Hello,

on a 1992 300D 2.5T - I am achieving the following max boost readings under load using a quality shop gauge - I believe that these values may be low but I am not sure.

@< 2000 RPM = 2 PSI
@ 2000 Rpm = 7 PSI
@ 2500 Rpm = 12 PSI
@ 3100 Rpm = 14 PSI

I am using the modded wastegate setup such that it is mechanicaly controlled via pressure right off the intake manifold.

Thank you

I think the 14 psi is high. I remember reading something about .8 atmospheres is maximum boost. Someone more knowledgeable than I will come along and help.

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

http://www.fuelly.com/sig-us/40601.png

Hello,
Congrats on your modification.
With the Pressure Activated wastegate setup we do not have Overload protection.
Typically you don't want to go above .85 Bar (12.3 PSI) at 4000 RPM 3rd gear. (Job 09-5911.pdf) Try this: http://www.google.com/search?q=09-5911.pdf (Go to page 4 Section B Engines without engine overload protection)

The actual Specification is (.75-.85 Bar approx 10-12 PSI) (14PSI = .95 Bar) @ 4000 RPM full load in drive position "3".

1 Bar = 14.5038 PSI

Your a little HIGH. But overall OK. Your turbo appears to be putting out more then enough. Vice being on the low side. Which could indicate more problems.

What are you maxing out at (PEAK). You may be slightly raising the EGT (Exhaust Gas Temps) with the higher boost. I personally wouldn't worry about it. You're not that far out of specifications. You could adjust the rod lenght (I believe shorten to decrease PSI, but your in the ball park)
Your might want to review the original thread (Wastegate actuator swap for OM602.962?) Page 11 answers your specific question.

How's the car running? Are you having any issues?

I would leave it alone and enjoy the ride.

Bob

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92 300D 2.5L OM602 OBK #59

I have a 92 300D 2.5 with the pressure wastegate conversion. Awesome conversion and should be done on every 300D 2.5 imo!

Your pressures seem just slightly high. The Mercedes spec is 12 psi max. I get about 2 psi less across the same rpm's you listed. The turbo is all-in by about 2500 rpm anyway, so 14 psi should be about your max even at higher rpm. 14 vs 12 shouldn't cause any harm. I have heard of pressures as high as 20 without damage, but don't want to say for sure 20 is ok. But I would think that 14 is probably ok. Enjoy that 300D 2.5, one of the best cars ever made by MB!

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1972 280SE 4.5
1984 300SD, 250K
1991 300SE, 89K
1992 300D (330K miles when KIA'd by mother-in-law 8/10/09 - still sitting in my barn)
1994 E320, 109K
1995 E420, 60K
Proud Member of the Mercedes Benz Club of America - Idaho Chapter

IIRC the 14psi is under the wastegate limit on the OM603.

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Gone to the dark side

- Jeff