frankcfalco

Hi everyone,

Total newbie to C4's. I own two C3 corvettes, but it will take a lot of work and $$$ to make a C3 competitive with a C4 for autocross. That being said, what year C4 with the 6 speed (non Doug Nash) would be the LEAST reliant on computer control or dependence. I'd like to install a 450hp crate motor. Can this be done to any 89-96 C4? The state I live in has no restrictions on emissions. So that is not a concern in terms of Cats etc.

Thank you in advance,
Frank

flannel_man

For autocross the engine isn't as big of a deal as the suspension.

Hands down a 84 Z51 for that use/build category, since you plan on tossing a crate motor in anyway why not toss the cross fire that gets complained about by non owners the most

Most auto cross events you'd be in 2nd or 3rd gear the most anyways

frankcfalco

I've heard that the 84 has the stiffest stock suspension. Any concerns about the 4+3 Trans? I understand the 4 part is just a T10, and the overdrive is the +3. So for racing I would never be past 4th even on an HPDE day. So I guess I can just not have the OD engage?

CA-Legal-Vette

If the overdrive unit is working properly and depending on the track, you may not have to shift at all once you get off the line. A high revving motor might help too. If the overdrive doesn’t work (or if you choose to disable it) you have a nice T10 four speed.

95wht6spd

I would think a lot would depend on what category you want to be in?

frankcfalco

Looking to run it in CAM-S

Gale Banks 80'

The 84-7s have the best Front suspension design for cornering. The 89-96 have the best ZF trans as you already know. The 84 manual Trans cars use the weaker Dana 36 rear ends. The 88's use front shocks of their own and can be hard to find aftermarket. The earlier Digital Dashes are easier to work with an aftermarket ECM (Holley etc.) The ZF Trans is not hard to swap into an earlier car. And the earlier Front Suspension can be swapped into a later car. (although very few bother) So, they all can be made to work. If I was forced to pick a winner, I would go with an 89 with the ZF trans, last year of the Digital Dash, and swap in an earlier front suspension. But I would also point out that the worst worn out C4 with the best driver is going to win out over the best prepared C4 with a novice driver every time. I consider the C4 one of the best user-friendly Autocross cars ever made. Pop the Hood and everything is easy access. I would definitely shop for a Manual Trans Z51 Car. Swapping a manual trans into an Auto car is a labor of love. Putting Z51 suspension in one without will break the bank.

iceman2003

The Super T-10 (4+3) was used in the Callaway Twin Turbo Vettes in 88', they produced well over 562lbs of torque and I believe even stock they can handle 600lbs along with the Dana 44 8.50 inch rear gear assemble...
a modified one which runs E85 made 560hp (475-whp) and 700+lbs (606lbs-rwt)... 85' to 88', vs the 89' to 91' ZF 6spd...

frankcfalco

Hey you still have your 95 C4?

dizwiz24

I didnt think manual 4+3 was an option until 1985

flannel_man

If that's true I'll put my '84 Z51 4+3 up for auction rapidly. Opening bid, $100k
DON'T LOW-BALL ME, I KNOW WHAT I HAVE!

Gale Banks 80'

ABS wasn't available till 1986. Maybe that's what You were thinking.

iceman2003

The only difference is that the 84 4+3 only came with the Dana 36 rear, 85' to 96' manual cars all came with the Dana 44...

frankcfalco

Thank you all for the good info and detail! I have an idea for the Car now. Thank you all again for the quick replies.

turbo6inky

You have to answer a question:

"Do you want to win or are you just having fun in a parking lot?"

If you just want to have fun, make your car mechanically sound and go have fun in a parking lot.

If it's the former, I hope you're financially secure, good at budgets, and patient.

iceman2003

I wholeheartedly agree with you statement... life is short enjoy it the mechanically sound fun car may be the best way to go.... most of us are financially challenged to fund a winning car/campaign... "how fast do you want to go? how much money do you have"... true-ism!