WideOpenThrottl

I am interested to see what kind of boost your primary is feeding your little turbo, for those who have a boost gauge between the turbos. I am interested in relatively peak pressures comming off of your big turbos.
Thanks a bunch,
Tim.

RonA

depends on fuel and hp levels. 30 to 35 on a 3B or B2. 30 will get you to about 60-65psi overall. 35 will get you around 70psi overall.

Ron

Jambbii

Same here...

95ram

With 35/3b I see 56 total. 24-26psi from primary. With 40/3b I limited it to 65 total with ~30 from the 3b.

WideOpenThrottl

Is that what your seeing on your set up?
I can see up to 50psi from the 3B if its pegged to the floor on the interstate. What seems odd is when the turbos are lit, any more throttle and the boost from the 3B jumps quicker than the boost in the manifold, from what I've noticed.
Tim.

signature600

32-35psi from the B2 back when I had the 40/B2 on the truck!

You're driving that 3b waaaayyy too hard!!

Chris

RonA

How much boost are you seeing at the manifold or post top charger? 50psi out of a 3b is alot of air. Alot. It seems like you almost have to be seeing 90 psi total, or more.

Ron

RowJ

Tim,
At 65 psi total boost I see 36-38 psi on my primary (S300 on BD Twins)... with drive pressures at 1:1
Agree with Chris. Have you played with wastegate setting on you 35/40?? What turbine housing on your 3B??
Something is way off.

RJ

WideOpenThrottl

I see about 60-65psi at the manifold with probably about 45psi out of the 3B, the exhaust housing is a 26cm, I have a external wastegate in the manifold dumping into the 3b, plus the internal wastegate on the little charger, but as of right now the external wastegate is blocked and i'm just using the little internal one. Its hard to explain but it seems once the wastegate is open, and the 3b is lit it reacts way to quickly to the throttle.

gman07

If you're making 65psi in the manifold with 45 out of the 3B, the secondary seems to be working at only a 1.33 pressure ratio. A 1.33 pressure ratio, if the compressor is being fed with air at atmospheric pressure, would only be 4.9psi boost. Maybe a problem with the wastegate on the secondary would be causing this?

Disclaimer: I have zero experience with twins, so I could be waaayyy off.

paulb

The only way I can think of, that would make it that far off, is if the external gate is stuck open dumping all the exhaust to the 3B. If that was the case it would be pretty laggy until the 3b lights. A 3B at 45 psi is way out of it's map. I am surprised that it is holding up. Can you block the external wastegate, with a block off plate? Check the internal gate really close as well. Does your secondary turbo turn freely?

Paul

hotmopr

I have mine limited to 48 total and I see 22 out of the 3B. I need to stud it and ring it so I can tighten up the boost controller..

WideOpenThrottl

paulb,
yep the external wastegate is blocked off. the internal functions fine, the 3b lights basically right when the wastegate opens at about 26psi. The secondary should be fine, i rebuilt it with a kit from HTT, after running it for a bit and finding that i had a small oil leak past the compressor.
I am just a confused to see such high boost off the 3b when many people see only about 30-35psi from the 3b.
tim.