Installed a pyro, got a surprise!

[Smokinyoda]

I bought a late model M35a2c out of WR a while back. Truck was bone stock, FDC still hooked up, safety wire still on the IP. I was always amazed at the power the truck had, rarely had to downshift pulling a grade. Decided to bypass the FDC before it started making oil, and since every other truck I have done this to seemed to gain a little power I wanted to install a pyrometer first... wish I had done it sooner!

Installed a 24v Auber 1813 with an exposed tip K type thermocouple. TC mounted pre turbo, back side of exhaust manifold. On the first and only test run I hit 1250 F on a very mild hill before quickly deciding to abort the trip and head back home. Mind you this was not very steep, and I was not even wide open on the throttle. What worries me is I have taken this truck up 7% grades, 3/4 mile long without having to downshift... hate to think what kind of temps she saw... really surprised I still have a functioning engine. Truck is now parked until I get the fuel turned down!

Anyway just wanted to post this as a warning to other deuce owners. Dont be like me, ignorant in your thinking that a stock truck right from the Military would be properly set to a "safe" range! Or that pyros are only for those who plan to turn there fuel up!!!

 

[gimpyrobb]

Well, you should be fine going over 1200*, but not for extended lengths of time. Also, the long skinny peddle is what makes the temps go up! Don't push down so far and the temps will back off, in addition, you can down shift and get more air through the motor to cool it down. It isn't a grenade waiting to go off as long as you are careful.

Have you checked the air filter? My wrecker(multifuel) would hit 1300* REAL quick till I figured out the filter was wasted. Once I swapped it out the temps were back to reasonable.

 

[Smokinyoda]

Well, you should be fine going over 1200*, but not for extended lengths of time. Also, the long skinny peddle is what makes the temps go up! Don't push down so far and the temps will back off, in addition, you can down shift and get more air through the motor to cool it down. It isn't a grenade waiting to go off as long as you are careful.

Have you checked the air filter? My wrecker(multifuel) would hit 1300* REAL quick till I figured out the filter was wasted. Once I swapped it out the temps were back to reasonable.

Yea I blew out the air filter while I had it off installing the TC. Just really surprised me how little effort it took to hit 1250*, skinny pedal not even close to the floor. I know I can safely drive it as is (been driving it for months, no boom yet) but want/need to idiot proof it for my own piece of mind. This is very steep/hilly country around here, want to set for max of 1100* to be safe.

 

[HanksDeuce]

I'd like to see you install a boost gauge and verify how much pressure the turbo is making to go along with the new pyrometer.

 

[cattlerepairman]

I second the boost gauge and would not turn the fuel down, but rather drive it with the pyrometer. Yes, you saw the temps going up to 1200, but YOU are in charge - back off the fuel pedal slightly (dramatic effect on EGT) or downshift (higher rpm, less load and lower EGT). Personally, I would prefer to have the power and be able to use it safely, rather than dial back the power, and have a "castrated" truck that really does not need a pyrometer.

In addition, you cannot undo what has already been done. If pistons have been damaged by excess heat, then that is what happened - you cannot undo it by turning back the fuel now. You do not want to make it worse - that is why you now have a pyro.

 

[RAYZER]

This is my deuce tractor pulling a 10k lb trailer on a slight grade, on steeper grades egt's will easily reach 1300° briefly before I downshift or back off,usually downshift, i have driven this truck in this fashion for 1000's of miles.
Having it tuned this way let's me maximize available power.
I have noticed egt's will run around 100-200° cooler when burning a 50/50 mix of wmo and diesel.

 

[tim292stro]

Also, black smoke when under load indicates you are spewing unburned fuel out your exhaust (i.e., "rolling coal" is a waste of fuel). Letting off the right foot and down shifting, while not getting you up the hill as fast, will put the engine into a more comfortable load range.

In my experience with a mechanical 2-stroke DD (admittedly not the same engine, but roughly the same principals), there is a sweet spot where you are generating the most power you can get out of certain engine speed - more fuel means that combustion finishes in the exhaust manifold as the exhaust valves open and you an start to heat soak your heads and headers (bad), beyond that fuel rate (more right pedal) the fuel never completely burns due to not enough oxygen and blows out your tail pipe - that's when you start to really see black smoke.

You may find rather quickly while driving with a pyro that you need to form new driving habits - this can be especially important if you've never driven a heavy diesel before (as was the case with me).

 

[Smokinyoda]

OK so I took everyone's advice and left the fuel alone for now. Took it back out and tried to drive by the gauge. Very hard to keep below 1300* unless on flat land. Will get the wife to ride with me tomorrow and shoot a video showing an overview of speed, RPMs, and EGT. Also I looked around the shop today for an air gauge but everything reads over 100psi, to wide a range to use for boost. Found a 30psi gauge on Amazon I will probably order to keep an eye on boost.

 

[steelandcanvas]

Found a 30psi gauge on Amazon I will probably order to keep an eye on boost.

If you can, find a 15 PSI gauge it will be more accurate.

 

[red]

The stock turbo has the ability to go over 15psi of boost. Out of it's efficiency range but it's capable of getting up there. A 20psi gauge would be great but never seen one, easy to find 30psi gauges.

