HDhotrod

I'm about to order on3 turbo kit for my 03 2500hd 6.0 that gets used as a work truck that hauls and a toy. I can't decide between their 76 or 78. Ive researched this a ton and there is several debates about small or large turbine for a truck gets used for work? I'm leaning towards the 78, would that work? I want grunt down low but not consistently in boost

Ray Finkle

Get the larger turbine in my opinion.

FFDP

iTrader: (2)

Either would perform just fine as you aren't going for all out power.

Even the 70mm turbo would be a great jump in performance over stock.

HDhotrod

Do you think the 78 would be a dog off the line?
Idk if matters about mods but I have a 220r cam and 243 heads

Mean Green z28

iTrader: (19)

7875 On3 on my 5.3 with a 4L80E and stock convertor and 3.42 gears and it's a dog off the line and picks up after about 2500-3000 RPM ... getting a 3200 stall shipped currently.

6865 Precision before with a 4L60E and stall was a beast amd put down 520 rwhp

6.0 may help it spool a bit earlier.

fctry286

I have a 70mm in mine with the 1.05A/R housing. it builds boost nice while cruising and while WOT turbo lag is about 2800-3000 then its a rocket. at 10lbs truck made 523rwhp and I have a 5.3l.

HDhotrod

Yea I think the ar for the on3 70 and 76 has a .81 ar. My trucks already a dog down low I just don't wanna choke it with the small 65 turbine.

Choda

iTrader: (1)

double check that AR. I thought they were 70/65 with .96 AR. I have the exact specd turbo and it lights off once i touch the throttle with my 5.3

BigBlock90

iTrader: (4)

I run the VS Racing 7875/.96 on my black truck and had the same results when i had the 5.3 in it. it was instant spool when touching the throttle.

HDhotrod

Your right, they all have .96. so ita matter of turbine size I guess. So you both have a 78/75 and it lights quickly?