tap for pyro

[BFR]

does anyone have any recomendations for what bit & tap to use on the exhaust manifold when installing the probe for a pyro?

 

[mangus580]

All depends on the thread on the pyro probe you have.....

 

[cranetruck]

1/8-27 NPT and a 21/64 bit should be sufficient for most probes.

 

[m-35tom]

get the probe before you drill. never seen an 1/8 npt probe, all the ones i use go in 1/4 npt. if you put the probe in the manifold, and the probe fails, it can wipe out the turbo. that's why most are put post turbo.

 

[cranetruck]

http://www.hewittindustries.com/instruments.htm

 

[BFR]

I have the probe, it is 1/4. I was mainly asking If I needed special stuff because of what the manifold is made of.

 

[sermis]

How much will the temp very pre and post turbo?

 

[WillWagner]

200-300 degrees. Well, the Hewett link that cranetruck posted says 150-200 less than a hot side reading. On the dyno with two identical engines, the one with the stinger placed 8-10 inches post turbo, the readings are 2-300 less than a hot side reading. Guess it would be determined how far after the turbo the stinger is placed.

 

[ken]

The manafold is cast iron. So a good quality drill and tap will work just fine. There is a rib in the middle of the manafold so be careful so you don't break the tools off in it. I strongly sudjest removing the turbo before drilling and tapping. To keep the chips out of it. Some have done it with the engine running to blow the chips out of the hole. They are braver than me. I also sudjest mounting it pre turbo. You need to see what the turbo is putting up with, not what it's putting out.

 

[m-35tom]

the turbo can stand anything the engine can create and more in regard to temp. the pistons cannot. where you put it is moot point in regard to protecting the engine, and that is why it will be there, right? if / when it fails it will not do the turbo any good. i have always been told that 6" post turbo is the location of choice.

 

[Recovry4x4]

My Hewitt is 1/8 NPT as well. The offered both sizes. If I can swing a second gauge and thermo, I'll install post and pre and determine the temp drop.

 

[jimk]

"We might mention that some mechanics fear installing the pyrometer thermocouple in the exhaust manifold for fear the probe will break or burn off and blow into the turbocharger.....While the above scenario is scary, it is also unlikely....It just doesn’t happen with a good pyrometer."

"It should be noted that when the EGT is measured after the turbine, the turbine outlet temperature at full throttle or under a heavy load typically would be 200º to 300º F. lower than the EGT measured in the exhaust manifold...."

"This variance is why installation of the thermocouple in the exhaust manifold is considered more accurate. "

"We’ve already mentioned that excessive EGT can cause engine damage or turbocharger damage, but let’s get more specific. Which parts will fail first is a matter of the design and materials used in the various parts of the turbo-diesel, but usually it starts with the turbocharger..."

Bits from:
http://www.bankspower.com/Tech_whyegt.cfm

 

[BFR]

fwiw mine (Isspro) recomended upstream installation

 

[cranetruck]

If I had two, I'd put one in each exhaust manifold section and have a reference as well, if readings are not the same, there is a problem. Also the response time is much faster for pre turbo....

 

[WillWagner]

"We might mention that some mechanics fear installing the pyrometer thermocouple in the exhaust manifold for fear the probe will break or burn off and blow into the turbocharger.....While the above scenario is scary, it is also unlikely....It just doesn’t happen with a good pyrometer."

Only seen this twice in a 25+ year + career. When it happens, it's expensive

 

[OPCOM]

My post-turbo is closer to the turbo outlet, about 2" from the turbo. If that makes it read a bit higher, so much the safety factor. If the turbo ever comes off for any reason, I'll move it to before the turbo. I back off the fuel if the needle hits 900.

 

[jimk]

Will wrote:
Only seen this twice in a 25+ year

Thanks,Will, I was wondering what you had to say. 2 seems like a lot. Do you remember any details? Excessive EGT damage the probe? Cheap probe? Metal fatique?If it was the former, and the probe got too hot, the gauge should have indicated it. Perhaps the driver is to blame???

Banks wrote:
"This variance is why installation of the thermocouple in the exhaust manifold is considered more accurate. "

Pre-T probe in a divided exhaust manifold means info on just half the engine. A post-T probe may be less 'accurate' but may be a more 'reliable' indication of overall engine EGT. It also eliminates the risk of turbine damage, however low that may be.

Having any EGT info should be enough to manage most of the risk.JimK

 

[WillWagner]

It was a long time ago, when you could jack the fuel up...non electronic. If I remember th one started life as a 400 hp engine and the owner jacked the rail pressure to around 370+ psi. The melted stinger thru the turbo was the least of his worries. All the pistons were cracked more than I have ever seen. His complaint when he came in was, believe it or not...low power! We dynoed it first and it smoked like a puller truck and blew all of the water out of the manometer used to check blowby. The other one was an L10 in a fuel hauler. Came in with a failed cam, we found a melted/broken stinger...didn't really see a reason for it 'till after the repair when it was dynoed. At the time, L10s only put 240 hp out. I warmed it up then started the test. I knew there was a problem when the RPM would easily go to 2500 with around 400 hp to the wheels! The driver had made a stinger for the governer. Nice! He lost his job.
Military content...I got a left rear, outside flat on the deuce. Gotta change it this w-end.

 

[FreightTrain]

Also,Not to mention the Reading after the turbo will be delayed since the turbo housing will act as a heat sink and cool the exhaust considerably for a few seconds.Never heard of a modern probe scattering a turbo.I could see it if you was pushing a deuce to 3-400HP with monsterous amounts of fuel and Drugs but personally I think it is impossible to do it now with modern metals.Heck,the Pyros are usually rated for 1600Degrees and it would be nearly impossible to get a multifuel up that hot.The pistons would fail before then.Aluminum melts at 1250degrees.

 

[OPCOM]

Stinger?