Hello guys,

I had a sluggish 300sd for a few weeks. I finally got around to installing a boost gauge, and I had no more than 8 pounds of boost! The ALDA screw was already turned almost all the way CCW when I bought the car so I turned it just a 1/4 turn ccw. I used vice grips to pinch the wastegate actuator line, and the car would build up to and over 11 lbs of boost easily, I was letting off the diesel pedal at 11 psi to prevent any engine damage.

If I want more gains, what are the limiting factors, and what do I have to monitor? My engine is very healthy, almost no blowby hot or cold, valves adjusted, etc. I believe I should add an EGT gauge and monitor the EGT's? Will excessive boost harm the engine? Can I turn up the boost on the stock turbo to, say, 14-15 PSI, and just monitor EGT's, and/or add water/methanol injection? I have tuned lots of gasoline engines, but diesel tuning is new to me! I know all the preignition concerns are mostly eliminated, so I just have to worry about EGT's, correct?

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1984 300sd auto with 246,000 miles