Choosing heads for the street
Thread Starter
Racer
Joined: Mar 2008
Posts: 315
Likes: 0
From: KY
Choosing heads for the street
I have a zz4 with lt4 hot cam and 1.6 rockers
I am looking for some heads that will work good on the street
Looking at the AFR 180 eleminators and GM fast burns
Which of these would be the best on the street
How much HP and torque might these combos make
I am looking for some heads that will work good on the street
Looking at the AFR 180 eleminators and GM fast burns
Which of these would be the best on the street
How much HP and torque might these combos make
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The ZZ4 already comes with P/N 12556463 L98-type heads; some porting investment here could get you into 250+CFM intake flow.
Need more information than "work good on the street"; I assume the L98's are already doing that
Need more information than "work good on the street"; I assume the L98's are already doing that
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Well, as a general guideline for a 350 CID engine intake runners around 170-180 CFM are the best fit - you could go as far as 195's with the Hot Cam's .525 lift (with 1.6 rockers)
The Fast Burn heads (GMPP P/N 12464298) are 210cc intake runners, which IMHO is too big for a street 350 with a relatively mild cam like the Hot Cam.
So, I would lean towards a 180-195cc intake runner head. AFR 180's are a great choice; I would lean towards the Streets vs. Competitions or Eliminators myself.
The problem you face is that your existing heads are 58cc combustion chambers, and both of the heads you're looking at are 64cc - so you're losing about .7 points of CR with the swap.
I'd estimate about a 40HP/30TQ gain from the swap. In terms of gain/$, not sure that it would be worth the swap. There are plenty of porting companies that would massage those L98's for you.
The Fast Burn heads (GMPP P/N 12464298) are 210cc intake runners, which IMHO is too big for a street 350 with a relatively mild cam like the Hot Cam.
So, I would lean towards a 180-195cc intake runner head. AFR 180's are a great choice; I would lean towards the Streets vs. Competitions or Eliminators myself.
The problem you face is that your existing heads are 58cc combustion chambers, and both of the heads you're looking at are 64cc - so you're losing about .7 points of CR with the swap.
I'd estimate about a 40HP/30TQ gain from the swap. In terms of gain/$, not sure that it would be worth the swap. There are plenty of porting companies that would massage those L98's for you.
Racer
Joined: Mar 2001
Posts: 467
Likes: 3
From: Dover AR
AFR 180s. Lot's of magazine tests with these heads post some pretty impressive HP and torque numbers. You can port L98 heads and not get near the flow numbers AFRs make. Let's say you can find L98 heads for $200, send them to DR-Js for a $900 port job and you still won't have heads that will flow like the AFRs. Spend $340 more and be happy!
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Safety Car
Joined: Oct 2005
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From: Algonac Michigan
Drifting
Joined: Aug 2006
Posts: 1,279
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From: Delray beach FL
Katech is state of the art race engine for sure.....
Not sure they will recommend any as they do their own job anyway.
Le Mans Master
Joined: Oct 2002
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From: Las Vegas - Just stop perpetuating myths please.
Burning Brakes
Joined: Aug 2006
Posts: 911
Likes: 8
AFR's !! With a little more cam and go 195's.
I have 195's that were milled to give me 58cc's topping off my ZZ4 rebuild.
L98 heads are no better than 1990 truck heads, except they are alumn.
Best power making purchase you can make is good heads - spend your money there.....
I have 195's that were milled to give me 58cc's topping off my ZZ4 rebuild.
L98 heads are no better than 1990 truck heads, except they are alumn.
Best power making purchase you can make is good heads - spend your money there.....
Burning Brakes
Joined: Aug 2006
Posts: 911
Likes: 8
But then again, I do remember a hole in the front of the cam that may have been for a dowel in LT4 application - and ZZ4 does use a cam retainer.......
Last edited by FastEddy; Jan 1, 2009 at 11:02 PM.
