Beast2B

Ok turbo gurus, I have been thinking again and my brain hurts. Here’s the question (with a few qualifications up front):
• All of the B1 turbos have the same compressor and housing,
• All of the B1 turbos are optimum at 46-48# boost with near 1:1 PR,
• I am externally waste gated (soon, and may go twins later) and it would be nice to change as few parts as possible!
• A kwik-spool exhaust housing will get to 46# boost sooner that a full B1 exhaust housing,
Now the question: Why would anyone use an exhaust housing larger than the KS housing when you can spool quicker to 46#, bypass any additional exhaust with the waste gate, and have less rotating mass because of the smaller turbine wheel? What is the downside to this equation?
I always read that the larger turbo exhaust housings have better top end versus the smaller housing’s spool-up, but if both turbos are most efficient at the same boost then top end should be the same **IF** they are wastegated to the same max boost.
Thanks for the the brain waves!

Beast2B

anyone? anyone? Bueller?

1320

46 psi of boost is not always the same amount of o2. Air density plays a part as well. so you could be putting in more o2 with a different turbo at the same psi. How much? does it really? is there a measurable diff in the two reffered to turbos? Who knows, other then opinion. It is implied that the larger housing/ larger wheel will flow cooler more dense air though.

Im in the midst of adding two more intercoolers now for this reason. twin turboed , triple intercooled.....ofcourse Im bias and think twins is best anyways.

Beast2B

I'm heading towards twins myself, I just want to optimize this setup first. Helps me understand the intricacies of our trucks while I grow my power!
What have you come across for intercooler efficiency? Are you using an aftermarket intercooler in the stock location and adding two more? Get some info posted once it's together, love to see the results. How about water/alcohol/? sprayed onto the intercooler surface to expedite cooling with evap?

RowJ

Some of your thinking is not quite correct.

All B-1's do not have the same PR...assume you mean TIP..or Back Pressure at the same boost. Some are working harder than others.Smaller housings will have more TIP than bigger housings...at the same boost. Also, different B-1's have different A/R ratios!

While it's true that both turbos have the same optimum boost level, its a question of how much HP it takes to get you there, there is a point of no return...even with a wastegate.

I agree with 1320 - same boost can product different air densities due to temp build up. Also different B-1's have different #'s of blades on both the turbine side and the compressor side. This may create different air flow efficiencys at the same boost.

But you are right..within reason...you can go over the HP recommended for a turbo with an ex WG and have some of the best of both worlds. However going to big on the wastegate can lead to "flutter": the wastegate opens to quickly...shuts down...opens full...shuts down, etc. Kind of like the rain cover on an 18 wheelers exhaust stack at idle.

With Turbos, all setups are a compromise. Change one thing and it affects other things you may not expect. Things like surging. It's best to stay in the right neighborhood when matching a turbo to HP...which you are w/ your B1-2. My KSB-1 is limited to about 450 HP (non wastegated). Not sure how much HP I can run with the Ex WG...Guessing 550? That's one of the things I'm experimenting with.

RJ

Beast2B

1320, I reread your post. Air density is a factor of the environment, so either turbo should have the same environmental specs: temp, barometric pressure, etc. in my (extreme) generalization. Where does the diff come from?

RJ, a couple clarifications: I thought I saw a post that 'all b1 turbos have the same compressor side'?
What does A/R stand for? How about TIP? Back pressure = drive pressure = TIP?
We read 'boost' pressure on the discharge side of the compressor before the head. If we read the pressure between the head and the turbo, that is the 'drive' pressure, right? The relationship between those pressures is the Pressure Ratio, right?
And last but not least, WHO SHOT J.R.???

Beast2B

Oh yeah, and RJ, did your wastegate adjustment change when you changed to the Mach4's? What benefit do you see from the H2O injection? Tried meth yet?

1320

Two turbos.......both can generate 46 psi of boost in a given restriction (the same engine) but one turbo does it a say 92000 rpm and its most efficent area of its map at 72% raising the the compressed air charge to 360 degrees..the second turbo makes the same 46psi of boost but spinning 120000 rpm slightly out of its map operating at 64% effecincy raising the intake temp to say 475 degrees. The sencond example is at the same 46 psi of boost but the air has been heated , there by expanding so in the same volume of compressed air there is actually less oxygen to burn.


Im adding two more intercoolers (large and small) between my turbos . Im keeping the stock intercooler. I will use a progressive water /alky set up but I want to try the intercoolers first.

Beast2B

1320, thanks for the added info. All of the pieces may eventually help me understand this better! Love the trial and error and R&D part of this, I just don't have the time or funds at this point to be immersed. Haven't heard of intercooling between charge stages, I'll be watching for results.
If I haven't said it lately, thanks to all of you willing to share info and results to get the rest of us up to speed.

RowJ

All B-1's have same compressor size...but different # of blades change how they perform. The KSB-1-2 has 7 double compressor blades. My KSB-1 has 6. Suspect this is main difference between -1's and -2's. Does yours have 7?

TIP is Turbine Inlet Pressure...the engineering term for back pressure.....also called drive pressure! All the same thing. To measure it...insert a pressure gauge into your Pyro Gauge Probe Port and go for a drive. On my KSB-1 at 45 psi boost I get 45 psi TIP...1:1. At 51 psi Boost I get 65 psi TIP.

A/R ratio deals with the turbine side. A = Area of the cross section of the turbine inlet. R = radius (distance) from from the center of the section area in the cone (leading to the turbine baldes) to the center of the turbine shaft. Confused yet? Simplified...it's the ratio between the size of the turbine intake cone and the distance to the turbine wheel. This ratio is important to Mfg's in determining the speed with which the air leaves the turbine scrool and hits the turbine blades.

Yes, going to Mach 4's increased boost. required readjustment of regulator to ex WG to maintain boost at 45-46 psi.

RJ

signature600

You mean...insert a pressure gauge into your Pyrometer Probe Port and go for a drive!...Right, RJ???

Chris

Beast2B

I misinterpreted the statement 'same compressors' as meaning same housing and same wheel. Thanks, I'll look at my blades to check it out.

RJ, how much fiddling did you do tuning your WG? Jetpilot (on TDR) has done a BUNCH of tuning on B1 turbos and it was inferred to me that max power may be lower than 45-46#. I'm sure a lot of variables go into that statement, but I guess I'm asking how low did you test your boost for max power?
(and what kind of increments)
(and did you just buy some dyno tuning time)
(and will this disease ever be cured, or is diesel hotrod-itis permanent?)

RowJ

Thanks Chris...Have corrected above!

RJ