apache

I finally got some guages for the 95(all stock,180 pump) and Im seeing 24 PSI boost if I wind it up to 2400 RPM. Is this typical? I did disable the waste gate a few days ago. when does the gate typically open and why even have it if max 24psi or so is OK.

farmer dave

I am not sure about the older 12v, but I am getting 24+ PSI at times. My brother is also getting around 25PSI with his 12v, so I would say you are OK. As for the waste gate, I think that they are supposed to open around 22 PSI, but not for sure.

88bird

boost is increased also my excessive (i mean more than stock) fueling..... i have a custom ground plate..... similar to a 6.... working on a 100.... with a semidisabled wastegate in my 96 i see 42psi at times but normally it's around 25-30ish under "almost normal driving conditions"...... i say you'll be safe at 24 ish..... but the more fuel u add in the future will really spool that turbo up.....

infidel

Stock boost with wastegate connected is 15-18 psi.
If you want more than 24 psi you have to add more fuel.

apache

I think I asked before but I dont recall?? Why then have a wastegate if the ungated 24 or so is ok and gonna give you lower EGT`s than 15-18? I really dont notice a huge diff between the 93 and my 95 as far as lag goes. wasent this the idea to have a smaller turbo giving quick spool up? Also I was under the impression that full boost would be reached by 2k or so if it was nailed. It would seem on a stock truck with it floored pulling a grade at 2k rpm and climbing it would be full tilt. when I hit 2500 rpm it was still climbing but I let off at 2500 rpm and 24 psi. Dunno?? just thinkin again. It always gets me in trouble.

RCW

You are sort of on the right track with your thoughts about fueling and the turbo. The 94 was notorious for a leaking overflow valve. The OEM valve was a one piece unit that never worked that well new, and would allow low enough injection pump head pressure to cost some power. If you have the one piece, replace it with the newer style 2 piece unit and you will find 50 horses right away.

The other common issue with all the P pumped Cummins was to low of a torque value on the timing nut on the injection pump. That allows them to back down to somewhere around 9 degrees, and then it will perform like a stock first gen truck.

Back to your waste gate question. The waste gate protects the turbo from exceeding 25 psi in most cases. When Cummins was developing this engine they went for durability, and expected to see a minimum of 250,000 miles of trouble free operation. What they got is a million mile engine, and a huge amount of room for the owner to boost power and timing, and still have an engine that will run 400,000 miles. You can run without a wastegate, but unless you do something to increase the rate of fueling it will be real tough to get above the 24 psi you see today.

Make sure you have a good two piece overflow valve, good fuel hoses, the tank pick-up hose in good shape, then move your fuel plate forward 60 thousands, move your timing up to at least 15.5 degrees, plug your wastegate, and nail it. You will have a rig that tromps any stock first gen truck by a very wide margin. Just make sure you have a pyrometer installed before you do the timing and fuel plate move, you do not want to exceed 1250 degrees F for very long without some oiling modifications to protect the pistons.

johnsjas

I was getting out 40 psi with my stock turbo. It did not last long though. Swithed to a superb and went up to 55 psi of boost and a lot more cfm

apache

My pyro should be here today, hopefully get installed by the weekend, but my work schedule been screwed up so who knows. Im real curious to see what I get. my injector/miss problem is back with a vengance as of yesterday. Last time I added stanadyne it ran great,shoulda left well enough alone cause now its running like poooooooooooooooooooooooooo. I replaced the OF valve months ago with one from Marty T. didnt really see any diff to speak of, the original was still in there it looked like. oh well??

2k1yzfr1

I was seeing 40psi when I had the 10 plate in for almost a year. Now that I took it out I am seeing right around 30 with the stock plate(not full forward).
So I would say you are safe at 24.