Head questions (ed)

[white1]

I have a LQ4 low compression 6l with the factory 317 heads. i have a set of mildly P&P 5.3 heads that need a little work I had thought about putting on there, but hear that the loss of flow may not be worth the extra compression. My question is by using LS1 heads, how much compression would I gain by using the LS1 heads, and shaving them .020 and how would using the LS1 heads affect my flow?

I guess what Im asking is would the high rpm power loss be noticable like with the 5.3 heads, or do the LS1 castings flow good compared to the 317 castings?

[Ed Curtis]

I have a LQ4 low compression 6l with the factory 317 heads. i have a set of mildly P&P 5.3 heads that need a little work I had thought about putting on there, but hear that the loss of flow may not be worth the extra compression. My question is by using LS1 heads, how much compression would I gain by using the LS1 heads, and shaving them .020 and how would using the LS1 heads affect my flow?

I guess what Im asking is would the high rpm power loss be noticable like with the 5.3 heads, or do the LS1 castings flow good compared to the 317 castings?

Have you considered just milling the 6L heads to get the compression up and leaving the ports as is?

Ed

[white1]

That was the original plan, Im not sure how mutch that would bring it up, I was thinking the smaller cc on the 241 heads would bring it up more. I run N/A so I was going to try to get to about 10.5:1, and didnt know how mutch Id have to mill off the 317's. Thanks for the options.

[Ed Curtis]

That was the original plan, Im not sure how much that would bring it up, I was thinking the smaller cc on the 241 heads would bring it up more. I run N/A so I was going to try to get to about 10.5:1, and didnt know how much Id have to mill off the 317's. Thanks for the options.

The bigger engine would repond better to more air than more compression. Especially a dual purpose engine. One batch of bad fuel and it's detonation city...

Taking a stab at the milling... .006" per CC is about average.

Ed

[white1]

The bigger engine would repond better to more air than more compression. Especially a dual purpose engine. One batch of bad fuel and it's detonation city...

Taking a stab at the milling... .006" per CC is about average.

Ed


.006 per CC? Excuse my ignorance, but I dont understand. .006 per cc of the actual combustion cahmber? ex. if teh heads have 62cc combustion chambers take .006x62?

[Ed Curtis]

.006 per CC? Excuse my ignorance, but I dont understand. .006 per cc of the actual combustion cahmber? ex. if teh heads have 62cc combustion chambers take .006x62?

Doh...

Mill .006" off the deck per 1 cc of chamber removal...

Ed

[white1]

Ahhh thatks for clearing that up. Do you by any chance know how that affects compression. I guess how many points it increases per cc of decreasing the cc.

[Ed Curtis]

Ahhh thatks for clearing that up. Do you by any chance know how that affects compression. I guess how many points it increases per cc of decreasing the cc.

This'll help..

http://www.slowgt.com/Calc2.htm#CompRatio (http://www.slowgt.com/Calc2.htm#CompRatio)

Ed

[white1]

DAMN Thanks Ed