I just moved to this forum from the C3 forum. I sold my 1981 and bought a 1990 black/black 6-speed, which is about 10 times the car the 1981 was. But, I'm still wondering about some minor upgrades. I was thinking about initially putting some 1.6:1 roller rockers on, and getting an aftermarket "chip". Would these two mod's work together or would I get into trouble with the computer? I'm thinking that would take me from 245hp up to around 270hp.

It already has a K&N filter, and otherwise is stock. It runs GREAT just like it is, but I want more.

Thanks

 

Get gears and skip the chip.

 

What do you want out of the car? what HP numbers? Drag ET's? We need to know for the serious mods to the intake.

For now:
1.6rr is good, usually for 10-15hp.
Chip is worthless, as are most anything you see in any vette-catalog, so dont buy it. If you want one to turn your fans on earlier, Marcho Polo (moderator in the ECM section) may still be burning chips.

Get a good catback exhaust, some longtube headers too. Those together should give 20-25hp on an L98. Port the heads, K&N filter and cut open the air lid, Bypass the coolant from the Throttle body (take the two hoses to it and mate them together).

You dont need a lower gear ratio for the L98.

65Z01 will send you some specifications on his mods if you ask him or if he sees this.

 

I'd start with the exhaust system first and take it from there. The stock exhaust system is very restrictive. :chevy

 

vader86 is wright you should begen with a good exhoust system for your L-98 and do some free mods also like take out the frisbee , trottle body coolant bypass , and also do a good engine tune up, theres no better than a healthy Chevy engine under the hood!! OOW I almost forget!! good luck with your new Vette welcome to the mod fever :cheers:

 

For the love of God leave it alone!!! Or you'll be spending every cent and time on upgrades; like me. It's like a drug; first you install better mufflers and headers, then next thing you know your throwing in bigger heads, larger cam, stroking out the block, mini/super ram, etc, etc, etc.
Actually, there's soo much to do with these engines. It depends how fast you want to go. This is a good place to check to see if some mods give you power or not. Good luck and welcome to the C4 section!
And as for the chip, wait until you replace the heads, intake, cam, etc.

 

If you are interested in quick 1/4s, do a title search in the archives for something along the lines of, "a few well placed mods....." I don't remember the member, but w/ a torque converter, higher numerical gears, and a few other minor engine goodies, he took an otherwise stock LT-1 and put it in the 12s. Good luck and welcome to our addiction!

 

Even with your Speed Density (SD) system you can get to about 300CHP with relatively minor mods.

Big returns come from exhaust mods like either a mandrel-bent front Y or long tube headers, hi-flow cat and good cat-back.

Next the intake needs some work, you have the K&N and you can port the plenum and upper runners and even the intake base if you like.

A 160 deg stat with fan sw, TB coolant bypass and MAT relocation are nice simple mods.

Toss the "frisbee" from the front of your water pump pulley and install an underdrive crank pulley with overdrive alt pulley for a little HP gain.

Upgrade the igntion with a HyperTech coil/cap/rotor, some spiral-wound wires and cut back plugs for more HP.

A set of ProMagnum 1.6RRs with new springs, tossed oil shedders and Ti locks will gain another 15hp and allow higher reving.

You still likely won't need a chip; and can use an Adjustable Fuel Pressure Regulator (AFPR) to increase fuel flow at WOT to match new air flow.

If you want more, a good cam and some head work will get you into the mid to high 300hp range. A super-ram intake will push that number even higher.

 

First things I would do are headers/catback exhaust, then throttle body bypass (takes 15 minutes, cost me $0.50 and is a proven 7hp gain at the wheels, on an LS1 F-Body anyway). As was stated you don't really need to change gears as the L98 doesn't rev too high.

 

Stay away from after market electronics. Do the catback and keep the k&N.
Use a lower thermostat. The only after market electronics i would use would be a chip and i havent seen much gain for the $180 and up you will spend

 

Heads and cam are excellent upgrades but to take advantage of this on the L98 you really need some intake work, either some serious porting or replace it completely.

As such I would start with the exhaust. Here's my reasoning.

The stock intake isn't that great in stock form. You can spend a lot of time getting more air into the motor on the intake but the stock cam might not really take good advantage of it. So if you start with heads / cam the intake won't feed them, and the exhaust won't support it even if you did feed it. If you start with a good free exhaust you will see a decent HP gain and you will set yourself up to use your other mods better.

If emissions aren't a concern I would throw in some Hooker 2151 long tube headers and a real 3 inch mandrel bent exhaust with some kind of crossover, be it an X or H pipe. Then I would work on the intake. Keep the K&N filter and port away on the intake. That should get you the most out of your stock heads and cam without having to crack the engine apart at all. Then if that's not enough for ya, toss in a cam and a set of heads and you'll already have the intake and exhaust setup to handle it.

 

:nono:

He has a 6-speed L98, it already has the right gears for it unless he goes and does some major modifications that would allow the engine to pull to 6000 RPM. Right now he should be shifting around 4400 and gears would pull him out of his power range way too quick.

The 1.6 roller rockers are good for about 10-15 HP. Your biggest restrictions right now are the exhaust manifolds and the intake.

If you are not familiar with the history of the L98 let us fill you in. :) The TPI intake system was designed for a 305ci engine by GM. GM thought that Corvette was going to have a 305 in it, bu at the last moment decided to stick with the 350 and did not redesign the intake system. This chokes our cars to stop making power around 4200 RPM as it can not pull enough air in.

The exhaust manifolds are the other choke point. A set of longtube headers is good for about 15-20 RWHP and nearly the same FT/LB of torque across the board on a marginally stock car.

You sort of have to make a decision as to where you want the car to be in a few years. Do you just want a little more pep, or do you want a LOT more in the end. Make a decision and we'll help you get a game plan in order so that you can work towards it. It stinks to have to end up buying the same part twice because you changed your mind down the road.

 

Thanks for all the great ideas. I think I'm more on the tweaking for a few extra horse side of things. I view this '90 as a very economical super-fun car to drive. I only paid $13k for it and it is in better shape than the 2000 Camaro SS I bought new for my wife.

I'd spend a few hundred dollars to get a little more horse, but it really doesn't need all that other stuff. It's fun an reliable and economical just like it is. If I wanted all that, I'd just sell it and go buy a '96 LT4 or a C5.

But, hey, that's just my opinion.

Thanks again. I printed out all your suggestions.

 

very nice lookin car you got there :cool:

 

Are those gotti wheels on your vette?????

let me know. OK...OK!!!! :confused: