Ported 853 or stock 706 heads?
On The Tree
Joined: Feb 2025
Posts: 105
Likes: 35
From: England
853 is equiv to the 241, so 200cc intake runner, so I guess your closer to 210cc with porting ?
But compression is King, so unless you want to have the heads milled, then the 706 would be head of choice for sure.
https://www.motortrend.com/how-to/17...der-head-test/
But compression is King, so unless you want to have the heads milled, then the 706 would be head of choice for sure.
https://www.motortrend.com/how-to/17...der-head-test/
Modified 5.3L Head Test: 706 vs. 241
Like the 317s, the 241 heads out-flowed the 706 heads, but once again, that airflow did not translate into power production. The increased chamber volume of 6.5 cc's dropped the compression ratio by nearly 0.80 points. The 706 heads bested the 241 heads by roughly 10 hp, but down low the 706 heads improved torque production by as much as 20 lb-ft. Given the minimal difference in flow and lack of power production, the 241s don't seem like much of an upgrade over the 706 heads. But on the upside, both respond equally well to porting.
Like the 317s, the 241 heads out-flowed the 706 heads, but once again, that airflow did not translate into power production. The increased chamber volume of 6.5 cc's dropped the compression ratio by nearly 0.80 points. The 706 heads bested the 241 heads by roughly 10 hp, but down low the 706 heads improved torque production by as much as 20 lb-ft. Given the minimal difference in flow and lack of power production, the 241s don't seem like much of an upgrade over the 706 heads. But on the upside, both respond equally well to porting.
853 is equiv to the 241, so 200cc intake runner, so I guess your closer to 210cc with porting ?
But compression is King, so unless you want to have the heads milled, then the 706 would be head of choice for sure.
https://www.motortrend.com/how-to/17...der-head-test/
But compression is King, so unless you want to have the heads milled, then the 706 would be head of choice for sure.
https://www.motortrend.com/how-to/17...der-head-test/
TECH Regular
Joined: May 2023
Posts: 418
Likes: 139
From: Franconia, PA
Here's my math. 241 head is 66.7cc. .020 off at .06 per cc brings it to about 63.5cc. The stock gasket is .052 and a .040 cometic would reduce by another 2 ccs.
Last edited by Abs; Mar 2, 2025 at 12:32 PM.
