I have a 1985 350tpi vette thats currently my project car i want to make about 500hp off the stock l98 thats in it my fear is that the base automatic transmission wont like that very much im willing to slowly build up but i dont know what to get as of right now im thinking about just starting with headers and exhaust the goal is 500hp with room to either run nos or supercharge down the road

 

Supercharge right off the bat....500 hp from a 2 bolt main 350 isnt worth it.
heads intake complete exhaust go in the trash
It can be done but too much $ and may as well go 4 bolt for a little longevity...it wont idle for crap youll need lots of gear etc

Is a number so important?

 

You would be better off transplanting one of the newer Corvette engines than to stick with the L98 block. You will have to have a good transmission shop build a transmission that will hold up to that HP. HP cost $$$$. Do your homework first. One of the issue you would have is that as soon as you change the cam in the L98 block you will have to have a custom tune. There are not many tuners that still work on C4 computers.

 

sorry im really new to all this... im not opposed to buying a newer engine and trans but if im going to spend more on a new engine t
and trans will i be able to achieve that 500hp goal easier? If so what do you recommend

 

LS swap. Not easy but that's what's implied here.

 

How much are you willing to spend? You will need to freshen up the short block, fluff the heads, intake, transmission, change the rear end to a Dana 44 and custom tune. So, how much money you got? Who do you know that can tune a C4 on a dyno so you don't have to "guess a tune"?

 

Where are you hoping to make that 500 horsepower goal? At the crankshaft? At the wheels? Why that specific number? A small block Chevy can make that power level but it will cost you. You'd need (at a minimum) heads, a cam, a better intake, tuning, and it would be wise to build the bottom end and go with 4 bolt mains, preferably splayed mains so it survives. A supercharger or turbocharger (there are supercharger kits, no turbocharger kits) would make it pretty easy to exceed that number. You will also need a larger fuel pump and larger injectors to support that power plus a proper tune if you expect it to run. Idle quality is going to suffer at those power levels.
My 85 is turbocharged and my goal with the next build is 500-550 horsepower at the wheels. I realize that power will have its own challenges and compromises with driveability. I could easily surpass that power goal with an LS if I chose to go that route.
The LS will easily reach that power, possibly cheaper. How much work do you want to do? Getting an LS in a C4 will take some work, especially if you want to keep your air conditioning. There are a few threads here of people getting that done. I believe DMITTZ is currently in the middle of a swap right now. It's a lengthy read, but I'd find that thread. Lots of info there.
The 700R4 in your car will have to be properly built if you expect it to survive with much more than stock power. You'd also be wise to upgrade the rear to the Dana 44.

 

500 crank or 500 wheel? 500 wheel in a C4 without NOS or Forced induction will probably make it borderline undriveable with a Gen 1 SBC. 500 wheel pushes you to more LS swap territory, where, because of the LS heads (primarily), its easier to make crazy numbers. Still might be a handful on the street but easier to make the number if the number is the goal, you just have to deal with the electronic swap headache.

85 being unique with the ECM may also push you to that as wheel, its just more difficult to tune, but it can be done.

500 crank is about what I have, 398 with a SuperRam, AFR 195 heads, Crower cam. That is more doable, pretty streetable if tuned well. Still will cost about 10K, maybe half that if you did everything yourself. The bulk of the tuning work needs to be done off the dyno, as in you have to log, reprogram, log, reprogram, to make it not cut off at a stop light or be a dog around city streets. You would have to lower compression though if you planned to add NOS or SC on top of that.

No, your 700r4 will not handle that power either way very long. How long is anyones guess but the torque you put through it will eventually wear out the 1-2 and 2-3 shifts first. I was lucky in that mine lasted a couple years to a rebuild. Budget 2-3K for that.

 

Fresh GM rebuilt. 9 months after the 383 went in. Soon after tuning, Linfenfelter asked if that was the stock trans. I asked why he asked. He told me it was toasted. I insisted it was a fresh rebuilt one. He basically said "it just doesn't know it yet.".

At that power level, I think the D36 died in a couple years when I installed the motor into the car. All street tires and no massive burnouts. Just hammering it at the stop lights and ramps.

 

Yes, eventually the D36 will go one day. But that one is more hit/miss than the tranny. The Tranny will definitely go. My D36 has lasted 8 years, though I have a 44 replacement ready for when it shows signs.

Slicks will kill the OPs D36 as quickly as the 1st pass down the strip, or could last 100 passes, its impossible to tell.

 

In these posts, there are some recommendations to put a 2,400-2.800 RPM stall Torque Converter or a 2,200-2,400 RPM stall in the future rebuilt TH700R4 tranny. Does anyone know what the factory stall RPM is on a 1990 or 1991 TH700R4 behind a L98 TPI 350?