afr head question
Thread Starter
Le Mans Master
Joined: Oct 2002
Posts: 6,799
Likes: 11
From: dudley MA
afr head question
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so im getting the afr's at 66cc. i have the fm11 cam. do i mill the heads or not? i dont want to flycut the pistons. how much power would i be loosing if i didnt mill the heads. i just dont wanna put the heads on and them have to take them off after. what is the minimal i could mill the heads and be safe with the fm11 cam? sorry for all the questions i just wanna do this right and once
so im getting the afr's at 66cc. i have the fm11 cam. do i mill the heads or not? i dont want to flycut the pistons. how much power would i be loosing if i didnt mill the heads. i just dont wanna put the heads on and them have to take them off after. what is the minimal i could mill the heads and be safe with the fm11 cam? sorry for all the questions i just wanna do this right and once
Drifting
Joined: Aug 2003
Posts: 1,751
Likes: 3
From: Ventura, CA Fight On Forever
St. Jude Donor '03-'04-'05
Why don't you get them milled to 60 or 62 cc? All the shops I know of are getting their heads millled to that or similiar spec. 62 cc is delivering a 11:1 compression ratio. Can't answer your cam question, but the popular grind seems to be 224/228 581/...... 112-114 LSA. Contact Tony at AFR> He'll be happy to recommend a good cam.
I'm going with a smaller cam for an A4: 220/224 581/581 115 LSA for an ultra smooth stealth idle
Best,
mtv
I'm going with a smaller cam for an A4: 220/224 581/581 115 LSA for an ultra smooth stealth idle
Best,mtv
Former Vendor
Joined: Jun 2002
Posts: 2,045
Likes: 3
From: Bridgewater Ma
Originally Posted by pdd000
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so im getting the afr's at 66cc. i have the fm11 cam. do i mill the heads or not? i dont want to flycut the pistons. how much power would i be loosing if i didnt mill the heads. i just dont wanna put the heads on and them have to take them off after. what is the minimal i could mill the heads and be safe with the fm11 cam? sorry for all the questions i just wanna do this right and once
so im getting the afr's at 66cc. i have the fm11 cam. do i mill the heads or not? i dont want to flycut the pistons. how much power would i be loosing if i didnt mill the heads. i just dont wanna put the heads on and them have to take them off after. what is the minimal i could mill the heads and be safe with the fm11 cam? sorry for all the questions i just wanna do this right and once
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
A couple of other things to consider along with ptv clearance when milling the heads are:
1: You will need custom length pushrods.
2: The intake manifold will sit lower and the space between the heads will increase. I'm not sure how this would impact manifold port to head port matching, but I suspect alignment may be a slight issue.
I would be nice if AFR produced a head with different cc volumes, like Patriot. This way you could choose the compression ratio you want and still maintain ideal geometries.
1: You will need custom length pushrods.
2: The intake manifold will sit lower and the space between the heads will increase. I'm not sure how this would impact manifold port to head port matching, but I suspect alignment may be a slight issue.
I would be nice if AFR produced a head with different cc volumes, like Patriot. This way you could choose the compression ratio you want and still maintain ideal geometries.
Burning Brakes
Joined: Jun 2002
Posts: 996
Likes: 0
From: Frisco Texas
Originally Posted by pdd000
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so im getting the afr's at 66cc. i have the fm11 cam. do i mill the heads or not? i dont want to flycut the pistons. how much power would i be loosing if i didnt mill the heads. i just dont wanna put the heads on and them have to take them off after. what is the minimal i could mill the heads and be safe with the fm11 cam? sorry for all the questions i just wanna do this right and once
so im getting the afr's at 66cc. i have the fm11 cam. do i mill the heads or not? i dont want to flycut the pistons. how much power would i be loosing if i didnt mill the heads. i just dont wanna put the heads on and them have to take them off after. what is the minimal i could mill the heads and be safe with the fm11 cam? sorry for all the questions i just wanna do this right and once
Drifting
Joined: Aug 2003
Posts: 1,751
Likes: 3
From: Ventura, CA Fight On Forever
St. Jude Donor '03-'04-'05
Originally Posted by ArKay99
I would be nice if AFR produced a head with different cc volumes, like Patriot. This way you could choose the compression ratio you want and still maintain ideal geometries.
mtv
Le Mans Master
Joined: Jul 2002
Posts: 6,147
Likes: 32
From: Dallas TX
Originally Posted by ArKay99
I would be nice if AFR produced a head with different cc volumes, like Patriot. This way you could choose the compression ratio you want and still maintain ideal geometries.
didnt LG say you could order them at different cc volumes for like 80 bucks extra?
the ones they put on their test car were 59cc i believe
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Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Originally Posted by kumar75150
didnt LG say you could order them at different cc volumes for like 80 bucks extra?
the ones they put on their test car were 59cc i believe
the ones they put on their test car were 59cc i believe
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Originally Posted by kumar75150
didnt LG say you could order them at different cc volumes for like 80 bucks extra?
the ones they put on their test car were 59cc i believe
the ones they put on their test car were 59cc i believe
Burning Brakes
Joined: Nov 1999
Posts: 901
Likes: 83
From: Los Angeles
Damn, me too. I thought I was all done learnin' I was going to go 62cc by way of milling and run my C1 cam. I did not anticipate any "deck height" varience that could potentially screw everything up. I am not motivated enough to assemble one side to check or try out a bunch of different gaskets. I thought people were milling all the time the only concern being either P/V clearance (cam size) and octane requirements.
