Help increase horsepower on L98 with $2000 budget.

[Leaf5817]

Just bought a 1986 with a bad interior. The interior is done and now I want to get as much horsepower for under $2000 without adding nitious. Where do I start? and how much gain do you think I can get? Thanks

 

[jrzvette]

Just bought a 1986 with a bad interior. The interior is done and now I want to get as much horsepower for under $2000 without adding nitious. Where do I start? and how much gain do you think I can get? Thanks

Before you start playing around with HP ask yourself what kind of driving do you do the most. The L98 has very strong low end torque, it just runs out of breath around 4600 rpm. If most of your driving is around town or on secondary roads you might want to consider replacing the rear gears (say 4.11s). Much easier, cheaper, and you'll really feel the difference.

 

[rocket22]

How many miles? going to race it? changing the TPI intake?

 

[WhalePirot]

Coated headers and more open exhaust. I did 3.73 gears and hated it because of the low 'torque ceiling'. It was quick off the line, but shift-shift-shift and I was done... quickly; too quickly, for me.

You will feel the change with the exhaust and will want it no matter what else you do further.

You might also check out Mad Mic's car. He runs strong drag numbers, for minimal dollars, with 'highway' gears.

 

[KANE]

Just bought a 1986 with a bad interior. The interior is done and now I want to get as much horsepower for under $2000 without adding nitious. Where do I start? and how much gain do you think I can get? Thanks

Big assumption... your engine's rings and bearings are in good shape, but here goes:

Vortec heads (Jegs- $600), Vortec base (Jegs- $500), after market TPI runners (ebay-$200), Fireball cam (Jegs-$200), custom burned PROM chip (Scott Hansen- $100), off-road exhaust ($400).

You'll need to do the work yourself. I'd say you'd have the potential to pick up about 60hp- if done correctly and tuned right.

 

[rocket22]

The exhaust is a for sure thing, headers, cat-back, it has aluminum head now, have the cleaned up, port match the intake, if you find a used super ram intake that would be nice, the motor has a roller cam so stick to a roller, something like a 224/230 or 230/236 will make good power, comp cams is IMO the best place for off the shelf cams that work, They grind all my custom grounds and love them. a cold air intake, a big thottle body like a 52mm will be an improvement.

 

[Black Bart]

Well you ruled out your BEST option.
$2000.00 will get you 40 hp or $600.00 for a nitrous kit will make 150 HP
On a stock motor I would not go with more than a 100 shot
Nothing changes with the nitrous the engine still runs just like stock when you are not spraying.

 

[speedmaster4]

86 was last year for ''flat tappet'' cams, rollers came in 87+...all that means is CHEAPER replacement cams with more choices...just don't go crazy and put in too much cam (wild cams sacrifice low end for 7k output, useless if ''capped'' exhaust and engine longevity are factors)

toss the tuned port intake, put on a modded lt1 intake with your new ''flat tappet'' cam...you'll have an extra 1500 rpm to use over the current 4300 ''nosedive'' and 50+ more ''horseprssure'' ez...and half your 2 grand still in your pocket.

 

[Edmond]

IMO, the 48mm TB is plenty enough for a 350 street motor. The $300 you'd spend on a larger would be better off spent somewhere else.

 

[Leaf5817]

What kind of modds do I have ahead of me on a lti manifold? Here is my plan:

1. lt1 intake
2 throttle body
3 4:11
4 exhaust
5 vortex ram air
6 new wheels

have not decided on headers/cam? Maybe down the road

 

[Rogue]

toss the tuned port intake, put on a modded lt1 intake with your new ''flat tappet'' cam...you'll have an extra 1500 rpm to use over the current 4300 ''nosedive'' and 50+ more ''horseprssure'' ez...and half your 2 grand still in your pocket.

If he were to replace his TPI with a "modded LT1 intake, wouldn't he need new injectors, a new ignitions system, a new custom tuned chip to allow the engine to use an "extra 1500 RPM? Also, to take full advantage of that, he should also put a freer flowing exhaust on it, and lower gearing to use the extra 1500 rpm's.

This sounds like it will cost over $2k easily.

On top of that, how will an older L98 motor with lots of mileage handle reving 1500 rpm passed the redline? How will the drivebelt and its ancilliary equipment handle that?

I'm thinking for a mod like this, it would be wise to build the new motor up to handle that extra RPM's and flow that extra air/fuel. Opinions?

His best bet would probably be to take advantage of the L98's torque and just try to improve its efficiency of moving air/fuel in and out without going overboard and overstressing all the other components.

Maybe, an open airbox, a good cat back exhaust, new higher flow cats, a mild camshaft and new timing chain, a custom tuned chip to take advantage of it all. No need to rev 1500 more. Just fatten up the existing power curve a bit. I think that can be done on just $2,000. What do you all think?

 

[speedmaster4]

If he were to replace his TPI with a "modded LT1 intake, wouldn't he need new injectors, a new ignitions system, a new custom tuned chip to allow the engine to use an "extra 1500 RPM? Also, to take full advantage of that, he should also put a freer flowing exhaust on it, and lower gearing to use the extra 1500 rpm's.

This sounds like it will cost over $2k easily.

On top of that, how will an older L98 motor with lots of mileage handle reving 1500 rpm passed the redline? How will the drivebelt and its ancilliary equipment handle that?

existing injectors, distrib, chip,etc., will work fine--new stuff, better exhaust, deeper gears, etc., likely would help even more, but are not mandatory to realize notable improvement with the lt1 intake....btdt
''redline'' will not be exceeded, ecm will still enforce programmed limit--even the tPi will ''eventually'' get to ''redline'' if you wait long enough, albeit with little enthusiasm--the lt1 intake ''pulls'' to redline ''now'' with good torque thru-out.
if you have ''high miles'' and/or a ''tired'' engine, STOP, a sick horse should never be ridden hard (applies to high speed and hard pulls at low rpm)


skip the bigger throttlebody, it will do nothing to help, may even SLOW you down, many have experienced ''bogs'' and idle probs with aftermkt t-bods...''ram-air'' might help over 150 mph, your oem air intake already is ''CAI'' due to pick-up location.

 

[WhalePirot]

the 48mm TB is plenty enough for a 350 street motor.

Yup. My 406 pulls very well to 6300 with a 52mm TB.