L92 head swap on 408, opinions?
10-03-2019, 12:19 PM
#1
Staging Lane
Thread Starter
L92 head swap on 408, opinions? ya, its another one of these threads.... But this time we dont give two ***** about low end TQ.
So....Im considering swapping from small port cathedrals(PRC Terminator 200cc) to stock/milled l92's. 1/4 mile only car with a 5200rpm stall, low end TQ does not matter.
Is it worth the effort? If I am only going to gain 20hp or 2 mph maybe ill just spray it more?
I have always felt my 408 was a bit of a dog and I have a set of stock L92's on the bench. I would also be going with 102mm intake and larger headers.
Also, my Current camshaft has quite a bit of split, I wonder if I could reuse it as well? If PTV allows of course.
1/4 mile only car. runs 11.00 at 125 typically on motor, #3250, sub 1.5 60's. has been 10.70's @ 127 on a few extraordinary runs. Current setup doesn't seem to make much power over 6000rpm,
408 lq4
Callies rotator
Wiseco -8cc reliefs
Old PRC Terminator heads. Edelbrock casting, 2.02 valves, 200cc runners. Were supposed to flow 300+cfm? cant find any info on these odd ***** anymore.
11.5 cr
fast 90/90 unported
Cam Motion 253/266 .643 .629 113
1 3/4 headers. open exhaust
Th400 w/Transbrake
5200 stall
9"
28" Et Drags
So....Im considering swapping from small port cathedrals(PRC Terminator 200cc) to stock/milled l92's. 1/4 mile only car with a 5200rpm stall, low end TQ does not matter.
Is it worth the effort? If I am only going to gain 20hp or 2 mph maybe ill just spray it more?
I have always felt my 408 was a bit of a dog and I have a set of stock L92's on the bench. I would also be going with 102mm intake and larger headers.
Also, my Current camshaft has quite a bit of split, I wonder if I could reuse it as well? If PTV allows of course.
1/4 mile only car. runs 11.00 at 125 typically on motor, #3250, sub 1.5 60's. has been 10.70's @ 127 on a few extraordinary runs. Current setup doesn't seem to make much power over 6000rpm,
408 lq4
Callies rotator
Wiseco -8cc reliefs
Old PRC Terminator heads. Edelbrock casting, 2.02 valves, 200cc runners. Were supposed to flow 300+cfm? cant find any info on these odd ***** anymore.
11.5 cr
fast 90/90 unported
Cam Motion 253/266 .643 .629 113
1 3/4 headers. open exhaust
Th400 w/Transbrake
5200 stall
9"
28" Et Drags
10-03-2019, 06:48 PM
#2
Moderator
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Your cam is screaming for ls3 heads. Use mid runners fast intake. If you have 93 octane that cam will let you run 12.3:1 compression which I would also recommend. Its a massive can for that 408
10-03-2019, 08:31 PM
#3
ModSquad
iTrader: (6)
Agreed on camshaft.
10-03-2019, 08:34 PM
#4
TECH Veteran
That much of a stall Im go say you'll benefit ditching the fast intake and going to a single plane intake....
10-04-2019, 11:08 AM
#6
TECH Fanatic
iTrader: (5)
I’m in doubt of those 200cc Cathederal heads flowing 300 cfm. L92 heads would be good idea along with a 102 intake or single plane as mentioned. Leave the cam, yes to bigger headers with 3” exhaust system dumped and say goodbye to 11s
10-04-2019, 02:48 PM
#7
Staging Lane
Thread Starter
Thanks guys. I may give it a try, got nothing to lose. If I had a ton of cash to throw at this thing the decisions would be easy..... PRC 260, LOD intake, the works.
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10-04-2019, 03:47 PM
#8
If they're just stock castings, some hand blending in the bowl into the valve job would be very easy to do and would pay dividends. A lot of the gains of a CNC job is just in the valve job and the bowl.
If you do it yourself it is the low low price of free
If you do it yourself it is the low low price of free
10-04-2019, 04:14 PM
#9
TECH Veteran
Send those Stock L92 to Frankenstein. After this past LS fest i would never buy a aftermarket LS3 head. I witnessed alot of aftermarket LS3 heads get they feelings hurt with some Frankenstein LS3 heads.