well, i am going to go TPI on my currently carburated car here before to long, but before i do so, i want to know what i can expect. I've heard that with a stock TPI setup, it is only good at the lower rpm range, and that at about 4500 rpm its like you hit a wall, and doesnt excellerate well after that, is this true? allso, if it is true, then if i get a stock TPI setup from a junkyard, and just add a good aftermarket TB to it, like one with the built in NOS passages out of jegs, then would this eliminate that problem?
i would just like to go ram jet, but there is a big money issue here, im only 16, money is hard to come by. any help is greatly appreciated.

Ian :hail:

 

If I were you I'd just get a better carb. TPI is great once you have it but it's not worth the swap in my opinion. It's only worth it if the car is a daily driver and you have weather that changes rapidly. Although newer carbs with electric chokes claim to have good results in bad weather.

The best reason to go to TPI is once it's in it's easier to work with because it doesn't need adjustments. In the lower RPM range it makes more power than a stock carb.

Reasons not to go TPI. It's costly. It's a pain to troubleshoot if it isn't working properly. (I just got my car out of the shop because I coudln't figure out my problem) And finally the stock system does really limit the top end of the engine.

Go carb. Emissions sucks.

 

I have to agree. I am a huge TPI fan but it took lots of cash to go quick. Us tPI guys would love it if we could get a brand new hi-po intake for only $150.oo headers for $99.00 bucks etc. Stay with the carb it is cheaper and will probably be faster.

 

Yeah TPI is cool if you start out with it. It's just not worth switching to it. And T/A_SXracer is right. It would be nice if I could get a new intake and a better carb for that little cash. To get a new aftermarket intake, computer, and injection system would cost a couple grand to do it all at once. I also think that it is harder to keep the car in tune to pass inspections and things like that. Emissions laws suck.

 

well heres the thing, my car WAS originally a TPI car, and when the previous owner put in the carbed engine they just cut off the wiring that plugs in underneath the passenger side fender, and now there are mustiple hacked off, hot wires pokin out, and i cant even find the wires for windshield wipers, i had to hardwire the cooling fan, i dont have any dash lights, no oil pressure, no water temp. and my headlights wont even close after you turn them on, unless you pull the fuse. SOOOO...i was just goin to start over, and rewire and redue the tpi from the ground up.

 

***, don't you just love other people's hack jobs?!

If it's a nice enough car to warrant the money spent on the swap, go for it. Oh and yes the TPI makes good power down low, not as much above 4500rpm. However, I have found that my 305 (with an upgraded cam) was still a lot of fun up to 6K!

MILT

 

Is that the absolute definition of an oxymoron, or what? Using "TPI" and "performance" in the same sentence is almost a Bush-ism. I've GOT a TPI - I understand...

If you really want to do it, it would probably be a lot easier with a wiring harness from a donor car. If it were mine, I'd convert to speed-density right away.

 

one of my questions is though, would an aftermarket throttle boddy help that whole 4500 rpm problem.
and as for the car, it is definatly nice enough, and i should have known that something was up when the guy asked 1500 for it, but, oh well. yes though, the body on this thing is imaculate, and freshly painted before i got it.

 

No, the throttlebody is not the restriction in the TPI system, the restriction comes from the runners and intake manifold and the length of the entire intake runner and tube runners together.

 

No. The problem is caused by the design of the intake.

 

Vortec heads, intake and cam for a tpi for about $1k and mine huals out pretty nice :-) im gunning for 12's on motor and figuring the cost of mine with getting the engine rebuilt(mismachined heads , sprinngs went mye mye grrrrrrrrrr) and im still at the $3k total mark in the engine so i wouldnt say its that expensive to make it go fast u just need to understand the system and work with what it offers not what people tell u to run(huge duration cams etc)

it can be done......i ported my own heads . intake and runners out , im still looking for flow numbers on the sdpc lower base that i have due to the fact they say it flows tons more than stock and comparing the too it appears to be the truth

just my 2 cents but i also had a tpi car to start with
later
jeremy

 

i have a few questions that ive been wondering about. first off, what is this sdpc base that i keep hearing about, and allso, What is the PROM, and with this whole, being able to burn your own prom.........oh i dont even know how to put the question without knowing what a prom is. besides the highschool kind, im in the dark, please turn on a light.?

