AFR Piston to Valve Concerns....
Thread Starter
Former Vendor
Joined: Mar 2004
Posts: 1,518
Likes: 7
From: Valencia CA
AFR Piston to Valve Concerns....
Hello Everyone,
Seems there is a little confusion regarding "P to V" (piston to valve clearance) when running AFR 205 cylinder heads. We get a handfull of calls on this subject as well as seeing different claims on various threads all over the internet. I wanted to take the time to clear this up once and for all.
All things equal, an AFR 205 head will provide you with an ADDITIONAL .010-.015 piston to valve clearance when compared to a stock 65-66 cc chamber LS6 casting. Assuming you mill either the 205 (which comes 66 cc's from the factory) or a factory LS6 casting to the same "lower" figure for additional compression (lets say 62 cc's for arguments sake), you will always have slightly more piston to valve with the AFR 205. The "delta" always remains the same.
The upcoming 225 head however will be a different story....considering the same 62 cc scenario, you would have approximately .020-.025 LESS "P to V" than a factory LS6 head at the same finished chamber volume of 62 cc's. By the way, while I'm on the subject, it is now "in stone" that the 225's will be offered with either 62 or 72 cc chambers from the factory....additional miiling can achieve anything smaller than 62 or a figure between the two, but no chamber volume larger than 72 will be available. Earlier information available had indicated 76 cc's, but we ultimately decided that 62 cc's and 72 cc's would cover more ground in various engine configurations. The two contributing factors regarding the 225's loss of "P to V" are the larger diameter 2.080 intake valve, and the slightly larger, more open chamber design the 225's will come equipped with complimenting the 225's different valve size and shape.
Hope this info help a few of you out....If any of you have any additional questions feel free to call me at AFR or email me direct at tony@airflowresearch.com
Regards,
Tony Mamo
AFR Sales / Product Design
Seems there is a little confusion regarding "P to V" (piston to valve clearance) when running AFR 205 cylinder heads. We get a handfull of calls on this subject as well as seeing different claims on various threads all over the internet. I wanted to take the time to clear this up once and for all.
All things equal, an AFR 205 head will provide you with an ADDITIONAL .010-.015 piston to valve clearance when compared to a stock 65-66 cc chamber LS6 casting. Assuming you mill either the 205 (which comes 66 cc's from the factory) or a factory LS6 casting to the same "lower" figure for additional compression (lets say 62 cc's for arguments sake), you will always have slightly more piston to valve with the AFR 205. The "delta" always remains the same.
The upcoming 225 head however will be a different story....considering the same 62 cc scenario, you would have approximately .020-.025 LESS "P to V" than a factory LS6 head at the same finished chamber volume of 62 cc's. By the way, while I'm on the subject, it is now "in stone" that the 225's will be offered with either 62 or 72 cc chambers from the factory....additional miiling can achieve anything smaller than 62 or a figure between the two, but no chamber volume larger than 72 will be available. Earlier information available had indicated 76 cc's, but we ultimately decided that 62 cc's and 72 cc's would cover more ground in various engine configurations. The two contributing factors regarding the 225's loss of "P to V" are the larger diameter 2.080 intake valve, and the slightly larger, more open chamber design the 225's will come equipped with complimenting the 225's different valve size and shape.
Hope this info help a few of you out....If any of you have any additional questions feel free to call me at AFR or email me direct at tony@airflowresearch.com
Regards,
Tony Mamo
AFR Sales / Product Design
Melting Slicks
Joined: Aug 2002
Posts: 3,333
Likes: 1
From: Central NJ/PA
Originally Posted by Tony Mamo @ AFR
Hello Everyone,
Seems there is a little confusion regarding "P to V" (piston to valve clearance) when running AFR 205 cylinder heads. We get a handfull of calls on this subject as well as seeing different claims on various threads all over the internet. I wanted to take the time to clear this up once and for all.
All things equal, an AFR 205 head will provide you with an ADDITIONAL .010-.015 piston to valve clearance when compared to a stock 65-66 cc chamber LS6 casting. Assuming you mill either the 205 (which comes 66 cc's from the factory) or a factory LS6 casting to the same "lower" figure for additional compression (lets say 62 cc's for arguments sake), you will always have slightly more piston to valve with the AFR 205. The "delta" always remains the same.
The upcoming 225 head however will be a different story....considering the same 62 cc scenario, you would have approximately .020-.025 LESS "P to V" than a factory LS6 head at the same finished chamber volume of 62 cc's. By the way, while I'm on the subject, it is now "in stone" that the 225's will be offered with either 62 or 72 cc chambers from the factory....additional miiling can achieve anything smaller than 62 or a figure between the two, but no chamber volume larger than 72 will be available. Earlier information available had indicated 76 cc's, but we ultimately decided that 62 cc's and 72 cc's would cover more ground in various engine configurations. The two contributing factors regarding the 225's loss of "P to V" are the larger diameter 2.080 intake valve, and the slightly larger, more open chamber design the 225's will come equipped with complimenting the 225's different valve size and shape.
Hope this info help a few of you out....If any of you have any additional questions feel free to call me at AFR or email me direct at tony@airflowresearch.com
Regards,
Tony Mamo
AFR Sales / Product Design
Seems there is a little confusion regarding "P to V" (piston to valve clearance) when running AFR 205 cylinder heads. We get a handfull of calls on this subject as well as seeing different claims on various threads all over the internet. I wanted to take the time to clear this up once and for all.
All things equal, an AFR 205 head will provide you with an ADDITIONAL .010-.015 piston to valve clearance when compared to a stock 65-66 cc chamber LS6 casting. Assuming you mill either the 205 (which comes 66 cc's from the factory) or a factory LS6 casting to the same "lower" figure for additional compression (lets say 62 cc's for arguments sake), you will always have slightly more piston to valve with the AFR 205. The "delta" always remains the same.
The upcoming 225 head however will be a different story....considering the same 62 cc scenario, you would have approximately .020-.025 LESS "P to V" than a factory LS6 head at the same finished chamber volume of 62 cc's. By the way, while I'm on the subject, it is now "in stone" that the 225's will be offered with either 62 or 72 cc chambers from the factory....additional miiling can achieve anything smaller than 62 or a figure between the two, but no chamber volume larger than 72 will be available. Earlier information available had indicated 76 cc's, but we ultimately decided that 62 cc's and 72 cc's would cover more ground in various engine configurations. The two contributing factors regarding the 225's loss of "P to V" are the larger diameter 2.080 intake valve, and the slightly larger, more open chamber design the 225's will come equipped with complimenting the 225's different valve size and shape.
Hope this info help a few of you out....If any of you have any additional questions feel free to call me at AFR or email me direct at tony@airflowresearch.com
Regards,
Tony Mamo
AFR Sales / Product Design
When will the 225 be out???
