LT headers worth it on an L98
 

The car is an auto 88 z52 with 3.07 rear 58K on the clock. What is everyone's opinion on LT headers? Was the cost worth the increase? Did the car lose anything from 0 to 60? I have read many of the old posts. I'm a little confused as to scavenging effects. Thanks for input.

mike

Long tube headers are the biggest bang for buck for a TPI,
back all those years ago when my c4 was standard I ran it at a quarter mile 14.5 sec quarter stock standard.

A week later after headers fitted down to 13.7, then set fuel pressure from standard pressure up another 15 psi. Advanced timing a little and more launching practice got it down to 13.4 quarter mile.

Goes to show C4s love long tube headers and more fuel pressure.

To do what? Is this part of a plan to do something big or is this the end of the road for mods?

That's a seriously impressive result. That with the intake, TB, etc untouched? Cuz the intake is quite a choke point on those things from all I've read. I've no practical experience with 'em, just my stock LT1.

It has a cut air lid, no pre cats and a high flow main cat. I wasn't planning on much further as it is a weekend cruiser. I thought headers might give it a kick in the pants plus a little sound. I do not want to sacrifice the low end torque however.

If that was all I was going to do, I really don't think I would do it myself. If I was going to do intakes and a dyno tune, absolutely.

Given this, you might want to think about a gearing change. Going from a 3.07 to something like 3.70s or even 3.50s would make quite a difference in acceleration.

Go with lt headers. You will gain from off idle to redline.

Probably the best way to go

No gear change needed on an L98 car. A TC would be a worthwhile change, since 88 has a crappy ~1600rpm TC, and really needs 2000 in stock form.

Yes go with headers, they sound great and they do give you some power. With the TPI intake still on it, you won't be shifting your powerband up enough to notice any difference in low end torque and it will still be faster 0-60. Mine was.

Agree. Plus you won't have to deal with additional engine bay heat, exhaust leaks, tightening bolts, etc.
You may want to recalibrate your speedo, but that's not a show-stopper because you don't HAVE to.......

Taken by themselves, headers will generally add little to performance. To your question, they won't detract from it, either.

:iagree:

Another vote for go with the headers.

The stock L98 manifolds are horrible.

It will help power at all rpms and frequently you will see mpg gains too.

I think they are the best bang for the buck and I have done them on quite a few of mine.

Good luck.

I also agree with headers vs gears too. The L98 already IS a torque motor. Add more torque via gears alone? Not necessarily a good plan (depending on stock gears which the OP has GOOD gears for a TPI). Headers, OTOH, if you can gain a whole second in the 1/4, that's impressive.

Plus, I've personally SEEN the stock manifolds before I sold mine. Unless you grind/port the heck out of them, they are the weakest link. OK...that and the diameter of the tubes on top.

Then the cam, then the heads.... LOL



Oh yeah...FWIW: If no serious mods INSIDE the engine are planned, 1 5/8" headers would be my vote for a stockish L98

thanks guys. I really appreciate the advice. I'm looking at the headers that are available for our cars now.

How much did those headers cost? Was it a good coated set for longevity? Easy fit? Most of those I have seen are north of $700 if you want it to fit well and have easy access.

Is that even worth the time and money to do?

And there goes his kidney and lung and whatever else he has two of. :rofl:

I never tried that. Does it make it easier to install? I can't remember which one we tried a few years ago for someone. It was a Royal PITA to install.

Speaking of porting the stock exhaust manifold, I dont see that mentioned a lot around here (for obvious reasons with LT headers). What CAN be achieved with the stock piece with grinding/porting? How much more can they flow? Say for example someone wanting to do a mild stock-appeance build.

I would think you can port it but from what I have read, the gain isn't that much so unless you are running in stock class on an autocross and you have no way to change it, that is your only option for better flow. I really don't think it is worth the effort for the little you will gain based on what others have said. I suppose if you are doing the work yourself and trying to learn how to port heads, it isn't too much waste considering the confidence you get from it and the education of how far you can go for the real project.

As to the headers, I would definitely be planning for an intake swap and headers and tuning to have the system make use of each part I am installing. Sure, you can get a gain from the header but I think all 3 components will really give you the bang for the buck or bucks. I wish I could say how much but I didn't have it on a dyno till we did the intakes and headers and tune. I do know it had hesitation with the Superram and Tri-Y headers and without the tune but it got fixed after the stock chip went out and LPE upgraded it.

Just on the headers alone, the cheaper ones will have to have you put something to make the braces work since they don't have the bolt bosses welded in. If the OP isn't going that far as intake to remove the weak links and optimizing what he has, I don't know if it is worth it to do just one component. Since I wouldn't, I'm not going to suggest someone else does it.

Yeah...if you want bolt and run, that's a reasonable estimate. OTOH...Gears are in the same ballpark installed.

Hedmans and OBX can be had on the cheap. They can require a bit of fabrication (which is what I did...though with a different product).

Porting stock manifolds might get you a little. Really, part of the restriction is the exhaust pipe(s) too. Another possibility....If you're looking for something on the cheap is to swap in an LTx exhaust -- including manifolds. Whether headers or LTx swap, look to position bullet cats on either side of the transmission. You can leave out the main (if your area allows it). I'd "Y" into a long glass pack that back to duals gets you muffling with psuedo x-pipe action. Plus, you can add other mufflers (turbo, Corsa, Targa, or whatever) at the back end IF you don't thing the cat/glasspack combo is quiet enough.

I like the idea of improving the intake too...whether just the tubes or a superram. Without a cam change, these two mods might run fine w/o a tune -- though it never hurts to get TunerPro to see what's going on. TunerPro is a good tool for general diagnosis as well...and is cheap.

Most sources would tell you that scavenging isnt' going to be terribly significant with your stock cam. There's not enough overlap where the intake/exhaust valves are simultaneously open for scavenging. Basically, I'd cite that as the reason LT Headers on an LTx car only show gains in the 10-15hp range.

But, the LTx exhaust is much better than L98's before it. Improving an L98 exhaust is worthwhile...even if you don't go for headers. If nothing else, you'll make is sound beefier and gain fun that way.

FWIW, I'm not saying gears wouldn't be fun as well. Mostly, you'd feel a bump in performance above 2nd gear. In essence you'd be lowering how your existing gears perform.