Boost pressures for 1995 C8.3 Cummin Turbo diesel

[Rettaray]

Hi all, just returned to tampa from western US trip of 6 mos. Turbo seems to be intermitant. Engine lags on up grades on interstate. Once every couple of days in 5th gear it felt like someone hit the NITRO button and I could actually gain speed on the up grades instead on dropping off to 45 mph from a speed of 65mph and I could actually gain speed to 80 mph. Turbo was found to frozen up in Jan 2010. Had complete rebuild done at that time and left on trip shortly thereafter. Nothing but sluggish since then. Unit had no Boost Gauge. Added an gauge this week and I'm getting 10 psi full pedal down with a rise to 14 psi and shift change and this is duplicated in each gear. This is without feeling the NITRO effect. It's in the sluggish state I get these reading. My Question-- What should normal boost pressures be on a 1995 GS TourMaster C8.3 300 hp be. I've got a mechanic working on it but $2000. repair bills seem to produce little in the way of results. I need to be educated to deal with him and get this coach running. Thanks for all the help I can get!

[RayChez1]

I don't have a Cummins engine, but I have being asking around about what pressure a Cummins engine like yours should have and what I have found out is that the turbo charge pressure when boosting up should be around 26 psi for that size of a turbo charger.

[Rettaray]

Thanks for the reply RayChez,
We remove the vacuum line before the turbo and pluged it up to see what the max boost would be. It is still 10psi full pedal down building to 13psi at the shift. Checked the wastegate and it appears to work freely with no sticking noticeable. Mechanic tell me when they rebuild the Holset turbo they might have used smaller fans, thereby causing less boost. I guess that sound reasonable to me, I know zip zero about turbo. They don't appear to be too complicated though.

[charlied]

I realize this is a dead thread but I found it looking for gulfstream turbo boost on google.

My son owns a 93 DP Gulfstream and I found his problem with power was directly related to the air inlet on the side of the RV rear right that was under sized to allow full boost from the turbo. The tip-off was a red air filter minder indicating a clogged filter, the filter was new. Off the air filter canister the air inlet tube went to a inlet grill on the side of the RV, the opening where the 5" flex tube connects to the grill necks down and makes a turn. In that area there is a restriction that causes the filter to be in a vacuum when the turbo goes to boost. If the turbo inlet can't get full flow, it can't generate the designed boost. This appeared to be a factory installed grill on the side of the RV. Remove the top of air canister and see if it affects the power. The filter is still filtering the air but the inlet grill restriction is eliminated.