Pyro readings before and after turbo

[paccool]

OK guys, I have always wondered about what people have said about the difference in the readings before and after the turbo. I had to se for myself. Was hard to believe that the readings could be that different in a span of about 8". I know about expanding gasses and all that but seemed hard to accept that kingd of difference. I originally had a direct reading (thermocouple)US Gear pyro located after the turbo and just last week installed a new ISSPRO electronic pyro in the ATS manifold (in front of the turbo) I put on last year. I went on a trip to Washington last Friday and returned Monday. Pulled a 5500 pound load up, came back with an empty trailer at 2250 pounds. Took a series of reading both directions and only took "stable state" readings. some were pulling a grade and some were on flat ground. Found some scary things and thought I'd pass them along.



The direct reading pyro is very slow to respond when compared to the new ISSPRO pyro. I could put the new pyro into the red and then cool back down before the old pyro hardly moved.



Also took readings with the transmission in OD going up a hill. Got the pre turbo temp up to 1200 degrees then shifted out of OD to get the RPM's up a little. Saw an immediate 150 degree drop in the EGT. This alone is a good reason to shift out of OD when towing up a hill!



Here are the readings I took pre and post turbo-at idle the readings were basically the same as the turbo wasn't working at all.



PRE POST TURBO

600 400

700 500

750 550

800 580

875 620

900 640

1000 700

1100 750

1150 800



As you can see, there is a 350 degree difference at the upper end of the scale. I took more readings but they were the same as these above. Based on this, I would try to keep the post readings at 900 or less if that was the only reading I had. I used to push it to 950 and a little higher when towing which put me up at 1300 degrees. Sure glad I put the new unit on as it is a much more realistic reading!

 

[BushWakr - RIP]

Ahhhh crap... Stan I wish I'd known you were going to do this..... I would have made your life a bit more difficult... . it would be very interesting to know the boost levels at those temps... . even every second or third pyro reading..... just to see how the 10*F per pound of boost related to real readings on the road... .



Ok, get back out on the road and git too it...



nice job Stan. .



pb... .

 

[paccool]

I still have the old one hooked up! I'll have to wait till I get the head situation taken care of first. One thing thet crossed my mind was if I go to a stage two head, will the increased airflow drop the difference closer? I'm guessing it will. What do you think Pastor?



Stan

 

[swankmetal]

stan, what's the difference between a direct reading and an electronic one? i've got an autometer w/ thermocouple. is that a direct reading one? it seems to move pretty quick?? thanks



dave

 

[JLEONARD]

Stan, That is good info and very timely for me as I just installed a post turbo pyro in my boat Cummins.

As a max at WOT I am seeing 900 F and was told by marine experts that is the absolute max I should ever see in this application... if I want any longevity that is.

I was also told that in an attempt to lower EGT the first step would be to clean out the aftercooler (I have the antifreeze type) so I will be doing that soon and let you guys know if it helps.

The marine guys use a mixture of Joy and water and spray it into the turbo intake while under a good load... followed by a "rinse" of plain water. That is supposed to remove the oily residue from the aftercooler innards and let it work more efficiently again.

Jay

 

[paccool]

Dave, the one I have has the thermocouple that hooks up directly to the back of the gauge with the two leads. I thought mine reacted pretty quick until I got the new one.



Stan

 

[TKingsbury]

I am kind of interested how a different exhaust housing would read. I still have the 21. 5 on my truck, so I wonder if the difference is smaller with a free (er) flowing exhaust housing. I started tinkering with my pump finally. While I think having it a little more snappy might be good, I think I'm gonna stick it out with my giant housing for a while.

Travis. .

 

[swankmetal]

do you think the response time has to do more with the pre vs. post placing than the type of pyro? just wondering because now you've got me worried. thanks



dave

 

[KLockliear]

Change turbine housings and watch the numbers change again. Smaller housing = more restriction, bigger difference.

 

[paccool]

Keith,



Thats what I'm thinking. I suspect there are a lot of items that can affect the EGT such as exhaust size, housing size, etc. I think there is a stage 2 PDR head in my near future so it will be interesting to see what the differences are with that.



stan