EGT probe location (???)

87 HJ60 · 06-16-09, 03:17 PM

I'm going to install my pyro in my HJ60 this weekend. I have a question about where the probe for the EGT gauge should be located.
I heard that I should install it directly on the exhaust manifold by drilling and tapping a hole.
I also heard that it should be located just after the turbo and on the exhaust downpipe but somewhat close to the turbo.
Any thoughts ??

Gold Boy · 06-16-09, 03:25 PM

Quote:

Originally Posted by 87 HJ60

I also heard that it should be located just after the turbo and on the exhaust downpipe but somewhat close to the turbo.

works good for me, that's where mine is located [13bt].

bvissers · 06-16-09, 04:00 PM

I had a dual Pyro on my 60, so I had both, in the manifold and in the down pipe 6" below the turbo, there was a good temp difference between the two as well as some what of a lag in the reading of the post turbo probe. That being the case, if I only had the one I would most definetely go for the manifold probe. After all its the exaust temp leaving the head and entering the turbo you are concerned about, If the turbo acts as a heat sink and cools the exaust some, that is of little consern.

amaurer · 06-16-09, 05:14 PM

Go pre-turbo. If you go post turbo you'll be using those numbers to try and guess what the pre-turbo numbers are, so why not just measure what you really want to know.

valdezhilander · 06-16-09, 08:26 PM

You need to keep in mind that the numbers are relative, your looking for major increases in temp, you will not be counting each degree. I have said it before and I will say it again, ever major truck engine manufacturer puts the EGT probe post turbo, not in the manifold.

amaurer · 06-16-09, 08:32 PM

Quote:

Originally Posted by valdezhilander

You need to keep in mind that the numbers are relative, your looking for major increases in temp, you will not be counting each degree. I have said it before and I will say it again, ever major truck engine manufacturer puts the EGT probe post turbo, not in the manifold.

... because the manufacturer has fully tested the engine in the engineering stages WITH a pre-turbo probe and knows how to correlate pre and post turbo readings.

On these old engines, where everyone's combo of mods, engine age, turbo type, etc, are unique, we have no such data.

Put it in front of the turbo.

valdezhilander · 06-16-09, 08:59 PM

What do you base that on? There are plenty of folks on this site that have the probe after the turbo and I am not aware of there being a trend for burn downs? I base what I say off of my personal experience as a diesel mechanic, and I tend to trust the people that design engines that put down 600+ hp and charge upwards of $40,000 for an engine. Here is one more reason, your cast iron mainfold was designed to have certain holes in certain places and expand a certain way, when you start drilling holes in any cast material in a spot not intended to have a hole you weaking that casting and creat a perfect spot for a crack to start. Here's my final comment, you can put that probe where ever you want, but I am going go with where the engineers that actually know what their talking about put it.

There it is...

Diesel42 · 06-16-09, 09:59 PM

If your using a 13bt exhaust manifold, theres a factory threaded hole just underneath the turbo adapter. You can drill this out and retap with a 1/4"NPT which fits most any EGT probe. I agree with Armuer on the pre-turbo. Why not get the quickest most accurate readings possible. This location is pe turbo as it just enters the turbo. Simple install. Good luck.

Diesel42 · 06-16-09, 10:05 PM

Sorry, misspelled Amaurer and i meant 1/8"NPT for the probe. Been a long day machining in the shop.

Garry · 06-16-09, 10:26 PM

Definately pre-turbo

onefsatchevy · 06-16-09, 10:30 PM

Mine is in the top of the manifold, been there for a few years in a hole I drilled, no problems, no leaks or cracks, this is after a fair bit of searching on this site, and the recommendations of the pyro manufacturer I bought. However valdezhilander makes some good points, thus neither is wrong, just make sure you specify where it is when asking questions about heat, and if your readings are good.

sandcruiser · 06-17-09, 07:06 AM

I installed mine pre-turbo (hd-t) by drilling/tapping the manifold.
if I were to do it again, I would probably do it the same way.

Post-turbo will not be as accurate, but if the install is easier/safer/faster/cheaper then I would consider that route. Unless you are planning to aggressively tune the motor/fuel delivery/boost, the exact reading of the pyro is not going to make a big difference to you.

Tapage · 06-17-09, 05:29 PM

another vote for pre turbo .. ( in both of my Cruisers )

rick_d · 06-17-09, 05:40 PM

as sandcruiser said, unless you are going for performance and believe it is critical to know if you are 1201 F pre turbo either position (pre, or post) does not matter. You should use the EGT as a general guide for operation of the engine and limit stress during the high end and allow sufficient cool down when shutting the engine down.

I see more issues with pre turbo vs a post install as far as failure of the probe and destruction of the $$$ turbo. Do put it close the the hot side outlet to get a solid reading.

I'm post, and avoid sustained 1000F operations (I've touched 1000, but less than 10 seconds) try to keep around 900F or less) and cool down I wait until 400 normally to shut the engine down.

The first 100K before I got the engine the owner never once used an EGT...I want to get another 200K without thinking...

Tapage · 06-18-09, 09:35 AM

funny and maybe a little paranoic .. but I never shutoff my engine before 350°F ( now running a turbo timer ) and I'm pre turbo ..

finderscuba · 06-18-09, 11:06 AM

Quote:

Originally Posted by Tapage

funny and maybe a little paranoic .. but I never shutoff my engine before 350°F ( now running a turbo timer ) and I'm pre turbo ..

My 1HD-T is always below 350 when idling. It rises with acceleration, and will sustain a higher reading while cruising, but it falls below 350 almost as soon as I stop. According to this, I don't even need my turbo timer. But I idle for at least one minute before every shutdown.

amaurer · 06-18-09, 11:20 AM

Quote:

Originally Posted by finderscuba

My 1HD-T is always below 350 when idling. It rises with acceleration, and will sustain a higher reading while cruising, but it falls below 350 almost as soon as I stop. According to this, I don't even need my turbo timer. But I idle for at least one minute before every shutdown.

After a long highway run I find that my 3B will soak up enough heat that idle will be over 350. It only takes a minute or so to bring it down below 350 though.

Given enough time, it'll idle just above 200.

Tapage · 06-18-09, 11:51 AM

Quote:

Originally Posted by finderscuba

My 1HD-T is always below 350 when idling. It rises with acceleration, and will sustain a higher reading while cruising, but it falls below 350 almost as soon as I stop. According to this, I don't even need my turbo timer. But I idle for at least one minute before every shutdown.

well if I drive gentle mine cools faster .. but if I'm with the AC and usually driving around the City at MD haven't lime to let it idlle ..

it's a matter of weather and outside temp ..

sandcruiser · 06-18-09, 01:09 PM

interesting notes about EGTs. Mine us usually at around 400 when I get home, and takes over a minute to get down near 350. I wonder if I should back the fuel off a little?

More importantly, I suspect my injectors aren't very clean/well tuned.

Tapage · 06-18-09, 02:29 PM

Quote:

Originally Posted by sandcruiser

interesting notes about EGTs. Mine us usually at around 400 when I get home, and takes over a minute to get down near 350. I wonder if I should back the fuel off a little?

More importantly, I suspect my injectors aren't very clean/well tuned.

mine cools much more easy and fast now with the manual tranny (without the auto tranny job on the rad )