Can a pyrometer probe be installed in exhaust pipe instead of manifold? (1 Viewer)

[peterdouglas]

I just got my new (used) Autometer Pyrometer, yay! ;p

The guy I bought it from had it installed, but never hooked up, so it's essentially new. Unfortunately, it didn't come with instructions... Does anyone know if the probe can be installed in the front exhaust pipe instead of the manifold? Manifolds can crack, which is loud, and expensive to replace, so it would be nice to avoid that potential problem. The cable/wire looks long enough to reach the exhaust pipe, but would that have any negative effects on exhaust flow, accuracy of readings, etc? BTW, this is for a 3B in a 1984 BJ60.

 

[peterdouglas]

Also, does anyone in the Barrie or Toronto area have, or know someone with a tap & dye for installing the pyrometer probe? Nobody around here seems to want to do that, and it's not possible to rent a kit (only purchase).

 

[Tapage]

Short Answer .. yes ..

When I have my 2H NA I ran it in my down pipe .. install it as much as close you can of your exhaust manifold in order to get the most accuracy readings ..

 

[peterdouglas]

That's great news. It sounds like the reading may not be as accurate as if it were on the manifold, but probably not too far off the actual reading.

 

[eleblanc]

No need for a tap is you are installing it in the down pipe. If you bought the autometer, be VERY carefull with the fiber washer. follow instruction, i used the collar.

 

[Dougal]

A pyro in the dump pipe is better than not having one. But it's nowhere near as useful as one in the manifold.

Your turbo causes a pressure and temp drop in the exhaust, if you're fitting a pyro in the dump pipe then you've got to guess what the temp drop across the turbo is, guessing is hard because it constantly changes.
If you guess the temp drop wrong you either run a long way from possible power or melt your engine.

 

[brownbear]

A pyro in the dump pipe is better than not having one. But it's nowhere near as useful as one in the manifold.

Your turbo causes a pressure and temp drop in the exhaust, if you're fitting a pyro in the dump pipe then you've got to guess what the temp drop across the turbo is, guessing is hard because it constantly changes.
If you guess the temp drop wrong you either run a long way from possible power or melt your engine.

he has no turbo.




Just go nice and close to the manifold. I put my unit in the downpipe before I went turbo. It will be accurate enough. I was only an inch or so from the flange. Follow the directions. It is easy and clamp works nice. eleblanc shows it nicely.


After I went to turbo I did still put it after the turbo. As it had a spot in the turbo housing for it. I know it won't be as accurate and I need to allow for some temp losses from the pressure decreasing...

 

[eleblanc]

They said 6" in the instruction, at the velocity in the pipe i guess two inches is good. Could turbulence cause miss reading? Anyhow mine is about 5-6 inches down.

 

[brownbear]

I'm not sure. The turbulence should be the same at 1 inch as it is at 6 inches....IMOP anyhow.

How was the instructions worded? I coule understand being 6 inches away from the head outlet. As the temps might get almost flaming there I dunno.

 

[Dougal]

he has no turbo.

:whoops:

 

[peterdouglas]

Thanks for the info, guys. I'll try to get it as close to the manifold as possible, and will always keep in mind that the reading could be slightly inaccurate if mounted in the downpipe.

 

[peterdouglas]

he has no turbo.

:whoops:

Sure, rub it in!

Haha, just kidding, I "wish" I had turbo! Maybe someday... ;p For now, I must settle for the neck-breaking acceleration of the naturally aspirated 3B. It just sets the road on fire. NOT! The other day, some little old lady (granny) in a Cavalier passed me going uphill, and she wasn't even exceeding the speed limit! So yeah, turbo would be nice...

 

[brownbear]

Thanks for the info, guys. I'll try to get it as close to the manifold as possible, and will always keep in mind that the reading could be slightly inaccurate if mounted in the downpipe.

it won't be inaccurate in the down pipe next to the manifold. It's too close to be effected by pressure/temp drops. It will be close.

Once your pyro'd read up on adjusting fuel. It is easy. But it needs the pyro to do it. Then you can add fuel to make it a bit more zippy. My truck did get better when I cranked the fuel. But then I had to watch the pyro on big hills to prevent overheating.

