thrashingcows

I bought a Isspro EGT kit from a local Diesel shop, I originally ordered a pre-turbo kit and never even looked at mine until I went to install it last week. Turned out I got a post turbo kit. I went back and asked for the pre-turbo kit, and was informed that they did not carry one and that I should just use the kit I have.

Now my concern is this, what size should the hole be that you tap into the manifold? If I remember from the "sticky" it was a 1/8 NPT hole? Now since this is a post turbo kit it came with the exhaust bung, and then an adapter to go from the bung to the probe. Now the bung thread is 1/2" , so the adapter is would need a 1/2" hole in the manifold.

Now I'm concerned that the size of the hole will be too big and could compromise my manifold. If this is the case I will return it and order a proper pre-turbo kit. Also how long should the probe extend down into the manifold, mine is approx 1" past the bottom of the adapter threads.

Thoughts?

jimbo486

i'm kinda confused... are you going to use the post-turbo kit or are you going to get a pre-turbo kit somewhere? the bungs that come with post-turbo kits are usually the type that need to be welded to the downpipe.

if you get a pre-turbo kit that requires an 1/8" NPT, you'll need 11/32" hole for 1/8"-27 tap.

ttcfan4476

1/8 pipe thread to 1/4 compression fitting is what my probe takes

JustRamIt91

Yeah i've seen 1/2", 3/8 and 5/15" thermocouple kits. I have seen people use the 1/2" style before and i was considering to do that to mine since my 3/8" seems to be coming loose and has stopped working.

I would have told the guy where he can stick his post-turbo kit, considering u ORDERED this under the assumption "i was getting what i paid for"(not what you had in stock) and since they don't carry one there, isn't that y u had to order one to begin with? Basically i'd say This it isn't what i wanted, and i don't know what kind of operation you run here but i want what i paid for!
Anything along those lines when spoken firmly seems to do wonders when dealing with swindlers.

KD93

x2. This from the Isspro online catalogue...
2 1/16” Pyrometers
Use type K thermocouple.
R607T 0-1500° None 250° black pre-turbo color code dial R607VW 0-1500° None 250° black post-turbo color code dial
I'm all about shopping local and keeping it in the community, but there's no reason to be loyal when you're not getting good service OR what you paid for. And from what I recall, the thermocouple should only be flush with, or maybe an 1/8" into the gas stream, not an inch down. Not 100% on that though, as I still haven't got a pyro .

JustRamIt91

Yeah mine doesn't work right... i think i burnt it up...

thrashingcows

I have got good service from them before, so that's not in question. When I ordered it I just assumed I was getting the pre-turbo kit I ordered. Then when I brought it back i was told they only carry the one kit, post-turbo. It would have been nice to have been informed before I dropped a couple hundred on the wrong kit, but I can always return it.

Thank's for the thought about it possibly burning up the probe if too far down in the exhaust stream. Hope someone will chime in with how far down their pre-turbo probe extends into the manifold.

Bencie

This may seem like a dumb question to some of you but why do y'all prefer pre turbo to post turbo probes? I understand there is a drop in temp post turbo but it shouldn't be more than 100* or so right?

jimbo486

actually, it's anywhere from a 250-300* difference from pre- to post-turbo. seeing 1200 pre-turbo on the gauge would basically be a warning to you that things are starting to get pretty warm. seeing 900 post-turbo on the gauge and forgetting about the difference for a split second could make you think just the opposite. nothing wrong with running it post-turbo though but you have to ALWAYS remember those are post-turbo temps.

CaptainChrysler

I would measure the diameter of the thermocouple and get a matching compression adapter for it. My experience has been with Autometer, and they use a 3/16" probe. I always try to install it so that the tip is in the center of the port(top to bottom and side to side). I have seen several install how-to's that say to install it that way.

Bencie

Thanks Jimbo, I got one for a Mack which is post turbo as all big trucks are, and there's a decal right on the glass of the gauge that says 1150* max. makes it easy not to forget I guess, don't know if there's any known probe failures as to where pieces took out a turbo or not but being post I won't have to worry about it. Thanks.

jimbo486

for the longest time (before i even had my truck) i was always against putting the probe pre-turbo for fear of it breaking after prolonged exposure to heat and getting sent through the turbo. also the potential for it to throw the shaft off balance, destroy the compressor wheel and send those pieces into your motor . i always thought of that after hearing stories from my diesel technology instructor about that exact situation. but really, you rarely hear about them breaking if they even break at all.

KD93

Yup. Much more likely to just stop working than break or melt. I've heard a few stories too, but most of those were '80's trucks. Metallurgy has come a long way since then, and most gauge companies have specific pre- and post- turbo thermocouples/probes.

BearKiller

Are you certain that the "post-turbo" thermo-couple hasn't simply just been adapted up to the 1/2" bung ??

!/2"-NPT seems awfully big for a probe; most are 1/8 and many are 1/4.

Mine is a 1/4-NPT threaded into a 1/8-NPT reducer.

The tip just protudes into the stream and it works immediately with no "lag".

You can always just go to a truck shop and buy a type-K probe with the NPT threads you desire; I never heard of them being differentiated between "post" and "pre" before; ----heat is heat, wherever it gets measured.

thrashingcows

Yes it has an adapter, it goes from 1/2" for the bun, and 1/4" for the coupler. I guess I could just get a straight 1/4" adapter then? Who might carry that piece, and what should it be made from, brass, stainless...?