Boost pressure vs air flow vs power - Page 5 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 06-10-2014, 09:29 PM   #81
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,831
Total Cats: 1,786
Default

If one turbo can stuff more air into a space during a given time period, lots of things being equal, which means more oxygen to burn, would not said turbo produce more power?
Braineack is online now   Reply With Quote
Old 06-10-2014, 09:32 PM   #82
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

Quote:
Originally Posted by soviet View Post
You are.
Sure, it made 20-30 hp more for a whole bunch or reasons, none of which oppose the points I made.
- Less restrictive turbo
- More stable boost control
- Lower air temperatures
- GT2554 was probably at the edge of the efficiency range
still have no idea what you're talking about, and I'm actually trying to follow you here

-obviously its less restrictive, despite the same size on all 4 inlets and outlets on both turbos
-I said nothing at all about boost control, since both use the same
-I said nothing about lower air temps, because they weren't
-No idea what that has to do with anything, and the test I referred to wasn't even a gt2554, but a td04 right in the middle of its efficiency range.

WAT

in the crap

are you talking about?

*edit: I actually did the same test on a vf39 (roughly 2860 sized turbo) vs a 20g, and achieved similar results.
I'll dig up the plots
18psi is offline   Reply With Quote
Old 06-10-2014, 09:36 PM   #83
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

Quote:
Originally Posted by DNMakinson View Post
As a matter of perspective on how much difference. Re the Subaru swap:
What would you say you would have to turn the boost on the VF39 down to in order to keep the max HP the same as stock? If from 10 to 8, then that would be one thing. If from 10 to 5, then another answer altogether.

If the first case, then we would say, "it takes 25% more boost on a small turbo for the same power". If the second case, we would say, "it takes 2X the boost on a small turbo for the same power"

Maybe on the next swap, you could try that, or you may already have the data.

Another correllary is that the situation sounds a bit like the net power from a supercharger. Some of the power stroke is negated by some of the exhaust stroke. Therefore, for the same net power (torque), the rods are more highly stressed with the smaller turbo (or restrictive exhaust) than with the larger.
I'd have to get back to you on the actual numbers, but it definitely wasn't 2:1. More like 15-20% increase or so.
Quote:
Originally Posted by turbofan View Post
Not really changing... just adding an aspect of the discussion that's been completely ignored.





Good example. I am not smart enough to understand the other examples and maths being bandied about, so I should probably stop commenting
I think you're implying that a EJ255 is choked up in my test example, vs a bp being maxed out when using a gt2554 vs gt3076r example.

That is not the case.
18psi is offline   Reply With Quote
Old 06-10-2014, 10:25 PM   #84
Newb
 
Join Date: Jan 2011
Posts: 22
Total Cats: -4
Default

I think everyone needs to read corky bells maximum boost for a good idea of what's going on
chiods is offline   Reply With Quote
Old 06-10-2014, 10:31 PM   #85
Elite Member
iTrader: (1)
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 4,682
Total Cats: 216
Default

Quote:
Originally Posted by chiods View Post
I think everyone needs to read corky bells maximum boost for a good idea of what's going on
Full_Tilt_Boogie is offline   Reply With Quote
Old 06-11-2014, 01:09 PM   #86
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,460
Total Cats: 782
Default

Quote:
Originally Posted by chiods View Post
I think everyone needs to read corky bells maximum boost for a good idea of what's going on

concealer404 is offline   Reply With Quote
Old 06-11-2014, 01:19 PM   #87
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Quote:
Originally Posted by 18psi View Post
still have no idea what you're talking about, and I'm actually trying to follow you here

-obviously its less restrictive, despite the same size on all 4 inlets and outlets on both turbos
-I said nothing at all about boost control, since both use the same
-I said nothing about lower air temps, because they weren't
-No idea what that has to do with anything, and the test I referred to wasn't even a gt2554, but a td04 right in the middle of its efficiency range.

WAT

in the crap

are you talking about?

*edit: I actually did the same test on a vf39 (roughly 2860 sized turbo) vs a 20g, and achieved similar results.
I'll dig up the plots
Repeat it with an 18g and a 20g both with the td05 wheel and 8cm turbine housing. I bet it doesnt change significantly.
Leafy is offline   Reply With Quote
Old 06-11-2014, 02:13 PM   #88
Newb
iTrader: (1)
 
Join Date: Nov 2012
Location: Oshawa
Posts: 34
Total Cats: 2
Default

Quote:
Originally Posted by Leafy View Post
The best video of turbo destroying spool up surge you can find on the internet is an RB26 with a GT35R on it, I think they're doing terrible things to it with a mustang dyno though to make it make the sound. I've also heard of people pushing 16gs on 2.5 subarus across the surge line on cold days.
This?
crazymittens is offline   Reply With Quote
Old 06-11-2014, 02:16 PM   #89
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Thats the one. Turbo go chu chu chu.
Leafy is offline   Reply With Quote
Old 06-11-2014, 02:20 PM   #90
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

