Garrett T25 Boost Pressures - PeachParts Mercedes-Benz Forum

joaquin suave · #1 03-02-2013, 06:46 PM

I have fit my new hybrid MTDI pump to my OM602 DE2.9LA motor and after getting the advance figured out (PITA), I am now working on the fuel delivery. I've "turned up the screw" and now the motor is slightly "peppier" than when it was electronic (and with the same or slightly higher EGT's)... However, I can't seem to get the boost to go any higher than 9 PSI (.62 bar).

Surely a Garrett 25 turbo should be able to produce quite a bit more boost!

Do you guys have any input?

Silber Adler · #2 03-02-2013, 07:02 PM

I made a manual boost controller and can dial it up above anything practical. You might try blocking off the waste gate port on the intake manifold and then seeing what kind of boost you can get.. Be careful you don't want too much. It would convince you to see if it is the turbo though.

compress ignite · #3 03-02-2013, 09:52 PM

[Nine (9) is maybe the Vacuum Operated Wastegate hanging up/bleeding off your precious Boost.]
Have you "86"ed the crapola on the right side of the engine ? (Yet?)

A La:

http://www.peachparts.com/shopforum/diesel-discussion/212097-wastegate-actuator-swap-om602-962-a.html

joaquin suave · #4 03-03-2013, 01:46 PM

Quote:

I made a manual boost controller and can dial it up above anything practical. You might try blocking off the waste gate port on the intake manifold and then seeing what kind of boost you can get.. Be careful you don't want too much. It would convince you to see if it is the turbo though.

I am told that manual boost controllers don't work on a VE style pumps. Too bad!

Quote:

[Nine (9) is maybe the Vacuum Operated Wastegate hanging up/bleeding off your precious Boost.]
Have you "86"ed the crapola on the right side of the engine ? (Yet?)

The crapola was removed a long long time ago!

After reading your comment about the wastegate bleeding off (it has been disconnected from the system for years), I went as far as cutting up the wastegate accuator making the rod an adjustable "stop" to lock the wastegate closed.

And still no more than 9 lbs... Could the mean that I'm in need of a bigger turbo?

BTW: I'm running 3" exhaust tubing.

compress ignite · #5 03-03-2013, 04:00 PM

"Locking a Wastegate" (Closed) with a "Performance Modified" I.P. WOULD seem
to be a formula for OverBoost disaster.
MAYHAPS, the Garrett Gods are saving your engine from disaster?

If the Turbo is within specs 9 PSI is low.

joaquin suave · #6 03-03-2013, 04:17 PM

Quote:

"Locking a Wastegate" (Closed) with a "Performance Modified" I.P. WOULD seem
to be a formula for OverBoost disaster.

I would agree under normal circumstances. I drive by my pyrometer and boost gauge, so if it became an issue... My right foot would respond accordingly.

I knew this was going to be a challenging project from the get go. However I didn't believe the challenge was could be this... Nonlinear.

Here is the engine bay before the mod's:

And after the mods: