408 - swap from Cathedral AFR 225’s to CNC LS3 heads
12-04-2022, 07:09 PM
#2
I will be doing this. Going from prc as casts to a set of tfs 255s. Bigger cam and more compression and a mid length fast. The as casts and small cam have no guts on the top end.
12-04-2022, 07:19 PM
#3
Are you keeping the same size chambers? I think the stock ls3 head and those old mongoose 225 afr’s flow about the same numbers.
The following 3 users liked this post by low2001gmc:
Trending Topics
The following 4 users liked this post by Mavn:
12-06-2022, 06:51 AM
#9
Mavn - I'm aware of those facts, I'm looking for real world gains. I currently have AFR 225'S , 11.7 :1 COMPRESSION, AND A 243/259 .62X / .6XX CAM
I will have a new cam ground to perfectly match the new LS3 style heads, so I'm really trying to justify the $$$ and real numbers from someone else who has made this change will help my mind on the $$.
I will have a new cam ground to perfectly match the new LS3 style heads, so I'm really trying to justify the $$$ and real numbers from someone else who has made this change will help my mind on the $$.
12-06-2022, 06:54 AM
#10
TECH Fanatic
iTrader: (13)
There's power to be free'd up forsure.
On my LS3 427, I went from 11.7:1 TSP PRC 225 cathedrals/FAST 102/102mm TB (trapped 126mph) to 11.1:1, a larger cam/ported LS3 top end with an 92mm TB (trapping 132mph).
The following users liked this post:
LCBE (08-18-2023)
12-06-2022, 07:02 AM
#11
What's your current intake manifold and what would you plan to run?
There's power to be free'd up forsure.
On my LS3 427, I went from 11.7:1 TSP PRC 225 cathedrals/FAST 102/102mm TB (trapped 126mph) to 11.1:1, a larger cam/ported LS3 top end with an 92mm TB (trapping 132mph).
There's power to be free'd up forsure.
On my LS3 427, I went from 11.7:1 TSP PRC 225 cathedrals/FAST 102/102mm TB (trapped 126mph) to 11.1:1, a larger cam/ported LS3 top end with an 92mm TB (trapping 132mph).
12-06-2022, 07:42 AM
#14
TECH Fanatic
iTrader: (13)
Cath port
550/502
Rec port
566/565
The following users liked this post:
LCBE (01-09-2023)
12-06-2022, 01:16 PM
#15
I wouldn't use gm ls3 heads. I would only use aftermarket heads with light valves and a shorter runner intake then the cathedral fast 102. Swapping to a gm ls3 head would probably slow you down tbh.
12-12-2022, 12:32 PM
#19
LOL I don't think they are junk and I just spent some $$$$ last year giving them a nice refresh - Valve job, general clean-up etc..... I do plan to convert everything to the LS3 stuff in the next few weeks so they will be for sale as soon as I can get the parts gathered for the swap.
Ill shoot you a message when they are removed.
Ill shoot you a message when they are removed.
The following users liked this post:
blackdak318 (12-15-2022)
01-09-2023, 07:31 AM
#20
Your combo is solid, but that stock intake is going to choke it some on the topend. Take KW's offer and get a Fast 102 LS3 or just go LSXHR. The stock intake isn't bad, but they choke out when you go bigger on the cubes w/ a cam your size. Just a thought.