blew uppipe, inst. drive pressure gauge

[GeneralTJI]

Ok....

I just recieved my isspro 60psi gauge that I had planned on using for a drive pressure gauge.

Interesting timing... I was driving my truck yesterday and started hearing a faint air sound.. sounded like a boost leak kind of. Noticed lower boost etc.

I have been meaning to pressure check my truck so I built a pressure checker and put it in the system just after my turbo. To my HUGE surprise my system is as tight as a duck's ass.

So I decided to go after my drive pressure gauge which I had planned on installing in the blocker plate I made when I deleted my EGR system.

And bam... there was the issue I was hearing before. I had actually braced my plate onto the head and the brace broke!! It wasn't small either. Of course once it broke, that let the bellows on the egr riser vibrate around and to eventually blow out

Fix: I cut that motherf*cker off and machined a plug and welded it in the riser to eliminate the bellows completely. I also drilled and tapped the plug for my drive pressure gauge. Two birds with one stone. So far so good...

Wasn't fun working in that area though whew, glad thats over with!!!!


Drive pressure gauge results:

Holy crap... I lowered my vane position after seeing the results!!! At high rpm I was seeing nearly 60psi (with only 25psi of boost)

This will be helpful with tuning!

Pic below,

Thanks for reading!

 

[DMAX403]

Sorry for the dumb question, what's drive pressure?

 

[SgtKilroy]

I'll take a stab at it. Please correct me if I'm wrong. Drive pressure refers to the pressure of the exhaust gasses that spin the turbine wheel of the turbo.

 

[duramaxdiesel]

Yup, you want as close to a 1:1 ratio as possible.

Nick

 

[hondarider552]

Yea stock turbos are horrible at DP. I remember mine at peak boost (40psi) was 72psi DP.

 

[02bigstrokin]

i dont think a 60 psi gauge is going to cut it for dp. jmo

 

[GeneralTJI]

I lowered my vane position down some and managed to get peak drive pressure (high rpm 3700+) to stay around 50-55psi. Boost is only 24ish up there (measuring after the IC) in 4th gear. I my truck doesn't shift that high but I run 4th out real high, it doesn't seem to really get out of wack until you exceed 3500rpms. But isn't real great below that either... and I'm not really pouring the fuel too it either being on a stock trans.

At lower boost and rpm there are places where it runs around 1:1.... but once I lay into it thats all over.

To my serious surprise.. still trying to figure this out.... I seemed to have cleaned up some smoke by running lower vane position. I have a couple thought's but I'm not sure whats going on:

1. Moving less air, so the MAF is limiting fueling? (though boost didn't really drop much)

2. Lowering drive pressure and allowing the exhaust side of the system to breathe easier has actually increased flow and is somehow allowing me to make better use of the fuel I have??

Haven't done much logging to try and figure this out yet.

Truck feels strong, even if boost is slightly down, I think it's breathing better and I'm sure it's happier with me! :thumb:

Yea stock turbos are horrible at DP. I remember mine at peak boost (40psi) was 72psi DP

What sort of vane position were you running at that time?