No way to bump the compression for a while. This is kinda my practice turbo setup. When I build a new motor I will go to a little nastier setup for sure. I want this to be very mild.

Oh I should also say I don't wanna go over 12-15 lbs of body. Not sure what I'm looking at with that s475 but I wanna keep it at that or below.

 

sorry I ment Garret budget turbos. They make some nice units that would work good for your setup. As far as oiling gos as long as the turbo is higher then the oil level in the pan all you need is to tap into your oil supply and run it to your turbo, Then have a large 8an return that drains back into the oil pan.

 

Sounds good. Looks like I'm gettin everything worked out. Just gotta start running down parts.

Any idea what either one of those 2 turbos would make for boost?

 

Hard to say what boost level, the Garrett 76 is rated to 1000HP so IM sure it will make the boost level needed to make 750hp your after

 

You'll control the boost level with a controller or just the springs in the wastegate. If I had your cubes and that motor id be looking at the Borg warner units with the big exhaust wheels so it doesn't choke out... Like Kyle said, any where from the 83-96mm wheels. 83mm the fast spooler and the 96mm for a little lag but with retarded top end pull. Or settle in the middle with the 87mm turbine.

 

That's about what I was originally thinking (85-91 single/ 76 twins), but one of the guys on the 454SS forum who runs mid 9's with twins on his truck pointed me towards the smaller turbo. I assumed it was b/c of the low compression and the low RPM's. This thing will never see anything passed 5500 for sure.

Would the smaller turbine help offset the low compression?

 

Small wheel mean with the same amount of air flow the air is moving faster in turn spinning the wheel faster, so yes a smaller wheel will spool faster, compression builds exhaust gas lower compression spools slower. I know it's a big engine but I think a 76mm with a 80 mm ex wheel would hold up to 5k rpm. It sounds like you want a quick spool for the 6 speed, if you don't mind a little lag then a 88mm with a t6 and a large wheel will make the most power once spooled up.

 

I def want it to spool quick. The 6 speed and 4:10s will help get the truck moving though.

Still haven't heard anything in crossover pipe sizes.

 

There are two side to the turbo.
With that many cubes you will no problem spinning the turbo. Unless you do something way off the wall.
There are several 76mm turbos.
76/67. Too small for that engine. I bet boost or zero on the gauge at cruisng speeds.
76/75. The compressor will
move about the same but the exhaust side will flow clean. Still spool agressively.
Several enbetween those.
75/83 even large exhuast less back pressure I am
betting still spool nicely.
75/92 this is getting up there on the exhaust side of things.

The wheel size dosen't tell the whole story.
Not all 76's flow the same. Even from the same mfg.
Cast wheel or billet. Etc etc.

If you have it already run it. See what happens.
Turbos are easy to swap out as long as you give youself room to grow in the area.

Interesting build looking forward to seeing how it turns out.

 

Crossover tubing.
2.5".