 

[TsgtB]

So, a post turbo, clamp on, probe.... just for a warm fuzzy on EGT range, would still be better than NO gauge at all..?
I'm usually running empty, and just want to see that i'm not cooking my internals.

i read about with the dual (pre and post) temp test that said they were almost identical.
I have had bad luck threading cast in my past....
I see the 200-300* difference... and the other diesel performance guys say up to 500*
does anyone do post turbo any more....?

 

[gimpyrobb]

Post is better than none at all, but I prefer preturbo so I don't melt the fins on the exhaust side of the turbo.

 

[m16ty]

The cast manifold is pretty easy to thread, just drill it the proper size and use a good cutting oil and you shouldn't have any problems. I like to have the truck running when I drill and thread as to blow all the shavings out.

 

[JasonS]

Post is better than none at all, but I prefer preturbo so I don't melt the fins on the exhaust side of the turbo.

Not gonna happen without destroying the engine first.

 

[HanksDeuce]

I drilled my multifuel exhaust manifold when I swapped from the D to C "whistler" turbo. Shavings fell to the ground instead of going into the turbo. Some people do it while the engine is running, others put grease on the tap, but it's just peace of mind for me to remove the manifold or drop the turbo to know where the shavings went.

 

[tim292stro]

...I see the 200-300* difference... and the other diesel performance guys say up to 500*
does anyone do post turbo any more....?

If you can't do pre-turbo (in the collector just before the turbo) post turbo is better than nothing. The temperature difference pre&post is a sign the the efficiency of the turbo - more back pressure across the turbo's exhaust/drive turbine means you are probably not running a very efficient turbo, but it will also create a big temperature difference across the turbo (especially if the turbo's restriction is greater than the rest of the exhaust system's restriction).

Remember that compressing a gas creates heat (what an intercooler/aftercooler would attempt to remove), likewise the release of pressure will cause a reduction of temperature. What you don't want to see is a huge drive pressure (what spins the exhaust turbine). Think of that like taking a big breath in with your mouth, then trying to blow that air out as fast as you can through a coffee stir straw...

That pressure you feel in your lungs and mouth when you do that is what your engine would have to overcome to get the exhaust gasses out of the engine - that's a power drain/loss, and in engineering the simplest loss is conversion of work/energy to heat (not good when you're adding heat to already hot exhaust gasses). Doing a pre-turbo will tell you the most about the overall health of the engine as a system, post turbo is a good "better than nothing" location if you can keep if within 6" of the turbo. If you want to make your dashboard look like an airplane's flight deck, you can put in a boost gauge, drive pressure gauge, pre&post pyros, a turbo tach, and an O2 sensor (because yeah, you can still measure the unburned air content of a diesel engine). Then you can train your other half (if applicable) to be your "flight engineer" to tell you if you're running the engine efficiently and keep your "flight performance logs" up to date...

Just a boost gauge and a pre-turbo pyro will tell you enough about the system - if your boost is "good" for a learned rev at a learned load, and your pyro isn't climbing rapidly above 1300, you're probably fine, if your boost drops while your pyro climbs under load, you've probably got a problem (either turbo damage or over-fueling) or you may have left the boost efficiency band for the turbo. Here of course experience is going to be key if you don't want to surrender to computers on modern trucks programmed by engineers at a factory somewhere.

In California the turbo is considered part of the emissions system for fairly good reason - how the turbo pre-charges the intake air and how the exhaust losses power the turbo can affect the emissions a lot, over-fueling with a bad or marginal turbo will cause smoke and high heat (generating more NOx, etc...). Getting the geometry of a turbo right is just as important as maintaining the turbo center bearings and turbo lube system - a sluggish turbo due to oil coking (burn-off in the bearing housing at engine turn-off) will kill your turbo RPMs leading to less boost, and more back-pressure. This will lower your power and increase the exhaust temperatures and leave you with too much fuel (if your IP is not boost compensated). Also occasionally taking the turbo off and cleaning its exhaust side out and inspecting the turbines is a good idea (especially if you've ever had trouble with your engine).

FOD can ruin the turbine fins and you'll lose power, or worse you could detonate your intake turbine wheel sending shards of aluminum into your intake and taking your engine with it. Filter maintenance is thus also critical as others have posted - you can probably imagine that breathing in through the above coffee straw would "suck"

 

[TsgtB]

EGT and Boost monitoring will be a worthy upgrade... may as well do it right.
I've gone this far, why not.

 

[Pugsley]

I have a Glowshift 3 in one. I have the extra PSI hooked up to the final fuel filter so I know what my pressure is. I can even tell if the in tank pump is working before I start the truck. It's a 12v gauge so you have to have a adapter/separate system to run it but its a great gauge and tells me everything else I need to know that the stock ones don't.

 

[rustystud]

I have a Glowshift 3 in one. I have the extra PSI hooked up to the final fuel filter so I know what my pressure is. I can even tell if the in tank pump is working before I start the truck. It's a 12v gauge so you have to have a adapter/separate system to run it but its a great gauge and tells me everything else I need to know that the stock ones don't.

Now that's one fancy gauge !

 

[mill424]

Did you guys that run boost gauges have any issue removing the plug in the intake housing to install the boost line and fitting?? I'm having difficulty backing that thing out? Is there anyway that someone might have put a nut on the inside of it?