Hi guys! I read with interest your comments on boost pressure. I drive a 84 300SD though it stays in the garage mostly. Recently I converted a 1960 studebaker 3/4 ton pickup by installing an engine from an 85 300 SD. It performs quite well but would like to find a speedo drive gear that would slow the speedometer down about 5MPH. The trans is from a 300D with a standard cable.
The interest in boost pressure comes from the new turbo recently installed in the pickup. 1.1 bar translates to 15.95 PSI boost. I have connected the ALDA direct to the manifold and eliminated the overide circut. That means I am depending on the waste gate to control the boost. How much greater than 16 is safe. My waste gate is adjustable and I have a 3" straight exhaust. Connecting a boost gage is easy but where would one best connect the EGT gage for the correct reading while doing trial and error with the waste gate. I have alwo removed the EGR.

16psi is already WAY too much. 12psi is all your engine can use, anything more is just heating the intake air.

unless an intercooler is added.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I run or try to shift at 16,but I have been as high as 26 psi with no lack of fuel.only mods were ALDA delete, and strait exhaust

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

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just curious....what was the temp while 26psi?


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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered