In the middle of fueling and boosting an OM617A - a couple final questions - PeachParts Mercedes-Benz Forum

EndlessEarth · #1 02-01-2006, 01:36 PM

Hi. I am in the middle of boosting and fueling my OM617A motor. It is currently in a Unimog 404.

Baseline for the truck is 10 psi boost at 4k rpm. 10psi is also the peak boost. I live at sea level in NH.

I have read pretty much every available document and thread I could find on two forums to get this far. But I still have a couple q's if you all do not mind.

I have already adjusted the wastegate tension screw on the Garrett 9 turns. I have opened the cap on the ALDA, but I have seen conflicting information on which way to turn the screw and how far. My thought is that 1/4 turn counter-clockwise is correct. Please verify or refute.

Lastly, exactly what screw in the injection punp should be turned and how far. I have seen articles on improving the OM617A that only mention adjusting the wastegate tensioner and the ALDA. Is the injection pump change critical? If I adjust the injection pump do I need to correspondingly increase the wastegate tension beyond the nine turns?

My goal is 14psi of boost.

Thanks in advance.

#2 02-01-2006, 02:46 PM

Quote:

Originally Posted by EndlessEarth

I have already adjusted the wastegate tension screw on the Garrett 9 turns.

You need two wrenches, one to hold the valve and one to turn the diaphram. In those nine turns you have not adjusted anything, you have just been spinning it around.

EndlessEarth · #3 02-01-2006, 05:34 PM

Quote:

Originally Posted by ForcedInduction

You need two wrenches, one to hold the valve and one to turn the diaphram. In those nine turns you have not adjusted anything, you have just been spinning it around.

Yes. Thanks.

#4 02-01-2006, 10:33 PM

Quote:

Originally Posted by EndlessEarth

I have opened the cap on the ALDA, but I have seen conflicting information on which way to turn the screw and how far. My thought is that 1/4 turn counter-clockwise is correct. Please verify or refute.

CCW is correct but 1/4 turn might not be enough. I have mine maxed out and it's still not enough. Keep adjusting it until you start to get black smoke out the exaust during takeoff.

vwbuge · #5 02-02-2006, 12:28 AM

I assume you have a boost gauge installed?

You may want to buy a boost controller instead of fooling with the wastegate.

veg_burner · #6 02-02-2006, 12:45 AM

can you say more about a boost controller and how it would bypass or modify the wastegeat, and where one can find such a thing...?
thanks!

babyjames · #7 02-02-2006, 01:04 AM

Talk to Brandon about the IP adjustments. He made a spanner that he loans free of charge. I think there is a pretty good tutorial he has written as well. Might try a search for "full load stop"? Is that right?

On a unimog - something that works real hard, but doesn't go all that fast - wouldn't EGT's be even more critical? At 95 on the freeway, you'd get a ton of air passing through the radiator/engine bay to HELP keep things from melting. At 0 mph trying to yank a stump, there'd be little or no air movement? Make any sense?

Planning on intercooling as well?

Jay.

1983/300CD · #8 02-02-2006, 04:22 PM

Quote:

Originally Posted by veg_burner

can you say more about a boost controller and how it would bypass or modify the wastegate...?

From what I recall, I believe that the boost controller cuts into the line that runs between the compressor and the wastegate actuator.

First you need to understand how the turbo and actuator/wastegate all works...
The exhaust gasses press on the turbine side, spinning the compressor side. When the pressure on the intake/compressor side becomes too great (sensed by the actuator through the rubber tube from the compressor), the actuator flips the wastegate to allow exhaust gasses to bypass the exhaust side turbine, slowing spin of the compressor wheel, lowering pressure to the intake. Simple?

The boost controller is between the compressor and the wastegate actuator. This allows you to determine how much pressure you want the actuator to "feel". For example, if you have the boost controller set to 15psi, the actuator will not get any pressure until 15 psi is reached. It's basically a wastegate actuator actuator that you can adjust from inside the car.

#9 02-02-2006, 04:35 PM

Quote:

Originally Posted by ForcedInduction

CCW is correct but 1/4 turn might not be enough. I have mine maxed out and it's still not enough. Keep adjusting it until you start to get black smoke out the exaust during takeoff.

Well, I found that 1/4 turn at a time was reasonable. When the smoke and mileage becomes unacceptable, back off 1/4 turn and see how you like it. I've tweaked mine back and forth a few times to get good power without excessive smoke.