Hey guys and gals

I have an 85 trans am TPI bone stock 4 speed auto.

Just rebuilt my engine and transmission in the shop so its pretty much a brand new car. Has 79K on odometer. Still looks pretty good with fresh black paint and gold factory rims.

Its my daily driver so i want the mods to be LIGHT and be CA smog legal.

Not looking for the best performance out there but at least 15 seconds FLAT in 1/4 mile compared to high 15'S from the factory...

I thought about 3.73 gears but seeing that i wont be able to tune the TPI, i quickly turned down that option, even though i have some 2 channel brand new 3.73's laying around...


Mods i am thinking about without breaking the bank or having to tune my car are:

Cold Air intake (ordered one already)
Intake manifold (maybe)
Throttle body (ported or aftermaket)
Catback exhaust with stock CATS

How would these mods benefit my car?? thanx.

here is my car:

 

Very nice ride...

Cold air intake is a plus, as you want your IAT's (Intake Air Temps) as low as possible...
Intake manifold will help, but is not really needed...
Throttle body is not needed...
Catback exhaust will help you dial in the exhaust note your looking for...

Now, this is what I would do. Along with your cold air intake, get your hands on an open element IAT sensor, as this will provide a more realistic temperature reading for the ECM. The ECM will retard the timing (which is why many complain about Closed Loop loss in performance) as intake air temperature increases. The stock '85 ECM itself is kind of slow compared to the later ones, but in any event, get a chip that will give you a better fueling and timing curve. I would also get my hands on an adjustable fuel pressure regulator, and bump up the pressure a tad. By the way, welcome aboard...

 

Appreciate a good helpful response. But why won't I need a ported throttle body or aftermarket intake manifold. I've had an ls1 fbody that I modded pretty well before. And those 2 mods would net me an easy 15 rwhp.

 

Remember though, the LS1's weren't subjected to 1.84" intake valves, not to mention were never subjected to very small runners and poor flowing heads, either. Think of it this way, what good is a bigger (in volume) intake manifold and bigger throttle blades being used with the stock runners? You may see a small difference in terms of power, but it's nothing really being added per se, power is just being moved (raised) in the RPM band. Real power is found in the heads and cam. The stock throttle body will easily provide enough air for your 305, anything larger than that is essentially detrimental in my book. You can port the stock intake and throttle body like I did to help speed up velocity. I'm running the stock TPI setup, and trust me, my 305 ingests a very substantial amount of air...

 

Makes sense, thanx again!