Adding a turbo to my SS 475
 

I am considering going to a compound setup for more power.
I have a stainless steel s475 turbo 5 blade , t4 running 350% injectors.

03 with a 6.7 sleeved block rated to hold 1800hp
Auto trans.

What turbo would be a good one to use with the SS475 ?

If you add a turbo, the 475 is going to spool slower. Are you ok with that?
Also, what is the intended use for the truck, hot street truck, drag truck, or a mix of both?

A mix of both more than likely . I really would rather it not spool slower as it seems to take a while to light as it is.

Any time you go to a compound arrangement, the small turbo will spool SLOWER, and the big turbo will make LESS power, than they will as a single.
A 468/488 would work well as a fairly drivable, high power setup.

This is the one I have.

5 Blade S475 T-4 turbo charger

Someone has suggested a 485 with the 475 . Not a good idea ?
Not really wanting to purchase 2 new ones unless I can justify it.

How would this compare to the 468/488 ?

How does a 5 blade charger bite more air at lower rpm vs a higher blade wheel?

I think this 491/96/1.32 would work well. You can always change the 475 for better spoolup later on. A 472sxe would be awesome for that.

http://www.competitiondiesel.com/for...d.php?t=200472

I'm personally not a fan of the S4 S4 compounds. The 96mm turbine does become a restricting point at big power. If your going to run a 488 or 491 you will want the biggest turbine housing you can get to help get the exhaust out. Might even need to gate the hotpipe as well. The SXE594 or new Garret 5544 would be my first choice with your 75 but would work better with a 67.7, 68 or 72 as the secondary.

I understand the desire to not buy any more parts than necessary, but you’re not going to be happy if you try to keep the 475 in there. It’s simply too big for a secondary charger on something you want to drive. They work ok as a single, but the added lag in a compound arrangement really makes them unhandy.
I personally think the 91mm compressor wheel is getting a little too big for the 96mm turbine to drive well, but it wouldn’t be quite as big a deal in a compound arrangement with a good secondary turbo.
I personally err a little to the small(er) size when sizing turbos because most times throttle response trumps a few more high rpm hp.

How about a power goal and what you intend on doing with the truck? Your short block may be rated to 1800hp but unless the fuel and driveline both will support it you are shooting in the dark. The step from a 1000hp truck to something that will support 1500+ is big money. Not lecturing just being realistic to get a better assessment of what you actually need.

Where's Farmer Frost to comment on this? He is running a 475/83 with a 102mm HX82 as the atmo on a 12 valve. The same combo I am building atm. I'm not sure he has had much time driving the combo but he could shed some light on it.

And if you're not racing, what's the point? It's going to be hard enough to throw down 1000hp on public roads with DOT tires.

I would like to be in the 1400 - 1500 hp range. If I need to replace the manifold and turbo for the optimal twin set up , I will do it. I have the philosophy "Buy once , cry once" .
6.7 block with custom iron sleeves
5.9 cummins 03-4.5 piston kit w/rings and wrist pins .020-.040 oversize
Bottom end has carillo HD rods/Carr bolts
Cummins mains tapped to 14mm
Girdled

hamilton cams 188-220 billet cam shaft
cummins 5.9 fluid damper
billet freeze plugs

Motor was built by Freedom racing engines 4 months ago.
also has
Industrial Inj. Dcp3D pump kit 1200+ HP

I am looking for a dual purpose truck ,if thats possible, in the 1400-1500 hp range .
If not , I want to lean towards the race end.May consider nitrous but would like to stay all fuel.

What would be the Ideal compound set for this motor and why ?

Thanks to all who has already responded !

Another option is triples. A couple of box s475 and associated plumbing might even save a few bucks if you can do the Fab work yourself.

Would certainly consider this as well.

I recently used a pt101 with a 472. I wouldn't hesitate to suggesting it to achieve your goal. Recently have seen a few "affordable" gt55's. Smallest compressor inlet I'd suggest is a 94. As long as you have the appropriate turbines/housings, driving it should t be an issue.

The new race truck build I did has a Hamilton solid 6.7 block, 5.9 crank, carrilo long rods, 6.7 pistons, girdled, bigger cam then yours, ported head, side draft, similar sized injectors with two 12mm stroker pumps. Turbos are an older Fleece 71/83 T4 with a 1.1 housing over a SXE594 with a 1.45 T6 housing. One 60mm wastegate on the exhaust manifold and one 60mm gate on the hot pipe. 06 ecm with tuning by Starlite. 2500 rpm converter and the turbos spool extremely quick. 20psi at 2500 in under about 3 seconds. Made 1500hp at the tire on my chassis dyno. Our first and only full 1/4 mile pass was a 9.43 @ 145mph. That was on our 1300hp tune.