Post and pre turbo temp

[ESchick]

I'm a new diesel and turbo charged engine owner. I was trying to figure out which would be better to use to cool down the turbo, 1) a turbo timer, device which allows truck to idle either for a predetermined time, or 2) a gauge that indicates the turbos temp so I know when it is safe to shut off the engine. I thought that I had it all figured out deciding on the gauge instead of guessing as to how long is long enough. Well this brings me to my question (about time huh).



Last night while reading other posts addressing the turbo cooling issue, several posts spoke of a pre turbo temp and a post turbo temp. Risking sounding like a complete idiot, I have to ask the question. What is the differance, do I need two separate gauges, and if I installed a Isspro monitor would it monitor both of these readings.



I appreciate any insight and help, thanks.



Erik

 

[rbattelle]

My opinion...

Pre-turbo temperature is what many call "true EGT". It reads the temperature somewhere in the exhaust manifold, before the flow enters the turbo. Post-turbo measures temperaturem after the exhaust leaves the turbine, and the thermocouple is usually mounted in the exhaust elbow.



Purists will tell you that pre-turbo is the only way to go. Personally, I think it all depends on your driving style. If you find yourself driving in hot weather at maximum (or greater than maximum) towing capacity, then pre-turbo would probably be the better choice. The risk lies in the fact that you must drill the exhaust manifold.



If all you want is to monitor your turbo temp for cooldown, then post-turbo is good. In fact, ISSPRO's temp monitor is designed to work with post-turbo EGT.



Remember that pre-and-post are related, and knowing either one will speak volumes about the internal condition of the engine,

 

[Car_nut57]

Originally posted by ESchick

I'm a new diesel and turbo charged engine owner. I was trying to figure out which would be better to use to cool down the turbo, 1) a turbo timer, device which allows truck to idle either for a predetermined time, or 2) a gauge that indicates the turbos temp so I know when it is safe to shut off the engine. I thought that I had it all figured out deciding on the gauge instead of guessing as to how long is long enough. Well this brings me to my question (about time huh).



Last night while reading other posts addressing the turbo cooling issue, several posts spoke of a pre turbo temp and a post turbo temp. Risking sounding like a complete idiot, I have to ask the question. What is the differance, do I need two separate gauges, and if I installed a Isspro monitor would it monitor both of these readings.



I appreciate any insight and help, thanks.



Erik

If you are only going to get one item, get the gauge so you can watch for high EGTs as well as cool down temps. We recommend a pre-turbo installation of the thermocouple for EGT reading, however for cool down the pre and post turbo temps will be very nearly the same. You do not need seperate gauges, just one pre-turbo gauge will work fine.

 

[Steve M]

I'm in my 4th Dodge Cummins. All have been post turbo in the elbow. I don't need to know the temperature of the exhaust coming out of the head for shutdown. I need to know the temperature of the exhaust coming out of the turbo. Turbos retain alot of heat even after the motor quits blowing hot exhaust through them. Having a probe pre-turbo for shutdowns is kinda like monitoring the tip of a torch to determine when it's safe to pick up the chunk of iron you just got done welding on.

If you're going to turn up the fuel, then a pre turbo probe will be helpful in monitoring the temperature of your melting pistons.

 

[Ladders]

Or, if you can afford 2 probes and can do the wiring, use 1 gage and 2 probes. Then you have the best of both worlds. I use the post for most of my driving for the cool down but when hauling I use the pre for the "melt" point. Then when I arrive I can still monitor the post for shutdown. If you can REALLY afford it, get the gage for the pre and then use the auto-shutdown with the after probe. Its amazing how long it takes the post temp to get below 400* when your running hard with the ac on and using an e-brake. The turbo is a big mass and retains the heat for a while. My gages are wired hot all the time and I can shutdown at 350* and come back in a few minutes and see 400* agn, due to no air flow thru the turbo (residual heat).



SOTSU!!

\\BF//