ok, i worked this out in my head
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ok, i worked this out in my head

  1. #1
    Senior Member miketeast's Avatar
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    Default ok, i worked this out in my head

    what is the torque on a turbocharger shaft?

    Operating conditions, you ask?

    600hp
    6000rpm
    6lbs boost
    120K turbine speed @ 70% eff.
    380cid

    i assumed a VE or the engine at 90% NA.

    I come up with 1 ior 2 ft/lbs

    some 20-30 compressor hp....seems a little low
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    I think you are overthinking stuff

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    Senior Member miketeast's Avatar
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    Quote Originally Posted by mdsheppie View Post
    I think you are overthinking stuff
    maybe not...in sizing a turbo you have to consider many of the things that go into the calculation...i just took it a little further....well, yes, maybe too far but it was a short road...i just wonder if i followed any road at all. Internet searches did not get me any turbo hp, not to mention torque on the turboshaft.
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    PM unchained,infomaniac and Hass
    your best bets and the most info right there

  7. #5
    Senior Member miketeast's Avatar
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    Quote Originally Posted by mdsheppie View Post
    I think you are overthinking stuff
    maybe...sometimes i get bored...or cant sleep. I was traveling 100miles round trip to get some (believe it or not) hotdogs i really like and to refill my nitrous bottle, just doing time.
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    I still say you're worried about 1 or 2 pounds of torque on a shaft?

  9. #7
    gn7
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    I'm trying to figure out what difference it makes. Are you're thinking of re-engineering the shaft? Because if you thinking of the absorbed HP, you're barking up the wrong tree even thinking about how much HP it takes to spin it.



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  10. #8
    Senior Member miketeast's Avatar
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    Quote Originally Posted by gn7 View Post
    I'm trying to figure out what difference it makes. Are you're thinking of re-engineering the shaft? Because if you thinking of the absorbed HP, you're barking up the wrong tree even thinking about how much HP it takes to spin it.
    i was not thinking of re-engineering the shaft, it amazes me that anything can spin that fast...nor how much hp it was 'robbing' from the engine....just the hp the turbo had to generate to push that cfm at that efficiency at that pressure, using the information i had. The torque on the shaft was secondary. I wondered if i used the calculations correctly.

    I would like to have a turbocharged SBC engine someday that i put together myself. I want it to run on pump gas. I got a ride in a 342cid one putting out some 500+++HP in a jet and 5mpg running the dogshit out of it, 6psi boost, no intercooler. My NA 377 gets 450hp at 5500rpm and gets 4mpg under the same conditions. It was done quite affordably. Oh yeah, this is jetpump horsepower, the only one that counts.

    This takes some knowledge of how the turbocharger works with the engine...got to start somewhere. Here i started with engine rpm/cid cfm, engine VE and turbo efficiency and boost...like i said i was bored, and known to bark up wrong trees now and again.
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    Senior Member miketeast's Avatar
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    Quote Originally Posted by mdsheppie View Post
    PM unchained,infomaniac and Hass
    your best bets and the most info right there
    i read, with great interest anything they say here, and other places i find them.
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    Quote Originally Posted by miketeast View Post
    i read, with great interest anything they say here, and other places i find them.
    You might find it interesting info on aircraft engines in WW2

    Some motors were supercharged and a combination of a turbo/ compounding, it was using the waste energy geared back to the crankshaft for more power

    F1 is working on allowing this technology for the next season to get better eff
    Last edited by BigSteve; 09-29-2012 at 08:38 AM.
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    Quote Originally Posted by miketeast View Post
    i was not thinking of re-engineering the shaft, it amazes me that anything can spin that fast...nor how much hp it was 'robbing' from the engine....just the hp the turbo had to generate to push that cfm at that efficiency at that pressure, using the information i had. The torque on the shaft was secondary. I wondered if i used the calculations correctly.

    I would like to have a turbocharged SBC engine someday that i put together myself. I want it to run on pump gas. I got a ride in a 342cid one putting out some 500+++HP in a jet and 5mpg running the dogshit out of it, 6psi boost, no intercooler. My NA 377 gets 450hp at 5500rpm and gets 4mpg under the same conditions. It was done quite affordably. Oh yeah, this is jetpump horsepower, the only one that counts.

    This takes some knowledge of how the turbocharger works with the engine...got to start somewhere. Here i started with engine rpm/cid cfm, engine VE and turbo efficiency and boost...like i said i was bored, and known to bark up wrong trees now and again.
    You need to get some books & read up on the subject. A great one is "Turbochargers" by Hugh Maclnnes, I dont believe it's available new any longer but used additions are easy enough to find. Another great one is "Maximum Boost" by Corky Bell.
    As for the shaft tq question. There is plenty of math in those two books to keep you busy and also teach you how to read a compressor map so you can pick out the correct turbocharger for your application. As for the design of the turbo itself, and the shaft size & tq capabilities, let the engineers from the turbocharger manufactureres worry about that. Just keep the turbo in an efficient range and it will live.
    If you dont want to learn the math there are numerous turbo companies that would be more than happy to look at your combination and intended use and recommend you a turbo setup.
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    Senior Member miketeast's Avatar
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    Quote Originally Posted by Hass828 View Post
    You need to get some books & read up on the subject. A great one is "Turbochargers" by Hugh Maclnnes, I dont believe it's available new any longer but used additions are easy enough to find. Another great one is .
    As for the shaft tq question. There is plenty of math in those two books to keep you busy and also teach you how to read a compressor map so you can pick out the correct turbocharger for your application. As for the design of the turbo itself, and the shaft size & tq capabilities, let the engineers from the turbocharger manufactureres worry about that. Just keep the turbo in an efficient range and it will live.
    If you dont want to learn the math there are numerous turbo companies that would be more than happy to look at your combination and intended use and recommend you a turbo setup.
    thanks Hass...i have read lots of the online stuff, used the online calculators, some which plot your data to a certain turbomap. I have no trouble reading or understanding the maps or applying the math i have found so far...and while not always the case i feel that the math should work...

    I have come to realise just as with a supercharger to gain any power one must start with a lower compression... i read a little about turbo camshafts, but still dont have a handle on them (low overlap and such is easy...valve timing not so much). "Maximum Boost" by Corky Bell was recommended by many.

    I was told long ago and am now convinced that fuel injection is the only way to go...and shown a way to control it relatively inexpensively via HPtuner and certain GM TPI bricks (the ones without the idle driver) i guess i have to learn about credits, read about them...a little on fuel maps and the use of open and closed loops, MF vs AD sensors and the reasonfor and value of intercooling I have a fair understanding and some experience of electronics as applied to control systems, as well as heat flow in various systems.

    and Big Steve i have looked at the turbocharger/supercharger designs from ww2. There used to be a place where research papers could be looked at dating to the late 40's...some about airframes some about engine functions...very technical with graphs, calcs...It was the old NACA...declassified stuff...sometimes rather complex, but they always had a summation. It is there i learned the value of understanding the centistoke.

    I am not redesigning the wheel. People MUCH smarter and more educated than i have already done that...turbochargers interest me as an efficiency device as much as anything....

    research may be time consuming but it is rather cheep, and i find it rewarding. I dont have anyone near that i can just cakewalk up to and get advice on turbocharging, and the ones far that would help me would say the same thing about the torque on a turbocharger shaft...'who cares'...right after they say 'WTF is a centistoke'....
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