Measuring stock exhaust restriction - Page 7 - 3000GT/Stealth International Message Center

RobBeck · 10-07-2005, 03:42 PM

I appreciate the figures. If I have time this weekend I might bench test with the air compressor... by blocking the outlet and inserting the airline into the inlet and manually seeing what pressure it takes to push it open.

Rob

twiceblown · 10-07-2005, 04:26 PM

i come up with:

flapper diam / diaphr diam / flap area / diaphr area / Flap PSI / turbine housing PSI / ideal acutator spring pressure
20.00 50.80 0.49 3.14 19.49 40.00 6.20
23.00 50.80 0.64 3.14 25.77 40.00 8.20
27.00 50.80 0.89 3.14 35.51 40.00 11.30

but note, that's at 40psi manifold pressure. if we increase that to say 50psi (not unlikely since we saw a 10+psi decrease manifold pressure by going to a 3" exhaust!) then these figures become:

20.00 50.80 0.49 3.14 24.36 50.00 7.75
23.00 50.80 0.64 3.14 32.21 50.00 10.25
27.00 50.80 0.89 3.14 44.39 50.00 14.12

So, it actually looks like stock may not be bad if you've only got manifold pressure of 40psi. higher than that, and you'll get flapper lift prior to the intended moment.

Also, it's interesting to note that you SHOULD NOT increase the size of the flapper on a TD04!!! Ideal spring pressure increases greatly for minor porting of only 3mm!!!

NOTE: flapper and actuator diameters in MM, spring pressures, manifold pressures and seat pressures in PSI.

twiceblown · 10-07-2005, 04:29 PM

hey Rob, did you port my wastegate holes? Glad i built those 9# actuators!!! hehehehe.

Multiades · 10-07-2005, 05:24 PM

Quote:

Originally Posted by twiceblown

Also, it's interesting to note that you SHOULD NOT increase the size of the flapper on a TD04!!! Ideal spring pressure increases greatly for minor porting of only 3mm!!!

I came to that conclusion before doing the math. It's only obvious. If your turbos don't boost creep, you don't need larger wastegate passages. Enlarging the wastegate passage/flapper has one purpose, and makes no sense to do until you have a specific problem to fix.

twiceblown · 10-07-2005, 08:41 PM

well, enlarging and reshaping/contouring would be two different things. if you can remove turbulance from the exhaust stream as it bypasses the turbine though the wastegate, then of course this would be beneficial. But, if you've increased the port diameter, then, sure, you need a larger spring just to bring things back to where they were.

I was actually wondering if Rob had attempted to smooth out the flow through the wastegate more than opening up the port.

RobBeck · 10-08-2005, 08:00 AM

Yours and mine both have been opened up about 2mm or so, along with reshaping/contouring. Be nice to see what actually happends pressure testing on a bench.... wish I had some aluminum here as I could compare to totally stock too. I guess I wont waste more time entertaining ideas of increasing flapper size..... too much influence on opening pressure per the math.

Rob

PS. Here is a pic someone sent me, check this one out!

FWombat · 10-09-2005, 10:42 AM

I think that at some point, wastegate flappers got caught up in the "bigger is better" line of reasoning that leads people to put huge turbos on small engines. No matter what angle I've considered it from, enlarging the flapper does nothing but cause trouble unless you're experiencing boost creep. I know DSMs get boost creep, but on our cars with two wastegates, I've never heard of it.

But...I've got the bullseye exhaust housings for my 14Bs, and they come with 38mm flappers. WAY too big.

But, I like the housings otherwise so I'd like to use them. I've played around with helper springs to increase the spring pressure, but they're kind of a pain to get adjusted right. Did we ever figure out if someone makes dual-port actuators for TD05 turbos?

- Brian

Multiades · 10-09-2005, 12:42 PM

Quote:

Originally Posted by FWombat

But...I've got the bullseye exhaust housings for my 14Bs, and they come with 38mm flappers. WAY too big.

But, I like the housings otherwise so I'd like to use them. I've played around with helper springs to increase the spring pressure, but they're kind of a pain to get adjusted right. Did we ever figure out if someone makes dual-port actuators for TD05 turbos?

Interesting that you mention it, but I believe StarQuests use dual-port actuators. They ARE bolt-on for some TD05 configuration, but I don't believe they are quite right for DSM-clocking 14Bs/16Gs/etc.

I wanted to get my hands on one to see what it would take to bolt it up, but I don't really know where to get one.

-Chris

FWombat · 10-09-2005, 01:32 PM

Well, it looks like TEC does make dual port assemblies for T25 turbos:

http://www.turboengineering.com/misc...actuators.html

The size and style sure looks similar to what we need...I wonder if just an adapter bracket of some kind could be rigged up?

