Doo

Father in law drove my C5 and now wants to increase horsepower on his 85. He has a new exhaust but wants to know the best bolt ons to increase horsepower. Headers seem to be too much of a project, what else is easy bolt ons which increase HP? By the way does anyone know the horsepower his 85 put out stock, he was just wondering. :cool:

Mark-44

Welcome to the forum... your father-in-law can get lots of tips to maintain and improve his 85 by joining us on the C-4 forum.

The 1985 Corvette has a Bosch tuned port fuel injection sytem and was rated at 230 horsepower. Many forum members have modified there L98's to over 300 horsepower... Lots of luck and wave...

:steering: :steering:

tpivette

there are TONS of relatively simple mods you can do to TPI Corvettes for more HP:

FREE MODS
- cut filter lid
- throttle body bypass
- bumped base timing
- porting the plenum
- gutting the cat converter
- remove screens on MAF sensor
- slightly bump TPS voltage
- cut back spark plug electrodes

CHEAP MODS
- K&N filter
- airfoil
- AFPR
- 160* thermostat
- underdrive crank pulley
- catback exhaust
- larger diameter front ypipe with no pre-cats (since you dont want to do headers)

these simple mods should get your 85 into the mid-low 13s with a good driver


[Modified by tpivette, 12:30 PM 12/28/2003]

65Z01

Here are some tips on small (relatively) mods:
-mandrel-bent 2 1/2" front Y, hi-flow cat, hi-flow cat-back, 20chp
-160deg stat & aux fan switch, 10chp
-cut lid with K&N filter, 10chp
-cut back spark plugs (link in sig. below), 10chp
-an AFPR to add more fuel for WOT operation, tuning
-TransGo shift kit, a big smile on the 1-2 shift

Though he has a new exhaust system, this is one of the places where he will pick up some nice power gains.

Doo

How about a hypertech chip? Are these all they're cracked up to be? :skep:

65Z01

Do NOT do the chip, instead do these:
-use the AFPR to add more fuel as required from mods
-bump the TPS & gase timing settings
-the aux fan switch brings the fan on around the 160deg stat

A custom chip may show some benefit after all major mods have been completed, but don't go with the off-the-shelf variety. With my mods I bought a HyperTech Stage II chip on e-bay for $50, tried it at the strip and sold it to a Forum member for $50.

vader86

NO chips. :nono:

He'll have to get his hands dirty to get real HP.
Exhaust is where most of us start, then the intake must be changed.

Red Tornado

I agree with the earlier post, first and foremost have your father-in-law join the CF!

I followed the advice from several folks here who know what they are doing (since I started out with zero knowledge), please see my sig for intended mods. The first phase is mainly exhaust - from headers on thru. The next phase is mainly intake, valvetrain & cam.

The free and cheap mods noted earlier - all combined - is a good start for a few HP. For the L98 in particular, exhaust is the next option.

Vic'89

1 word, garbage.

Once the car has heads/cam , then a nice custom chip would help.

Vic

tobijohn

Hey Brad, have you finished those planned Stage I mods that you've got listed in your sig? If not, you better get cracking - you've only got three days left! :)

Bustedknuckles112

Hey boss.....can u define cut the lid for me? Are u talking about cutting open the air box lid open?

aklim

I'd pass on those mods and if you really want to, cut the slits off the air box. Not sure how much real gain there will be but if your butt can notice it, you must be extremely sensitive or the imagination on overtime

cv67

18 years later....

Phobos84

Wow 18 years ago. GW Bush was president. I wonder, when these old threads get brought back from the dead do all the people who posted in them originally get email notices?

449er

I have an idea for this 18 year old thread....how about an LS swap?

Phobos84

It's funny how time changes peoples perspectives on stuff. Back in 03 not many people were thinking about LS swaps. It was just too expensive. I remember back then guys here were trying to figure out how to put a big block in a C4. Now it's how to take a junkyard LS with 300K miles and a turbo to make 500hp to the wheels.

aklim

I passed on the LS. We had either done or participated in junkyard swaps. They last for a while but we have longevity issues after a couple of years. So I would say it is "hit or miss". You get lucky and you get a while on it. You don't and you are back at it again. If I were to do it again, I'd be getting a crate motor or a built transmission myself. Factor in the cost to get it done and it becomes an unknown and the advice was that I either love the car enough to do it, whatever it takes or get an LS car.

sahhas

It is funny to see an 18 year old rise from the dead!!!
wonder if the OP did anything to his ‘85 to increase HP?

seeing this reminds me of the ‘85 I saw a few years ago, asked the guy if it had the original engine in it?
he said: “that thing was junk”, and he put a 400 engine in it, that thing went like hell for sure!!!

was looking at a car last summer, it was an 80s C4, can’t remember the exact year, and the guy put a 454 vortex truck engine in it, it was cool looking for sure….