Why can't I mount my EGT probe...........

[in2b8u]

On the downpipe? If there any reason that this should not be done. I know that a lot of OTR tractors do. Any input would be appreciated. Thanks in advance, db

[layson]

You will have no idea what your temps are pre-turbo or right at the manifold. That is the temp that matters, otherwise you are just guessing.

[texasaggiesrocks]

Your EGT's are roughly 200 degrees less after your turbo but it varies on what your doing. Mounting it on the manifold or the up-pipe before your turbo is what you need to do to get readings that will matter to you.

[jbeasts10]

Mine is mounted in the DP.That is where the bung was welded from the factory.I just keep an eye on it when towing.I try not to get over 950* if I can help it.I figure at most ,it cant be more than 300* difference.Just my opinion.

[fallendown]

The "Banks" egt I had with my six gun on the 7.3 was in the down pipe. When I got a hold of banks they claimed it was calibrated for this position.

[choupique108]

the manifold give you a more accurate reading. When its in the DP is gonna be about 200-300 degrees cooler vs. the manifold.

[superduty4x4]

Temps can be as much as 500° different between the manifold and down pipe... RubberDuck (not sure if he's a member here) did some testing in his OBS while running a gauge in both spots.

[mas360]

If you know the temperature difference between the location of the sensor and the manifold, wouldn't it be a matter of simple math to know what temperature it is at the manifold?
It would be a lot less risky to drill and tap at the down pipe for a DIY person doing it the first time.

[scraph]

The temperate difference between the downpipe and the pre-turbo location are not going to simply be a number that you "know". Not to go too deep into it ... but the temperature difference between the two locations is a dependent on both the differences in pressure and in heat content (enthalpy). Basically, the temperature difference between these locations is going to be a function of how much work the exhaust is doing on the turbine-end of the turbo ... as well as conductive heat losses through the plumbing on the way.

If the purpose of watching EGTs is to protect the turbo... then monitor upstream of the turbo. The amount of uncertainty of the relationship between EGTs upstream and downstream of the turbo is so large that monitoring it downstream would be unnecessarily limiting.

You might just end up ignoring the parameter in the end ... if you decide a "safe" number is 500 degrees difference but the truck isn't fast enough for you or can't tow long enough then you might just decide this week that 400 degrees is probably safe enough ... or 300 ... or you'll just drive it until it performs like you like and set the limit there.

[layson]

Originally Posted by mas360

If you know the temperature difference between the location of the sensor and the manifold, wouldn't it be a matter of simple math to know what temperature it is at the manifold?
It would be a lot less risky to drill and tap at the down pipe for a DIY person doing it the first time.

I think it is pretty much worthless in the down pipe. It is easy to drill the manifold or up-pipes. How do you know the temperature difference between the two locations? Each truck is different. That is something I wouldn't guess on.