good amount to mill 5.3L heads, what compression
Thread Starter
Joined: Nov 2001
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From: Tallahassee, Fl
good amount to mill 5.3L heads, what compression i plan on getting PP 5.3L heads this week to go with my 224/581/112 cam
what would be a good compression to run. i was thinking something along the lines of 11:1, maybe a little higher.
i only run 93 octane and the car is a daily driver, what compression should i go with and how much should the 5.3L heads be milled to achieve this
thanks
ryan
what would be a good compression to run. i was thinking something along the lines of 11:1, maybe a little higher.
i only run 93 octane and the car is a daily driver, what compression should i go with and how much should the 5.3L heads be milled to achieve this
thanks
ryan
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From: PA
Re: good amount to mill 5.3L heads, what compression .030" . this should put you at 10.5:1 compression. especially if high octane is not available to you this is all i would go. that should be good with the cam you have also.
Re: good amount to mill 5.3L heads, what compression
wont .030 on a 5.3L heads put me at 11-1
Don't forget you'll need shorter pushrods when milling that much off your heads. I already had stock length hardened pushrods so I ordered my heads without any milling to keep from having to buy pushrods again.
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Re: good amount to mill 5.3L heads, what compression I was told by Jay @ Absolute that my CR was right at 11:1 without milling my 5.3's! Might want to talk to you head porter (miller).
Re: good amount to mill 5.3L heads, what compression They are slightly higher, but most porters remove material from the combustion chamber on the 5.3 heads to "unshroud" the exhaust valve on the head.. the removal of the material equates to a larger cc of combustion chamber and lowers the static compression ratio over what it would be with an unmodified 5.3 head, therefore most people mill the modified 5.3 head to regain the lost compression.
Thread Starter
Joined: Nov 2001
Posts: 3,406
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From: Tallahassee, Fl
Re: good amount to mill 5.3L heads, what compression what length pushrod would i need with the heads milled .030
also how much could you mill and keep the 7.400" pushrods
i belive i was told by terry from patriot and jason at texas speed that i could mill about .015 to get 11-1 compression. does this sound right, i spoke with them i while ago and dont really remember. also could i use the same pushrods i have (comp 7.400")
basically im trying to figure out what a good compression ratio would be on an NA daily driver running 93 octane and how i would achieve this?
also how much could you mill and keep the 7.400" pushrods
i belive i was told by terry from patriot and jason at texas speed that i could mill about .015 to get 11-1 compression. does this sound right, i spoke with them i while ago and dont really remember. also could i use the same pushrods i have (comp 7.400")
basically im trying to figure out what a good compression ratio would be on an NA daily driver running 93 octane and how i would achieve this?
Re: good amount to mill 5.3L heads, what compression I'm running my heads uncut, but I think your cam has a smaller base circle than a stock one ( know the TR cams do ) so you could probably get away with .015 on stock length push rods.
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From: SW Florida
Re: good amount to mill 5.3L heads, what compression gomer is right....
Case in point: Non- surface milled TEA 5.3L heads will have a chamber volume of approx 63cc after the CNC machine removes the needed chamber material in order to un-shroud the valves.
The 63cc chamber on a stock displacement 5.7L will get you a 10.8:1 CR when stock graphite head gaskets are used.
Ron,
Case in point: Non- surface milled TEA 5.3L heads will have a chamber volume of approx 63cc after the CNC machine removes the needed chamber material in order to un-shroud the valves.
The 63cc chamber on a stock displacement 5.7L will get you a 10.8:1 CR when stock graphite head gaskets are used.
Ron,
Thread Starter
Joined: Nov 2001
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From: Tallahassee, Fl
Re: good amount to mill 5.3L heads, what compression so unmilled 5.3's give you about 10.8:1, so i could mill them about .015 to achieve 11:1 and still run the 7.400" pushrods?
if that is correct,sounds good to me
would you go with a higher comp ratio on a street car, buying new pushrods would not be preferable, but if running a high comp ratio would benefit me i would do it
if that is correct,sounds good to me
would you go with a higher comp ratio on a street car, buying new pushrods would not be preferable, but if running a high comp ratio would benefit me i would do it
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From: SW Florida
Re: good amount to mill 5.3L heads, what compression I don't know how much a givin amout of head milling changes what the chamber cc volume is, but if your head porter will actually CC the heads for you and give you the numbers, this is what it will equate to in compression ratio on a stock displacement 5.7L LS1:
72.27cc = 9.1 CR
71.71cc = 9.2 CR
71.05cc = 9.3 CR
70.59cc = 9.4 CR
70.03cc = 9.5 CR
69.74cc = 9.6 CR
68.91cc = 9.7 CR
68.35cc = 9.8 CR
67.79cc = 9.9 CR
67.23cc = 10.0 CR
66.67cc = 10.1 CR (stock LS1 head spec)
66.11cc = 10.2 CR
65.55cc = 10.3 CR
64.99cc = 10.4 CR
64.43cc = 10.5 CR (stock LS6 head spec)
63.87cc = 10.6 CR
63.31cc = 10.7 CR
62.75cc = 10.8 CR
62.19cc = 10.9 CR
61.63cc = 11.0 CR
61.07cc = 11.1 CR
60.51cc = 11.2 CR
59.95cc = 11.3 CR
59.39cc = 11.4 CR
58.83cc = 11.5 CR
58.27cc = 11.6 CR
72.27cc = 9.1 CR
71.71cc = 9.2 CR
71.05cc = 9.3 CR
70.59cc = 9.4 CR
70.03cc = 9.5 CR
69.74cc = 9.6 CR
68.91cc = 9.7 CR
68.35cc = 9.8 CR
67.79cc = 9.9 CR
67.23cc = 10.0 CR
66.67cc = 10.1 CR (stock LS1 head spec)
66.11cc = 10.2 CR
65.55cc = 10.3 CR
64.99cc = 10.4 CR
64.43cc = 10.5 CR (stock LS6 head spec)
63.87cc = 10.6 CR
63.31cc = 10.7 CR
62.75cc = 10.8 CR
62.19cc = 10.9 CR
61.63cc = 11.0 CR
61.07cc = 11.1 CR
60.51cc = 11.2 CR
59.95cc = 11.3 CR
59.39cc = 11.4 CR
58.83cc = 11.5 CR
58.27cc = 11.6 CR
Re: good amount to mill 5.3L heads, what compression 11:1 on pump gas in Florida heat is the absolute max I'd run personally. I've talked to a few sponsors and they think thats the cutoff point for pump gas. Jason 99T/A burned his pistons on 11.5 I believe. You'll just have to be sure to only use good gas and if you hear the motor detonating, take it easy on it. As for the exact compression ratio, I'd cc the combustion chambers and then decide how much to mill them since material is removed from there to deshroud the intake valve. I'm going to shoot for about 63cc on my 5.3 heads over the winter.
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From: SW Florida
Re: good amount to mill 5.3L heads, what compression
My 5.3 heads were milled .40 and I was told I had a 57cc chamber
I can't see how it runs on pump gas unless it's loosing all it's timing due to knock retard.
Thread Starter
Joined: Nov 2001
Posts: 3,406
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From: Tallahassee, Fl
Re: good amount to mill 5.3L heads, what compression
My 5.3 heads were milled .40 and I was told I had a 57cc chamber