Kjdad

Just wondering at what point to too much power for a C4 chassis..stuff like axles and rear-end.

I've dabbled in the idea of picking up another C4. Most likely a basket case missing an engine and putting in the all aluminum ripper of an LS I have on an engine stand. Do a 6 speed swap... That motor is 650 hp without leaning on it very hard.

At what point does the drive train and frame say no thanks in these cars?

Whaleman

I think when the experts here attempt to answer your question they will need more info. Like 650 HP with all STOCK drive train? How would the car be used? Do you mind changing rear bearings every year? Would you upgrade to the stronger 44 rear end? Would you have custom steel halfshafts made? What tires are you planning on? Questions like these. Dan

AftonJay

For drag racing or track days or just street.

Kjdad

Street..sticky tires..stock as possible drivetrain.

96GS#007

Define sticky tires. Drag Radials? Nitto NT01s? 200TW high performance street tire?

Kjdad

200 or less tw street tire.

96GS#007

I'll also add that 650hp on the street will likely be fine. Driveline shock and torque is what breaks things, not hp. If you have 600lb/ft of torque and you're planning to side-step the clutch every day, the life will be short. If the vast majority of the time is rational street driving, you'll be fine.

The weak link in a C4 is the frame. It's a wet noodle so the handling, while great for its time in the 80s with 250 or less hp, doesn't match up to modern cars.

Gale Banks 80'

I did 6 Autocrosses last year with a 400HP SBC and all stock Dana 44 components with 315 Hooser Slicks. I drew straight lines on my 1/2 shafts to see any twist and they have not. Another club member has a 468 CI SBC in his and has broken every drive line aftermarket part ever made and ended up using a 9" axel. I think with even the best Street Tires your going to be OK by just using Solid U-Joints and nothing more.

FAUEE

You'll have basically no grip with that sort of power level in a narrow body C4, but you're not really gonna break anything.

Despite what people will say, the C4 frame is quite stiff, not as stiff as the newest ones out there, but FAR from.a wet noodle. You're not gonna twist it or anything like that.

That said, 650hp crank in a C4, C5, or narrow body C6 will have no traction. A C6 widebody would struggle with that level of power (stock ZR1s struggled to put less power than that down). Especially on the street, on 200TW tires, you may as well forget about it having any sort of street manners.

96GS#007

I will freely admit that the definition of wet noodle is subjective. However, the C5/6 chassis was 4x the stiffness of the C4 and the C7 is 60% stiffer than the C6. That's a HUGE difference no matter what you want to call it. It's also the reason, according to Tadge, that the C7 Z06 and ZR1 were able to have targa tops and convertible models at their power levels.

At those power levels, you'll feel it in a C4. I did in mine at >500whp

Kjdad

What crazy is that my bmw 550i chassis making about 550hp and 650 tq handles it without drama..lol..modern chassis that's engineered well.lol

FAUEE

The C4 chassis is also 40 years old at this point. I would hope they'd figure out how to make a chassis stiffer in that time, lol. It's still a chassis that pulled a g on a skidpad.

The c4 chassis is stiff for its time, and plenty stiff enough to handle well at the power levels it existed at. You put 650hp.in it, and you're gonna have a bad time.

Phobos84

There have been several people here who have broken the aluminum half shafts. I also remember seeing a pic of a broken factory drive shaft. So I replaced all of those in my 84 with forged 1350 steel from Action Machine. I have a 500 hp LS now with a 4L80e. Ill be punishing it with a 200-250 shot of nitrous this summer so I guess I'll see what I break.