wastegating facts

lol...have fun with it.

I think my old thermo book was published back in 1999.

Yep, H = internal energy + the whole P*V work thingy...so, from what I remember, pressure is already accounted for.

The nice thing about gas turbines over steam is the fact it's always superheated...you never have to deal with the quality of a possible wet vapor. But it it can be a pain acounting for the combustion products.

shoot, as you know...the air we breathe is superheated.
 
My Thermo Book dates back to the Early 80's. According to my son's friend that is when all the great classic music is from.

I'll stick with Ideal Gas properties, and make the assumption that I have enough air to keep it from sooting.
 
Diesel Freak said:
I highly recomend school over bombing the truck!!!!!! Doing both at the same time really eats the funds!!!
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Ha yea i guess ill just have to suck it up....where did you go to school? for?

Hmmm.....yea...maybe sponsors????:hehe:
 
Diesel Freak, you went to WSU? No wonder.... did you drink more beer than study? My brother went there for computer science. I'm graduating finally in April with Construction Management degree.


Anyway, this discussion has diverted down a ton of paths.

I agree with JWT that the front three cylinders in a divided scroll turbine section will experience higher pressure than the back three. That might actually explain why so many Dodges blow the head gasket on the front half of the block.

A big question that I have has to do with overspeeding a compressor. At what point does the rising drivepressure overcome the increase in mass flow from the over sped compressor?

Is the point at which power output from the engine, measured at the flywheel, come when the compressor is in at 50% efficiency? I noticed that most compressor maps stop near 60%.

At 50% efficiency does half of the pressure rise come from increased mass flow and half from increased temperature?
 
I need to clarify, that last post makes me look stupid!

7 blade 54mm ind 78mm exd HX35 for example, most claim that peak HP is made when boost pressure, measured at the intake manifold, is limited at 35 psi.

So, lets say you push this same charger, with more fuel, up to 40 psi. Does the increase in exhaust back pressure overcome any gains that might be made by more boost, or is the compressor being pushed so far out of it's efficiency map that it is actually pushing 0 extra mass, just adding more heat energy to raise boost 5 more psi?

If you super over speed an HX35 to say 170K shaft rpm, does it compress the same mass of air as it does at 150K shaft rpm?
 
Diesel Freak said:
Naval Nuclear Power School

Washington State University: Mechanical Engineering.
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Oh wow naval what??? i see...im going to purdue university and majoring in either farm mngmnt or Ag Systems Mngnt...

Yea BigBlue is right about the conversation taking a cpl turns...you guys just keep goin and ill just keep settin here watchin and learnin...this stuff is pretty interesting, if i can understand it...and if i have any questions about chargers ill know who to talk to right?
 
Not sure it will be 20:1 but for simplicity, I will pretend that it is. Calculation is allready complex as it must take into consideration the heat capacity of the gas at variable pressure and volume. I havn't read far enough to find the QED statement.
 
well, actuallt 28:1 would ensure almost no smoke

less thasn 18:1 is smokey

attempt to run stoic (14.5:1) incomplete combustion with toasty egt results. Smokes like a MO FO too
 
Big Blue24 said:
I need to clarify, that last post makes me look stupid!

7 blade 54mm ind 78mm exd HX35 for example, most claim that peak HP is made when boost pressure, measured at the intake manifold, is limited at 35 psi.

So, lets say you push this same charger, with more fuel, up to 40 psi. Does the increase in exhaust back pressure overcome any gains that might be made by more boost, or is the compressor being pushed so far out of it's efficiency map that it is actually pushing 0 extra mass, just adding more heat energy to raise boost 5 more psi?

If you super over speed an HX35 to say 170K shaft rpm, does it compress the same mass of air as it does at 150K shaft rpm?
Click to expand...


In actuality, no more air goes into the engine. The excess fuel just richens the mix and as a result EGT gets high. IMO, it's ok to run the drive pressure/Boost pressure ratio uo to 1.2:1. Over that and you really start to loose power as the engine no longer is in the middle of the "pressure teeter-toter" i.e. equilibrium between intake and exhaust



Somewhere in this thread there is posted a tip speed limit.
 
:what: I thought something interesting would have come out of this.... Like maybe JWT would have said who he was.... rather repeating info he got from a turbo engineer. :poke:

We'll see what happens when you take a 97mm turbo, intercool it, shove that into a 63mm turbo and then intercool that also. Control it all with a 50mm wastegate on the manifold directly and a 48 on the hot pipe.

The heck with it, go back to a huge single with a huge wastegate and add a ton of *nx* . LOL
 
chrleb1 said:
:what: I thought something interesting would have come out of this.... Like maybe JWT would have said who he was.... rather repeating info he got from a turbo engineer. :poke:

We'll see what happens when you take a 97mm turbo, intercool it, shove that into a 63mm turbo and then intercool that also. Control it all with a 50mm wastegate on the manifold directly and a 48 on the hot pipe.

The heck with it, go back to a huge single with a huge wastegate and add a ton of *nx* . LOL
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now thats my kinda lingo. wonder who has a turbo setup like you mentioned:evil i will stop by on my way home from modesto. and why are you not at work? jeez i wish i had your job eric lol. see ya later budy
 
:ft:
chrleb1 said:
:what: I thought something interesting would have come out of this.... Like maybe JWT would have said who he was.... rather repeating info he got from a turbo engineer. :poke:
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check out thread #76, I believe he signed his name at bottom, (once someone called him Mr. Todd ):st:
 
Oh ok.... i think that's when i was getting bored with the whole thing and started to skip ahead. :doh:
 
Signature600 said:
His name is John Todd, one of BD's turbo engineers.

Chris
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Who told... LOL

I am sure John was attempting to stay unanimous so he could keep his focus on turbo engineering instead of spending his valuable hours typing on forums. When I came in that morning and seen his first post I told him that he was gonna be busy man :badidea: the temptation to reach such a vast audience got the best of him. Although it started off a little rough I think most will agree it was both educational and entertaining.

I hope its obvious to anyone reading this forum that he is not "posting what he read on another website", he is very well educated! It is impressive to see the amount of knowledge on this forum and that some of you are able to keep up to him, as I often struggle to. LOL

I am sure he would like to come on here full time and discuss turbo charges but the truth of the matter is he gets paid to much to sit here and type on a forum all day :bow:

I will do my best to translate in a way the majority of us can understand, for the rest of you, you will have to wait till JWT has some free time to come on here and split hairs with ya.

Dave
 
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Sorry I meant to say ANONYMOUS not UNANIMOUS on my last post...

I don't think John meant to be Unanimous LMAO
 
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