Compound Turbo Charging Theory - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 04-04-2008, 01:13 AM   #21
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

Oh yeah good luck with your Thermo class, really It is tough, but really interesting. Plus when you are done, your knowledge will be fresh (much fresher than mine) so maybe you can work the equations for all this discussion. It would be an interesting class project for sure.
ZX-Tex is offline   Reply With Quote
Old 04-04-2008, 02:01 AM   #22
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Lexington, SC
Posts: 2,084
Total Cats: 0
Default

could you just route the exhaust gases out of one turbo into the other?
mazda/nissan is offline   Reply With Quote
Old 04-04-2008, 02:08 AM   #23
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Quote:
Originally Posted by mazda/nissan View Post
could you just route the exhaust gases out of one turbo into the other?
Yea, that's how it's setup. The order is manifold, small turbo, big turbo, downpipe.
patsmx5 is offline   Reply With Quote
Old 04-04-2008, 02:09 AM   #24
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Lexington, SC
Posts: 2,084
Total Cats: 0
Default

then what have a 2-1 intercooler?
mazda/nissan is offline   Reply With Quote
Old 04-04-2008, 02:11 AM   #25
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Quote:
Originally Posted by mazda/nissan View Post
then what have a 2-1 intercooler?
What? Explain your thoughts a little bit better. What's a "2-1" intercooler? The charge isn't intercooled until it comes out of both turbos usually.
patsmx5 is offline   Reply With Quote
Old 04-04-2008, 02:13 AM   #26
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Lexington, SC
Posts: 2,084
Total Cats: 0
Default

ok nevermind i went brain dead for a minute. What are the odds that you will get the temps down that low though? also your car is gonna have some major heat cycles
mazda/nissan is offline   Reply With Quote
Old 04-04-2008, 02:17 AM   #27
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Down how low? I dunno, I think they could be pretty low, 0*F or lower. On paper it seems they could be much lower. It's weird. What do you mean by heat cycles? Feel free to explain yourself. I'm still wondering why nobody does this.
patsmx5 is offline   Reply With Quote
Old 04-04-2008, 10:32 AM   #28
Elite Member
iTrader: (39)
 
Zabac's Avatar
 
Join Date: Sep 2007
Location: High Point NC
Posts: 4,854
Total Cats: 8
Default

If this was beneficial and efficient enough someone would have this on their production cars...I don't get it, why would you want to raise boost higher than what's normal, add to the complexity, add to the cost of a turbo system just to drop it later down stream to get lower IAT's? There are much simpler, cheaper, easier, better ways to do it.
Zabac is offline   Reply With Quote
Old 04-04-2008, 11:11 AM   #29
Senior Member
 
Join Date: Jan 2007
Location: Maryland
Posts: 701
Total Cats: 0
Default

But none of these other ways result in charge temperatures UNDER say...40 degrees Fahrenheit and this talks about possibly less than 0 degrees. Think about it, he's gonna have frost on his intake manifold.

I think it's a very interesting idea, you'd end up with some rediculous extremes in your engine bay. Exhaust is gonna be so hot with 2 turbos keeping heat around.

Seriously...someone should talk to someone who knows something about this. In the meantime I leave you with another great example of tractor pulling tech.



Yeah, that's 3 V 16's strapped together.
MX_Eva is offline   Reply With Quote
Old 04-04-2008, 11:27 AM   #30
Senior Member
 
Join Date: Jan 2007
Location: Maryland
Posts: 701
Total Cats: 0
Default

Ok, seriously....tractor motors are rediculous, I mean I know none of these are for any real purpose tractors. but common, these things are awesome.



Totally stole that rotary motor out of a plane.

and this guy also stole his **** from planes.



Given how nuts most of the motors are, it really just makes me curious as all hell what this one is.



END Thread Jack.
MX_Eva is offline   Reply With Quote
Old 04-04-2008, 11:45 AM   #31
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Quote:
Originally Posted by Zabac View Post
If this was beneficial and efficient enough someone would have this on their production cars...I don't get it, why would you want to raise boost higher than what's normal, add to the complexity, add to the cost of a turbo system just to drop it later down stream to get lower IAT's? There are much simpler, cheaper, easier, better ways to do it.
For the same reason you run an intercooler or WI or lower your compression. Your trying to stop detonation and make HP. You would use a turbocharger to bring the air above ambient pressure, and then you would cool with an intercooler it to remove some of the heat so that your charge going into the engine has less heat, but more oxygen. That makes HP. More oxygen and more fuel with less heat seems to be the winning combination. We all know that the less heat and more oxygen there is, the more reliable HP you can make. This is basically just a larger scale version of what's normally done.

Are there really easier cheaper ways to do this? If so, I wanna hear them. On paper, it seems that you could have -100*F intake temps pretty easily.

EDIT: Oh yea, and the idea of compound turbocharging is not just limited to tractor pulling. There are kits available to compound big diesel trucks like the Fords, Dodges, and Chevrolets. They don't try to expand the air back after compressing it though.
patsmx5 is offline   Reply With Quote
Old 04-04-2008, 11:56 AM   #32
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

If the intake temps get too low there could be some problems trying to get the fuel to atomize and combust. That might be your lower limit of practicality with the inlet temperatures.

A direct injection engine, like a diesel, or some of the newer gas engines (like the Mazdaspeed 3) could overcome this since the air is reheated during the compression stroke before the fuel is injected into the charge.

