Some people are saying the late 2000 241s are the same as 2002 241s, are they? I was told different by a head porter.( sand vs. foam cast?)

 

i was actually reading about that today in an LS1 book that my friend let me borrow. there is a slight difference, i can't remember if they called it "foam cast" in the book, but they said that the ones that were sand cast for some reason produced 5-7 less hp than those that were not. the ones that were foam cast have a triangle casting mark left under the sparkplug hole, i believe that is the easiest way to tell them apart.

maybe someone could shed more light on the subject.

 

2002s are the only foam cast, right?

 

SPM, look for triangle shapes arounfd the exhaust ports on the heads, not sure when they started doin it

 

As I stated in another thread on this topic, the 241's that came on my 2000 Z28 are identical to the 241's that came on my 2002 SS. All of the cast surfaces have the same texture. Even in the intake ports. I believe all 241's are the same and the 853's differ from them. Explain why my 2000 Z28 M6 with just a lid, LS6 intake and an SLP Dual-Dual exhaust throws down 334 RWHP 341 RWTQ. Runs 13.10 @ 109 with a 2.25 60'. I have HPTuners to bring the fan temps down for the stock thermostat, turn off CAGS and removed 2 degrees of timing in the upper RPM's to alleviate spark knock. The LS6 valve springs were installed because the factory ones weaked and allowed for valve float. With just a lid and cat-back the 2000 Z28 made 323 RWHP 330 RWTQ. For comparison my 2002 SS M6 with the same lid and cat-back as the only mods made 319 RWHP 340 RWTQ and ran 13.3 @ 107 with a 2.25 60'. I don't have any faith in that earlier or later 241 heads make any more or less power than the other from my expeirences.

 

Yeah, I think it was mentioned in handzel's book that the semi permanent mold heads were worth a few more HP. I believe this is misinformation as I have heard all 241 heads were SPM.

 

the name of the book is "How to build Chevy LS1/LS6 V-8s" (or something like that)
page 47 for reference

but actually i agree, i don't understand how the same casting could have a 5 hp difference, i was previously just stating what i had read in that book that afternoon. the book didn't explain very well how the difference in 5 hp was gained, but did say that someone had seen a difference after extensive testing.

cool z, thanks for the input, but no offense you information seems kind-of inconclusive. my WS6 has 241 castings, and from what the book was saying (i re-read it again today) 2/3rds of the 241 castings were SPM, it didn't have as much to do with when they were produced, more of the plant that they were produced in. a 4 hp difference in a single test could be any number of small things.