Why not. Two hx35's

This is where a compressor map for the HX35 would be handy, you could see where you are at and where you would be. You might be at a better spot in the map compressing X volume to 35 psi than compressing X/2 like you would with two chargers. Maybe not. With running two chargers in parallel, you're not gonna get the pressure muliplication like a multistage setup. To increase flow through a given restriction, you need to increase the pressure. You're not changing anything in the engine, so the restriction there is the same.
 
#1 wont work, they will surge like a mofo.
#2 will work, but youll need a couple VGT's or possibly a smaller charger like a HY-9 but you will have to spin it pretty hard ot get it to go. in the long run you wont be gaining much.
 
SuperSonic said:
#1 wont work, they will surge like a mofo.
#2 will work, but youll need a couple VGT's or possibly a smaller charger like a HY-9 but you will have to spin it pretty hard ot get it to go. in the long run you wont be gaining much.
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Good enough for me!
Chris
 
Cummins Driver said:
The CFM flow of the engine is always the same. You are not changing the cylinder head and camshaft by putting any turbo on it. By putting an aftermarket turbo on a truck you are increasing the density and volume of air available. Two 35's would be twice the volume of one, with an air density probably as good as any if kept at 35psi. Im not talking about making a 800hp truck, and i think 450-500 is plenty doable with 2 of them. Heck, people make a hot smokey 400hp on one HX35 every day.

Im not saying this would be the best thing since sliced bread, I just havent seen an opinion that has changed my mind about it yet.

I think ZStroken might be right about bad spoolup on setup #2 though.
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35psi is 35psi... you're not increasing density... you might get a LITTLE more density due to lower charge temps, but not a ton. two 35's would not be twice the volume of one... they're still blowing through the same cylinder head at the same boost pressure :confused: they would be the same volume as one, but they'd take twice the engine RPM to spool up
 
Forrest Nearing said:
35psi is 35psi... you're not increasing density... you might get a LITTLE more density due to lower charge temps, but not a ton. two 35's would not be twice the volume of one... they're still blowing through the same cylinder head at the same boost pressure :confused: they would be the same volume as one, but they'd take twice the engine RPM to spool up
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So you are saying it takes more boost to have cooler EGT's, and volume doesent matter a lot. Do you think a sps62 at 55psi will support as much fuel as a K31 at 55psi?
 
With compounds the idea is to let the hot exhaust gas expand into the small turbine, then expand again into the big turbine. The cold side gets compressed by the big compressor than compressed again by the small compressor. If you just ran two hx35 compounded you wouldn't see either of these happening. I'd image the drive pressure with two hx35's would be twice as bad as it gets with just one =P
 
I understand it wouldnt work well in a conventional compound setup, so that is why i was thinking maybe having each turbo use its own compressor instead of piping one compressor back into the other.

Im sure i wont be doing this, I was just trying to get a better idea of why it wouldnt work. I can see a few drawbacks of it now, anyways.
 
If you call Scott Hovey at Massdiesel,or any of the NETDP guys,they may know the name of the NETDP owner who did this split cylinder(3 cylinders into each charger)HX35 deal along time ago on his truck.It was never a powerhorse and was removed from what I know due to terrible lag as the cylinder pulse from 3 cylinders did not provide enough pressure to make any low end power and they were very inefficent.I remember seeing shots of the truck at one of the NE groups Dez Dyno rolls and it has since been changed........Andy
 
Cummins Driver said:
So you are saying it takes more boost to have cooler EGT's, and volume doesent matter a lot. Do you think a sps62 at 55psi will support as much fuel as a K31 at 55psi?
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yes, it takes more boost to have cooler EGT's. and yes, I will concede that 35psi out of two HX35's will be a little denser and cooler than out of one HX35, but not THAT much better...

if you want to see about how it would be, hang a K31 on the truck and run around at only 35psi... now, just imagine spooling up another 500-700rpm later than the K31 does, and you'll at least have a good idea of how it's going to drive
 
Forrest Nearing said:
I've got no problem with trying to reinvent the wheel, but when you talk about making it square shaped, I feel obligated as a fellow human being to try to keep you from wasting your time
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I saw this post and couldn't help but post up.


~Wes~



SquareWheel.jpg
 
Cummins Driver said:
I understand it wouldnt work well in a conventional compound setup, so that is why i was thinking maybe having each turbo use its own compressor instead of piping one compressor back into the other.

Im sure i wont be doing this, I was just trying to get a better idea of why it wouldnt work. I can see a few drawbacks of it now, anyways.
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Some one above stated basically "Set-up #1, will surge like a mofo". I think this is correct plus Set-up #1 will have other issues.

Unless you tuned the wastegates carefully the second HX35 will want to spin backwards initially because boost created by the first HX35 will be higher most likely. I could also imagine terrible spool up lag, making it not very streetable. I bet that set in that configuration would be barking and snorting continuesly until fully spooled, if it could even get spooled.

I like your idea of trying to put more exhaust heat to work though, keep poking through it.

Personally, I would think you would have better luck compounding your compressors. Just keep in mind that in sequencial compressors the first compressor reduces the air volume, let say for example, by 50%. Now to be half way efficient the second compressor needs to be basically 50% smaller than the first. If there was a 3rd stage, then the 3rd compressor should be roughly 25% the size of the first or 50% the size of the second and so on. More or less thats the idea in general. The air keeps getting compressed by each stage it takes up a smaller and smaller volume.

My advice is to find yourself a good s400 and build a proven twin set. :rockwoot:

Good Luck;
Jim
 
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