jsmith309

I have a 99 z28, my buddys SS has 241 stamped on his heads. I have another friend his say 243 i think and they are all 99's but whats the difference. I pulled the 6 spd ss with the same bolt ons.???

JScamaro

iTrader: (6)

243>241>853

jsmith309

Meaning my heads are the worst?

dgcustomz

iTrader: (127)

YUP^^^^

jsmith309

Well that sucks donkey dick

philsblwnz28

iTrader: (10)

they are very very similar to the 241's

Mike454SS

iTrader: (4)

243's are LS6 heads (and after the LS6 they were also used on LS2's and I think some other engines).

853's are stock LS1 heads on 99's and a lot of 2000's, 241's are stock LS1 heads from somewhere in the middle of the 2000 model year and up. The ports and chambers are very very very similar with 853's and 241's, 243's are much better.

LS1Formulation

iTrader: (13)

I have one 241 head and one 853 head. Both were CNC ported using the exact same program. Identical ports, identical chambers. The only real difference between the two is how they're cast. You might have 5HP less stock with 853's than 241's, but that's nothing. Don't worry about it.

01ssreda4

iTrader: (96)

i believe most flow pretty similar in stock form. One buddy with a 00 Z has 853 and (on a side note) a first gen pinion seal, another buddy has an 01 Z with 853 heads and a first gen pinion seal, I have an 01 SS and have 241s but I have the second gen pinion seal. Im thinking the second buddys 01 is a very early year production.

SOMbitch

iTrader: (8)

I have seen a 99 853 car put a length on a 01 241 car back to back. Both dead stock to the lid. I say **** on the difference,,,,

NAAllTheWay

^^^ agreed, i heard the 241 is worth like .5-2.0 horse over the 853...all else being equal, be glad to pick up not a tenth but a hundredth of a second. 243's however, will stomp. 10-15whp added to a bone stock ls1, throw in cam, full exhaust, intake da da da, 20whp gain is not out of the question.

blue00ZZleeper

iTrader: (5)

stock 853's to 241's arent a big deal...241's are cast a little better....the coolant temp sensor is different as well depending on year

Mike454SS

iTrader: (4)

There are some gusseting differences around fastener locations between 241's and 853's that are easy to see when the 2 heads are right next to each other...power/efficiency wise there's no big deal at all, but the 241 is probably a slightly stronger head.

pony2ls1

Where is the casting stamp located at on ur heads

jsmith309

by the power steering pump

elias_799

iTrader: (8)

the reason why 243's will make you more power is not just because the head lows better. it has smaller combustion chamber witch increases compression. and when you increase compression in a motor you get more power, provided you use the appropriate fuel.

OMGWTFBODY

iTrader: (5)

806> *

what say ye?

https://ls1tech.com/forums/new-ls1-o...casting-s.html

Oh, and there's a decent resource.

elias_799

iTrader: (8)

^^^ 807 ? i never heard of that casting

OMGWTFBODY

iTrader: (5)

Fixed. =/