706 casting questions and flow potential
706 casting questions and flow potential I am building an lq4 for my camaro. I originally planned on doing a turbo setup...but I am more and more leaning towards a decent n/a motor with a little spray.
I have a set of 706 casting cylinder heads stripped and ready to go to the machine shop. It is my understanding that the 706s have 61.15cc chambers. I plan on having them cut slightly, so I guess I would be right at 61cc. If the information I have been reading is correct, I would be at roughly 11.1:1 cr correct?
I found the stock flow numbers from these heads, im assuming the info is accurate...
706 heads
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches
Stock Head Flow Numbers
Chamber 61.15 cc----0.100--0.200--0.300-- 0.400--0.500---0.550---0.600
Intake 200 cc----------63 ---128----179-----210----218----221-----226
Exhaust 70 cc----------54 -- 93 ----121----145-----163----168----174
With that being said...what are the "ported" castings flowing? Is it reasonable to shoot for 280ish lift with these heads around .550 or am I dreaming? Do these heads successfully flow more with larger intake/ exhaust valves?
I like the idea of the added CR, but the flow numbers are slightly lower then the comparable 243/317 castings...(im sure much of this has to do with the smaller intake valve?
Thanks in advance...
I have a set of 706 casting cylinder heads stripped and ready to go to the machine shop. It is my understanding that the 706s have 61.15cc chambers. I plan on having them cut slightly, so I guess I would be right at 61cc. If the information I have been reading is correct, I would be at roughly 11.1:1 cr correct?
I found the stock flow numbers from these heads, im assuming the info is accurate...
706 heads
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches
Stock Head Flow Numbers
Chamber 61.15 cc----0.100--0.200--0.300-- 0.400--0.500---0.550---0.600
Intake 200 cc----------63 ---128----179-----210----218----221-----226
Exhaust 70 cc----------54 -- 93 ----121----145-----163----168----174
With that being said...what are the "ported" castings flowing? Is it reasonable to shoot for 280ish lift with these heads around .550 or am I dreaming? Do these heads successfully flow more with larger intake/ exhaust valves?
I like the idea of the added CR, but the flow numbers are slightly lower then the comparable 243/317 castings...(im sure much of this has to do with the smaller intake valve?
Thanks in advance...
We do a lot of porting on 862 and 706 casting heads. If you follow this link it will give you an idea of what we do to the heads and how they flow once finished:
http://www.texas-speed.com/shop/item...id=84&catid=20
My compression calculator would have you at 10.55:1 with that setup, keep in mind the LQ4s have a dished piston. We do offer porting on customers heads, if you would like to send them in.
http://www.texas-speed.com/shop/item...id=84&catid=20
My compression calculator would have you at 10.55:1 with that setup, keep in mind the LQ4s have a dished piston. We do offer porting on customers heads, if you would like to send them in.
I've been shaving heads since my third day as a machinist, and I've never seen any aluminum head that I shaved take less than a 0.004" cut, and generally I prefer to just set the RP1200 to a 0.006" initial cut, so it'll be taking right at 1 cc.
At 0.004", that'd be about 60.5 cc, so 10.60:1 or so.
At 0.004", that'd be about 60.5 cc, so 10.60:1 or so.
TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
I found a nice compression ratio calculator here if you wanna give it a try. I don't know all your engine specific's, but you may. But it's got a static compression ratio and dynamic compression ratio calculator all built into one.
Check out this article, 383 Stroker Build by Truckin Web, for an idea on how well the 5.3L heads can flow with a good port job. Good article for a modern day 383, based on a 5.3L too boot.
Check out this article, 383 Stroker Build by Truckin Web, for an idea on how well the 5.3L heads can flow with a good port job. Good article for a modern day 383, based on a 5.3L too boot.
Originally Posted by From the article linked above
In stock trim, the 5.3L castings offer flow numbers near 245 CFM on the intake and 180 CFM on the exhaust. Treated to Stage 2 porting, the revised TEA 5.3L heads offered an amazing 314 CFM on the intake and 261 CFM on the exhaust.
Last edited by hrcslam; Dec 21, 2010 at 11:35 AM.
TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
We do a lot of porting on 862 and 706 casting heads. If you follow this link it will give you an idea of what we do to the heads and how they flow once finished:
http://www.texas-speed.com/shop/item...id=84&catid=20
My compression calculator would have you at 10.55:1 with that setup, keep in mind the LQ4s have a dished piston. We do offer porting on customers heads, if you would like to send them in.
http://www.texas-speed.com/shop/item...id=84&catid=20
My compression calculator would have you at 10.55:1 with that setup, keep in mind the LQ4s have a dished piston. We do offer porting on customers heads, if you would like to send them in.
Last edited by hrcslam; Dec 21, 2010 at 11:33 AM.
The thing nobody has mentioned is that a usual port job will include opening the chamber up for a larger bore thus increasing the cc... We cc'ed my old TSP 5.3's before I sold them and they were 63cc and a little change....
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Thanks for all the replies guys!
John, You guys certainly have some big bang for the buck. Before I read all the responses I stumbled across the flow numbers on youre site...pretty impressive, and exactly what I wanted to here. I am keeping the heads local and I dropped them off at my machinist today.
I guess stock compression isnt really a concern at this point since I am looking into a set of Weisco pistons. If I did the math correct, and I use there flat top piston with the -3cc valve reliefs I should be right at 11.3:1 (factored on a .030 overbore and). I plan on running the Manley Race Series 2.02/1.575 valves and a set of the patriot performance gold springs with ti retainers (not running any crazy cam. Looking to run the GMPP ASA hot cam from the 376/515 motor).
Thanks for all the great info guys.
John, You guys certainly have some big bang for the buck. Before I read all the responses I stumbled across the flow numbers on youre site...pretty impressive, and exactly what I wanted to here. I am keeping the heads local and I dropped them off at my machinist today.
I guess stock compression isnt really a concern at this point since I am looking into a set of Weisco pistons. If I did the math correct, and I use there flat top piston with the -3cc valve reliefs I should be right at 11.3:1 (factored on a .030 overbore and). I plan on running the Manley Race Series 2.02/1.575 valves and a set of the patriot performance gold springs with ti retainers (not running any crazy cam. Looking to run the GMPP ASA hot cam from the 376/515 motor).
Thanks for all the great info guys.
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