I'm currently looking at a 92' RS w/305 that I'm hoping to buy, I read somewhere that some v8 RS models came with factory TPI, but I've been searching and haven't been able to find any proof, all the ones that I've seen with it were conversions. So my question is did any of the RS's come with factory TPI or was it only available on the 305 in the z28?

 

RS's were either V6 or TBI 305. TPI only came in the Z28.

 

There are B4C cars that look exactly like and RS and I believe have RS badges that have the L98 TPI engine. Good luck finding one!

 

Cool, thanks for the replies, I figured the TPI 305 only came in the z28 but I wanted to be sure. Anyone know what the power gains are when converting from TBI to TPI, does it match up to the power from a stock 305 w/TPI (manual tranny), or does it make less? What's needed for the swap, ecu, harness, etc? Sorry if these are stupid questions, I'm new to the domestic world.

 

Here's the difference mine made:

This is an easy way to go faster.
Dyno'd 158hp 220tq w/TBI
" 175hp 290tq w/TPI change, ran the times below after cam swap.
Going to dyno this week w/cam change.
14.92@92.xx

 

not only does changing to TPI help, but TPI came with much better heads. (compared to TBI)

 

TPI rocks, TBI ..... you know what..

 

tbi rules what are you guys talking about

...well over carbs

id say just wait and find a tpi car its same prices 3rd gens are a dime a dozen right now cause they are pieces of **** that break down and need lots of help, thats why i have 3 92 rs, 87 trans am ta, 89 iroc

 

That doesn't sound very comforting, oh well my previous car was an FC, sweet car but a pain in the a** so I think I can handle a 3rd gen, I hope.

 

speak for yourself, buddy. My RS has 194,xxx on a stock tranny and stock bottom end of the motor. And it runs fine, daily driven. I coulda left the stock L03 setup on there, and with normal maintenance, I'm sure I coulda got 250,000 plus out of it. No blue smoke, normal compression. And it's sure not babied.

I had the stock TBI setup until 180,000 miles, when I swapped heads, cam and intake/FI to TPI. If you're going to TPI, you might as well get rid of the stock swirlport TBI heads and the stock truck cam. They're junk for performance.

A decent amount of work involved in the swap though. There are several articles and such on TGO about the swap. If you look around, they're not hard to find. Good luck with the swap if you do it. You find that TPI will give you "a bit" more torque than you're probably used to with your RX-7.


EDIT:
"when I swapped heads, cam and intake/FI to TPI"

I obviously didn't replace my TBI heads with stock TPI heads/cam. And depending on your budget, you might not want to either. But, when we start talking about getting aftermarket or GMPP heads/cam, then we're talking about building a 305 (as opposed to a 350 or bigger), and that's opening a can of worms.

 

check with willie on this one but the 305 tpi option was available on RS convertibles, but no one ordered it, so none exist.

 

Dyno Don took my RS (which was a 305TBI 5 speed) and swaped in an L98 355TPI and a 6speed..

umm.. yeah its better

 

Damn, if this is true wonder why noone would order it?! Maybe after adding the cost of the TPI you could get the Z28 for the same price?!

 

On the subject of changing cams, I've never messed with a ohv cam, does it require tearing everything apart just to change the cam or can it be done with the engine still in the car.

L98 with a 6 speed that sounds like a lotta fun, wish the IROCs came like that from the factory, I just don't understand the whole automatic only thing.

 

tbi are only better over carb maintanence wise. performance wise, the carbs own

 

Deuch.....the T-5 manual tranny was rated for 300ftlb. The L98 TPI motor put out 340ftlb. GM didn't want to have to warranty every tranny out there. The T56 swap is the popular thing to do these days. I did it about 5 years ago and it's the best mod I've done to my RS yet. Better even than the 305-355 upgrade (although not by much.) Also you can change the cam with the motor in the car but you have to pull the radiator and condensor for clearance. It's tight but it works (been there, done that.)


Porky.....my '91Z (L98 auto.) has 217k on the clock and the longblock has never been touched. As far as I know, the intake had never even been off until the StealthRam swap. The valve seals leak a bit (very typical at her age,) but other than that she runs like a top. Reliability depends on maintenance. If you keep the car up, the car will keep going.


TBI itself is a great system. It's as dependable as a rock (I've worked on a few 350TBI trucks with 300k+ miles,) and not half as hard to work on as TPI. It just has a bad name because GM always used it for the low-power applications (i.e. crappy heads and cam.) Like anything else.....you can make plenty of power with TBI, you just have to know how to work with it.

 

Awesome, thanks for the answers and the added confidence.

 

a buddy of mine swapped his LG4 out of his 84 Trans Am and but a TBI 350 in. I dont know how fast it is, but he says it will melt the tires to the rims. it depends on what you want to do and how much power you want to make, but TBI is a good system. it may be cheaper to make big power with TPI, but if you just want a street bruiser that is reliable, you cant go wrong with TBI.

 

Both my Girlfriends cars were RS's and they had TPI!!!!

Well I kinda cheated and installed it myself. lol

 

Yeah, TheGreatJ you couldn't have said it better. My '90 IROC 305 has over 180k on the odo right now and runs better than most 3rd gens around...smokes just like yours (I would almost miss it if it stopped..heh..) Just advanced the timing up a buttload today (nice pickup), did an oil change, and I'd drive it across the country if I had to...aside from having a suspension that's sloppier than a mudslide, i love my Z...and its got plenty more miles before its ready to go. By the way...anyone in the NJ area interested, I'm selling it :-( Sorry people...got an 87 Turbo Regal in the driveway...speed is speed. I'm asking $3000, but in the real world chances are I wont get it. Offers?

 

Damn, if only you weren't so far from TX, I'd probably take the car off your hands, my former car's buyer just picked it up today, so now I'm really in the market.