Baller

Looking for advice. I've got a 1990 L998 with the following mods;

Bosche injectors (*think* they're 28#)
AFR
Frisbee removed
Ported intake
Accel large tube runners
Ported Plenum
1.6 RR

I originally bought some lt1 manifolds I was going to put on it along with converting it to a true dual exhaust because I lived in Cali and figured the odds of any of the local smog guys recognizing the different manifolds would be pretty slim.

I've since moved to Oregon and don't have to get the car smogged anymore so am wondering if I should go ahead and just use the LT1 manifolds or should I sell them and go with long tubes?

Realistically because I'm on the coast in a rural area really airing the thing out is not much of an option and there's the ocean air to consider, so the question becomes would the gains of the headers over the LT1s be worth the expense and short life span the previous things considered?

Thanks

jemidyette

I guess that depends on how nice of headers you wanna get. You can some really nice ones that will last forever, but they aren't super cheap. I'd say if you can do it, go with a nice set of headers. They make a huge difference in power for these cars. I haven't looked back.

Deakins

Being it's an L98 that loosing steam up top pretty bad (even with your mods) I would stick with a nice shorty manifold and hold power down low. That's just me though. Just my .02

Baller

Thanks for both of your replies. I think for now I'll just throw the LT1s on since a) I've got them already and b) as I understand it there's not a lot to it (I think mainly elongating some of the bolt holes in the down pipe flanges. Initially I'll keep the Y pipe and single and then convert over to a true dual.

I've heard the LT1 manifolds offer a pretty large performance gain over the l98 ones which is why I originally bought them. But the thoughts of hearing long tubes through a true dual exhaust is also pretty appealing...

cohocarl

I'm not trying to talk you out of putting on the LT1's, but unless there's dyno runs to prove it, I find it hard to believe they'd be much or any better than the L98 tube manifolds. I have been wrong before.

It looks like LT1 manifolds are getting around $100 on Ebay. You could sell those and put that $ towards some long tubes.......

But it would be easiest to run the LT1's with your stock exhaust though. Personally, I wouldn't change out the rest of the exhaust until I had some long tubes. Would have to do some modifying if you then went to long tubes down the road.

powerpigz-51

There was an article in a Vette mag (I do not remember which one) a few years ago, They replaced a stock LT1 exhaust with a stainless steel long tube, hi flow cats and an X pipe. 1800 dollars later.....6 HP gain. The L98 manifolds truly suck, the LT1's are a big improvement I suspect. I have Pacesetter shorties for my L98. They will go on when I do my cam, head, intake swap.

Tom400CFI

Say...WHAT!? Sorry, but "shorty manifolds" don't make more power down low. In fact, LT headers are better for improving tq, due to the tuned runner length.

Baller

That seems to be what I remember hearing. I think it may be like you said, the L98s suck beyond belief.

I remember my first build, it was a 383 Mopar I put into a 63 Plymouth. Couldn't afford headers so I scoured around and found exhaust manifolds that were part of a package for a 440 Hiway Patrol option. Years later added some headers, no appreciable seat of the pants difference. Those things flowed way better than I thought they did.

Probably just throw them on for now and then when I decide to do a build add the LT headers, they'd definitely make a difference on a 383.