Mods on an L98?

[Stu]

My Buddy just got a '91 Vette and he wants to start modding it he's giving me total control of his mods but capping me off at $1k. I Know LS1's but not L98's from what I've seen Intake runneres are a good start he wants a Chip though do those work good for L98's? Any input would be great. :confused:

[jmd]

I'd start with headers first. Vettes have a decent dual exhaust system so that might be cool for now.

I wouldn't bother with runners, plenum, or base mods. I'd go straight to an aftermarket intake and cam it appropriateley.

tq. converter would be a good mod too.

[Stu]

OK thanks I'll check on headers then he has a M6 so a Tq Conv. wouldn't help any.

[BP]

The L98 intake sucks for power, I agree get something different. It's going to be expensive though!

For headers I'd recommend the TPIS long tubes (http://www.tpis.com/). Myron earned his salt racing those cars, he knows how to make power with them!

The problem with catbacks on those cars though is that it seems no matter what you do they resonate badly and are extremely loud inside. There is atleast 40hp to be gained by ditching the stock stuff though.

I'd also go with a 160 degree thermostat and possibly rig up a manual fan switch. The stock airbox and air filter are also somewhat restrictive, if you can find a cheap aftermarket alternative go for it.

[BAT TA]

Aftermarket intake would be one of my priorities. Super ram, mini ram, and stealth ram are the most popular. Check out www.thirdgen.org for a lot of good L98 advice. I've read over there that some owners have been using LT1 intakes on L98s. That would save some cash vs buying a new aftermarket setup because the LT1 intake is basically the same as a mini ram.
Also what kind of gears are in the car? If it's the 259's he might want to get rid of them as well.

[jmd]

Originally posted by BAT TA
Aftermarket intake would be one of my priorities.

:yup:

Super ram, mini ram, and stealth ram are the most popular. Check out www.thirdgen.org for a lot of good L98 advice. I've read over there that some owners have been using LT1 intakes on L98s. That would save some cash vs buying a new aftermarket setup because the LT1 intake is basically the same as a mini ram.

Not quite true.

To begin, the ports on LT1 heads are raised compared to traditional small block heads. Porting must be done for things to end up even close to correct. The salesperson of the modified intakes claims that the LT1 intake matches Gen I heads and the LT4 intake matches something else (FastBurn heads?) Not true unless "pretty close is good enough" for you.

I wouldn't run an LT4 intake on LT1 heads because of the port mismatch. Similarly, why would you want the port mismatch of an LT1 intake on an L98 head?

The Mini-Ram is a bolt-on and go. The LT1 intake is a port-mismatched customize signifiicantly option. I personally wouldn't do the LT1 intake.

There's more but that should suffice.

[86irocthd]

ok just registered... i also have a tpi motor and i am in the middle of a lt1 intake conversion... the best way to mod a tpi set up is to get rid of it... its to restrictive... there are some options ie stealth ram, mini ram, the 1000cfm accell setup tpis big mouth but all will run u over 1400 bucks the best bang for your buck is a hellified (sp) cam, headers which are very expensive on a vette, and an intake the company that is doing mine is www.lt1intake.com he has everything u need in order to make it work.... BIG BIG gains on this intake.... and the lt4 intake will not bolt up to any other head and work as intended unless its a lt4 head.. but the lt1 intake ports are a really close match for an lt1 intake :) go there for all other info needed....

[zsb383]

FL headers, good catback, gears and Nittos. Over a grand. Thats the least I would do.

[Stu]

Thanks for all the input guys:D

[01 B4C]

I remember when I had my 89, I used a 85 Y pipe which contains no pre cats. Then I just gutted my main cat (or leave it) and it sounded great! Give GM a call see if the 85 Y is still available. I would also save your money on the headers, due to the stock ones being decent. That is unless your going all out.