I have a 1991 Z28 350 TPI L98. I want to get more power (not a ton more). Eventually I am looking to try to get about 320 hp out of the car. The car is rated at 245 hp. I am looking to do as much "cheap" performance stuff that I can. I heard about the Vortec heads and I don't want to spend money on a new base plate right now. I am looking for heads that are better than stock. How much gain would I get having the stock heads ported? What about Corvette heads? What years would work? like I said, I am not looking for a ton of power, just enough to keep up with the 4th Gen. cars.

 

Kevin91Z is running ported L98 vette heads I believe, and hes in the 12s with HP numbers higher than what you're looking for.

 

COOL! Thanks for the tip!

 

Yeah those Alum. Vette heads have a ton of potential. They can be used with a mild port job or experienced people can actually do a very crazy race port. Lingenfelter's old book claims he could make 425-450 HP with his CNC ported versions...Who knows what kind of cam he used and at what RPM he got those numbers but good luck man..



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Denny Villemure
1989 Camaro IROC-Z Convertible, 305 TPI, 2.73 Gear, Flowmaster 2 chamber. 15.60 on motor, 14.20 on a 75 shot from NX. Woo hoo!
www.denny.cz28.com

 

I dont know if you have a preference or not, but www.theengineshop.com has world product heads aluminum bells and everything for around 795.00 per pair.. Check it out.. Same as dart, a lot better price..

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86 Chevrolet Camaro Iroc Z-28 Fully Loaded With T-Tops
Mods;
Spohn SubFrame Connectors, S&W Race Car Chassis 8 point Roll Cage, 1997 SS Aniversary 3.42 POSI Rear End with 12" Rotors and 4 Piston PBR Calipers, Balanced Drive shaft... Others soon to come...

Best times before any mods done, Complety Stock;15.6 @ 87mph
Waiting for the tracks to open again to see what I got going on Now!

ntimad8.cz28.com

 

What about the self-aligning rockers? What heads are direct bolt ons? If I am gonna do a head swap, do I have to stay with the self-aligning rockers? 1.6 rollers are about $100...the self aligning ones start at $200. The non-self aligning requires guide plates. I want to keep the Stock Valve covers (center bolt). What year Vette heads would be the best? Clueless on Vette info. Let me know what you guys think

[This message has been edited by BryGuy1 (edited July 10, 2002).]

 

As for self aligning and non self aligning rocker arms...

Basically you NEED Self Aligning rocker arms on stock heads because they have no guideplates. the extra cost for the rocker arms isn't bad at all. Why is it not bad? Mainly because if you wanted non self aligning rocker arms you would need guide plates foryour pushrods. To use guideplates, you need screw in rocker arm studs. To do that you need to take the heads off of the engine and have the rocker studs popped out, holes need to be drilled and threads need to be tapped, then you can have new studs screwed in with guideplates and viola..you saved $100 on the rocker arms..

But then again the machine work to do all that is probably a BIT more than $100...get me?

Anyone know the cost of a conversion like that?

I ended up getting Crane Gold Race roller rockers. I think they were around $300 out the door at a local race shop. Goodluck man

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Denny Villemure
1989 Camaro IROC-Z Convertible, 305 TPI, 2.73 Gear, Flowmaster 2 chamber. 15.60 on motor, 14.20 on a 75 shot from NX. Woo hoo!
www.denny.cz28.com

 

You are absolutely right. I don't have a problem staying with the self aligning rockers. aftermarket heads usually come with the non self aligning, Aftermarket heads or performance GM heads would be nice, I just don't know exactly what is good out there and was wondering if you would know the good heads are that I could pick up at a swap meet or buy brand knew for a good price. I am looking for something possibly aluminum, have 2.10 1.60 valves or the potential to have them. about 180 flow, I am not building a drag car, it'll be more of a street car. I eventually plan on porting the intake. the car has 100,000 miles and geting heads and porting the intake is as far as i want to go before the rebuild. By then I can choose a cam...etc... thanks guys..

 

You'd probably be pretty happy with some hogged out aluminum L98's. Will keep your compression ratio decent too if you're running a 305... which you're not (oops). Still, they are pretty nice heads with a lot of potential.

[This message has been edited by Yellowknifer (edited July 11, 2002).]

 

So does anyone know what year car the aluminum L98 heads came on? How about the comustion chamber volume and valve sizes?

 

im sure it has been saud.. but i dont feel like reading.. but get some vortec heads and have them ported alottle and a 3-way valve job. oh, and also port/match the intake/gaskets/heads this will really wake up the motor.

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1986 IROC-Z
406 SBC TPI
399.6 rwhp 436.1 rwtq
*damn injectors running lean*

 

Just adding my .02, let's say you score some used L98 aluminum heads for around $400 - $500, then you pay to have a valve job, etc. For around the same money you can buy Vortec heads and the better base manifold. Also, if you are running a stock cam - with a killer set of heads, the car will feel sluggish in the lower RPMs. A cam swap might not be on your mind right now, but if you are going to go through the trouble of a head swap - save yourself some grief and do a decent camshaft now. ZZ4 or LT4 Hot cam with Vortech heads and a SDPC base would net you a nice gain and have you very close to your 320 flywheel HP goal.

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1986 IROC-Z, 8pt. cage, 383, Mini Ram, DFI, Art Carr 700R4, 12 bolt.....