Location for Pyro installation

[kaiser2help]

A much debated topic. Being a diesel mechanic it does make sense to mount the temp probe in the pre-turbo location. However, most leading truck manufacturers for years have always mounted their's post turbo. Mack, CAT, Cummins, Int'l, and many others mount it post turbo. Also if one were to mount it pre turbo sure its a good idea to remove the turbo. But being that the manifold is cast this material does cut, tap, and drill quite differently from most ferrous materials. I have a LDS 465-1A for the application. Couldnt one start the engine let it idle to create a little back pressure ( positive pressure in the manifold) and drill with patience, periodically clearing the flutes of the drill bit? Most cast iron when it is drilled produces a powdery type filings . I am sure there has been larger carbon particles that have gone through the turbo that are much harder than cast drill shavings. Same would be for tapping the manifold. Grease the flutes and go easy. If anyone can elaborate on this one I could use the help. Thanks.

 

[54reo]

You are correct on the fact that the cast iron manifold produces "powdery type filings", and one could probably follow the procedure you outlined to a certain degree of success.

BUT.....

With it being so darn easy to remove the turbo on these engines, why take a chance? What would be gained by something (tap, drill bit) HARDER/TOUGHER than the cast iron parent material, breaking off in the exhaust stream and potentially getting sucked into the turbo? It only takes about 20 minutes to remove/reinstall the turbo. It would take a little longer than that to find a new turbo, and possibly replace the engine. Let alone the extra hit to the wallet!

I'm not trying to flame anyone, just my two cents.

 

[steelsoldiers]

Yes, I have drilled and tapped a manifold without removing the turbo. I did this on my 1995 Dodge Cummins. I did NOT do it with the truck running. I stuck a magnet down the hole to get most of the shavings. After that, I just started it and the shavings blew harmlessly past the pinwheel. Me and a couple thousand other guys have done this on the TurboDieselRegister without problems. Just don't rev the truck up so the turbo spools.

I did my 2004.5 Dodge with the turbo on using grease on the bit and tap to catch most of the shavings. Then I used a magnet to get any that made it past the grease. After that, I just started it and let the exhaust carry any extras out at idle.

 

[kaiser2help]

Thankyou for the helpful response. 54REo I do agree as well, good point. Now I am curious about the debate over pre and post turbo location. I do really think it will be pre turbo. But if I could gain more insight as to why all the other manufacturers go with the post turbo setup I would feel better to know. Thanks again.

 

[army_greywolf]

should be pre turbo at the point where the exhaust converges downstream towards the turbo. So at the center of that big ol iron log about 4-6 inches from the turbo inlet.

Take the turbo off. Because it's so easy to do, just take it off... What those thousands of guys don't tell you is that every now and then they tap the manifold and start the truck, and something goes wrong... sure most get away with it, but you don't want to be that minority.

It also affords the chance to check your turbocharger for signs of wear, and the need for a good cleaning.

 

[ygmir]

I don't quite understand the necessity of the pre-turbo install.
I know the temps are higher there, maybe somewhat more accurate in relation to the exhaust valves, etc.
But,
as long as you knew max temp for the location, why would it matter?
IE:
If 1200 deg F is max, pre-turbo, and, that equates to 900 deg. F post turbo, then, you just don't let it get over 900 deg. F. and install it where a parts or mechanical failure is not so critical.........

Maybe I'm just slow........

HEnry

 

[kaiser2help]

My feelings exactly Henry. That would be the difference in the temp for that specific location. For some reason, maybe for labor purposes, big manufacturers put their pyro post turbo. I would surely like to see the reasons why, explained, to undestand. But I am with you on this one. Thanks.

 

[DaveP]

after the turbo cuts the risk of sending the probe thru if it burns off.

 

[ida34]

I know some of you guys are newer and I really hate to be the one to say"use the search function" but this has been hashed out a few other times. There were arguments both ways. If I remember right the threads were quite long. Search and you can read the other responses already given.

 

[cranetruck]

The exhaust manifold is divided before the turbo and placing one probe in each section offers the opportunity to monitor the performance of the injectors by comparing the front three with the back three.....

FWIW, mounting a probe before the turbo will give you faster response time also, especially visible on a digital type readout.

 

[steelsoldiers]

I hear what you are saying armygreywolf. You guys are welcome to do it any way you want. I personally have not heard of any problems doing it with the turbo on the truck. I always make sure to get as many chips out as possible with grease or a magnet. My Cummins 5.9's ran for tens of thousands of miles after an install and were just fine when I sold them. You guys can take the turbo off if you want to inspect it, etc..., but I don't think it's necessary.

 

[jimk]

The dual plane exhaust manifold was the primary reason I placed my single probe post turbo. I felt second hand info would be better than [the unlikely event] wrong info if something went wrong in IP system. There is good info available on both sides of the turbine.

I think the swallowed probe scenario is most likely the consequence of an operator ignoring warnings provided by same instrument (i.e. 2000*F). Temps that damage a probe damage other parts too.

Most diesels can get by without a pyrometer because they are designed to run safe EGT's under any and all driving conditions. The LDT is set up this way.

My LD to LDT upgrade resulted in maybe 20% more power available without any EGT risks, and perhaps 30% more power with the only threatening readings during abusive operation(lugging the engine).

I'd be concerned for any vehicle [without a pyrometer] where there is ANY CHANCE change(s) were made, intentionally or inadvertently.

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

JimK

 

[ygmir]

do people really run them that tight, for, that long?
Overheating the exhaust does damage with time, I know.
Just speaking for myself, I don't run my engine on a hard pull, full throttle, for any length of time. If it's a long hill, you just gear down, lighten up on the fuel, and, enjoy the ride.......easier on everything.......
Pushing it to the power limit, and therefore heat, for extended periods, IMHO, is just showing disrespect for the machine, mechanics ( myself), and designers ( who probably know more than me about this stuff).

Of course, your results may vary........

 

[cranetruck]

...the pyro is an interesting diagnostic instrument, found out that biodiesel/veggie oil lowers the EGT, for example.....

 

[jimk]

I run max output while towing the ~13 ton trailer, often for hours on end. Boost varies with rpm - higher rpm gets more boost(and lower egt, up to 13psi at 2600 w/ current higher settings on IP (though I do like to stay below 12psi/2500rpm). Temp gets high only at the low end of the operating range. Hills are tough and as rpm falls temp rises so at 1500 or 1600rpm it can get hot at 975*F (post), and climbing very slowly, however a downshift is past due then and always solves the problem. I don't mind 1000*F if duration is short. I'd like to think this is all pretty conservative but can't seem find the [2-1/2ton] TM page that allows for 13T towed. JimK