engcogod

I have a question about mounting the pyro post turbo, if you only plan on doing slight modifications i.e. small fuel plate and aftermarket air filter is there going to be a big difference between pre & post turbo. I noticed ISS Pro makes both a pre turbo, and post turbo guage. Just wondering what you guys think?

MnTom

I have been told that preturbo was better for monitering temps. HOWEVER the probe (if it breaks) will damage the turbo. A lot of the class 8 trucks that I drove had the probe mounted postturbo. I guess it is more a matter of choice than anything.
Tom

fboese

You can expect a difference of 200 - 300 degrees at certain times, the higher naturally being pre-turbo. The responsiveness is far better too.

I would never rely on a sensor that is far removed from where I want to measure. Your probe is not going to break.......

I know guys that run three pyrometers on the PSD to really get an idea of what the EGT is on both banks of cylinders as well as the mix of the two closer to the turbine.

Diesel-Dan

Wow! 3 Pyro gauges.....how many trees have they hit! ;D Better get two boost gauges for the hot and cold side to round it off! ;D

Dr. Evil

[quote author=Fredy link=board=16;threadid=22900;start=0#msg214624 date=1069893169]
I would never rely on a sensor that is far removed from where I want to measure. Your probe is not going to break.......
[/quote]

Not exactly true, Ive heard of it happening before. As a matter of fact, the guys at Isspro tell me that it does happen. Although, I have a hard time believing anything would happen if the thermocouple was installed properly. I believe most of the OTR trucks go post turbo, but like you said, they are pretty much guessing at the actual exhaust temperature. Lots of guys go preturbo and have no problems. And hey if it explodes and takes out your turbo, you have a good excuse to get twins or a B1 ;D

engcogod

Thanks for the info, the guage is probably responds a lot faster as well pre-turbo. And pre turbo would let you know exactly whats going on in your engine. One more quick question, is it necessary to mout a tranny temp guage for a automatic if you don't plan on doing tons of towing, but still some performance upgrades. Because I was thinking a pyro, boost and possibly a tranny temp guage.

Desperado_359

I have a pre and post pyro gauge and the 200~300* difference is not true, I have seen as high a difference as 600* and as low as -100* (meaning the pre turbo was 100* less than the post) so I would say go with a pre turbo gauge if you only wan to run one.

Push Rod

Please, only mount the probe pre-turbo. The chances of a probe breaking is infintesimal (in 25 years around diesels, I have yet to see a broken probe). Post-turbo mounts are virtually useless, as you have no real indication what the pre-turbo inlet temperatures are (the differential varies on boost). And the pre-turbo inlet temps are what you are concerned about.

In heavy equipment, you'll often see the probes mounted post-turbo as the boost is predictable. On highway, a heavy truck will be boosting to its max (around 20 PSI) virtually all the time. And at 20 PSI of boost, the differential between pre and post is usually 200F (very rarely more).

Rod