is 106mm turbo over kill for a 383 lt1/lt4

engine:LT1 block with splayed 4 bolt mains
Callies 4340 crank
Oliver Billet rods 5.85"
JE custom blower pistons, 9.5 to 1 with 65cc heads
Total seal rings
Federal race bearings
ARP fasteners and studs everywhere
Milodon Oil pump and kicked out oil pan with windage tray
Cloyes double roller chain
Custom ATI damper for blower, it has a BBC sized hub
AFR Competition Ported 220cc heads, exhaust bolt pattern for stock or spread port headers
T&D 1.6 Shaft rockers
Custom Competition solid roller cam, new CC solid roller lifters and pushrods
new ported LT4 intake matched to heads
1-7/8" Hedman longtube headers with 3.5 inch collectors
custom fuel rails
monoblad TB
accel 83lb injectors
brand new msd opti
new msd wires

with a built t-56 and s-60 with 4.56 gears red line at 7300rpms

A 106mm is very large and i think your going to need more cubes than a 383 unless this is an all out race engine.
You plan on shifting at 7.3k with an opti? I dont think thats going to work out. Same with those 4.56's gears, typically when using a power adder you would want a 3.42 gear or something around there. Maybe a 3.23 or 3.73 but anything over that and you ll be in 5th gear by the finish line.
Next, those long tube headers, what are your plans with those? I would get the hot parts from RealQuick if i were you. Theres some lead time but hes doing some great work recently. Look around and you ll find results.
Third, that ati damper for blower, what are you using this for? Between this and the lt's it seems you have a supercharger and turbo mixed up.
Give some more info.

IS 106mm overkill?? Yes. Way more than you need. I want to say there was a guy who built a 91mm large frame kit a while back and that thing didn't spool until way late. If your not getting the thing to spool with a transbrake off the line lag would be horrible, and not really fun on the street.

to use that size turbo you will need a large shot of n2o to get it to spool sometime this year!
i would step down to an 88mm..
my buddy is using one 76mm rear mount ITSDBB 76 R best pass 10.13 @ 132.72 19 psi [1.48 60'] 72 degrees, 3300' DA 3850lbs race weight,yes it is an Ls base but still..he just stepped up to a larger turbo (ST80) this car is a FULL weight SS

i just noticed your injector size,they are not big enough! 96lb. is the neighborhood you should be looking at!
your hedders wil have to change aswell

i know some stuff would need to be changed it was orginally a s/c set up

Was it originally your supercharger setup? Just curious cause a YSi or an F1a on there would run some good times at the right boost level.

Ken R.

i know some stuff would need to be changed it was orginally a s/c set up

Unless you wanted to go STS style....:|

Do you already have the 106? I have a 91 that I'd trade for the 106.


No way that 106 will be powered by a 4.030" bore 383 lt1.