 

[peterdouglas]

Once your pyro'd read up on adjusting fuel. It is easy. But it needs the pyro to do it. Then you can add fuel to make it a bit more zippy. My truck did get better when I cranked the fuel. But then I had to watch the pyro on big hills to prevent overheating.

Yes, I've heard you guys talk about adjusting the fuel. Having found this thread, it looks like too little diesel, and it lacks power, but the EGT's drop too. More fuel, and the power and EGT's go up. Someone mentioned going to a shop with a dyno to find just the right setting for acceptable power and EGT's.

What do you do if it starts overheating... pull over and let it cool down, or drive slower in a lower gear? I'm a bit nervous about adjusting the the fuel for fear of damaging something, even with a pyrometer. As far as I know, my truck is at stock fuel settings. Are the stock settings the best, or can it be tweaked just a bit for better power or fuel economy (probably not both at the same time)? I kind of like the idea of "set it and forget it" when it comes to fuel settings, in case I forget to check the pyrometer and melt the engine with altered fuel settings.

 

[eleblanc]

Yes, I've heard you guys talk about adjusting the fuel. Having found this thread, it looks like too little diesel, and it lacks power, but the EGT's drop too. More fuel, and the power and EGT's go up. Someone mentioned going to a shop with a dyno to find just the right setting for acceptable power and EGT's.

What do you do if it starts overheating... pull over and let it cool down, or drive slower in a lower gear? I'm a bit nervous about adjusting the the fuel for fear of damaging something, even with a pyrometer. As far as I know, my truck is at stock fuel settings. Are the stock settings the best, or can it be tweaked just a bit for better power or fuel economy (probably not both at the same time)? I kind of like the idea of "set it and forget it" when it comes to fuel settings, in case I forget to check the pyrometer and melt the engine with altered fuel settings.

Install the pyro, don't touch any setting, drive it alot and report back about the temperature you get.

 

[bc81]

egt's for any diesel engine should stay below 1200 deg. F in the exhaust manifold.down pipe temps will be approx. 200 deg. F, lower depending on distance from the exhaust manifold. stock settings could still produce these temps depending on the situation, restricted exhaust, plugged muffler etc. combined with a heavy foot and a hill.
if you see reading this high , ease off the throttle and or shift to a lower gear to push the hot exhaust out.
momentary spikes in temp won't melt your engine.prolonged lugging will.

 

[peterdouglas]

OK, that sounds like a good plan. I'll monitor temperatures for a while at the current settings. I usually downshift if the engine starts lugging anyways, except sometimes I get lazy and take corners in 3rd gear instead of 2nd. But, it's certainly not prolonged driving, maybe a few seconds. Still, I should get out of that habit.

 

[eleblanc]

egt's for any diesel engine should stay below 1200 deg. F in the exhaust manifold.down pipe temps will be approx. 200 deg. F, lower depending on distance from the exhaust manifold. stock settings could still produce these temps depending on the situation, restricted exhaust, plugged muffler etc. combined with a heavy foot and a hill.
if you see reading this high , ease off the throttle and or shift to a lower gear to push the hot exhaust out.
momentary spikes in temp won't melt your engine.prolonged lugging will.

You see where my probe was, about 6" down the pipe. Before i re-geared the truck to 4.88 and was running stock exhaust i could easily get temps to 1350-1400. I only had the gauge installed early this summer and had been driving like that since July 2006. But like you said, it peak at those temp, highest steady temp i would get to run 65 mph was about 1250-1300.

 

[cbmontgo]

Reviving an old thread, but I have aftermarket headers and would like to install a pyrometer. Could I install it in one of the sections where three pipes go into one? Or even further down towards the flange and still get a fairly accurate reading?

 

[RufusTheDufus]

I think a pyrometer installed that far downstream from the exhaust valves wouldn't be of much value. The response time would be slow and there's no easy way to know how much the exhaust has cooled before it reaches the sensor. I wouldn't be surprised if it drops 400 degrees F at the collector.