I need the specs for the s400 everyone uses in a twin setup?

 

http://www.citydiesel.net/b2-s400-tu...ml?cPath=32_34

 

Already stepping up to twins? Didnt you just get the S300 about 2 weeks ago?
Anyway you want the S400 with a 75mm wheel.
I bought mine from here
http://www.dallasturbo.com/specials1.html

They are about $100 cheaper than city diesel for the same turbo.
Talk to Dave, they also have a flange kit for another $192. It will save you about $70-$75 buying it from them versus say source automotive.

 

I always thought those "B2" style turbos had excessively larger housings. 1.32 is a VERY large housing on a turbo that size. It will take a bigger top charger to get it rolling well, and it will be a little laggier than some other options....

jmo

 

you can get a 1.10 ar s400 if your top turbo is not a ss13 ex s300 if it is the 1.32 will be a good driver ,theres more heat energy in the ss ex than a cast iron ex to drive a 1.32 ar s400 i have tryed both

 

62/65/14 with a 75mm S400 is Rips twins.
This is the most common twin setup.
If you want a twin kit for towing, 62/65/12 or 14 with a 71mm K31 is what industrial injection uses.

 

i have a sps 62-71-14. every shop i talked to told me to use a 1.32 ar housing. how much better will the 1.10 housing spool. but how bad will it restrict the top end. i know you cant get both spool and top end but id like to find the best middle ground.

 

The 1.32 ar housing is a good match for a 62/65/14 top turbo. If you go with a tighter housing on the bottom turbo you will want to wastegate the bottom turbo. It not just about spool, but about the balance between the two. If you go with a 1.10 housing on the bottom turbo, then it will be doing more of the work, and you will not be getting as much compounding from the top turbo. You should give Rip a call, he's tried a lot of combos and will make recommendations on what you want out of a twin set.

Paul

 

Any opinion on how a 64/65/12 would do for a top charger paired with a S400?

 

how would it work with a 62/71/14?

 

I hate to give opinions... I would like to try a 64/14 on top of an S480 though.

Paul

 

Bingo. You are not getting as much compounding from the top turbo-- which is precisely my point.

Because the top charger is compressing air that's already under pressure and MUCH hotter than ambient air, the big charger should be doing more work.

Given typical compressor efficiencies (70%), you have to triple the inlet pressure to double the flow. For example, if I have a top charger that is capable of moving 60lb/min and I want to increase total flow to the engine to 120 lb/min, then I have to feed that top charger with pressure that's THREE TIMES higher than atmospheric from the bottom charger.

Putting numbers to it, we'll round off and say CIP is 13psi after airfilter restriction and barometric variance. If the top charger is flowing our previous 60lb/min with 13psia CIP, then we have to provide it with 26psig boost (39psia, or 3:1 PR) to get it to flow 120 lb/min.

A good twins setup, imo, runs the bottom charger at 3:1 or higher, and top charger below 3:1-- closer to 2.5 or 2.7.

3:1 on top and 2:1 on bottom is plenty for 550hp at only 2700rpm with LOTS of EGT room left.

As you lower the top charger's operating PR, it becomes proportionally less restrictive and overall effectiveness should improve.

IMO, the main cause of drive pressure problems is a top turbo that won't "get out of the way."

JMO

 

RonA and I discussed that at the Redding race track last year. He seemed under the impression that I should try it. As I remember the conversation he said that I would gain some on the top end by reducing drive pressure a little. If and when I need to have my 62/65/14 rebuilt I plan on having it either upgraded to a 62/71/14, or a 64/14 (and having the S400 made into a S480).

With the mods that I have right now, I don't have any complaints about the 62/65/14 on top of the S400.

Paul

 

Paul I know it s a race truck and all, but what rpms does it start spooling when you're cruising around?

 

No thats not me with the s300 i am using the stock turbo.