Joshiedoom

I have some l98 10088113 casting heads and Ill be putting them on a l98 block.
My dad worked at a "stealership" since the got outta the army so he already purchase at a
managers discount(retired) guides seals etc etc. In 93-94 at point point they changed head design and
he wanted to know about "gauling" the head.

I dont know much about the lift but I would like to install a small cam and I would like to be show some links to
a good streetable one. Like to see about 300hp but I do not know if the lift will be too much for the stock springs.

Anyway. Basically want I want to know is the tips/tricks to building a reliable 300hp(at the flywheel) l98.

Posting this for my dad because im the gen III/IV guy(98 trans am) and he still wants to stick with his gen I and II.

Anyway.
Honestly Id like to have a book on the TPI and LT1/4 engines.

navyCM

iTrader: (3)

TPIS insider hints 1&2

wanab03ss

iTrader: (20)

The 113 wasnt being run in the fbodies in 93-94, your maxlift will be around .470 with stock guides, I dont have any links but 300fwhp shouldnt be a problem with a l98 at all, all the info for those heads and good cam selection for a 350 tpi is here just search. heres what I know... 58cc chambers, 1.94/1.50, d port exhaust, they flow around 190cfm intake/150cfm exhaust in stock form

TKOPerformance

The L98 aluminum heads are capable of supporting about 400HP unported. Porting can increase that number, but needs to be done by an experienced porter. These heads were the basis for the GM Fast Burn heads, and are probably the best stock first gen SBC head ever offered.

The hinderance to horsepower is going to be the TPI intake. It made massvie torque, in fact it was too good at making torque. That's why these engines usually peak at 5,000RPM or less! All the low end torque does is create wheelspin that is hard to control, ultimately making the car slower than a car with a higher winding engine that makes less low end torque, but more top end power. Read up on the TPI mods on this site. You can do some things to them to get them to turn a little more RPM, you need to get to about 5,500 RPM without running out of air.

I said all that stuff first because the cam selection means nothing if the engine can't spin fast enough to use the cam you need to make the power you want. 300HP isn't a lofty goal. I'm not sure what year the engine you are using is, and it makes a difference because in 1986 GM started switching over to hydraulic roller cams. If the block has three posts with threaded holes in them in the center of the lifter valley and two bolt holes for a cam plate on either side of the front cam bore you've got a roller block. If not you've got a standard block. If you've got the roller block you're in luck because running a roller cam is easy and cheap (lifters are $100 a set instead of $400 a set for retrofit roller lifters). A roller cam will add about $400 to the cost of the engine build if the block is a non-roller. It's money well spent though because a roller is worth 15-20HP everywhere other than the peak (peak power will be the same roller or flat tappet). In a street car this adds seat of the pants power you can feel. As for a specific profile, Lunati makes a nice hydraulic roller under Summit Racing part number LUN-54760LUN. It has .447/.471 duration and 213/219 duration at .050. It has a 112 degree LCA, so it should work well with stock style engine management and help you sneak through emissions if you need to. Powerband will be fron 1,500-5,300 which is perfect for a TPI. This should help you make an easy 300-330HP. If you want a little more power once you get it together you can always step up to 1.6 rockers from the 1.5 stockers. Or you could try 1.6s on the intake only, as this cam is heavy on exhaust timing, which the L98 heads may not fully need.

Make sure to run a set of 1-5/8" primary headers, free flowing Y-pipe, free flowing cat(s), and a good after cat exhaust. The stock manifold and exhaust will probably not flow enough to make 300HP.

Stock 22lb/hr injectors from a 5.7 TPI will flow plenty of fuel. Get an adjustable regulator though.

Have TPIS or someone who knows what they are doing burn you a custom PROM. Doing this with wideband feeback is much better than without, as the fuel tables will be more accurate. Lean is mean, but too lean burns and melts stuff. Rich just wastes fuel and makes no power. You want a 12:1 AF ratio at peak power. You can tweak part throttle for economy.