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Discussion Starter #1
what do you think about an hx30w on top and a hx40 or hx50 on bottom? have these been tried? haisleys told me they ran a hx30/hx35,but didnt get to experiment with it too much. seems like manifold presure might be a little high? not enough flow from the 35?im readyto start fabbing somthing up as soon as i get the turbos.i just dont want to go into this whole thing blind.a little help would be apriciated.thanks
 

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You could follow the thread on 400HP. There is some really good info there if you can decipher the math. I'm sure a couple of those guys would give some input on your set up as well.
 

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thanks,i checked that thread out.good info.i checked a hoset website and the info i got on the turbos flow was [email protected]/s,[email protected]/s,and
[email protected]/s. from what ive read the bottom should flow twice as much as the top.so if i was planning on an hx30 top,then the hx55 would be suitable for the bottom?i think that would work.
Basically.
Small turbo is your stock turbo. Bigger turbo depends on what your goals are.
Smaller turbos give you more low end, bigger turbos give you more top end.

You want wastegates to control your boost levels. Otherwise your chances of damaging the engine are quite good.

Did I mention the rack of pyro, boost and backpressure gauges to set everything up properly?

I'm still in the accumulating parts and planning stage. Got turbo placement sorted, still designing plumbing.
 

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Discussion Starter #5 (Edited)
dougal,what turbos are you running. i an planning on both top and bottom turbos to have wastegates.i also will inlarge wastegates if possible.im looking for boost up to 45psi, but probably a little less.i have a boost gauge and my pyro should be here today.is the backpressure gauge nessesary?what amount of boost are you aiming for and what are you upgrading on your engine to prepare it for the extra boost? thanks
 

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dougal,what turbos are you running. i an planning on both top and bottom turbos to have wastegates.i also will inlarge wastegates if possible.im looking for boost up to 45psi, but probably a little less.i have a boost gauge and my pyro should be here today.is the backpressure gauge nessesary?what amount of boost are you aiming for and what are you upgrading on your engine to prepare it for the extra boost? thanks
I'm keeping my engine stock and plan to start with 30psi boost. It's not running yet, still in the design and planning stage.

Small turbo is a Garrett GT2256V variable vane, big turbo is a T28. I plan to use a dual port wastegate as the actuator on the variable vane turbo. This will hopefully allow me to balance the boost between the stages to whatever I want.

Engine is a japanese 4BT (Isuzu 4BD1T).

A backpressure gauge isn't necessary, but it can tell you when you're trying to extract too much boost from the little turbo.
 

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With such low boost numbers and a VV turbo, why go compound? Just curious.
The main reason is I think this will give me a much wider and stable boost curve. The VV turbo might run into surge trying to get the same levels of boost at low engine speeds.

The second reason is futureproofing. More performance is on tap, so to speak.:grinpimp:
 

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I've read Cummins stock head gaskets will take around 50psi. I hit about 23 right now and I'm smoking at that point. I'm not even hitting over 1000F for EGTs. I think instead of injectors it would be time for a turbo upgrade followed by injectors maybe later.

I would like to go with some twins and somehow keep my hy35 as the small turbo. Think an HX40/16 would make a good bottom turbo?

Twin setups are very interesting indeed.
 

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I've read Cummins stock head gaskets will take around 50psi. I hit about 23 right now and I'm smoking at that point. I'm not even hitting over 1000F for EGTs. I think instead of injectors it would be time for a turbo upgrade followed by injectors maybe later.

I would like to go with some twins and somehow keep my hy35 as the small turbo. Think an HX40/16 would make a good bottom turbo?

Twin setups are very interesting indeed.
Are you smoking because you're not getting enough air or smoking because your injectors aren't spraying well?

Are others running similar EGT levels having smoke problems?
 

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What color smoke do you have?
If its black smoke thats to much fuel or not enough air, or timing is retarted
if its white smoke that is a timing issue, caused by a bad injector or low compression.
blue is oil usually a turbo
 

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As to the boost pressure where the headgasket lets go.....

Can't really look at it like that. I could run 4 or 5 degrees more timing and my boost would drop along with my bottom end through the oilpan and the heads through the hood. However, I could pull out about 4 degrees and the boost would skyrocket but cylinder pressures would actually fall along with the chance of rodding the block and lifting heads.

Just be carefull using boost as a gauge for engine stress. Too many variables for that.

Good Luck.
It's another tradeoff though.
Retarding the timing to reduce the peak pressures hurts your efficiency. If you're chasing big power numbers then it's probably worth it as you'll gain more power from the extra boost than you'll lose from the retarded timing.
But if you're looking for the best fuel consumption, then you're probably better dropping the boost and keeping timing at the optimal.

If you've got an engine smart enough to change it's own injection timing, then you've got the best of both worlds. But most of us have strictly mechanical pumps.
 

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Discussion Starter #15
after talking with several people i decided to go with the hx30w and the
hx50w. from what ive read the hx30w will spool super fast but chokes out around 2400 rpm.the hx50w will give me plenty of top end flow.ive got them mounted to the engine in the engine compartment with most my 4"exhaust ran as well as my turbo oil feed lines. i still need to fab some oil return tubes and intercooler tubing.but im making progress every other day.im eager to get this beast driving.
 

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You are the man,

I will follow your thread closely and will have to PM you in ohh I don't know...a year.

I can't wait to check it out and hear how it does.

You know maybe some dyno runs (posted on youtube for all of us to enjoy)bounce
 

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for my 2 bob's worth. i did some reading in an old textbook about compound turboing diesel stuff. the small turbo is just there to get it all happeneing. when the big turbo starts to work, the little one does very little. when there is positive pressure at the inlet, the shaft speed drops dramatically. doing some pressure ratio based calculations will show this. one other advantage of a well set up compound setup is it is possible to get boost pressure higher than exhaust back pressure. cooler egt's and more efficiency. as for sizing, a 4bt produces similar power and torque numbers to a 6b. could you use a 6bt turbo for the second stage ? or a larger 6bt upgrade ?
 

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for my 2 bob's worth. i did some reading in an old textbook about compound turboing diesel stuff. the small turbo is just there to get it all happeneing. when the big turbo starts to work, the little one does very little. when there is positive pressure at the inlet, the shaft speed drops dramatically. doing some pressure ratio based calculations will show this. one other advantage of a well set up compound setup is it is possible to get boost pressure higher than exhaust back pressure. cooler egt's and more efficiency. as for sizing, a 4bt produces similar power and torque numbers to a 6b. could you use a 6bt turbo for the second stage ? or a larger 6bt upgrade ?
What textbook?:confused: Only one I've found so far is $85 and out of print-The diesel Engine Reference book. Thanks

Clarance
 

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Discussion Starter #20
ive got my ic mounting brackets built and the ic in place now.also got most ic plumbing done.still need to wrap up exhaust and figure out were to mount intake filter.i only have about 1 hour a day to work on this.but i do work on it most every day.i love seeing progress.im also trying to figure out how to route my turbo water coolant lines.id like to post pics but i suckwith computer stuff.maybe my wife will help. andy
 
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