Little Known Fact @ certain LS1 heads...
02-15-2005, 08:25 PM
#23
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Originally Posted by SSmokinmaro
I dont know how many of you read "CAR CRAFT", but they just did a few large articles concerning the LS1 engines.
On a sidenote, i found VERY INTERESTING.. it said that LS1 heads with a TRIANGLE loooking mark near the spark plugs were cast better than heads withouth that mark (60% of heads carry this mark)...
the heads with this mark generally put down atleast 4-7 more RWHP than non-triangle marked heads..
just thought I would share..
-A
P.S. I checked, and my engine has the marks.. I checked some heads on ebay, some had it and some didnt....!!
Here is the EXACT wording of what the article says..
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of these casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads."
December 2004, p.35
On a sidenote, i found VERY INTERESTING.. it said that LS1 heads with a TRIANGLE loooking mark near the spark plugs were cast better than heads withouth that mark (60% of heads carry this mark)...
the heads with this mark generally put down atleast 4-7 more RWHP than non-triangle marked heads..
just thought I would share..
-A
P.S. I checked, and my engine has the marks.. I checked some heads on ebay, some had it and some didnt....!!
Here is the EXACT wording of what the article says..
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of these casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads."
December 2004, p.35
these heads are "LS6" heads that have the "TRIANGLE" casting mark under the exhaust ports between the head-bolt bosses on the side of the heads.
these marks are left by the semi-permanent-mold (SPM) casting process used by two of the three cylinder head casting facilities creating heads for GM.
Apparently in random testing the SPM cast heads have been about "5-7" HP. more than the sand cast heads.
Both of the heads have the same, INT. port, EXT. port, combustion chamber
design, the only diff. is that the sand cast head has a rougher finish in the ports, and C/C.
A good port, and polish job will fix the problem, and yeld the same flow #s. and HP. #s. as a "SPM" cast head with the same port, and polish job.
hope that helps.
02-18-2005, 04:43 PM
#26
Originally Posted by FELBER632
As well as the 6 sets of GTO heads I just got in, and the other 10 5.3 706 castings...~50% of my 317s do, and the 862s are about 25%. It's the foundry.
Felber
Felber
Give me a call when you get a chance.
