boost and pyro readings

[FreightTrain]

Finished installing my boost gauge and Pyrometer today.Tested it by firing up the truck and reving it in neutral.I managed to get 1-2PSI with no load and the Pyro was VERY slow.It took 30 seconds after cranking to get up to 300Degree at idle but wouldn't move when I was reving it.I know on my Fords I could get the boost to about 7-8 in neutral and could get the EGTs up to around 500Degrees.Do I need to check everything or is this about normal for a LD465?

 

[cranetruck]

I'ts normal. Take the truck for a ride to load the engine.

 

[FreightTrain]

Roger.I was wondering.I knew there was a slight difference in the Ford IDI and the Deuces LD(Ummm,Like config,cubic inches,cylinders,piston design,Head design....Ok,only thing they have in common is No spark plugs) but the readings threw me off a little.

 

[m-35tom]

i assume you maen ldt since a ld has no boost, 1200 f and 9 psi are the highest you should ever see.

 

[jimk]

Pyrometer location is an important factor. 1200*F is too high if you have a post turbo pyrometer.

When running high EGT the duration should also be considered.

For max boost (or any substantial boost) the throttle needs to wide open -and- engine under a load. Boost will climb as RPM does. Boost can/may be controlled with the fuel pump adjustment. JimK

 

[FreightTrain]

Well,Took it for a real test run today.15 miles one way on the highway.backed out when it went past 1050(dang gauge goes 25,45,65,85,105 Etc X10 so I will just use a shade past 1050 as the max.) and normal peak was 9PSI.Hit 10 on one hill but was about tached out and fixing to shift.Oh that turbo sounds sweet!!!

 

[Westech]

1200* is not too much but I would not go any more on a post turbo. I have mine post turbo and its in the elbow pipe right before the flex and I run mine up to 1200* all the time but I don't keep it there long. I will hold it at 1100* all day long and not a problem. So if your only hitting 1000* befor the turbo you can turn her up a bit no sweat.

 

[cranetruck]

Aluminum Symbol: Al Atomic Number: 13 Atomic Mass: 26.981539 amu Melting Point: 660.37 °C (933.52 K, 1220.666 °F)......

 

[Armada]

Aluminum Melting Point: 1220 °F

Yikes.

 

[Stretch44875]

Git'er done Westech.... Anyone know what alloy the aluminum pistons in a deuce are and it's melting point?

Normally run 1150 pre-turbo on a long hill. Crusing empty is about 900.

Right now I think I have the used oil mixed a little heavy in the tank, have to watch the pyro because the truck was able to hit 1400 on the way home from haspin. After I saw that I backed the throttle down to 1200 pre-trubo. But talk about power, could pull any hill, and serious smoke.

Dennis

 

[Westech]

You have to remember there is oil splashing on the pistons and cool air coming in too. Its not like there is a constant blast of over 1200* blowing on the pistons. Hey I have over 12k on that motor with that fuel setting and not a problem. Im not saying its the most smart thing to do in the world but if you keep really close watch and not be dumb with it you should be fine. There is no reason why you cant turn her up a bit and have a better driving duece. Lets face it when there "stock" they really stink on the highway and thats where 90% of us drive them.

 

[jimk]

Even under high load pistons run cool. 400-500*F. There is a lot of heat transfer via rings to cyl wall. Oil from below helps cool, as does the intake charge. The combustion flame front is MUCH higher than EGT, but the duration is very very small, a few dozen degrees of crank rotation out of every 720. If you don't believe me remember that oil burns at ~450, and you can't have burnt oil/coke falling off the bottom of the pistons.

High EGT is hard on exhaust valves and turbos. At 752*F cast iron starts getting red. At 1000 red shows in daylight. The hotter these parts get the weaker their structure. Exhaust valves and turbines are special steel alloys that have higher strength at even higher temps, but they still have a limit. At extreme EGT they are the weak links.

As for melted pistons I have seen a few. Every one was some gas job that leaned out, didn't have oil in it, or had poor ring sealing. The latter lets combustion gasses get to an area of the piston that it shouldn''t be. The failure goes like this: the piston overheats, expands and make direct contact with cyl wall. With no room for oil a fast and vicious cycle starts - more heat, more expansion... till the piston skirt smears. This [almost] always smears the ring grooves. Blow by is still controlled by the direct contact so combustion continues. If you don't stop the piston seizes. Engine speed grinds down to 0. It that happens too fast something breaks. Sometimes a lot of things break. Afterwards [a not too dramatic event] if you shut off the engine it may never start again because the piston(s) contract and rings no longer have tension.

The [diesel] deuces are very well built and very conservatively tuned. For recreational usage higher limits may be ok. For me towing 14T may be more abusive than anything the army could throw at them (well, maybe not). I stay under 1000*F(post). If I went to 1050 for a few sec. I would not worry. If that sounds too conservative for some remember I would rather go sailing that rebuild an engine.

Here, again, is a good piece(s) on EGT. JimK

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

http://dodgeram.org/tech/dsl/FAQ/turbo_faq.htm