Pyrometer and Boost Gauge Probe Location

[dsluder]

I am now part of the BOMB sorority. All of you are at fault for this. I am in the process of installing a pyrometer gauge and boost gauge and I value your input as many of you have done this. My questions are as follows: 1. On my 2001 24 valve where is the best location for the boost inlet in the intake manifold? Pictures would be nice. 2. I realize there can be significant temperature differences (300F) in where the probe of the Pyrometer is installed either in the Turbo Inlet or Turbo Outlet. Having said this I am requesting your input. Once again pictures of the location would be nice.



Thanks for the info... ... ... ... ... ... Dave

 

[Big White Beast]

Opinions are like............

Most people tap the exhaust manifold and intake horn. Piers Diesel sells a tapped bolt for the boost gauge. It replaces one of the intake horn bolts. That's the route I would take with that.



As far as the exhaust you can tap the manifold. Instructions should have come with the gauge as far as size and location.



E-mail me and I'll send you a photo of what I did,



-- email address removed --



Garrett

 

[redeye]

I’m preparing to do the same thing here. F. W. I. W. I’ve decided on Isspro EV gauges for boost, temp and Westach for fuel pressure. The pyrometer I’m using is color coded so I asked their rep this same question. His recommendation was to place the probe after the turbo. He explained:

 Placing the probe in the exhaust unnecessarily increases risk of damage to the turbo by providing another place for carbon build-up, which could break loose, or by the probe coming apart. I don’t know how likely this is, Isspro might just be protecting themselves against any possible damage claims.

 The Cummins safety limits I’ve seen are based on after turbo temps.

 Most importantly the BD exhaust brake I’m installing comes pre-tapped for a probe, that makes it easy, I like easy.

 

[Michael Hughes]

If you would like pictures of installing a boost gauge and EGT probe(s), that a look at my HOW TO. Hope this helps.

 

[fj40charles]

Hey Dave,



If we joined the BOMB sorority how come we don't see too many girls on this board????? Ha Ha Ha!!!!!!!



Charles

 

[redeye]

Michael,

Nice set-up, thanks for the photos

What are the temperature differences between the two locations? Have you found it to be constant?

 

[Max Wedge]

Welcome. I sweated over this for months before I did mine. I removed the intake horn, and drilled/tapped the backside for the boost connection--piece of cake--4 bolts and remove one side of the rubber hose.



I put my probe before the turbo in the exhaust manifold--drilled/tapped, then used small magnet to remove shavings--I have since completed 3 more just like this--no problems.



The tapped bolt sounds great, but I am to cheap--just drill and tap the air horn.



Max

 

[RJOL]

dsluder

With the 2001. 5 there is a 3/4" NPT plug just in front of the MAP sensor, just behind the fuel filter. Just take the plug out, replace with a 3/4" to ? (mine is 1/8" NPT) reducer, and hook your boost up there. No tapping required.



For you Pyro, I was also concerned about the "pre-turbo" installation, but after searching TDR, I couldn't find anyone who has ever had a first hand experience with a "pre-turbo" installation and a probe failure. I want the real temps, not the inaccurate temps aft of the turbo, so guess where I installed mine...



Here is an excellent thread:



http://www.showmestate.org/stltdr/how-tos/EGT_how_to.shtml



Note: The tread reference for the 7/16" drill in the manifold is for a 1/4" probe. If you have a 1/8" probe, use a 5/16" drill.



Also, you don't need to go from a 3/4" reducer to a 5/8" to a 1/8" on the boost plug. Just go directly from a 3/4" to whatever size you need...

 

[redeye]

Real Temps?

I want the real temps, not the inaccurate temps aft of the turbo

Can you explain, I haven't installed yet and I'm pretty sure I don't want UNREAL temps





:

 

[NVR FNSH]

Both temps are real - it's just a matter of what you want to use. Post turbo the gas has been expanded and thus the temperature has been reduced some amount - ~300 degrees. Either location works.



Me? I'm going to mount my TC post turbo because if I screw up the threads for whatever reason the elbow is a lot cheaper than a new manifold. That, and if post turbine was good enough for the 75KW gas turbine generator I was working on it's good enough for my engine. We had TC both pre & post turbine but the ECM was controlling off the post turbine TC. The ECM 'trimmed' for efficiency based off post turbine temperature - tried to maintain a constant 1200F. The pre turbine TC was way too expensive for production use.



Brian

 

[RJOL]

Closer is Better

Originally posted by NVR FNSH

Both temps are real - it's just a matter of what you want to use. Post turbo the gas has been expanded and thus the temperature has been reduced some amount - ~300 degrees. Either location works.



Brian

Well, let me put this another way... The closer your probe is to the source of heat (cylinders) the more accurate it is for current temps. When you put it aft of the turbo, it may be +- 200, 300, or whatever. If you want the most accurate temperature readings, put it pre-turbo. If your uncomfortable with that, then put it post-turbo and fudge the temps... .

 

[Michael Hughes]

redeye:

Thanks. I did that page for all the people like me that didn't know for sure what to do. It took me a while to drill the hole in the manifold!!



I can't really tell you about the difference in the temperatures. I can tell you when you get on it the pre will go to 1,000 while the post is only 550-600. And when you come stop a stop to shut it down, the pre will drop to 300 and the post can be as high as 500.



