lt4 fd

I am concentrating on low and mid range torque production and would like to keep the stock size tpi setup unless there is something that works better for this. Im curious what can i do to it to make it give the l98 more mid and low range torque, maybe something can be done to make it work even more efficiently in those rpms by modifying teh stock tpi in some way or maybe 1.7 rr's, basically im using aluminum l98 heads and stock bottom end trying to maximize the stock power band as much as possible with boltons and whatever else besides going into the motor more than rr's....

DarthIROC

Well for torque down low you dont have to do anything to a stock TPI unit. Thats all the damn thing does is make low end grunt. Now as far as the midrange thing, it depends what you consider midrange. Cause the TPI is gonna hit a brick wall around 4500 RPMs.

lt4 fd

ide say mid range stops at 4500 or 5000 in my case

DarthIROC

You should be good to 4500, with some porting of the stock manifold, and a bigger TB you should be alright to 5000.

lt4 fd

When you say manifold do you mean the base, would that decrease low end at all? Also would a larger tb be needed, my lt1 is good to over 6k and 350rwhp before most people even bother.... just curious if the l98 responds differently. Thanks for your help so far.

DarthIROC

A throttle body would probbaly help some, but your right probbaly not enough to be worth the price. ANd when I say port the TPI, I mean the whole thing, plenum, base manifold, etc. And I suppose porting it would raise the powerband a little, but it makes so much low end torque yu wouldnt notice any loss.

lt4 fd

how exactly do I port the plenum I figured it was an empty box? also do you mean port match the base or hog it out or what? Also I heard of sort of blending the runners at both ends together as a half siamese runner setup. Someone reported no loss of low end but major top end bump, like to see dyno numbers or any reports of success with that....

aklim

Upper Plenum

DarthIROC

Ive never tried it, Im sure there are faqs for it on the net. Try TGO.org

doug791

assuming you have some money to spare just do it right and get a holley stealth ram, the thing will make almost as much power down low as your tpi and will ruin it through the mid range.

aklim

I wouldn't recommend HSR for a person who has to pass emmissions. I'd go with the Accel Superram. That has EGR passages which the HSR doesn't have. Since I don't yet have to pass it, I will try the HSR later this year.

doug791

well he doesnt mention emissions and its texas they dont have emissions in texas do they?!?!? Regardless if you got the aluminum l98 heads professionally ported, got a holly stealth ram, and an appropriate cam, you would be nearing the limits of your stock bottom end but i would expect it to hold together. I'm hoping to do that combo to my car eventually and my guess is that itd push a little over 350 horsepower maybe even 400.

Now that brings up the whole other issue of blowing your transmission and rear end but thats going to happen if you want any sort of serious power.

aklim

I doin't know. I'm in Madison, WI and in Milwaukee they have testing, and if they do, how would he explain the HSR to the testing place if they want to see an EGR?

The rear end would need some sort of support girdle to precent the end caps from walking and the tranny will have to be beefed up. Also it would take a torque converter that is matched to the cam for max performance.

doug791

agreed you obviously need everything to match and be strong enough to be successful, and i have no idea what he needs for emissions so if you dont need em go stealth ram, and if ya do go super ram easy as that

aklim

You know, (not admitting anything), I have a friend who stuck on an EGR with JB Weld and hooked up the wires and tubes before he went to his test and they passed him.