What's that? There only 170 HP in a 5.0L L03 V8? Sure it torques, but, man, that's so little. What is the highest HP possible/measured on that kind of engine? Does substitution with TPI brings it to 200 HP range? Is it expensive? Thanks Charles

Probably not unless you swap all of the goodies from the tpi engines. you'll need the heads, cam, and such to go along with the tpi setup. The tbi cars got some of the worst heads ever produced by gm. Once you get all the goodies you should be pretty close. Considering all th effort though you are much better off to just find a complete tpi engine. Or if you can find one, just buy a tpi car.

Some big chokes on the L03 are the stock TBI unit, the exhaust, the heads&cam. If you were to correct those 4 areas, you'd have similar power to TPI.

Similar? If you correct those problems on any engine you better be doing better than "similar power to a TPI"

The TPI intake really only increased gas mileage and torque, it was the bigger exhaust and better intake assembly, and slightly better(but with far more potential) heads that gave it the extra hp. Oh, and if the 305 TPI came with a stick, the better cam too.

Hey you could be stuck with a 82 LG4 making 145hp.

Gotta look at the torque numbers too.

I apologize. What I meant to imply was that the L03 intake, exhaust, heads&cam werent even up to snuff when compared to better designed stock heads.

If he could get a hold of some stock cast iron l98s & cheapo lt1 cam, free up the TBI, freeup the exhaust - I say he'd be making similar power to a 305 TPI... thats a very conservative head and cam combo tho. Of course, if he were to put more money in the heads and cam he should damn well surpass 305 TPI power. I was making an assumption that he wanted cheap *** power.

I quit

He would be better off with LB9 heads, if it was stock, that way he wouldn't lose compression.

Or better then that aluminum L98 heads stock off vette same 58cc chamber as the 305 heads.

TonyC im with ya all the way

you know what, in some cases(done correctly), exhaust and an hei distributor alone can give you more power then a TPI 305, a lot more. They've shown upwards of 57 hp gains from just those two things.

Sorry if I am asking many questions regarding these 305 but I find it very interesting!

So by the way guys, what is the difference between an L03, LG4 and LB9?

My car will be converted into an American Sedan to be raced in SCCA. The more information I have the more chance I have to beat the Mustangs!

Thanks

Charles

This is what I have planned for my L03:

1. Ultimate TBI mods
2. Lt1 cam
3. 081 heads ported and polished
4. HEADERS
5. Underdrive pulleys
6. Open element (already have, may build a ram air for it)
7. Holley Pro Jection intake (gettin it dirt cheap)
8. 3' cat-back

I don't know what kinda power these mods are gonna get, But I do know that the money I'm spending on these parts is much less than trying to put a 350 in right now.

I'm hoping to be in 250-260 hp range.
Scoty

rsscoty, toss some gears and posi in there and you'll be golden

Heads can always be slightly modified to raise compression,and I believe the L98 heads (iron or alum) are better than the Lb9 heads... I'm not what I said that upset you, Tony C. (?)

yeah gears are another area, but they will have to wait awhile

actually you should probably get the gears first, thats where your car as is will really wake up. Remember, engine power is nothing if you lose it all going to the wheels.

Hmm, I thought LB9 heads were better.

Ask, F-Bird'88 he would be able to tell us for sure.

LB9 heads and L98 are very similar. The combustion chamber size is obviously different and the intake runner volume is slightly more on the L98's. The aluminum L98's are better than both, however it's still all 80s technology.

If I am not mistaken the 305 TPI only made about 205 or 210 hp with the auto and 230 with the 5sp. If I was going to do the heads, cam and headers I would certainly hope to make more than 210 hp if I was starting at 170.

I have done the dual snorkel intake, a Borla exhaust and a 160* thermostat. Although I do not have any dyno numbers I would think I am sitting at about 185hp.

I would like to get to the other stuff sometime soon. But getting the house in #1 priority at the moment.

Bill

I don't see how a HEI Distributor and exhaust could give you a more powerfull motor than the TPI 305. Correct me if I am wrong but that 57HP increase still isn't going to match the torque of the TPI engine. TBI just isn't as good a system as the TPI. TPI does have it's drawbacks like anything else.

LO3 mods

It's all about the torque isn't it?

My L03 made 178 rwhp 3900-4900 rpm and 271 rwtq 2800 rpm with the stock cam, stock heads, stock intake, and stock TBI. That's ~205 hp and 310 ft*lbs of torque (same as stock TPI) and ran high 14s @ 92-93 mph. It even made 260 rwtq/~300 ft lbs flywheel as low as 2200 rpm.

I think the stock heads will limit power to ~250-275 hp flywheel.

L03 is TBI, peanut roller cam, swirlport heads
LG4 is carb, flat tappet cam,
LB9 is TPI peanut(most autos) or L98 cam(most 5 speeds), better than swirlport heads.

If the rules don't limit you to keeping the engine stock, then I'd go for something with a larger bore and short runner multiport fuel inj. for high rpm hp/torque.

The swap from TBI to TPI is not worth the time or money. The swap from TBI to an aftermarket multiport system would be a better idea.