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post #1 of 10 (permalink) Old 10-14-2008, 11:45 AM Thread Starter
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AFR Heads

What is the average HP gain i could expect to see with a set of AFR 205cc or 225cc heads? :-?
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post #2 of 10 (permalink) Old 10-14-2008, 04:02 PM
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Re: AFR Heads

I'm no expert, but from my personal experience it depends on your other intake/exhaust mods and how well your engine flows. But I've heard typically 20 to 30 rwhp.

I added a FAST90/90 setup with stock heads (had LG Street headers and Blackwing already) and picked up zero (that's right, the big donut) 0 HP.

After adding AFR heads I thought I would get back what I didn't get with the FAST90 setup, (typically 15 to 20 rwhp) but I only picked up 22 rwhp total with both mods.

(it just occurred to me that I haven't considered that the Blackwing may be limiting my air flow?) Hmmmm...

So it seems to depend on how well your engine is breathing already. An engine is just an air pump with a gozinta and a gozouta. You have to optimize both pressures for them to work in harmony with each other. So it will depend on your other mods to determine if you need 205 or 225 heads - stuff like intake and exhaust.

Again, I'm not an expert, just foaming at the mouth. Maybe Lembo or Pitt or Ernie will speak up.
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post #3 of 10 (permalink) Old 10-14-2008, 04:05 PM
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Re: AFR Heads

Originally Posted by 1fast02 View Post
What is the average HP gain i could expect to see with a set of AFR 205cc or 225cc heads? :-?
Man, you will get all kind of numbers because of the different cams and setups. Roughly though, with a mild cam, heads, headers and tune...about 65-80...on up I would guess. Just putting different heads on without anything else, maybe 15-20+


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post #4 of 10 (permalink) Old 10-14-2008, 07:34 PM
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Re: AFR Heads

There are way too many variables to try to put an accurate number on a head swap. Alot depends on what cam you have in your motor currently.
There are a few cams that work great with out of the box AFR's. There are ways to optimize each combo, mainly depends on head flow and compression ratio. On my H/C 346, I picked up 17rwhp when I went from the stock LS6 manifold to an unported Fast 90/LS2 TB setup, but that was after tuning by one of the best in the business. (FRC Tom). A set of AFR 205's on a stock 346 won't give you much unless you've got the right cam to go with it.
Post up more info on your current set-up and we might be able to make some educated guesses.


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post #5 of 10 (permalink) Old 10-14-2008, 09:49 PM
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Re: AFR Heads

I have no clue since i'm still running the 243 Z06 castings on my LS1...but I did pick up 19hp with the fast 90.


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post #6 of 10 (permalink) Old 10-14-2008, 10:27 PM Thread Starter
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Re: AFR Heads

well currently its all stock execpt for supermaxx long tubes and borla cat back, i also have a varam installed. The internals are stock and sooooo, i was thinking of a AFR or trick flow heads/cam set-up. NOW, what is the major difference between the FAST 90 and a LS6 upper intake, that will be my next purchase instead of the heads and cam; apparentely they all get better HP gains if you change to the LS6 or FAST 90. OH, incase you havent figured it out, i have a TR coupe, not the Z!!! BUT, its just as fun!
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post #7 of 10 (permalink) Old 10-15-2008, 09:22 AM
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Re: AFR Heads

On my old car they were worth about 25 HP milled for 60cc chambers.

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post #8 of 10 (permalink) Old 10-15-2008, 01:45 PM
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Re: AFR Heads

The 205 head is better suited for the stock displacement. The 225 is more of a big bore cylinder head.

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post #9 of 10 (permalink) Old 10-20-2008, 12:49 PM
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Re: AFR Heads

If you have an '02, you already have the LS6 intake manifold/TB combo. As to head selection/expectations, I gained approx. 130 RWHP with my combination.

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post #10 of 10 (permalink) Old 10-21-2008, 04:09 AM Thread Starter
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Re: AFR Heads

outstanding!!! NOW...what are the chances of me messing something up if i up the nitrous shot from 100 to 150. Its already progressively controlled, so i think im safe there! I am worried about the internals, which are all stock!
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