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 Post Posted: Sun May 13, 2012 10:33 pm 
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Joined: Tue Jan 08, 2008 12:43 am
Posts: 69
Wasnt sure if this goes here or int the carb section so her goes lol
So i run a Lsx style sb in my car
Combo was
4.030 bore 6.0 liter ls block studded mains ,heads
4.0 stroke callies crank callies h beam rods
wiseco dome piston 14.0 compression
1.2-1.2mm low tension backut ring package
vacuum pump 12" or so for wet sump?
aftermarket pan with modified full lenght factory tray
55 mm cam core -26x-27x at 050 650-660 lift hyd roller, but w solid roller comp enduro lifters -008" lash(i talked to chris at comp and he and i designed this cam that way to ahve better stabilty )
w 1.85 rocker ratio
13.5 degree ls based 245cc runner tfs heads - cnc ported by TEA -and gone over a little by hand
these flow 345-255CFM at 650" lift ,heads
2.100 INT-1.600 EXH VALVES
mildy plenum ported supervictor intake with bigs `1000hp based carb on top of 1 in 4 hole super sucker, on top of 1/2" in nos plate
1-7/8 headers 3 in bullets

Its run a best of 9.93 at 135 in Denver at 7500 ft of air with 14% converter slippage:(
Also i only had 12 passes on motor so i didnt do much tuning yet(timing change 2 degrees 1 time and never touched carb jetting yet !)
I had a 4150 1000hp carb on it last year with a mildy ported ls style supervic
Im, thinking of putting a Mast Motorsports 2 piece cnc'd intake on it this, year and if so i was thinking of going to a 4500 carb
Problem is last year i tried 2 different 4500 style 1050's on the car using a 1-1/2' 4150 to 4500 adapator and both times the car slowed or ran the same et
On 1 occasion i actually went back to my 4150 car the same night and picked up et and mph again
This is a really good 4150 carb imo, as it been on 3 different engines and 1 of them has run 9.50's up here in Denver on motor,so i know it works well
Im wondering,if its more important to get a really good intake on the car that maybe is better suited for the heads flow and has more equal lenght runners(ls motors are similar intake wise to a small block ford with two diff length runners from innner to outer)or if the carb cfm difference is more important

I also think maybe a 4500 style intake will have showed diff results as the adaptor wasnt matched as ell as it could have been in the plenum area
I had a 383 sbc in the car before ,that i ran a 1050cfm-4500hp carb on ,a 4150 supervic ,with a 2in hvh -supersucker adaptor and that also had a mismatch ,though somewhat better,but ran very well so i wonder if this style manifold may be more conducive to liking a 4150 carb than a 23 degree style deal?
Changes for this year inlcude
4.070 bore aluminum block -420 inch this year
15-1 compression
car is 100 lb lighter
fixed converter i hope as well some more chassis work as well as will tune it better i hope with more passes
Any opinions im all ears
thanks


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 Post Posted: Wed Sep 12, 2012 5:43 pm 
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Joined: Mon Sep 10, 2012 4:08 pm
Posts: 39
mostlikly at that thin of a air da your booster signal is lost on the bigger bore carb and booster combo .
you may need to tweek the boosters and air bleeds to get it right to see a gain . can you graph your carbs on a o2 . ?
efi or mfi wont have these problems .

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