FWombat · 10-09-2005, 01:46 PM

....and, it looks like these folks sell a dual port actuator upgrade for the Starion/Conquest...

http://www.racetep.com/starturbo.html

10-07-2005, 03:42 PM	#61 (permalink)
RobBeck POLYCHRONOPOULOS Join Date: May 2002 Location: St. Louis, MO Drives: On 1 Wheel Trader Rating: (219)	Re: Measuring stock exhaust restriction I appreciate the figures. If I have time this weekend I might bench test with the air compressor... by blocking the outlet and inserting the airline into the inlet and manually seeing what pressure it takes to push it open. Rob

10-07-2005, 04:26 PM	#62 (permalink)
twiceblown Mmmmm, Boooooost! Join Date: Nov 1999 Location: Disneyheim Hills, CA Drives: 300 yards. Trader Rating: (26)	Re: Measuring stock exhaust restriction i come up with: flapper diam / diaphr diam / flap area / diaphr area / Flap PSI / turbine housing PSI / ideal acutator spring pressure 20.00 50.80 0.49 3.14 19.49 40.00 6.20 23.00 50.80 0.64 3.14 25.77 40.00 8.20 27.00 50.80 0.89 3.14 35.51 40.00 11.30 but note, that's at 40psi manifold pressure. if we increase that to say 50psi (not unlikely since we saw a 10+psi decrease manifold pressure by going to a 3" exhaust!) then these figures become: 20.00 50.80 0.49 3.14 24.36 50.00 7.75 23.00 50.80 0.64 3.14 32.21 50.00 10.25 27.00 50.80 0.89 3.14 44.39 50.00 14.12 So, it actually looks like stock may not be bad if you've only got manifold pressure of 40psi. higher than that, and you'll get flapper lift prior to the intended moment. Also, it's interesting to note that you SHOULD NOT increase the size of the flapper on a TD04!!! Ideal spring pressure increases greatly for minor porting of only 3mm!!! NOTE: flapper and actuator diameters in MM, spring pressures, manifold pressures and seat pressures in PSI. __________________

10-07-2005, 04:29 PM	#63 (permalink)
twiceblown Mmmmm, Boooooost! Join Date: Nov 1999 Location: Disneyheim Hills, CA Drives: 300 yards. Trader Rating: (26)	Re: Measuring stock exhaust restriction hey Rob, did you port my wastegate holes? Glad i built those 9# actuators!!! hehehehe.

10-07-2005, 08:41 PM	#65 (permalink)
twiceblown Mmmmm, Boooooost! Join Date: Nov 1999 Location: Disneyheim Hills, CA Drives: 300 yards. Trader Rating: (26)	Re: Measuring stock exhaust restriction well, enlarging and reshaping/contouring would be two different things. if you can remove turbulance from the exhaust stream as it bypasses the turbine though the wastegate, then of course this would be beneficial. But, if you've increased the port diameter, then, sure, you need a larger spring just to bring things back to where they were. I was actually wondering if Rob had attempted to smooth out the flow through the wastegate more than opening up the port.

10-09-2005, 10:42 AM	#67 (permalink)
FWombat AEM Veteran Join Date: Jul 2001 Location: Tacoma, WA Drives: '94 VR-4 Trader Rating: (14)	Re: Measuring stock exhaust restriction I think that at some point, wastegate flappers got caught up in the "bigger is better" line of reasoning that leads people to put huge turbos on small engines. No matter what angle I've considered it from, enlarging the flapper does nothing but cause trouble unless you're experiencing boost creep. I know DSMs get boost creep, but on our cars with two wastegates, I've never heard of it. But...I've got the bullseye exhaust housings for my 14Bs, and they come with 38mm flappers. WAY too big. But, I like the housings otherwise so I'd like to use them. I've played around with helper springs to increase the spring pressure, but they're kind of a pain to get adjusted right. Did we ever figure out if someone makes dual-port actuators for TD05 turbos? - Brian __________________ Brian Geddes '94 Danube Blue VR-4 Replacing everything that moves. '94 Pearl Yellow VR-4 It's dead, but its drivetrain lives on!

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10-09-2005, 01:32 PM	#69 (permalink)
FWombat AEM Veteran Join Date: Jul 2001 Location: Tacoma, WA Drives: '94 VR-4 Trader Rating: (14)	Re: Measuring stock exhaust restriction Well, it looks like TEC does make dual port assemblies for T25 turbos: http://www.turboengineering.com/misc...actuators.html The size and style sure looks similar to what we need...I wonder if just an adapter bracket of some kind could be rigged up?

10-09-2005, 01:46 PM	#70 (permalink)
FWombat AEM Veteran Join Date: Jul 2001 Location: Tacoma, WA Drives: '94 VR-4 Trader Rating: (14)	Re: Measuring stock exhaust restriction ....and, it looks like these folks sell a dual port actuator upgrade for the Starion/Conquest... http://www.racetep.com/starturbo.html