jutammel

Question is this, if you port your stock L98 TPI plenum and intake manifold as much as you can and add LPE high flow runners and 52mm TB. How much hp is that combination good for?

I am wondering this becouse you save over 1000$ if you dont have to buy superram plenum/runners kit and the superram intake manifold.

In my mind that money would be best spent for good heads!

88421VETTE

I've been told max is a just under 400 hp with siamesed and port matched runners and a fully ported plenum

jutammel

That might just be enough for me. My goal is fully streetable corvette around 400-450hp from engine.

Are there any others who can verify this?

vader86

Around 400 is really as far as it'll go, even then youll probably need a bigger engine to get there.

350hp is roughly as far as you can go on a 350ci.

cv67

w/vader-TPI cars arent relyy suited to be built for high rpm/hp due to manifold design. Try and put your build emphasis on torque. Plenty of guys here with 300-350rwhp running 12's.Good Luck

88BlackZ-51

is that 350chp with doing the heads? and cam?

could u get 400chp? with doing those along with a full port jon on the intake?

kwik_ta

I used to own a TPI 91 Trans Am. If I remember correctly, TPIS recommends buying the bigmouth lower end (or comparable) and porting the stock upper end with large tube runners. The intake can support 450hp as long as the motor can generate it.

Scoggin Dickey has a kit that gets you the fast burn vortec heads and intake that the TPI unit bolts to. I can not remember the price off hand, but it was very reasonalbe and produced good power.

mos90

i have tpis big mouth, asm runners, zz409 cam, ported plenum, 52mm tb, dart pro 1 heads on my 91 and im making about 400 fwhp and 480 fwtq.the zz409 cam is about as radical as i would go with a tpi setup. but i can pull hard to 6000 rpms over the stock cams 5000. i did notice some loss in low end torque. it moved up about 1000 rpm's.
as far as ive heard you cant get the flow #'s out of a stock ported base as you can out of a big mouth base or accell. maybe im making 400 hp because i had the base ported even more to match larger head runners, felpro 1205 intake gasket.

kwik_ta

I also remember reading a CarCraft 4 or 5 years ago that did a TPI build up. They chose the TPIS bigmouth because it out flowed all of the competition.

If you are budget minded, I still recommend the Scoggin Dickey's TPI Vortec set up. With a cam, you should be around the 400hp range.

TA

There are guys here who are in the 12s with less HP than that

vader86

Yes, after heads/cam work.

Its doubtful youll get anywhere near 400 without switching an intake or digging into the motor.

cv67

Should be more encouragement for you, Ammel!

DANSURE1

What size gear you running to have low in torque. Torque= hp

jutammel

Basicly this is the combo that I am thinking of:

-52mm TB
-LPE high flow runners
-fully porter stock plenum to match tb and runners
-fully porter stock intake manifold to match runners
-good heads, maybe AFR
-Camshaft I don't have a clue yet, but basicly what I want is torque and that rumbly big block like corvette idle

I already have all minor mods, SLP cold air intake combined with Big Mouth air dam, Heddman headers and Magnaflow car back (without cats). Rear end is 3.07 but I am leaning towards 3.54 gears. Oh yeah and it's automatic 1988 corvette.

jutammel

With that above mentioned combo I should be nearing 400hp but my question was that is this ported TPI going to be restrictive factor with 400hp or is it going to be enough?

mos90

i have a 6spd with 3.33 gears. its not that its low in torque its just moved up in the curve some. i do need to fine tune my chip some but i havent been to the dyno yet to see the facts. over the winter im debating 3.73's

Red Tornado

jutammel, your proposed setup should get you right at about 375chp - provided that you get rid of the idea of using a ported GM stock intake manifold - there simply isn't enough material to port for enough airflow you'll require. Your setup looks great, just get yourself an LPE-Accel Superram intake base or TPIS Bigmouth base, and have it mildly ported (not mandatory).....and you'll be off to the races.

An excellent proven cam to go with you setup of course would be the venerable LPE 74219....especially when the time comes to upgrade the ported stock plenum/large tube runners again, to a full Superram plenum/runners kit.

This all assumes that you must upgraqde your heads and have a full exhaust upgrade - featuring long tube headers.

Once all this is done, then you should be right at about 400chp on a 350cid.

Unfortunately, since you are "overseas", purchasing parts is going to be major killer expensive - its bad enough for us over here! Try to buy any parts that don't move (such as intake, etc.) as used parts and ask the seller to deflate the price significantly (on paper only) to avoid the ugly choking high import fees....you'll ave some good cash there.
Even so, expect to pay about twice as much as you might otherwise would......which is terribly unfair

Good luck!

comp

so what is about the MAX torque to build with a 383 and mod. shock
TPI parts ???

jutammel

Thanks bradvette for insight. My goal is to utilise the stock parts as far as they go. We can do a very demanding porting here so the stock TPI parts are going to flow as much as they can.
I have a another question about the stock heads then. With extensive porting will they do the trick?
And another question about that LPE 74219 camshaft. I REALLY want that BIG lumby idle so is this cam going to do it?

Red Tornado

For your '88, a great port job on your stock heads should yield nice results, according to many posts from folks here. If you can get flow in the mid-lift area something in the 250+ cfm range you'll be doing very well.

The 219 cam has incredible lift (use 1.6RR's to take additional advantage), given the duration. Thats why its an excellent choice, lift = torque = power. This cam really maximizes torque in the L98. As for the idle, its relatively lumpy, believe me you'll know your engine is cammed, althought its not that crazy. You don't want too much overlap cut in the cam, this cam probably hits the upper limit for the street (280* duration @ .006" lift if I remember right). Use your idle RPM setting to control this; I have 850 RPMs burned into my chip and I think it has a nice distinct idle. Aagain, you don't want it too lumpy, this will affect your low end take-off. I would say anywhere from 750 - 950 RPM idle will work out well.

Please feel free to PM or email me if you have any more questions! Take care, good luck!