So there is a guy who built up a TPI motor for his 69 camaro and then had a kid. Another guy bought the car and didn't want the engine. So it sat in this guy's garage for the last 5 years. It is a 350 TPI with fully polished intake components. I am going to look at it tomorrow night to possibly put in my 89 GTA. So, anyone have any ideas on how he managed to ring 400hp out of this thing? He says he has all the paper work for the work that was done on the engine and dropped 5 grand in it. Sound possible? What I am looking for is any suggestions on what to look for while I am checking it out. To kind of figure out if the 400hl claim is legit, or is he full of Sh+t. Any help or suggestions are always appreciated!

If he is using factory TPI components I highly doubt it polished or not. If he used aftermarket components there are a lot of us over 400 horsepower. So that is posible.

Oh, he definitely has aftermarket internals. I am just thinking he cant make 400hp with the original TPI intake on it. He says that is still on there, but with alot of add ons internally. Anyone making 400hp w/ their original runners and plenum?

At the crank? Yes its possible.

stock tpi will not hit a 400 hp output.
it was best on a 305. it would work ok on a 350 but anything bigger or a 383 - not going to happen. there are limits to hardware.
your HP is limited to the lest efficient modification.
if you cam cant hit it - you will not hit it even if everything else will go over 400.
stock tpi will not get it and i love stock gm tpi.

Wont? I beg to differ. Figuring typical drivetrain loss, I went past 400.

Hey Madmax... What kind of things did you do to your engine? Did you have to make other modifications to the car to run the 400hp engine? Thanks for the replies!

I'll just list the items I think are important, and disregard things like hyperubreakit pistons and part colors

The run in reference:
58mm BBK TB (though I'm pretty sure the net from this part=zero)
Stock plenum, EGR walls removed, opened up to 58mm, one welded area for transitioning the 58mm hole to the plenum opening
Stock runners, they even have some dents in them. Not modified in any way.
ported Edelbrock base. 1.75" at the runner, 1206 Fel-Pro at the head.
AFR 190's, ported. Flow a little better than the new 195 Elims, but not by much. 10:1 compression
Shorty headers
350 block, stock crank, stock rods (different bolts)
Comp XFI 280 cam
MAF with 89 code, and a whole lot of tuning
Vigilante 3k stall converter
200-4r trans (not in a F-bod)

I dont think the question is how much you can get out of a stock TPI, but rather how much you are losing by using it. There is probably 50-100hp being choked out of this combo from it, as a guess. I'm pretty sure my hacked up stock base if I had it welded up to match a 1206 port at the head could do the same if not better power wise, just havent felt like getting it welded and porting it out and undoing bolts to swap it in. Call me lazy. So 400hp is possible, but is it really making that much or did someone pull a number from a hat or a dyno program?

Well...looked at the engine tonight. It is an 87, supposedly from a corvette. No aluminum heads though. Completely stock intake system. Not sure what the heads are off. They had the numbers 348 on the right and 140027 on the driver's side. The block had v01032JJ on the front of the block. The exhaust ports were more of a square then the shape of the ones in my 89 GTA. I am guessing this guy pulled 400hp out of his as$. The exhaust ports had been left open for the past 5 years too. So, I think I am going to pass, especially since he had NO paperwork to show for anything.

Madmax's motor is quite impressive considering the stock runners. You will notice that he is running an aftermarket intake manifold. I believe the motor you are talking about is using a factory intake manifold.