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

[Snake]

Originally Posted by 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.

Great information, and very well said. Thank you for posting this.

--Snake

[coaltrain444]

but you also risk it breaking off in the manifold and running through.... my .02

[Southpaw]

EGT's aren't cooled by the turbo at the same rate all the time. It is going to be different @ different speeds and boost psi's. There is a reason all you hear is words like 'roughly', 'between 200-300', and 'up to 500°'......because noone knows. Like Layson said, it is all guesswork, there is no magic formula. It's not worth the risk, Tapping the manifold is easy, and I have always heard people say you can grenade your turbo with the pyro if it breaks, but i've never heard of it actually happening. There are thousands of people with pre-turbo pyros. It's not a big deal.

Also, for the record, I don't have an EGT gauge to save my turbo. I have an EGT gauge to save my motor by making sure I'm not heat-soaking my pistons. I want the most accurate reading, and I want is as close as possible to what I want monitered.

[wriott]

Originally Posted by coaltrain444

but you also risk it breaking off in the manifold and running through.... my .02

only if you are a moron... how would you drill thru it??? you would drill thru one side hit a big void... cant miss the giant void before you hit the other side...

what would break off in the manifold... as long as you are smart about drilling it and tapping it nothing will break...

[elibenson]

Originally Posted by Southpaw

Also, for the record, I don't have an EGT gauge to save my turbo. I have an EGT gauge to save my motor by making sure I'm not heat-soaking my pistons. I want the most accurate reading, and I want is as close as possible to what I want monitered.

^^^ What he said. A turbo will set you back $1000 give or take. Not a big deal compared to a new engine ($15,000 for me). The whole point of this exercise is to not burn your pistons and valves, etc.

[strokin_early_99]

Originally Posted by 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.

Very well said.

[strokin_early_99]

I used 300* as my variable and I melted down a turbo before I moved my probe. I ran both locations for a while to compare temps. I found as little as 100* all the way up to 600* while in the mountains pulling a load.




You too can have one of these should you run your EGT probe in the down pipe and trust a fixed variable. Or you can have even worse, melted piston(s).

[mas360]

A stock PSD does not have the EGT gauge, how does a driver avoid this situation when towing heavy load in mountain terrain? Keeping rpm below 2000 ??

[scraph]

More or less ... a stock Powerstroke is derated from the factory enough that it simply won't produce enough power to melt the motor. Of course, I can't promise no damage if you overload the truck and keep your foot into the floor as the terrain slows you to a stop... but "before the days of tuning" (as if there was such a time) doing that to a vehicle wasn't a good idea. I guess a decent rule of thumb is ... if you can't maintain _any_ speed then you probably shouldn't try.

[99250on14inches]

so here's a dumb? if you have the extra money and REALLY want it there, why couldn't you get a 4 guage pod and and 2 pyrometers and mount one in the manifold and one in the downpipe?.....possible or no?

Chad