Quote:
Originally Posted by Leafy View Post
Repeat it with an 18g and a 20g both with the td05 wheel and 8cm turbine housing. I bet it doesnt change significantly.
I don't even waste time on td05 or 18g, except 1 that a friend talked me into tuning for him. I've done plenty of 20g's. It depends on your definition of significant - if 20-30hp is insignificant then I guess its insignificant.
18psi is offline   Reply With Quote
Old 06-11-2014, 02:22 PM   #91
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Quote:
Originally Posted by 18psi View Post
I don't even waste time on td05 or 18g, except 1 that a friend talked me into tuning for him. I've done plenty of 20g's. It depends on your definition of significant - if 20-30hp is insignificant then I guess its insignificant.
I guess I should have said, go repeat that with two turbos that use the same exact hot side. Both turbos will behave nearly the same except for the small intake temp changes due to the differences in efficiencies and the behaviors at the left and right hand sides of the compressor map.
Leafy is offline   Reply With Quote
Old 06-11-2014, 02:30 PM   #92
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,831
Total Cats: 1,786
Default

Quote:
Originally Posted by Leafy View Post
Repeat it with an 18g and a 20g both with the td05 wheel and 8cm turbine housing. I bet it doesnt change significantly.
that's because there's pretty much nil difference between the two turbos.

no advantage on the hotside, coupled with compressors that are nearly identical, so there's no efficiency advantage or shaft speed advantage.

one is simply better suited for higher pressure and lower flow (18g - steeper surge line) the other lower pressure and higher flow (20g - shallower surge line, capable of higher CFM output).


again, another Braineack post that suggests an actual understanding, so im sure everyone will ignore this.

Last edited by Braineack; 06-11-2014 at 02:40 PM.
Braineack is online now   Reply With Quote
Old 06-12-2014, 06:00 PM   #93
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

For a given engine you can map and thus predict power (or torque ) production based on 3 things:

- RPM
- MAP
- TIP (turbine inlet pressure, aka exhaust backpressure)
(ignoring temperatures)

bigger turbo -> less TIP -> moar powah
JasonC SBB is offline   Reply With Quote
Old 06-12-2014, 06:02 PM   #94
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Quote:
Originally Posted by JasonC SBB View Post
- RPM
- MAP
- TIP (turbine inlet pressure, aka exhaust backpressure)
(ignoring temperatures)

bigger turbo -> less TIP -> moar powah
Yes, especially on those magical times when MAP/TIP > 1.
Leafy is offline   Reply With Quote
Old 06-12-2014, 09:41 PM   #95
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,653
Total Cats: 1,559
Default

Quote:
Originally Posted by Leafy View Post
Yes, especially on those magical times when MAP/TIP > 1.
Just the TIP.


I promise.
sixshooter is online now   Reply With Quote
Old 06-12-2014, 10:34 PM   #96
Newb
 
Join Date: Jan 2011
Posts: 22
Total Cats: -4
Default

Other than being slightly dated can someone tell me why we should be reading internet forums and self made experts on turbos instead of reading a book about it? Someone explain to me why this thread isnt laughable but maximum boost is
chiods is offline   Reply With Quote
Old 06-12-2014, 10:42 PM   #97
Junior Member
iTrader: (1)
 
Tmorgan's Avatar
 
Join Date: Nov 2009
Posts: 79
Total Cats: 13
Default

Quote:
Originally Posted by chiods View Post
Other than being slightly dated can someone tell me why we should be reading internet forums and self made experts on turbos instead of reading a book about it? Someone explain to me why this thread isnt laughable but maximum boost is
https://www.miataturbo.net/diy-turbo...big-post-4288/


Read the first line buddy.
Tmorgan is offline   Reply With Quote
Old 06-12-2014, 10:45 PM   #98
Elite Member
 
DNMakinson's Avatar
 
Join Date: Jan 2013
Location: Seneca, SC
Posts: 2,698
Total Cats: 267
Default

Quote:
Originally Posted by Tmorgan View Post
It's laughable because we've all read Corky's book. That's the starting point.
DNMakinson is offline   Reply With Quote
Old 06-12-2014, 11:12 PM   #99
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

Quote:
Originally Posted by chiods View Post
Other than being slightly dated can someone tell me why we should be reading internet forums and self made experts on turbos instead of reading a book about it? Someone explain to me why this thread isnt laughable but maximum boost is
This thread IS laughable. It started off full retard, and it just keeps retarding.

Maybe it will go full circle.
18psi is offline   Reply With Quote
Old 06-12-2014, 11:14 PM   #100
Newb
 
Join Date: Jan 2011
Posts: 22
Total Cats: -4
Default

Quote:
Originally Posted by Tmorgan View Post
Considering the next line says buy an engine management unit but still tons of people use bandaids, what's your point? All the retard physics in this thread from soviet proves he either didnt read it and/or was high throughout all his physics classes in high school.
chiods 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 57 07-19-2017 05:11 PM
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
Changing from 460cc to flow force 610cc in diypnp 90 Turbo MEGAsquirt 19 10-19-2015 04:23 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Moroso Air Oil Separator Catch Can Aroundcorner Miata parts for sale/trade 2 10-01-2015 04:20 PM


Tags
hustlers tiny turbo, i stuff your intake, overfilling, stretched assholes, superhomogay

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 07:12 PM.