin turbos either.

The front end of one of the c8 with the camo pulled up, and it has the zr1'esk intakes on each side of the front.... there is your car right there.

vndkshn

To me, at least one of the videos of the cars driving on the street sounded like it had turbos. Could just be a weird audio illusion of course.

They could be testing one just on dynos at this point as well, meaning it may not have been visible to the public yet.

Mikec7z

and the reasons i say what i say with such conviction, a couple of my friends and I, we all had 1000hp c6 zo6. so larger v8, twin turbos, 1000hp, and our cars were quieter than stock z06 at the time.

So, IF you consider GM is running an even smaller displacement engine now (regardless if its the LT1 or the 5.5 with overhead cams), their car SHOULD be even quieter than mine was.

You will not hear a thing.

Same problem ferrari had with the 488, they had to TRY to make it be heard, turbos silence the exhaust big time.

RapidC84B

None of the mules have had the tire width for a 1000 horse car IMO. Now if they have electric front drive and a really fancy TCS I could maybe see it, but I doubt it.

RJ-92

Along with full competition roll-cages. The race cars aren't lacking for stiffness.

Mikec7z

the 1000hp car is not going to be released in the first year. If you are GM, you dont want people looking at it and saying "wait, whats that? I want that! Ill wait for that!"

long story short... you are correct, GM is not going to flare the rear fenders and put an inch wider tire on the back of the car, during initial testing, just so that you can postpone purchasing a base c8 or a c8 z51.

Rest assured... they have cars with OVER 1000hp being tested as we speak. Even if the car is not released with that power, they are testing for that power, to see where the fail points are, so they know what they are dealing with and what they have.

ArmchairArchitect

Probably just testing this variant on a track for now. It's likely not going to be a Year 1 car. As it gets closer to release (Year 2+), it will probably be seen on public roads.

Mikec7z

keep in mind, tubos, while they do not put high temp air into the engine if the air is ran through an intercooler, that intake air will be cooler than the top mounted blowers incoming air temps....

but turbos DO radiate MUCH more heat into the engine bay.

That means on the 1000hp car, they also have hot pliable metal car frame surrounding the engine instead of colder rigid metal.

JoesC5

I'm guessing they are testing at the Yuma, AZ compound that GM shares with the US Army. That compound has a non fly over restriction in place. It is highly restricted from those that grab "spy" shots of mules on city streets.

RapidC84B

That was my next question. We saw early acceleration testing of the C8 in what was apparently "standard" configuration, but we've seen nothing of this monster. That's probably where they'd test it to keep it under wraps.

Zaro Tundov

Yes, IVERs would have been built of all the planned model variants. No, they're not on public streets. Right now the focus is to validate the base model, with all the newly engineered fixes, for production.

The bit about cracking the rear glass seems fishy to me. Could be a marketing tactic. What better way to sell a supercar than start a rumor that the engine is so powerful it breaks the windows and twists up the frame? It's like a scene straight out of Hollywood.

RapidC84B

The "frame issue" came up awhile back as a rumor and now it's making the rounds in a little more official manner so I'd wager it's real. I agree that cracking the glass seems odd. The rear hatch should have enough "float" relative to the rest of the body to avoid that, but who knows.

Warp Factor

The sound of a turbocharged engine without mufflers is pretty hard to differentiate from a N/A or supercharged engine with mufflers.

Some people are scammed so easily.

Mikec7z

again, i dont think the glass is cracking from the cars power, i think they cracked glass early on with heat changes... hot engine, hot glass... downpoor of rain or guy taking a hose to his car to wash it...

or opposite, cold, snow and ice on glass, engine warms up, and heats the glass (much hotter than a cars defroster vents do) and all the sudden extreme heat on one side and melting ice still on the other, and crack.

Thus, i believe GM needed to put the suspension mechanism all the way around the glass to allow it to move and expand contract as it wants to do, and can do so freely, AND also lessen the heat of the engine on that glass, which is why that suspension is also a vent, which also lets cool air in around the glass.

I believe that has already been solved long ago. I believe now they are having issues with frame bending, or rear diff/trans/engine breaking from each other, as GM is NOT used to what happens when the back tires DO hook up.

And the reason I have no sympathy for GM, is ALLL of this could have been avoided, very early on, if they just threw a derestricted LT5 in the car, and went out and saw what it breaks first. Then you INSTANTLY reinforce those areas, and then you go back out with the 1000hp and torque LT5, and you go try to break it again, and again.

Instead, what we have are "genius engineers" who think they are going to account for every possible real world scenario in their math equations, and cad simulations, and thus they know EXACTLY where the limits are and are going to design just above... "will you please pass me my white gloves, i have math equations to look at. This is why GM hired me, im really great at math and looking like im making big breakthroughs"... and they dont have a boss who keeps them in check... just like he did not keep them in check when testing showed the cars overheat on the c7s. We have engineers, not saying "yeah, our design sucks, we need to fix it" instead we have engineers attached to their work saying "well yeah, but people should not drive their cars like that, my design is very well thought out, and if it fails it is someone else's fault for being abusive"

they need a guy in there who says "i dont care what your equations say, or how long you worked on it, or how much your mom says your ideas are the best, its broken, now we fix it, and if you cant fix it, find another job"

The amount of time GM spends "talking about problems and how expensive they will be to fix"... that same time could have been used to fix the problem.

And this is why I have zero sympathy for Tadge. Testing a new car and a new frame and a new transmission and rear diff (transaxle) is common sense... big torque... go try to break it. Make it strong where it cant be broken with big torque. okay, now we put the smaller engines back in.

This IS TESTING that should have happened 3-4 years ago, as soon as the lt5 was conceived, and whatever their "transmission" is that they plan to use, would have also existed at that point. Both should have been in the car, and if they need a guy to show them how it breaks, and such a commodity is rare, im for hire

But if you tell any of that to Tadge, he will talk for 10 minutes about how his way was better, and this is all unforeseeable, but they are super humans since they managed to find it now, and its all going to be fixed at the fastest possible rate since they are geniuses.

This is not brain surgery.

RapidC84B

I agree with you on some of that. I can see younger engineers, "But my modeling says it should be good!". Build it, go try to destroy it.

That said, we have no idea of the timeline of any of this. Maybe the frame issue came up early and has been long fixed and the electric issues are the current delay issues. It's all conjecture at this point.

Mikec7z

i dont think GM will tell us if it is the frame issue or rear end issue... but I will know once i see the fine print when the first broken transaxle claim comes through a dealership, and then GM says "oh, this was due to abuse"

and we will also know, if the 0-60 times are lacking, and also know when the OBD readers that tell TB blade position etc tell us how much they are holding the engine back in first and second gear.

I think they are breaking rear ends. And I think that is being kept secret. I do believe there is an electronics issue, and that I forgive... that stuff is getting very complicated, its understandable they might have issues with it.