Engine/Transmission (1998.5 - 2002) Turbo drive pressure....

[Steve Campbell]

I was playing around yesterday afternoon. I was installing a SPA Pyro/Fuel Pres gauge. I drilled and taped the exh. manifold. I then started thinking about just checking drive pressure first and then do the thermocouple install. The ole noggin kicked in and I used a close nipple and a 1/4" tee to elevate the Pyro threaded attachment. I then took a 2' section of brake line, made a couple of fancy bends to clear the valve cover and connected it, via. some aeroquip hose, to an old pressure guage I had laying around. Placed the gauge/hose under a wiper and added some duct tape.



Now for the test drive. Up to 10 lbs of boost, there seems to be a one-to-one relationship in boost to drive pressure. By the time I hit 20 lbs of boost the drive pressure was at 30psi. At 30 psi boost the drive pressure was 45lbs. I also kicked the US Gear exhaust brake on at 2500 RPM and the "back pressure" was 55lbs.



This was without a trailer, just going down the highway at an "excessive speed for the conditions. "



Food for thought!!!

 

[Diesel Freak]

sounds good! Don't you wish you could drop drive pressure to about 25-30 PSI at 30 PSI of boost?

 

[Steve Campbell]

Yes I do...

... so how does one go about doing that without giving up "too much" in responsiveness?



Is there any correlation between the percentage increase in exh. housing size and decrease in drive pressure? Like a 50% larger exh housing (16cm) would give you a 1/3 decrease in drive pressure at the cost of some total boost and responsiveness.

 

[Diesel Freak]

Re: Yes I do...

... so how does one go about doing that without giving up "too much" in responsiveness?



A PDR HX40 can help.



Is there any correlation between the percentage increase in exh. housing size and decrease in drive pressure? Like a 50% larger exh housing (16cm) would give you a 1/3 decrease in drive pressure at the cost of some total boost and responsiveness.



no clue on that one