onebad400

I just ended up with a 91 gta trans am with a 350 tpi. I am going to be pulling the motor to repaint the car, and am planning on rebuilding the engine. My questions are what mods are going to get me the most bang for my buck. My goal hp number is around 350+. I figured I would start with a cam, tune/chip, headers, and possibly a stall. Where else would I need to improve to make my goal?

onebad400

after doing some research I have found that the FIRST intake seems to be a popular part as well as heads being a weakness. Does anyone have the factory valve/flow/cc size of stock heads?

watajob

iTrader: (29)

I'm thinking a FIRST setup w/stock heads would be kinda' pointless. Stock 113's flow about 200/170, the cast iron ones less. Glad to see there's still believers out there like me!

burnout88

The First Intake is NOT a bolt on part. You have to do a decent amount of fab work to get it to work and will have to elminate EGR.

cuisinartvette

Shoot, if you can get the first and save for some better heads
Then you dont have to monkey with buying aftermarket TPI stuff, porting it etc etc. Believe me its less expensive in the long run to get the first. No need to be porting siamesing etc with it. They are real good out of the box
For the larger CI guys I hear they are coming out with an even larger dia runner than they offer now.

1989GTATransAm

iTrader: (3)

"For the larger CI guys I hear they are coming out with an even larger dia runner than they offer now."

If it is like anything I have been doing then with the right heads and cam one can make peak power at 6500 rpm. With the right supporting mods we are talking over 400rwhp would be posible.

88fastgta

iTrader: (9)

ive done the FIRST intake swap last june and its alot of work imo to put it on. it costed me 1100 bux but with the fuel regulator (which is required) and fuel lines and other stuff i was about 2 grand into it...

check out my thread on converting to the FIRST intake

https://www.thirdgen.org/forums/tpi/...injection.html

then here is another thread i made discussing how lame the FIRST throttlebody is
https://www.thirdgen.org/forums/tpi/...onversion.html


it technically "bolts on" but you have to do alot to make it work... first off there isnt enough vaccum ports on the intake and i had to custom make two more vaccum holes.. i had to take the manifold off twice because it didnt fit properly.... you got to buy a universal fuel pressure regulator and make up your own fuel lines... you need to lengthen several things like the iac and some other i forgot... then i had to take the manifold off again because i couldnt get the dizzy to turn because there is soo much meat on that intake, i had to trim it down... if you have a MAF equipped car then the boot has to be shortened because the intake is like 2 inches longer...then that lame *** throttlebody was giving me alot of trouble so i had a conversion plate made up to accept the stock throttlebody...

after all the hassle it does perform alot better but be aware that its custom and fab work is required for this.....

Blackdog36

iTrader: (3)

First can be made to have EGR. Will have to use an EGR valve from a late 80's truck. Those will fit up to the triangular bolt pattern on the First unit.

Not that total airflow is everything, especially with TPI intakes. The stock heads and TPI intake flow about the same air at 210 cfm. So getting a better flowing intake (either through porting or aftermarket unit) has to be paired with the right heads. Regardless of this, the main restriction with stock TPI is the runner diameter. They are too small to feed a 350. Also know that cam duration is key for determining the tune wave effect, you don't need large duration.
https://www.thirdgen.org/forums/grou...ction-tpi.html

Not matter what you do, to keep a TPI intake and make more power you will be spending some money. That's why a stealth ram is a desirable, cheap option.

I don't mean to sway you one way or the other. Just to do some more research and figure out your upgrade path so you are not wasting money. There a many engine combos already done on here that would make your car a screamer on the street.

BadSS

My experience with “bolting on” the FIRST was more favorable than 88’s. However, as indicated it is not a direct replacement. I didn’t have any problem with the throttle body, but I was running a Lokar TPI cable and ran the return spring a little differently than pictured on the FIRST site. I think how most hook up the return spring causes most of the “issues” people have had with the throttle body. The way the IAC mounts does make the wiring tight and makes it almost impossible to unplug once the t/b is installed. However, adding in a $8 weather-pac 4 wire connector solves that. The only other wire I lengthen was to relocate the IAT sensor to the air box,,, but it has been a few years and don’t recall if I “had to” relocate the sensor.

The large cap HIE distributor does require a little grinding to the bottom of the housing, but the FIRST web-site shows you where you need to grind. A $10 bur bit from the hardware store used on a drill will take care of that. However I had bought a small cap HIE dizzy for the StealthRam and must say, it is a better “fit”,, but not necessary.

You do need a stand alone fuel pressure regulator, steel braided fuel lines, fuel rail fittings, and special “converting” fittings for the stock fuel and return lines. However, you need those things to run a StealthRan as well. I ran the big $130 Aeromotive regulator, but you can run a less expensive one,,, and can even convert the TPI regulator to work as a “stand alone” unit if money is tight.

I also test fit the intake before installing it and found a little metal at the oil sending unit needed to be ground down, but I wasn’t running the stock “tree”. I also found that some of the runner bolts bottomed out in the intake,, but I think the newer units come with the correct length. I will say that I used Teflon washers, like those you can use on the Holley fuel bowls, under the runner bolts to make double sure there wouldn’t be a vacuum leak – I’d definitely recommend going that,, they’re cheap insurance.

So,, as indicated earlier, it is not a direct replacement, but what is required to “bolt it on” isn’t really all that bad. While those with very little experience could do the swap to the FIRST,,, as with most things,,, how much “trouble” you have installing the intake is probably going to be directly proportional to your wrenching experience.