Last edited by ZX-Tex; 04-04-2008 at 01:17 PM.
ZX-Tex is offline   Reply With Quote
Old 04-04-2008, 11:58 AM   #33
Elite Member
iTrader: (9)
 
TurboTim's Avatar
 
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,485
Total Cats: 248
Default

Quote:
Originally Posted by patsmx5 View Post
It would be a chore to build the stuff. I would have to have two turbochargers and I'm not sure there is room for both. I could probably figure it out though, I'm sure I could.
Yes you could figure it out cause there is room for 2 turbos in there in series. I had a nice seq. setup modeled at one time and I know you could figure it out too. It was actually easier to package than the parallel twins.
TurboTim is offline   Reply With Quote
Old 04-04-2008, 12:04 PM   #34
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Quote:
Originally Posted by ZX-Tex View Post
If the intake temps get too low there could be some problems trying to get the fuel to atomize and combust. That might be your lower limit of practicality with the inlet temperatures.

A direct injection engine, like a diesel, or some of the newer gas engines (like the Mazdaspeed 3) could overcome this since the air is reheated during the compression stroke before the fuel is injected into the charge. At least that is the case with a Diesel. I do not know the timing of the direct injection on the gas engines.
Well, it would still be compressed in the engine, so wouldn't it reheat and atomize then? I understand it's not atomize as well because of it being cooler, but would this really cause any noticeable effects? I guess it's really vaporize right? The injectors spray a fine mist of fuel to better atomize t so it can vaporize.

From just thinking about it, this system probably wouldn't even make "boost" after the orifice, because the air would loose a lot of it's volume when passes through the orifice.
patsmx5 is offline   Reply With Quote
Old 04-06-2008, 12:43 AM   #35
Elite Member
iTrader: (11)
 
Join Date: Jun 2007
Location: Overland Park, Kansas
Posts: 5,382
Total Cats: 43
Default

I had an old ford ranger 2.3 pickup in highschool that I swapped an 88 T-Bird turbocoupe engine/trans in. Sold that truck to my brother whos been rebuilding the engine and obsessing about the idea of adding a second turbocharger and secondary A/C system to the truck -- He has the space.. The second A/C evap would be a secondary intercooler after a retard sized 4" thick TRUST FMIC to cool the charge down even further.

If I remember correctly, he figured out the charge temps would be worst case right around 35 degrees F at the throttle body and parasitic drag on the motor right around 14% total.

Hes also been planning on a compound boost retrofit for another project of his.. Like couple a 3.2 liter whipplecharger with a T76 turbo on an 8:1 355 chevy motor.. I think hes crazy (not like, tarded crazy.. but has too much time / money / plans, etc) crazy.. *shrug* It sounds like a good idea, and its definatly going to be more efficent in the long run than standard water to air intercooling.
elesjuan is offline   Reply With Quote
Old 04-06-2008, 11:09 PM   #36
I'm Miserable!
 
Join Date: Dec 2007
Posts: 46
Total Cats: 0
Default

I don't understand how this expansion orifice will lower MAP. Is it in the thermodynamics of uncompressing then re-compressing a gas?

Aren't the differences in MAP recorded on a single car fitted with various turbos flowing 300lb/min a function of compressor efficiency and turbine resistance?
opek is offline   Reply With Quote
Old 04-10-2008, 01:51 AM   #37
I'm Miserable!
 
Join Date: Dec 2007
Posts: 46
Total Cats: 0
Default

What ever happened to a simple sequential setup? Seems like it'd offer more!

I'm still interested in hearing how this expansion chamber lowers map (since, of course, the air has to be put back into the intake manifold).
opek is offline   Reply With Quote
Old 04-10-2008, 02:04 AM   #38
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

If you compress a gas, it gets hot and expands. Roughly speaking, temperature rises 5*F per 1 PSI of increase in pressure. If use anything to compress a gas, it's temperature will rise. The turbo isn't a fixed displacement, so it will maintain a given pressure ratio, even if the intercooler pulls heat away from the charge, causing it to drop in pressure and increase in density. That's what it does. Anyway, air coming out of the IC is cooler and denser then it was, then you drop the pressure. Now, for every 1PSI you drop pressure, air temp drops roughly 5*F.
patsmx5 is offline   Reply With Quote
Old 04-10-2008, 02:19 AM   #39
I'm Miserable!
 
Join Date: Dec 2007
Posts: 46
Total Cats: 0
Default

Right, but that doesn't explain how you are going to drop the pressure with the orifice. Whatever you do after the intercooler you are going to have to reverse it as you pass the intake charge through the TB and manifold, then into the ports.

To change manifold gauge pressure, you have to impose or eliminate a restriction. Will putting a 5" section in the middle of your 2.5" charge piping do that? I'm sorry, but I'm still terribly confused.

I just don't see how the expansion orifice will allow the manifold gauge pressure to change.
opek is offline   Reply With Quote
Old 04-10-2008, 02:27 AM   #40
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

I'm sorry you don't understand it. It's physics. Do some research on it or read a book on A/C systems or something. I understand it, but I'm no teacher. I suck at explaining things.

Ok, this is the same Opek that was posting in the thread about exhaust flow earlier? If you understood all that, I don't see you having a problem with this.
patsmx5 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 12-15-2017 09:00 PM
WTB MP62 (Hotside) (NB2) Rick02R WTB 3 01-03-2016 08:18 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
ISO 1.6 turbo cast iron manifold cale saurage DIY Turbo Discussion 16 10-01-2015 12:25 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:49 PM.