924Board.org

[noisybrother]

Hi all,

Put the car on a dyno today and got some interesting results.

168.3hp
Fuelling @ between 10.5:1 and 11:1 Air:Fuel ratio on boost
9psi boost throughout the range.

Pics of the scanned stats to follow.
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2002 BMW 325ti Sport - Sapphire Black
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Ex Porsches:
1982 931 S2 - Hellblau
1990 944 S2 - Zyclam 'Pearl Effect' Red
1989 944 S2 Cab - Tahoe Blue
1984 944 Lux - Guards Red

[noisybrother]

Stats below:

HP & Torque

HP & Boost

HP & Air/Fuel Ratio

So, question is - how to increase booooooooost!!!! Or why isn't it producing more!!!
_________________
2002 BMW 325ti Sport - Sapphire Black
------------------------------
Ex Porsches:
1982 931 S2 - Hellblau
1990 944 S2 - Zyclam 'Pearl Effect' Red
1989 944 S2 Cab - Tahoe Blue
1984 944 Lux - Guards Red

[morghen]

well you are about 9 HP down..so its not that much i guess...the max boost comes in a bit late..it only comes out of vacum after 2500 RPM...mine already sings at 1900-2000 RPM...but i'll have to get a gauge to be able to tell exactly what and when.

might worth checking for leaks in the intake...maby replace the intake rubber set and checking the turbocharger for wear.

EDIT: also the boost is slightly less than one would expect. as i remember it should be 0.67 BAR ~= 9.7 PSI.
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Supercharger and EFI kits
https://www.the924.com

[noisybrother]

I was thinking it could be a weak wastegate spring or weak/leaky overboost protector...? I've checked for leaks in all the usual places on the inlet tract. The turbo to pressure pipe seal is new though the TB to pressure pipe seal is the old one - I guess I could change this first.
_________________
2002 BMW 325ti Sport - Sapphire Black
------------------------------
Ex Porsches:
1982 931 S2 - Hellblau
1990 944 S2 - Zyclam 'Pearl Effect' Red
1989 944 S2 Cab - Tahoe Blue
1984 944 Lux - Guards Red

[endwrench]

Just wondering, do you know why the HP and torque curves cross at 4300rpm rather than the usual 5250rpm? Maybe the HP has been corrected for drivetrain loss but not the torque?

Todd

Edit: Never mind I see they didn't scale them the same so they would have crossed correctly if they had.
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

[-nick]

Late boost + low boost + VERY rich: all points toward a pressure leak. Did you check the rubber elbow that leads to the pop-off valve on the turbo compressor?

If you can regain the slight bit of boost and get the AFR leaner (it's off-the-chart rich!) then it looks like you'll be hitting right at the factory's 177hp mark.

ps - what is the non-corrected rear wheel HP number?
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[noisybrother]

Non-corrected rear wheel is 139hp - will post the scan later ;o)
_________________
2002 BMW 325ti Sport - Sapphire Black
------------------------------
Ex Porsches:
1982 931 S2 - Hellblau
1990 944 S2 - Zyclam 'Pearl Effect' Red
1989 944 S2 Cab - Tahoe Blue
1984 944 Lux - Guards Red

[924RACR]

I agree, that's quite rich, not helpful, should be a bit leaner (I think you're supposed to shoot for 12's on a turbo car?) and more even...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[noisybrother]

at the wheels graph
_________________
2002 BMW 325ti Sport - Sapphire Black
------------------------------
Ex Porsches:
1982 931 S2 - Hellblau
1990 944 S2 - Zyclam 'Pearl Effect' Red
1989 944 S2 Cab - Tahoe Blue
1984 944 Lux - Guards Red