 

PROM= Programable Read Only Memory.
That has all the Vehicle/Engine specific data for a particular combo. The ECM's were used in several vehicle platforms (cut expense) So the Prom is what made it specific for 1 type of vehicle.

SDPC base..I think they are refering to the Scoggins Dickey TPI intake for TPI engnes for use with the Vortec heads....anyone with corrections here?

 

TPI can be cheap if you can find the parts cheap (I'd buy a wrecked tpi car off an auction and use what you need and sell the rest a good deal around $1000 with good engine and tranny). BUT If you can't find the parts cheap and you have problems getting it set up right it will be horribly expensive to have mechanics diagnose and misdiagnose.

NOW thats only for a basic stock setup which with basic mods will run 14's... TPI will get very expensive for a faster car, just search around the tpi message boards and you'll see the times and setups people are using.

A prom is the chip that contains all the information that the car uses to get the right amount of fuel, air, and spark to the engine. Read the intro article to prom burning in the tech articles and diy prom message board.

The sdpc is the scoggin dickey parts center the base goes for about $400 bucks and you'll want larger runners too ($280)and the vortec heads which start around $500 a set. Check www.sdpc2000.com Also roller cams are around $175 (gm hot cam) and up...

What it all comes down to is what times do you want to run? and How good are you at working on cars?

If your shooting for low mid 13's you'll be able to easily and quite cheaply do that with a carburated car or with TPI, but the tpi will probably twice as expensive by the time you complete the swap.

 

OK, well as far as being able to work on the car. i built the current engine from a bare block up to what it is now, the only thing i didnt do was bore the block, and do the valve job. allso, i would be kinda interested to see what kind of times it could put out currently, the problem is finding a track to run at. if ANYONE, might know where a track is near me please let me know, i live in north central kansas. either that, or maybe someone could give me a good estimate? currently the car is running, my sbc 355, with a performer intake and dominator carb, the heads are ...624's with 1.94 and 1.5 valves, 700r4 goin back to 3.73's with some 50 series tires. Any guesstaments?

Thanx,
Ian

 

Come on now, no body can even give a remote estimate.?!

 

on the TPI swap stuff its very expensive, i bought a 85 Z about a year ago, the prev owner did a 350 swap under the orig. 85 TPI car ran like ****, he blew the motor and sold it to me for cheap, i got lucky picked up another 350 TPI motor cheap too (500$) but the harness was hacked, i bought the painless kit and stared at it for a few hours got fed up sent it to a friend that just rewired the entire car for me for 700$ it does get expensive and then going from there to making the car fast takes enough cash and effort, im in for it though, i like the tpi system

 

Hey guy if you are only 16 and still in high school and low on cash..just stick with the carb setup. Drive it as is and make some cheap mods along the way "cash flow allowing" scenario. My advice is if the car is in great shape as you say hold onto it..keep it lookin good and when the time comes when you do have some money to spare then go for the TPI. The carb will do just fine...later..

 

yeah...what he said...the only thing I have to add is that the harness for the windshield wiprs, lights etc is seperate from the tpi harness and could be obtained in the JY for cheap off of a similar firebird or T/A....I like tpi but it is more expensive to make power with...tune what you have...

 

I picked up my tpi intake (computer ect. ) for $300 and another $300 for a painless Wiring Harness ( should be painfull) Could not fine a donor car. but It was all worth it woke up the car big time ( even mor with my new rear( 3.42) posi. Fuel injection is not for every one . It is hard to figure problems out But I hate carbs with a passion , since my Datsun 510 days. so hard to tune injection does it for you.

 

Sorry T/A_SXracer for taking so long to post again, any way I would think that your running probably low 15's with everything running good, give or take a second or two, because i really don't know a whole lot about carburated.

As for the nearest track, I think Heartland Park in Topeka is going to be closest for you, but thursday night test and tune has been closed for a couple monthes because its seasonal. They're currently have $ trouble and its not completly sure that they will have it again next spring. Every time I've gone to it they've had a lot of people there, so i don't think it will get cut. I'm not sure when they'll start it up again but if you email me in a month or two I could probably tell you. It costs $10 to go to watch or to drive and you'll need to be over 18 or have both parents sign a form to drive.

If i were you I'd get a full new exhaust with some vortec heads and a good cam and intake to compliment it. That should be able to push you into the 13's easily.

 

hey thanx a lot. sounds like a plan. ill start saving.