Hello everyone. Ten years ago when I was 14 years old I picked a 1985 Iroc with a 305 tpi. Red/silver package, t-tops, auto-obviously for this motor setup in 85. After beating it to death throughout high school I eventually parked it back in 2003. I pulled it out of the shed the other day, took it for a 100 mile ride, which brought back so many good memories I can't even believe it. Needless to say the fuel pump went out on me here the other day, but that is to be expected after sitting I suppose. I love this car to death and will never part with it, unless my family needs something more important. 90% of my memories from 16 and up are in this car. My first traffic ticket, my first love, etc. I finally am at a point in my life where I can give this car the attention that it deserves. It will be painted in October-new corvette red. New interior-some of it is already on the way from Classic Industries. New motor-this is were you opinions, experiences, and advice come in. I love the TPI setup and will not change it. I have 4 options. 1. rebuild the stock 305 and give it a little more power 2. 350(that i have) 4 bolt main etc. 3. 383 stroker tpi 4. 400 small block tpi. I have heard that I will run into a bunch of issues with the 400 so I am about ready to count that option out. I would really love to do the 383 stroker tpi, but am concerned about: fuel pump, injectors, computer-programming, knock sensors, map sensor, tranny strenght, etc. Now I know alot of people have done the 383 and seemed to go easy, but they may have started with a 350 tpi motor, harness, etc. What needs to be changed from a 305 to a 383 to leave it tpi? I also would love to eliminate my air injection but worry about the dreaded check engine light? What do you guys think? Sorry for the loaded question. And I am sure I could find a ton of good info on this using the search function-which I will do eventually. Looking for a relatively easy, and fairly cheap, bolt on setup, with more power. I put myself through college as a mechanic so I do have a little bit of knowledge regarding this stuff. Thanks again in advance to all who respond. ANd it feels good to be interested in these cars again, they really are great.

 

Maybe I should also be asking about a nicely built 350, and using all of my stock tpi things. It looks like people here are not big fans of the 383 tpi. Thats exactly what I wanted to hear/see. I just want to leave things the way the are and get a little more power, while keeping the reliability. thanks

 

When people poo poo 383 TPIs, they're not matching goals with results.

Most bench racers will tell you a TPI chokes the life out of a 383. That's true - to an extent. Remember that many Pontiac and Chevy 400-455s came from the factory with two-bbl carbs. Yes. 2 barrel! They were awesome off the line to the next stop light. If you're looking to race at Taledaga, then TPI will not work. There will be untapped HP. Do you know what the infamous SE T/As of the late seventies were rated at for HP?

If you can find an old article from Car Craft, "Twelve Ways to go Fast" (late eighties, I think) Lingenfelter gives a good recipe for a 383/TPI.

 

Let's see your TPI 383 results, then. Attempting a paper comparison to 2 bbl combos of old is moot.

Start with a Holley Stealth Ram, and you might have my ear.

 

I didn't say I have one. You can read "Twelve Ways to go Fast" if you want to. It's been referenced here for years.

How did your 400/2BBL run?

 

where can i go to find that article

 

I'm looking at this same swap and have been reading old posts. I have the T-5 which is rated at 300lb-ft and a 383 I saw made 425lb-ft on a mild build (new heads, stock TPI gear). Thats the main thing that worries me but I am not racing or an abuser so I think I can make it last. But I also wonder if I should put the extra $1500 towards brakes and just rebuild the 305.

 

I have not done such a mod as you are wanting, but I have been looking into it. I don't think you will get good results from a stock TPI intake. A stock l98 will run better with a modified intake, so to build a HO 350 or 383 will require more airflow than a stock TPI.
So I think you are looking at a aftermarket intake, bigger injectors, bigger fuel pump, custom chip or aftermarket ecu,
........then you need to upgrade the trans, rear end, exhaust, ect.
what kind of power goal are you after anyway?
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My '77 SE TA made like 200hp and 320 trq. With a 3.23 gear and th400 She would just edge out a stock 5.o 5speed mustang in 1/4. It topped out around 130, and got 13mpg. I fail to see why that was impressive. or what that has to do with running a 2bl.......

 

Really I would like to bump up from the stock 220 or so (prob like 200 with age) up to around 300. That should be enough to make me happy.

I got talking to the engine guy and a 383 was not much more money. 3500 (rebuilt 305) vs. 5500 (rebuilt 350 with stroker and heads). Both options include crap like boring, pistons, rings, head job on 305, etc.

I do realize the other downstream upgrades required with a 383 like tranny, diff, rad, fuel, etc but it might be worth it. What I am not sure of is stock TPI stuff, computer, injectors, etc.

I don't really need the 383, would prefer to squeeze some more out of the 305 but he and many others seem to think they won't make much more power.

 

100 hp per cube is easy with any sbc so a 300 hp 305 is not difficult. It would get better mpg, but would cost more than a 300 hp 350. Most parts interchange between the motors but the ones that don't(like pistons) will cost slightly more for a 305.
the guys on the Fuel Injection are of this site can give you the low down on what mods are required for your TPI setup. The low end torque of a 383 making around 300 hp should work well with a TPI. You will still want better lower intake, runners, bigger injectors, and a custom chip, at the least

 

That would be a 30,500 HP 305!!!!

 

oooops! Brain Fart! Please forgive..........
that should be 1 hp per cube, but yall already knew that

 

im also interested in building a 383 stroker tpi. ive got a 305 right now and i got a 350 lined up to go in, but i just want more power, so i aswell was wondering what was needed, i know for sure is knock sensor, and injectors. i dont know if ill have to prom tune, or if i can keep the radiator i just bought for my 305.

but let me know how it goes, if all goes well, by next year my 86 iroc should have a 383 tpi in it.

 

Stock TPI hardware can't handle a 383 (it could be argued it can't handle a 305). As a minimum, you should figure on getting a Holley Stealth Ram. The next bottleneck will be the stock MAF.

Most factory 350's have junk heads. Find out what your 350 has, and plan on needing to budget for something better.

PROM tuning isn't necessary for a MAF system to run a 383, but it is for getting the most out of it.

 

is it that the TPI wont be able to handle it? or that it wont be the most efficient for HP? because i mean aslong as the car can run with the stock tpi parts on(with new high flow runners and base) for a while before i save up money for a carb setup then id go with the TPI setup for a little while. or do u think id develop other problems?

 

Even with aftermarket base & runners, you'll be down on power. The Stealth Ram doesn't cost any more, so why spend the $'s on base & runners?