turning up fuel and egt questions

[big hoss]

Everybody says to much fuel is bad because of the extra heat on the turbo, but im wondering. I go to diesel school for caterpillar and i have always been taught that the engine will only burn a certain amount of fuel, and the unburnt fuel is the black smoke you see. One thing that is not going to raise egts is UNburnt fuel, its just there and not serving any purpose than looking cool coming out of the exhaust. So I am confused why everyone is saying running to rich will blow up the turbo. http://test.steelsoldiers.com/images/smilies/icon_confused.gif

 

[G-Force]

Not the turbo but the top of the piston will go into melt down mode and then pass the liquified aluminum out the exhaust and that usually takes out the turbo.

 

[patracy]

Whoa, what are they teaching in diesel school?

 

[SMOKEWAGON66]

Im no mechanic, nor do I understand why it does what it does, but as a truck driver I can tell you that under a load, diesel engines can get VERY hot. Ive seen EGT and CHT gauges touch on 1300 + degrees, which in some engines will melt the pistons, not the turbo. My deuce has the fuel turned up some and I have an EGT in it, and going up hill its hit near 1100 deg. Ive heard that 1175 deg in a multifuel engine will start melting pistons. So if you do turn the fuel up in your Deuce, be sure to put a good EGT gauge on it, and watch it when cruising around.

 

[big hoss]

i turned mine up a little bit and i have an egt. I am confused that fuel that is not burning is still adding heat.

 

[Flyingvan911]

I think the general concensus for the multifuel is not to go above 1,400 degrees. No matter what the chemistry or physics, multifuel pistons melt with too much fuel. Look up the thread "How to remove a piston through the exhaust port."

 

[RIDDLE1]

i turned mine up a little bit and i have an egt. I am confused that fuel that is not burning is still adding heat.

It has more to do with how much fuel is being burnt in comparison to how much air is moving through the cylinder. You will notice that a diesel that is lugging will run much hotter EGT's that a motor that is turning higher RPM's. It takes air coming into the cylinder to cool it off.

You can dump a ton of fuel on a motor that is turning 3000RPM but dumping the same amount while turning 1500RPM is going to be a problem. To much fuel can also cause cylinder wash. Washing all the oil off the cylinders leads to major problems.

 

[big hoss]

Never thought of it that way. The guy that told me about the unburnt fuel thing did truck pulls. He was turning 4500 rpms in a duramax and used water methonal injection.

 

[patracy]

Pre turbo I wouldn't take it above 1300F. Alum melts at a little over 1200F (although these are an alloy metal and are cooled by oil).

Smoke and EGTs are linked together.

Also know, the turbos on multifuel engines weren't there for performance at all. But to help cut down on smoke at STOCK power levels. The C and D turbos are a stoneage design with a poor map.

 

[RIDDLE1]

Never thought of it that way. The guy that told me about the unburnt fuel thing did truck pulls. He was turning 4500 rpms in a duramax and used water methonal injection.

The water/meth injection works by lowering the temp inside to combustion chamber when it vaporizes. The cooler you can get the charge of air/fuel, the more dense it becomes. The more dense it becomes the more you can air/fuel you can pack into the cylinder, that in turn makes more HP!

 

[wreckerman893]

The big mistake some people make when running a "hot" engine is keep their foot in the firewall when under load. Running the engine wide open with a lot of fuel going in it is going to build heat.

The idea is to find a gear it will pull in and hold a steady speed.......I always back off the throttle just a little and let it pull about 1900 RPM (on a multi).

This is one reason knowing how to split shift is handy......if you are going to drop below 35 MPH it is better to be in Low Range 5th or 4th. The truck will pull better and run cooler.

 

[rlwm211]

I did a study of the fuel settings on the multifuel and also dug up some additional data about turbo charging diesels. I would point out that one of the multis weaknesses are the headgaskets and too much fuel can cause them to leak.

The study was done in conjunction with replacing my headgaskets which was done at JATONKA's. Dual pyrometers were used to evaluate the differences pre and post turbo.

