What is the difference between the EGT probe before the turbo and it after the turbo? Is it better to have both or is the one before the turbo good enough?

 

I'm actually beginning to get more curious about this as well. I THOUGHT pre turbo was the way to go, but now I'm getting the impression that after the turbo may be the way to go. Hopefully someone will enlighten us both.

 

It would be nice to see the light it's still pretty dark where I am[sm=insomnia.gif]

 

The elbow on my Jakebrake exhaust brake has a pre-tapped hole for a probe and it is after the Turbo. In my opinion its all relative. Post-Turbo my have lower temps compared to Pre-Turbo but when eithertemps start going up itstill means the same thing.....there could be trouble

Just like the probe for my transmission temp.......It is in the pan which some people same it not very accurate but its all relative. When I see the temp going up then I know there maybe a problem......

 

pre turbo will tell you what the engine valves are seeing, and will also react quicker when you mat the throttle. . .post turbo will tell you what the turbo is doing and how hot it is getting.

generaly the difference between pre and post turbo is the pre turbo mounted probe is 300F hotter.

 

Since it doesnt hurt to have two I have decided to just put it after the turbo, if I do additional mods later that require aegt sensorbefore the turbo I will do it then.

 

all the boxes that have EGT readout's and will defuel if EGT's get to hot can be adjusted for this temp. just remember the 300F rule.

 

I've got one pre and one post. The one before the turbo is an a-pillar gauge. Like was said above that one shows the temp that the valves and turbo are seeing. The one that is after the turbo is for the attitude monitor. It works great to tell you when it is ok to shut off the truck, which is why I have the attitude set to shut off the truck based on EGT's. As far as differences here is what I've seen. When I start the truck and it is idling the two will read about the same since the turbo runs off of heat energy and at idle it isn't doing much. Now when I'm under boost the pre one will read higher, how much higher depends on how much boost. At 10 psi or so it will read about 200 degrees different at 25 psi it is between 250 and 300 different. Now the reason I say it is good for shutdown is because when you get off of the truck the post turbo will read hotter. This is the exhaust pulling heat out of the turbo. If you get off of the interstate or you were working the truck so the exhaust temps were up for a while the pre turbo will drop a lot quicker than the post turbo. As far as the pre turbo one reacting a lot quicker it isn't much of a difference. The post one only lags a little (quarter of a second or so) because when the turbo is spooling it takes a little more heat energy to accelerate the wheels.

 

Thanks guys, that really answers that question. It sounds like two are better than one.

 

That's kinda what I was thinking, however since I'm only interrested in knowing when to turn the truck off I think I'd be best off mounting it after the turbo.

WOW ... I was all set to drill the manifold !! I'm glad this question was asked !!