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Discussion Starter · #1 ·
Hey guys just wanted to share my updated compound set up for my 01 ford expedition as I build it.
I have been gleaning advice from a bunch of guys here and hopefully it turns out as well as their trucks.
So you see here i've got a big set of compounds and was sick of the slow spool and lack of drivability while towing.
So I bought a hx30(44mm from dieseltuff) and i'm gonna put it with a 7blade hx35, 12cm housing.

20210306_140317[1].jpg
 

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Discussion Starter · #2 ·
New hx30 44mm, thanks Dieseltuff! I've never drive my 4bt with anything smaller than an hy35 or hx35 so i'm excited to see how it turns out. 20210309_172106[1].jpg
 

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You will likely see boost that is lightning fast compared to the bigger turbos. One question. Is that HX35W the one that has the wastegate actuator attached to the compressor housing like in the photo below? If so, that might prove an issue should you need to change the clocking. That one was designed to mount in only one position.
 

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You will likely see boost that is lightning fast compared to the bigger turbos. One question. Is that HX35W the one that has the wastegate actuator attached to the compressor housing like in the photo below? If so, that might prove an issue should you need to change the clocking. That one was designed to mount in only one position.
The best thing about the 30/35 combo once dialed in is the improver drivability on the front half of the torque curve, the most FUN might be running up a grade at WOT but always having good boost well below peak torque that just makes the vehicle truly pleasant to drive around and for a truck that makes a tool that just fits.
 
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Discussion Starter · #6 ·
20201030_194159.jpg I had previously modified it so I could clock the compressor housing independently of the exhaust side. I've got a mambatek actuator with repksvable springs. It's a great product. Full flapper travel with any pressure which u can't do with factor wastegated.
 

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Discussion Starter · #7 ·
A few questions tho, I've got gates on both chargers. What should I set them to?
20 psi on small turbo, 15-20 On big turbo? What kind of overall boost would that equate to? I'm looking for 40-50 max.
I'm not sure on the math how to do this other than trial by error
 

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A few questions tho, I've got gates on both chargers. What should I set them to?
20 psi on small turbo, 15-20 On big turbo? What kind of overall boost would that equate to? I'm looking for 40-50 max.
I'm not sure on the math how to do this other than trial by error
My 30 is set with a boost elbow to open at 38 and when it opens boost will drop 2-4 psi initially then start to climb again slowly with engine RPM, so with no waste gate on the 35 I am using the stop on the 30's waste gate and fuel to balance the WOT load between the two.
Where I'm at now at WOT the 35 is feeding 20 psi to the 30 with the manifold seeing 40+, during normal driving from takeoff to ~1,600 the 30 is handling at least 2/3 of the load between 1,600 and 2,000 it's a pretty even split, should I wind it out in direct the 35 will eventually take the lions share of the load but I really do not ask it to do that as it's not happy there.
I have thought that the 35's gate controlled by drive pressure might be the best way to get them to balance the loads across the RPM and load ranges.
 

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Discussion Starter · #10 ·
My 30 is set with a boost elbow to open at 38 and when it opens boost will drop 2-4 psi initially then start to climb again slowly with engine RPM, so with no waste gate on the 35 I am using the stop on the 30's waste gate and fuel to balance the WOT load between the two.
Where I'm at now at WOT the 35 is feeding 20 psi to the 30 with the manifold seeing 40+, during normal driving from takeoff to ~1,600 the 30 is handling at least 2/3 of the load between 1,600 and 2,000 it's a pretty even split, should I wind it out in direct the 35 will eventually take the lions share of the load but I really do not ask it to do that as it's not happy there.
I have thought that the 35's gate controlled by drive pressure might be the best way to get them to balance the loads across the RPM and load ranges.
Ok makes sense, but isn't 38 psi on a 44mm hx30 out of its efficiency?
 

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100% the 44mm hx30 is out of it's efficiency at 38psi if it was running in a single turbo setup but it doesn't work that way in a twin turbo setup. The secondary turbo thinks it's running at way below sea level for air, as the primary turbo is feeding it positive air. And yes, it sure doesn't hurt to port the waste gate flapper hole, as long as it still seals fine.
 