Damn.
Damn.
Thread Starter
Le Mans Master
Joined: Oct 2002
Posts: 6,799
Likes: 11
From: dudley MA
Originally Posted by Mirek
I did not anticipate any "deck height" varience that could potentially screw everything up. I am not motivated enough to assemble one side to check or try out a bunch of different gaskets. I thought people were milling all the time the only concern being either P/V clearance (cam size) and octane requirements.
Damn.
Damn.
Le Mans Master
Joined: Sep 2001
Posts: 8,840
Likes: 43
From: State of Confusion.
Originally Posted by MTV
As far as I know, AFR will produce any size CC anyone orders, within reason, of course. LG ordered one with a 59 cc, A&A gets 62 cc. The AFR standard spec is 66 cc and 76 cc, but I don't know why anyone would ever want a cumbustion champer of 76 cc. Anyway, you can have it your way no extra milling required. Best,
mtv
mtv
Drifting
Joined: Aug 2003
Posts: 1,751
Likes: 3
From: Ventura, CA Fight On Forever
St. Jude Donor '03-'04-'05
Originally Posted by LuvmyC5
The big chamber would help ALOT in a Forced Induction app. It'd lower the compression, so you could crank the boost up without detonation/KR.
Another mystery solved courtesy of CF contributors! Best,
mtv
Race Director
Joined: Nov 2003
Posts: 16,066
Likes: 4,148
From: Bergen county NJ
Depending on the final compression ratio you should only lose 3% per full point of compression ratio difference..
I believe the 66cc heads run approximately a 10.6? to one compression ratio? versus 11 to one of the 62 cc milled AFR heads..
So the difference might only be 5-6 rwhp? as a guess..
The stock cammed Z06 of Stano put out 409rwhp with the 66 cc and no headers even..
Maybe it doesn't pay to dic around with shaving the heads to get to 11 to one ratio?
Not sure but just trying to help..
I believe the 66cc heads run approximately a 10.6? to one compression ratio? versus 11 to one of the 62 cc milled AFR heads..
So the difference might only be 5-6 rwhp? as a guess..
The stock cammed Z06 of Stano put out 409rwhp with the 66 cc and no headers even..
Maybe it doesn't pay to dic around with shaving the heads to get to 11 to one ratio?
Not sure but just trying to help..
Burning Brakes
Joined: Nov 1999
Posts: 901
Likes: 83
From: Los Angeles
No way man it always pays to dic* around for more HP, It is just a matter of how much dic'*ing and what type. The 66 AFR's run 10.25:1 which I believe is less than stock. Somebody set me strait if I am wrong here.
If this deck varience is true wouldn't everyone be running slightly different compression STOCK and what with all the folks running milled heads and GM heads with all the different gaskets on F & Y bodies, I wonder why this does not come up more often - I'm not saying I doubt it, I know gaskets themselves can effect compression. I wish a vendor would close the loop on this. Good thread though !
If this deck varience is true wouldn't everyone be running slightly different compression STOCK and what with all the folks running milled heads and GM heads with all the different gaskets on F & Y bodies, I wonder why this does not come up more often - I'm not saying I doubt it, I know gaskets themselves can effect compression. I wish a vendor would close the loop on this. Good thread though !
Race Director
Joined: Nov 2003
Posts: 16,066
Likes: 4,148
From: Bergen county NJ
Ok..I agree.. 
Hope a vendor steps up to the plate and answers the question.
I'll be watching for an answer as well.
Stano did hit 409 rwhp in his stock cammed Z06 though with the afr heads with 66cc chambers and no headers as a point of reference.
Hope a vendor steps up to the plate and answers the question.
I'll be watching for an answer as well.
Stano did hit 409 rwhp in his stock cammed Z06 though with the afr heads with 66cc chambers and no headers as a point of reference.
info only
Racer
Joined: Jul 2003
Posts: 460
Likes: 18
From: Conroe, TX
[QUOTE=ArKay99]I just got off the phone with AFR. They gave me interesting info. THey have found that GM's deck tolerances vary up to +-.025", and that they use varying thickness head gaskets to maintain the proper CR. They also told me that they found you can remove .035-.040" without manifold fitment issues., so that is one thing less to worry about. QUOTE]
I can understand the production tolerance of +/- 0.025" for the deck to TDC piston height. But I find it difficult to believe that GM's automated engine assembly process has the capability to measure this tolerance and select a different head gasket based on a 6 sigma distribution model for every LS1/6 engine built since '97. . .
I also don't think that an extra 0.025" of quench means the difference between zero KR and serious detonation.
Finally, AFR should know enough to mill the intake mounting surface the same amount as the deck to ensure proper intake manifold fit. Otherwise the intake will sit too high between the milled heads.
There's got to be more to the story. . . Do you have that AFR number available? TIA!!
I can understand the production tolerance of +/- 0.025" for the deck to TDC piston height. But I find it difficult to believe that GM's automated engine assembly process has the capability to measure this tolerance and select a different head gasket based on a 6 sigma distribution model for every LS1/6 engine built since '97. . .
I also don't think that an extra 0.025" of quench means the difference between zero KR and serious detonation. Finally, AFR should know enough to mill the intake mounting surface the same amount as the deck to ensure proper intake manifold fit. Otherwise the intake will sit too high between the milled heads.
There's got to be more to the story. . . Do you have that AFR number available? TIA!!