C4 mod questions

[Joshta]

i'm looking into buying an 86' auto C4. it's been rebuilt with 20k miles on the motor & tranny. has a rebuilt title and he wants 3500 for it.

anyhow, i'm new to vette's and TPI's so i was wondering what are the best simple mods (intake, exhaust, udp's) for this car. another thing that was bothering me is the 2.73 gears. just had em done in my stang, and don't really wanna do it again. i noticed that it makes max hp at 4000 and redlines at 5500. does the motor work well with the gears? and also under WOT, does the auto shift out at 5500 and is that good for times or does it need to come out sooner?

any help is appreciated.

[Scott85]

Simple mods -
gutted airbox
K&N
airfoil
port the runners to match the TPI plenum (get an AFPR at the same time, you have to take off the plenum to install the AFPR anyway)
computer chip
mufflers
coolant bypass (reroute the coolant hoses that go to the throttle body)

[Joshta]

thanks, how's it run with those factory gears in it?

[TEXAS-HOTROD]

Mine had 2.59 gears and now has 3.40ish (I forgot the exact ratio). It made the engine come to life, it does pull harder.
It's worth it to port match the runners and do the fuel regulator trick as well. I installed SLP runners since the intake was apart, hoping for less restriction. I bent up bigger front pipes and installed a cat-back muffler system too. I replaced one part at a time to find out if there was any improvement in that area.
I have driven TPI cars that fell off over 4K rpm. Mine pulls good up to 6K w/o any hint of running out of breath.
Most mods do help. Just don't expect a lot, these engines/TPI systems max out around 300h.p.

[Schrade]

Originally Posted by Joshta

i'm looking into buying an 86' auto C4. it's been rebuilt with 20k miles on the motor & tranny. has a rebuilt title and he wants 3500 for it.

anyhow, i'm new to vette's and TPI's so i was wondering what are the best simple mods (intake, exhaust, udp's) for this car. another thing that was bothering me is the 2.73 gears. just had em done in my stang, and don't really wanna do it again. i noticed that it makes max hp at 4000 and redlines at 5500. does the motor work well with the gears? and also under WOT, does the auto shift out at 5500 and is that good for times or does it need to come out sooner?

any help is appreciated.

$3.5 K is not enough for any C4 with a motor+tranny rebuild. Beware.

Airflow limitation on a 5.7 TPI is on the intake, as opposed to the exhaust. I can't remember if it's the throttle body, or the plenum, or the intake manifold. Google Gordon Killebrew / C4. He's the C4 guru.

2.73 is not a bad thing. The TPI is a very high torker. That gets it off the line with only 230 HP ('86).

[Scott85]

Originally Posted by Joshta

thanks, how's it run with those factory gears in it?

When I first got the 85, it would do 14.9 stock with the 2.73 rear . With the mods I listed , it was around 14.2-14.3 , very consisitant too.

[88camaroproject]

msd blaster coil brings it to life too. you can feel the difference. you might have to get the kit for hei distributors with the 6al box and coil though. not sure if msd has a coil that will go in the cap