measured exhaust backpressure and turbine inlet pressure
#1
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Anyone measure these numbers?
I think my fancy metal cat took a **** from all the oil burning due to a leaky turbo seal... it used to show ~ 4 psi at redline and 10 psi of boost ...
But the turbine inlet pressure numbers look good...
GT2560 internal wastegate
ETD shorty manifold
BEGI custom divorced pipe downpipe
TDR i/c
2000 motor
turbine inlet pressure (includes exhaust backpressure)
4000 RPM/5 psi 6 psi
4000 RPM/10 psi 10 psi
6500 RPM/5 psi 10 psi
6500 RPM/10 psi 20 psi
exhaust backpressure measured behind turbo
4000 RPM/5 psi 1-2 psi
4000 RPM/10 psi 3 psi
6500 RPM/5 psi 3 psi
6500 RPM/10 psi 6 psi
I think my fancy metal cat took a **** from all the oil burning due to a leaky turbo seal... it used to show ~ 4 psi at redline and 10 psi of boost ...
But the turbine inlet pressure numbers look good...
GT2560 internal wastegate
ETD shorty manifold
BEGI custom divorced pipe downpipe
TDR i/c
2000 motor
turbine inlet pressure (includes exhaust backpressure)
4000 RPM/5 psi 6 psi
4000 RPM/10 psi 10 psi
6500 RPM/5 psi 10 psi
6500 RPM/10 psi 20 psi
exhaust backpressure measured behind turbo
4000 RPM/5 psi 1-2 psi
4000 RPM/10 psi 3 psi
6500 RPM/5 psi 3 psi
6500 RPM/10 psi 6 psi
Last edited by JasonC SBB; 09-30-2008 at 11:45 PM.
#3
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Went to plumbing store, bought 1/8 MPT - 1/8 compression fitting.
Bought 1 foot 1/8" copper pipe.
Bolted fitting into top of turbine 1/8 NPT tapped EGT hole
Cinched down pipe into fitting.
Used a length of 1/8" vacuum hose to driver's seat and a 0-30 psi pressure gauge.
If you want to see how compression fittings work look here at the exploded view:
https://www.miataturbo.net/forum/sho...0&postcount=21
There's the same kind of adapter there, but a larger size. Note the copper sealing ring, called a "compression sleeve".
Bought 1 foot 1/8" copper pipe.
Bolted fitting into top of turbine 1/8 NPT tapped EGT hole
Cinched down pipe into fitting.
Used a length of 1/8" vacuum hose to driver's seat and a 0-30 psi pressure gauge.
If you want to see how compression fittings work look here at the exploded view:
https://www.miataturbo.net/forum/sho...0&postcount=21
There's the same kind of adapter there, but a larger size. Note the copper sealing ring, called a "compression sleeve".
#4
Junior Member
iTrader: (1)
Join Date: Jul 2007
Location: Johannesburg, South Africa
Posts: 109
Total Cats: 0
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
wow !
thats incredible - props to you ! I always wanted to try that but I feared the heat of the exhaust gas and I also anticipated that the pressure there would be about 4 times what you measured !
thats incredible - props to you ! I always wanted to try that but I feared the heat of the exhaust gas and I also anticipated that the pressure there would be about 4 times what you measured !
#6
Elite Member
iTrader: (15)
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,847
Total Cats: 27
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Very cool!
There is no significant flow of exhaust gas through the gauge, so the main heat transfer enemy is conduction down the pipe. If one uses a long length of copper tubing to allow it to air cool, followed perhaps by a rubber hose, then it works. The same idea works for O2 tail pipe sniffers on dynos.
Pressure drop is also negligible down the tube. Simply put, no flow means no pressure drop.
There is no significant flow of exhaust gas through the gauge, so the main heat transfer enemy is conduction down the pipe. If one uses a long length of copper tubing to allow it to air cool, followed perhaps by a rubber hose, then it works. The same idea works for O2 tail pipe sniffers on dynos.
Pressure drop is also negligible down the tube. Simply put, no flow means no pressure drop.
#11
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Last time I measured it, it was 1-1.5 psi max IIRC... with the next smaller bodied magnaflow muffler than I have now...
I measured backpressure because when I was installing the downpipe, the brick in the cat was clunking around when I shook it... dammit that cat cost me ~$100.. I'm sure it's more than that now.
#12
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
OK I had a louvered core 2.5" glasspack installed, louvers pointing rear:
https://www.miataturbo.net/forum/t26866-2/#post325138
Exhuast is quieter than with cat.
Backpressure is 40-45% lower and I get:
at 10 psi of boost:
4000 RPM 2 psi
6500 RPM 3.5 psi
Is this acceptable?
https://www.miataturbo.net/forum/t26866-2/#post325138
Exhuast is quieter than with cat.
Backpressure is 40-45% lower and I get:
at 10 psi of boost:
4000 RPM 2 psi
6500 RPM 3.5 psi
Is this acceptable?
#13
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
OK I had a louvered core 2.5" glasspack installed, louvers pointing rear:
https://www.miataturbo.net/forum/t26866-2/#post325138
Exhuast is quieter than with cat.
Backpressure is 40-45% lower and I get:
at 10 psi of boost:
4000 RPM 2 psi
6500 RPM 3.5 psi
Is this acceptable?
https://www.miataturbo.net/forum/t26866-2/#post325138
Exhuast is quieter than with cat.
Backpressure is 40-45% lower and I get:
at 10 psi of boost:
4000 RPM 2 psi
6500 RPM 3.5 psi
Is this acceptable?
Those number look better ut back pressure still seems kinda high. 1-2 PSI would be good I think. It climbing on you like that doesn't seem right. But your's is 2.5" not 3, so that's probably about right. 3 would perform better for sure.
Thread
Thread Starter
Forum
Replies
Last Post
Zaphod
MEGAsquirt
47
10-26-2018 11:00 PM
StratoBlue1109
Miata parts for sale/trade
21
09-30-2018 01:09 PM
stoves
Suspension, Brakes, Drivetrain
5
04-21-2016 03:00 PM
JesseTheNoob
DIY Turbo Discussion
15
09-30-2015 02:44 PM