I'm looking at the BD twin turbo system in the future. The kit is supposed to be good to 575hp. What are the specs on the turbos used? I can't find anything other than airwerks s300. One is definently smaller than the other from looking at pics. Anybody here running this kit? Would they be a good match to my current combo? My HTB2 (62/12) is not keeping up anymore with the Mach 4.5's at WOT. Would turbo lag be any better? worse?

 

My experience on a truck we built here at the shop. they're good for about 500hp, the spoolup is super fast.
But anymore than 500hp and the drive pressure kills your top-end power, drive pressure too high.
They are now offering their twin kit with an S400 as a bottom turbo, that would work better for high hp.

 

Forget the twins and just step up to quads.

 

Throw an s400 under that 62/12. Rip Rook has all the piping you need.

 

Wouldn't using my current (62/12) turbo with a S400 create a laggy system?

Any links to see this setup from B-D?

 

Not with Manual where you can keep the RPM's up. You should have plenty of fuel to light em.

 

I'd think the BD's would be quicker to start spooling due to the smaller secondary turbo. 57mm vs 62. I'd also expect the smaller primary to light sooner- 66mm vs 74 (for the b-2 s400 commonly used).

They say you can expect a twin setup to spool slightly slower than your single does by itself. Super b and a 62/12 are known for their quick spool up so I wouldn't be afraid of a lag monster either way.

 

I didn't notice spool up being much different than the stock HX35. Last dyno pull I did was 615hp and I haven't seen any issues. I've done a couple other things for power since that pull and it seems like I've still got plenty of air. The Super B twins like I've got are supposed to be good to 650-700, then the Super B Special twins (S400 on bottom) are for 700 plus hp trucks. My thoughts are that they are pretty much race only twins. For towing and the other stuff I do, I wouldn't want to sacrifice the spool and EGT control of my current Super B twin set up. What I will say is that these twins do a much better job than most give them credit. You'll hear they are small towing twins, etc. If you run a set, you'll appreciate them. No complaints on my end. The statement of "good for 500 hp"......that is not even close to the limit.

 

So the smaller B-D twins kit would be a good choice for a truck approaching 500hp? ( I haven't dyno'd with new injectors yet) Thanks for the replies and info.

Tiger Rag, how much boost are you running currently? Would I be able to set the wastegate to below 45psi and still see the benefits?

 

I think they advertise 450-650.

 

As far as I know the S400 twins from BD are still not available?

My drive pressure at 65 psi boost is 1:1! I still run the H20/Meth system I had with a single Turbo. Without it, I can tickle 1450* egt's by the end of a 1/4 mile.... but on the street, towing or hauling heavy - no EGT problems at all!
BD has two 2nd gen trucks at 600 hp running their twin S300's with no problem on drive pressures.
Specs are classified and not given out but the turbine housing on the bottom turbo is very big. The top turbo is their stock SuperB, AFAIK.
As stated, these twins spool very fast. Two other members that have driven my truck claim my twins spool as fast as their HX-35's.

RJ

 

I would be comfortable running that set up with my auto.
As stated....with a manual tranny, no problems at all. Just keep the 12 turbine housing. Lag will show up with a 14!

But if staying under 550 hp, you can't beat the BD's!
JMO.

RJ

 

Whoops, missed this question. Generally, not over 50-55, but if I have everything cranked up you see can 60+ psi. The wastegate has an adjustable arm so you can limit it. They come from BD set for 50 psi and BD claims they don't require head studs. If you have M4.5's, I'd say studs would be good thing because I don't think you'll keep them under 50 psi on the factory setting without adjusting it some. I also bought a wastegate spacer plate from HTT to allow the wastegate to fully open.

 

I think a really large turbine housing on the bottom is a key part of keeping efficiency high and drive pressures down.

Properly matched turbos don't need a super tight housing on bottom to spoolup, imo-- though obviously the tighter ones WILL spoolup faster.

The irony is that the tighter housing on the big charger makes the top charger spool slower because there's less pressure differential across the top turbine. A large housing on bottom (or just a large turbo in general) lets the top turbine get to work earlier.

Justin

 

They're available, and the former set is upgradeable to the R700. I forgot they were calling them the R700's, they were calling them the specials. The R is for race, and the 700 is for over 700hp. Here is a link to a story regarding them: http://www.cumminsforum.com/forum/bd...-official.html