243's on 4.8 and 5.3
12-09-2008, 08:07 PM
#2
Yessir, though, I do not know why. I have seen them also. If I had more time in the junkyard I would have pulled them.
One thing I thought about was the chambers being bigger. The new motors must have flat top pistons to make up the difference in compression, but then I got to thinking - the 4.8L already has flat tops! I'm not sure how GM does it.
One thing I thought about was the chambers being bigger. The new motors must have flat top pistons to make up the difference in compression, but then I got to thinking - the 4.8L already has flat tops! I'm not sure how GM does it.
12-09-2008, 08:17 PM
#3
Launching!
Join Date: Sep 2008
Location: Ashland,VA
Posts: 234
Likes: 0
Received 0 Likes
on
0 Posts
yea they are the same exact casting. they are actually the same as the LS2. The LS6 heads had sodium filled valves i beleive it was. thats the only difference. chambers and valve size are the same. also some of the 5.3s have 799 casting heads which are actually the same as the 243s just casted in a different process. It is beleived that there is only about a 3 hp loss between the 799s and the 243s just because the 243s have smoother ports over the 799s. both great heads that are easy to get a hold of because they are widely used now.
12-10-2008, 09:38 AM
#5
The new 5.3's do have flat tops and the 4.8's took a loss of compression. The 5.3 is now 10.0:1 while the 4.8 is down to 9.2:1. I guess the better flowing heads make up for the loss, but it seems to me it would have made more since to retain the older heads on the 4.8.
