Traitor LS1

Heads off a 98 LS1 856s? (I think) vs. some 241 heads what are the differences I always see people wanting the 241 heads from the newer LS1s and I want to know why

KCS

iTrader: (20)

The newer heads were cast using a different method which made the port surfaces a little smoother. Some claim its worth a few horsepower unless you are gonna have them ported, then it doesn't really matter.

Traitor LS1

and the intake ports on some 241s are rough anyway so I cant imagine some from a 98

Asmodeus

I don't know for sure, but I had heard that "the 241's and 243's had a slightly raised port floor.. which is the small radius that doesn't get touched much during head porting, allowing the same or betterflow numbers without a bigger volume and reduced air velocity" I'm sure I butchered what someone said to me.. but hopefully someone can step in and clarify.

KONG

iTrader: (4)

Well, 98 heads are 806's. They are rough castings and flow a little less than 853's and 241's. That is probably the main reason why 98 cars had bigger cams. When 99 F-Bodies came out the cam profile was even tamer due to the fact that they could make the same power with a better flowing head and less cam. If you are deadset on using factory heads why not just use 243 castings???

KCS

iTrader: (20)

Here's a pic of some 853's I'm workin on...



You can see how grainy they are.

I don't know about the 241's, but I know the 243's (LS6) and the 317's (6.0L truck) have the taller short turn which allows better flow and reduces the localized velocities over that turn.

Traitor LS1

well I have a 2000 Z28 with 90k miles that has been beat the **** out of and I can give a buddy a little bit of cash (really low $$$) and I can get a 98 longblock with only 30k miles but I have to give him mine as a core so I think I will probably just swap the heads from them

KCS

iTrader: (20)

That might be OK, but make sure the 90K mile heads are in good shape. You may have a leaky seal or slightly bent valves which would negate any advantage over the lower mileage heads.

Traitor LS1

well I have another set of 241 heads with like 25k miles on them, but I do not have and extra set of coil brackets to mount my coil packs. I will just put my 90k longblock in this other car as a core for the longblock from this 98. Then just slap these other 241 heads with 20k miles on them on that motor. I just didnt want to have to get another set of head gaskets and head bolts. I thought the 98 heads were good enough but I guess not.

AutomagicLS1

iTrader: (18)

To my understanding the 241 243 heads flow better stock but if you get them ported it doesnt matter anymore. The 98's 99's 853 castings have the notch in the deck of the head so you have to run the graphite gaskets instead of the MLS gaskets unless you have the notch welded which I dont think I would do.

GR33N GoblinM6

iTrader: (14)

i changed over from 98 806 heads to the 241 heads. i got a set of cleaned up 241 heads... had them milled .028 to get 63.5cc's.. used the 01 GM MLS head gaskets.. i cant tell about the HP increase because i did a cam and headers swap at the same time.. so.. i cant help you out there.