Everything I have read suggests that 1300 is the absolute maximum temps you ever want to see. Overheating beyond that causes permanent damage to the engine. Damage is accumulative so if you continue to over fuel and overheat you will eventually melt a piston and that will essentially ruin an engine when things come apart.

Here is a link to the report.

http://www.jatonkam35s.com/DualEGT.pdf

You can do as you wish and the results will become obvious if you do not approach this carefully and with some means of accurately reading EGTs.

RL

 

[rickf]

Just remember, you are hot rodding a 50 year old engine that had a dismal reliability record in stock form. Stock up on extra engines!

Rick

P.S. You might want to talk to the school administrators about what they are teaching you! The teachers need some teaching. You need to learn the basics and fundamentals before learning the high performance side of it. Learning just the high performance part will guarantee lots of broken expensive motors.

 

[crazywelder72]

Big Hoss,
Take your time and listen to these guys. Their guidance will help save you weeks and months of headaches and $$$$. Your teachers may be excellent teachers but it dosnt mean they are correct 100% of the time.

I think the confusion with the xtra fuel comes in to play is there is a point under power when the excess fuel that is unburnt goes out the pipe and there seems to be a point that the exhaust is burning clean and that would tell me the extra fuel IS being burnt at those rpms adding to the excessive heat.

I am probably wrong in my analogy but experience and physics dosn't lie. The melting point of the alloy is what it is. These guys have ALL the experience. Some even have a few melted pistons on their workbench.

 

[gimpyrobb]

Never thought of it that way. The guy that told me about the unburnt fuel thing did truck pulls. He was turning 4500 rpms in a duramax and used water methonal injection.

Don't make the mistake of comparing a diesel motor that has computer controls with a multifuel motor. They are two different animals.

 

[adamax]

you need to think of it like this more fuel = more heat its like throwing another log on the fire. the fuel contiues to burn and expand all the way out of the exhaust. I have a pyro and boost gauge on my deuce and regularly see 1200 deg. for short periods of time. i've had my dodge to 1600 deg for short bursts,the problem is when you dont pay attention and keep it above 1400 deg too long then the piston will start to melt and expand.

 

[patracy]

I did a study of the fuel settings on the multifuel and also dug up some additional data about turbo charging diesels. I would point out that one of the multis weaknesses are the headgaskets and too much fuel can cause them to leak.

The study was done in conjunction with replacing my headgaskets which was done at JATONKA's. Dual pyrometers were used to evaluate the differences pre and post turbo.

Everything I have read suggests that 1300 is the absolute maximum temps you ever want to see. Overheating beyond that causes permanent damage to the engine. Damage is accumulative so if you continue to over fuel and overheat you will eventually melt a piston and that will essentially ruin an engine when things come apart.

Here is a link to the report.

http://www.jatonkam35s.com/DualEGT.pdf

You can do as you wish and the results will become obvious if you do not approach this carefully and with some means of accurately reading EGTs.

RL

Someone's been copying Gail Banks.

 

[rlwm211]

Here is the link to the original thread which was on the Steel Soldiers site. I did add some information that I copied off a site to help explain why excessive EGT's are destructive no matter how short the time period is.

I explained clearly what my intentions were in offering this information.

Once this project was completed I combined all the posts and additional information in a PDF and made it available through JATONKA's site.

Here is the link to the original thread.

http://www.steelsoldiers.com/deuce/69213-changing-head-gaskets-dual-egt-gauge-test-program.html

If I made any impression that this information was from me, I was not attempting to do so and regardless of the attribution the information is accurate and useful as it applys to pretty much all applications.

RL

 

[Flyingvan911]

Pre turbo I wouldn't take it above 1300F. Alum melts at a little over 1200F (although these are an alloy metal and are cooled by oil).

Smoke and EGTs are linked together.

Also know, the turbos on multifuel engines weren't there for performance at all. But to help cut down on smoke at STOCK power levels. The C and D turbos are a stoneage design with a poor map.

I upgraded the map on my C turbo to a GPS.

 

[patracy]

I upgraded the map on my C turbo to a GPS.

I upgraded the powerband in my deuce as well. I've got one of the faster red ones now.