My buddy has an 87 lg4, and I have an 89 TPI. I'm planning on getting headers in a month or two, and he thinks my TPI exhaust manifolds look bigger than his lg4 manifolds. I told him he can have them when I get headers.

Is there any difference? I don't want him to waste his time replacing working manifolds with the exact same manifold, if they're the same.

 

no, the tpi's got bigger exhaust manifolds, but i dont think it would be worth it for him to change them. It wouldnt make that big of a difference. Just tell him to get headers when he has enough money.

 

I know some thirdgen manifolds (I think it's the l98s) have a bigger outlet on them, but I can't imagine going to the time and work of swapping them. You wouldn't gain enough flow to justify it, IMHO. Besides, right behind those manifolds is a very restrictive Y-pipe that's at least as bad as the manifolds.
Maybe this isn't the answer you wanted, but I'd tell your friend to get headers, more money, I know, but worth it.

 

I agree, it's not worth it to swap them, but he disagrees. I'll probably show him this thread and let him decide.

he's just one of those "anti-headers" kinda guys. You know the type? you just can't convince'em

 

I know, I was one of those guys after a bad experience with them. But headers, gaskets, fasteners, and coatings have improved over the years, so my opinion has changed. My SLPs are getting coated this week.

 

Don't forget, he'll need the appropriate y-pipe to match the larger outlets of your TPI manifolds.

Pete

 

I just happened to compare the '86 LG4 manifolds and '87 LB9 manifolds (that are in my garage attic) last night. The flange/opening happens to be bigger, but the driver's side (I think it was that one - at least it was one of the two sides) LB9 manifold was extremely small just above the flange. No bigger, actually, than the LG4 manifold when you take the effective flow path into account.

I have a bud who's maxed-out ZZ3 still uses TPI manifolds. He took his die grinder to them before installation. With dual cat exhaust and Big Mouth cat-back, he run's low 14's here (translates to 13 flats at sea level).

Get headers. Don't bother with factory iron manifolds. That's what he's doing.

 

I swapped the L69, which I believe is the same as the TPI, exhaust into my LG4 (It was pretty much a free-be). Difference in the two--huge. No doubt that headers would be better, still.... Here are the y-pipes in question.

JamesC

 

The stock intermediate pipe is larger than the aftermarket that I previously had as you can see.

JamesC

 

OMG!!!! That big pipe could eat that small pipe. lg4 stuff is TINY

 

Black,

By the way, the TPI manifolds won't have the heat stove for the air box (carb) or the EFE valve--what used to be called the heat riser. You can probably still purchase these pieces from GM. While this system, to include the y-pipe, etc, may be restrictive compared to headers, remember that the L69's (with other stock differences between them and LG4's, of course) could whack a 350 from time to time. Top speed was somewhere around 135.

JamesC

 

Yeah, I know that. My first car was an 87 Camaro LG4. I learned a lot on that car. It was a beater, too. EFE was froze open, and the pipe for the heat stove was missing.

EFE just warms the intake manifold when it is closed right? I never understood what that thing did until I had to pull the intake and got a good look at it. When the EFE closes, it just causes exhaust from the pass. side cylinder bank to pass through the manifold, warming it up faster, right?

As for the THERMAC/heat stove, that never worked either. That things just there to prevent carburetor icing, right? I drove the car in some zero to 10 below weather (cold as it gets in my part of missouri), and i never had any problems with carb icing. Not even on long highway drives. I think the engine compartment in thirdgens is so compact, that everything stays warm enough with out it, so it's not really necessary, unless you live in Canada, or Alaska or something like that.

I'm sure if the EFE had worked, it would have warmed up faster, but that was never really a problem either. It was always good and warm in no more that 2 or 3 minutes.

 

JamesC & Black,

I've got an LG4, and I want to put 350 headers on it in order to get 3" exhaust all the way back. If those headers won't have the EFE or heat stove openings, what should I do? Can I just ignore them?

I live in Mass., not the arctic circle, but it was regularly down to zero last winter.

John

 

John,

To verify, you might do a search; however, I believe the L69 has the same exhaust manifold as the TPI cars, 305 or 350. If it were me, I'd simply purchase a set of Edelbrock TES headers for an 1983 to 86 Camaro/Firebird HO (4 barrel) part number EDL 6874, page 51 of the Summit Cat. These come with heat stove, air injection, O2, y-pipe, etc. There are, no doubt, other choices, again a search might help your decision.

JamesC