I've been reading that the L98 aluminum head is an excellent upgrade for the LB9, especially when ported. The issue is however I also read that the vette heads do not have the same egr provisions as the stock heads. Is this true? What about ZZ4 heads? Are those emissions compliant? I'm on a really tight budget so aftermarket is not an option considering what I see L98 vette heads go for. My last comment is that I tune my own car and ever since I installed my Accel intake, I had installed a new EGR but always got the EGR code so in my tune I fixed it so I didn't get that code from the EGR. The car passed smog just fine like that. If I install aluminum L98 heads anyway, will it still pass smog just fine?

The original L98 vette heads and their kissing-cousins, the ZZ4 heads have no exhaust crossover and therefore no way to get exhaust gasses to your stock F-body EGR system. Technicall, emissions illegal. But if you can pass without a truly functional EGR system it will still LOOK like everything's there and functional from the outside. Definitely it'll throw EGR codes when you deny it any EGR gasses to send into the engine (there is a temp sensor in the TPI EGR valve the positively verifies if any hot exhaust is flowing through the valve when the ECM commands it).

scoggin dickey sells a conversion kit that allows you to maintain stock EGR function.

BUT you will need a corvette base TPI manifold..which u can get for cheap on ebay or classifieds corvette forums. EDIT: i see you said ACCEL intake... if you have an aftermarket TPI BASE, it is setup for both vette EGR and camaro EGR. if you do the vette EGR, you need a block off plate to cover the holes for the camaro/firebird EGR

basically converts your motor to a vette style EGR. Like above said, the L98 aluminum heads do not have exhaust crossover....so what the corvettes do to get exhaust gasses, is that they take a tube attached to the headers/log manifolds and run that exhaust gas up to the EGR valve port, which is located on the BACK of the TPI baseplate. Fbody's have the EGR in the middle of the manifold, and get their exhaust gasses from the cylinder heads.

SO, if you get a vette manifold and the EGR adapter KIT, which i think is 60 bucks, you can still maintain functional EGR.

Do you guys know if the vette heads are center bolt or perimeter for the valve covers?

what's your budget like? i can point you in the direction of some really really nice heads for a reasonable price.
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i believe 88+ should be center bolt

A couple hundred for the heads, maybe more. Depends how complete they are. Ready to bolt on I'd like to stay under $250.

damn dude you aren't gonna find anything usable for that much. i was gonna say i can find you something decent for 450 each ready to go. but that's about it. if you find a set ready to bolt on for 250 bucks i wouldn't trust them.

Thanks for the advice. I guess I'll hold off on this mod then since I don't have the cash right now.

All the aluminum L98 heads are centerbolt, regardless of year. They also all have the 'early' intake bolt angles.

yeah usually 87 up are centerbolts, i'm not sure when they came out tho.

and most L98 heads are 400-500 bucks COMPLETE for the PAIR ready to bolt on.

i dont think they are worth more than 300 complete unless they have very low mileage or new springs/retainers and such.

First, how much have you searched? I have posted my info on my L98 heads over and over to everyone who asked. Surely the info is still floating around this website somewhere.

Only on the MAF cars. On speed density cars like ours, the EGR valve does not have a temp sensor. It monitors the vacuum to see if the EGR is open.


No, the F-body and Corvette EGR valve is in the same place, the center of the intake manifold under the plenum. You only need a block-off plate if you are using the f-body EGR setup, to cover the hole for Corvette EGR passage in the back of the manifold.

I have attached some pics of my setup and a Corvette setup for reference.

what i ment was the place where the EGR pipe from the headers connects is at the back of the manifold, not the EGR itself. camaro intake manifolds dont have a connection at the back
but your right. you dont need a blockoff plate if you run EGR. i had it confused

Originally Posted by Damon
Definitely it'll throw EGR codes when you deny it any EGR gasses to send into the engine (there is a temp sensor in the TPI EGR valve the positively verifies if any hot exhaust is flowing through the valve when the ECM commands it).
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FINALLY, a forum that is more than armchair Budlite, horsef*rt philosophy. Gentlemen, can you PLEASE help me with an 88 Vette problem? Our Hawaii mechanics couldn't wire a Christmas tree. I'm $10,000 in the hole and still have the same hot engine performance problem. Changed everything but the rear tires, and now since I have headers, I'm also getting a Code 32, most surely because our Corvette Einstein welded the old header tube shut. I probably need to address this first. Can I bypass the EGR entirely? I have no smog pump. Or do I have to tap the rear header tube and fabricate a connection (other forums say you have to have an original flex tube and it cost a hundred bucks, but it won't fit anyway. What diameter tube would I have to have minimum if I do this?)

Car runs great cold, then misses like a thrashing machine hot (with a 4 to 7 mpg readout and no power. Very loud harmonic drone miss. Also running no cats but this happened BEFORE code 32, headers and all the mods). Something harmonic throwing the computer off? Do L98's have knock sensors? There was a big iron disc on the water pump pulley when I got it which was hell on the bearing so I took it off, Runs the same with it.

If you have any ideas, an old retired Marine on a pension would really appreciate it. This madness all started because the Vette specialist pin head here said I had a plugged catalytic convertor!!

At least I have horsepower cold now (early C4's are such factory dogs! This is my third ...one with every divorce, ha, but this one, like my women, has me stumped entirely).

Aloha and Merry Christmas!

Wm. Chiles, author
"The Secrets & Mysteries of Hawaii"
Amazon 5 star rating for over a decade

Pila, it's not enough to just remove valve & block off the EGR port you still have the programming to contend with.

I believe the camaro v6 has the flex tube you need.
Be sure to check into the Diagnostic EGR Temperature Switch as well.

Plugged cat...well, was it?

Yes all TPI engines have knock sensors.

Yes you could remove the EGR but you'd have to get custom chip programming to remove the code.
Keep in mind this isnt smog legal but you're already illegal with the removed air pump and cats.

It sounds like you have something physically wrong with the engine, but internet mechanics isnt an exact science.

sounds like wat im doin, i dont care about codes, the car isnt goin on the streets, and we have no emissions out here for under 96, yeah, i know im lucky. i have an 87 iroc, different motor entirely, its out of an 87 monte carlo, its the 305 h.o., im getting the tpi setup, with the AIR and i believe the EGR bypass chip. egr will be a waste for me, and that 9th injector, useless. i have straight headers with the o2 ready to go, after i find wat o2 to buy. i heard i need like a nock sensor, and all this. wat do i need, and like on carbs, can i bypass that coolant flow into the base, just block it off. this motor is pretty much equipped with a sensor on the pass side of the block, right where the block meets the pan, idk wat it is.
this cars not running, hoping it is tho
wat do i need, and will it run
im using the MAF, stock computer, all that
thanks for your help

did you have to disconnect one of the air tube insert and use that for the vette bypass? is there a dmv problem with that?

Now by any chance do you have the part # to this kit?

Or is this it?

http://www.sdpc2000.com/product/PP52...DAPTERKIT.aspx

Parts of that kit were discontinued by GM, so the kit was as well.