Project_1986_TA

Well today i had 3.73's put in my '86 T/A. Before they were 2.77's wich i was thinking they were 3.27's before i checked. Here's a little background info on the car:

1986 Trans Am WS6

-Fresh 350 TPI with 268* comp cam
-21lb Accel Fuel injectors
-K&N filter (in stock airbox)
-3.73 Posi/limited slip rear
-Stock 700R4
-Magnaflow muffler w/ high flo cat.

Im excited to feel the difference from the 2.77's to the new 3.73's. I should have it back by tuesday/wednesday but wont be racing it till i get another job! lol

So what does everyone think I will be running with a new set of gears?

SLP IROC-Z

iTrader: (1)

slower at the end of the track with stock TPI

Project_1986_TA

would say, headers and a custom CAI help? I cant really aford to do much else but am thinking about building a custom CAI. Just curious what it could run as is with the new gears.

SLP IROC-Z

iTrader: (1)

3.73s are way to much for stock TPI even a modded one wouldnt need gears like that, ud need an engine that has power to about 6k to get use of a 3.73 ratio. 3.27s or 3.45s would be better. 3.45s in the auto would even be pushin it with out some other mods. port the plenum, headers, free flowing exhaust, CAI, runners and the 3.45s will do u good.

Project_1986_TA

The place i had my custom chip done at and who also dyno'd the car said that with the cam i have i should be hitting about 6k RPMs. It doesn't do too bad up around 5000RPMs now, it redlined stock at 5500 and now supposedly its about 6k. Never really had it that high.

SLP IROC-Z

iTrader: (1)

if u have a cam in that car that is good to 6k ur not getting full potential out of it, a fully modded TPI will maybe make good power to 5500 on a 350. 5k is about normal, therefore the 3.27s or 3.45s would be good. if u plan on keeping it TPI then that cam is probably not the best choice since the TPI starts to fall off after 4500rpms. or u can buy an HSR and match that cams potential as well. personally i think the tpi is good for a 305 but on a 350 it just doesnt cut it. if i were to get a 5.7L iroc the first mod would be an HSR then a decent cam and head work.

rubbermanZ28

Grats on the new gears, you will notice a big diffrence.

Project_1986_TA

so nobody has any estimates of what my car could be running in the 1\4 mile??

3504mula

If you have tires that will hold up to the modded 350 with 3.73's (slicks or at least DR's) I am sure you will turn mid 13's or better depending on tuning/track conditions/weather etc. Oh yeah and probably right over 100 mph. Good luck and let us know what it REALLY does run...

Jonathan

Project_1986_TA

Anyone else with a guess?

Project_1986_TA

Ok, im bringing this back from the dead because i am too curious to know what it "should" be running as is. I have had the 3.73's for a while now and it is AWESOME! It pulles really good even around 5k on the tach, never taken it above and wont until i get an aluminum driveshaft to stop some vibration. My tires are very good and allow very little tirespin if any when i launch it right (wich is 90% of the time).

So what should i be running in the 1/4 with the listed mods above?

Thanks, and sorry for bringing it back from the dead!

vwdave

Not to be a jerk, but why dont you take it to the track? This thread IS almost 6 months old.

Project_1986_TA

because the track around here is closed right now and i also dont have the dough to spend $30 just to find out right now.

vwdave

I forgot tracks close for the winter in other places.

Project_1986_TA

So does anyone else have a guess besides 3504mula?

gen3z

91 5.7 z28 w/slp runners typical mods,slp 1-3/4s full slp ex.system,slp 2400 stall,58mm tb,pulleys,cut air boxes w/k&ns,3.23 stock gears 1.76 60' and 13.37@102 we thought for sure the 3.73s would help 1.73 60' and13.34@100 so we did a cam and heads as well as the slp t-ram the car went 1.71 60' and 12.70s a grip of money spent at this time but my boy had it to spend,so he then built a 408 and enjoyed the 11s all day at sea level till he sold the car 2-months ago!!!!!!!plenty memories terrorizing the mustangs of houston to last a life time......

84zeddd

I would say 14.0-14.2@96-97mph.

gen3z

our cars have mor tq than hp so swaping in more gear does not help,now if you change intakes to say Lt1 or mini ram the gear will help or a 5-6spd conv.

Project_1986_TA

I should be getting a set of edelbrock headers within a few weeks so i could be looking around high 13's with the new headers? im hoping for mid 13's with headers.

need4speedb4c

My bolt on's are in my sig, and I pulled 13.7's with 2.0 60" all day with 102-103 trap speeds. The AFPR was set at stock PSI, so it didn't help any. I also removed my cats and smog pump.

I just switched from 3.73's to 3.42's though because my RPM's were around 5200 when I crossed the 1/4 line. With 3.42's I used a calculator to estimate what I should be at, it said around 4800 RPM. 3.73's were fine, but I feel that the 3.42's would be more appropiate for a TPI.

When you get the headers, I would guess around 13.8-14.0 at around 100mph.
Just curious, have you ever gone to the track before? if so, what did you run?

-Mace

AlkyIROC

I shift at 7000 rpm which is a few hundred rpm over my peak hp curve. I'm swapping out the 4.56 gears for some 4.30's just to bring my rpms down.

In theory, I should also pick up a bit more ET because I can shift at the peak hp instead of wasting power going over it.

If the gear swap doesn't help like all the software programs suggest, I can easily swap back in the 4.56 gears. That's the nice thing about using a 9". I have 2 different center sections all set up ready to go. I could do the swap at the track in less than an hour.

Project_1986_TA

need4speedb4c:

No i haven't been to the track yet. As soon as it opens back up im going to go though and i'll post the results. I have had my uncle drive it (he used to own it before the swap) and said it is a lot quicker then the old LB9 305. He said he would gaurentee its in the mid-high 13's. I seem to believe him about 85% just because he is a very experienced drag racer.

JaysZee

I'll guess low 14's. Like has already been said, 3.73 is too much gear unless you plan on running a taller tire to compensate. Also, you won't get the most out of a cam that's good to 6,000 RPM when the stock TPI manifold limits you to about 4,800 RPM. I'm sure it feels a lot stronger from a roll, especially in second gear but across 1/4 mile it would be better with less gear. Plus you'll get better gas mileage, which means more $$$ for mods.