RJOL:

If I could have found a bushing to go from 3/4 to 1/8 I would have done it that way, but I live in a small town and you do with what you can get

 

[MAX A/C]

dsluder--



Just wanted to give you some more info on pyrometer location. Bruce Mallinson. owner of Diesel Injection of Pittsburgh, has been working on/upgrading our favorite trucks since they came out in '89. The first mod he recommends is guages. He always installs pre-turbo. To quote from his handout:



"Most diesel engines... have various parts made of aluminum, including the pistons. Aluminum will turn molten at 1350 degrees. It is critical to ensure that engine temperatures are monitored and do not exceed safe limits.



"During the ascent of Pikes Peak the pyrometer indicated an EGT of 1400 degrees. The problem was not lack of horsepower. Horsepower was available but could not be used because of the high EGT. After 5 seconds at 1400 degrees downshifting from fourth to third and then to second solved the problem. "



He goes on to say that, especially at altitude, EGT can and does rise and fall within a few seconds. In my conversation with him, he indicated that if you install after turbo, you may not be able to react quick enough at the critical time to save your engine. The after turbo readings do not rise and fall as quickly as what is really happening inside the motor.



Have fun with your mods!

Scott

 

[redeye]

#ad




The gauge on the left is intended for pre-turbo use. Right is post-turbo

The difference in safe zones is around two hundred degrees.



My question is what needs protection from excessive heat, the cylinder or the turbo? I read some where that running turbo temps must remain below eight hundred degrees except for very short periods and shut down temps should be around three hundred degrees. Post-turbo would show turbo temps most accurately

If it is the cylinders that need protecting then pre-turbo would be the better choice.

 

[Bigsaint]

Dave, you have to make a decision... do you want to guess what your egt's are when climbing a hill and worry about your engine or do you want to guess at the proper shut down time for the turbo ? The problem with post turbo is that boost psi's come into play and there is no exact formula that you can do in your head for the proper post turbo egt's while running. Pre-turbo is easy, watch the pyro gauge while running and wait for 300 degrees before shut down, then add few seconds to be sure. I usually just wait until I hit 275f pre-turbo before shut down.



Scott W.

 

[tgbol]

I am going to really throw fuel on to the fire. All of the trucks we have at work with Cummins engines have the pyro probe post turbo. The shop manual for the Big Cam 300 says to install the probe 4" to 6" post turbo. I installed mine in the outlet elbow. The new Isspro EV pyrometer reacts a lot quicker that the regular one I had until the EV came in.

 

[Big White Beast]

Opinion time.........Uh Oh!

Here's how I see it. In commercial applications they are monitoring the temps from stock diesels being used in applications they were designed and built for. In stationary applications, it's a great diagnostic tool. In the big rigs they have gearing that we don't, and that's a great way to control EGT's.



Dodge doesn't build one into the Rams because the design they have built it for doesn't require one. Stock the EGT's wont get out of control. Not so in our heavily modified trucks.



I personally could care less about turbo cool down in relation to engine melt down. I want to know what my internal temps are. Based on that cool down of the turbo can easily be figured.



Cummins ISB = $4K



New Turbo = $800



Let the flames begin,



Garrett

 

[redeye]

Excuse my turbo ignorance.

Don't pre-turbo exhaust pressures vary with the amount of resistance encountered, before doing the work and expanding? Wouldn’t post-turbo pressure be more predictable?



Help me understand, towing up hill at, let’s say, nine hundred degrees post-turbo (halfway) into the warning zone, the cylinder temp could be approaching melt down and you would not know it?

That is scary. :

 

[RustyJC]

As an engine manufacturer, we install our EGT probes (type K thermocouples) at the exhaust outlet of each cylinder and at the turbocharger inlet. What's the rationale?



The individual cylinder exhaust probes are used to diagnose individual cylinder problems such as bad injectors, fuel prechamber check valves, gas injection valves, spark plugs, etc. They also give the best indication of the cylinder temperatures critical components such as the exhaust valves, exhaust valve seats, piston crowns, etc. are being exposed to. The engine control system generally has alarm and shutdown points on both cylinder low temp and cylinder high temp.



The pre-turbo inlet thermocouple (colorfully called TIT, for turbine inlet temperature) is primarily there to protect the turbocharger itself. Turbochargers will have a maximum rated TIT based on the materials used for turbine wheels (in the case of radial turbos) or turbine blades, discs and nozzle vanes (in the case of axial turbos). The engine control system will have an alarm and subsequent shutdown on high TIT.



We very seldom install a post-turbo thermocouple as, unless we're mapping turbocharger performance or are concerned about the exhaust temperature into a catalytic converter or waste heat recovery boiler, it really doesn't mean much to us.



On my Cummins, needless to say I installed my type K thermocouple pre-turbo!



Rusty

 

[Ram4Sam]

In my other life...

A while back, when I didn't know anybetter, I used to own a POSD and this subject was tossed around alot on the Ford site. A few of the Ferd owners put two t-couples on their trucks, one before the turbo and one after. What they found out was that the temperature drop from pre to post turbo was not always the same. If I remember right one truckowner said the drop varied from 200 to 500 degrees, depending on conditions(boost, rpm, load, gear, etc.



Sam