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Ok makes sense, but isn't 38 psi on a 44mm hx30 out of its efficiency?
As Mark stated the 30 is being fed around 15-18 psi when the gate opens so the pressure ratio for the 30 is within it's limits, as the 30's gate opens the 35 really starts to take over the load that is why the stop has helped me with balancing the two.
 

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Discussion Starter · #15 ·
I've been thinking about wastegate pressures and im not sure I'm understanding you guys correctly.
So my old set up hx35 over h2e. Hx35 has a wastegate set to 32 open, 36 fully open. H2e regulated by fuel. 2 gauges. Manifold pressure went to around 30 and then 2nd boost gauge installed in boost pipe between turbos(let's call this interstage psi) started to move and went up to around 20. At this point manifold psi was just over 50 psi.

So where I'm hung up is hx30 gates at 35 then hx35 starts to build at this point say hx35 is gated to 20 I should see around 55??

I'm not getting it when eggman says the hx30 is fed 18-20 psi when it's gate opens, I thought at 35 psi when it's gate opens the hx35 is just starting to build boost...

Are u taking small turbo wastegate signal from its own compressor housing or from somewhere else?
 

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I'll try but to be honest I probably understand what's going on just well enough to make a hash out of this...
The compressor takes in outside air at sea-level so the pressure is 14.7psi ambient or 0psi gauge, in a 2 stage system like ours the 35 is the only compressor that has access to air at 0psi. Even at below peak torque the 35 will start making boost so whatever pressure the 35 is making is what the 30 thinks is ambient so anytime you are on the throttle the 30 is being fed air under pressure as its starting point so it does not have as far to compress it to get the higher numbers.
This is what is called the pressure ratio so it's the percentage that each compressor wheel compresses what it was fed so my goal has been to have each stage carry an equal load so the 35 gets me half way there and the 30 closes the deal.
I need to go to town today so I will take some notes as to the loading of each stage at different loadings just so you have an idea of just what's going no between the two.
 

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This is a bit confusing. Steve, are you saying you HX30W wastegate is locked at 38 PSI? I've never heard of such a high number on the secondary turbo. Normally, you'd want that gate to open around 18-20 PSI for the compounding effect. The gate on the primary is probably insignificant because the HX35W won't go beyond 15-20 PSI without a gosh awful lot of fuel. Now having a total system boost of 38 PSI would sound about right.
 

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This is a bit confusing. Steve, are you saying you HX30W wastegate is locked at 38 PSI? I've never heard of such a high number on the secondary turbo. Normally, you'd want that gate to open around 18-20 PSI for the compounding effect. The gate on the primary is probably insignificant because the HX35W won't go beyond 15-20 PSI without a gosh awful lot of fuel. Now having a total system boost of 38 PSI would sound about right.
Yes my 30's gate starts opening at 38psi but by that point the 35's feeding the 30 well over 15psi, only after the gate is open does the boost climb beyond 38psi though this is only under a real load at WOT while RPM's climb beyond 2,000rpm.
As I have this figured at least in my head the 30 is not working any harder making 40psi when being fed 20 psi that it is making 25psi from ambient pressure...
Now I know what results I have experienced BUT as you know I have also been required to rework some of the experiments I have conducted as they were less of a success than others so the Goblin might want to wait till one of our more knowledgeable members sound off ;) don't want anyone else to pay the fiddler for one of my misconceptions.
 

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Discussion Starter · #20 ·
This is a bit confusing. Steve, are you saying you HX30W wastegate is locked at 38 PSI? I've never heard of such a high number on the secondary turbo. Normally, you'd want that gate to open around 18-20 PSI for the compounding effect. The gate on the primary is probably insignificant because the HX35W won't go beyond 15-20 PSI without a gosh awful lot of fuel. Now having a total system boost of 38 PSI would sound about right.
That's kind of what I thought. Now I've only set up one set of compounds, so I'm no expert. I do know mine worked Well, just for a more of a play truck rather than daily driver
 
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