M59 and EGR Valve

[kuboman]

My mistake, I was thinking of a different engine. The 5740 is timed to 10.25*btdc. It would definitely benefit from advancing the timing. Less smoke, more power and better fuel efficiency.

 

[rScotty]

My mistake, I was thinking of a different engine. The 5740 is timed to 10.25*btdc. It would definitely benefit from advancing the timing. Less smoke, more power and better fuel efficiency.

Kuboman, I'm glad you corrected that number. It's making more sense now. Ten degrees is the OEM spec for our EGR equipped 2.4 liter motor - and I agree that the performance could benefit just as you say with some more advance. Just how much to advance it is the question, and I'm not sure how to go on that. How are you measuring that angle?

For the non-mechanics out there, there are several different methods used to measure any kind of cam lobe timing...and just like the engine valves do, our injection pumps respond to a lob on the camshaft. But unlike engine valves or gas engine spark timing - both of which are easy to measure - the entire fuel injection process takes time for the fuel to move up from the pump and out the injector nozzle. So how we measure the injector timing makes a difference. Do we want to measure the timing when the injector cam begins to deliver fuel? (easier to do)....Or do we do it later when the spray actually happens? (more difficult). Due to fluid lag time, the different methods will give us different degrees BTDC.

In the shop manual, Kubota bases their 10 degrees BTDC on their own measurement method which they go into in good detail. I like their method because they are measuring the crank angle while the injection pump is in mid stroke and has just pushed fuel up to the level of the injector nozzle. By doing that, they are compensating for some of the injection lag.
rScotty

BTW, I'm still feeling a lot better about the soot my Kubota's motor makes when I throttle up. At least now I am beginning to understand why it smokes and what trade-offs were made to make it so. One big trade-off is the soot/N0x ratio which was mandated by the "interim Tier IV" emissions legislation back in 2007.

 

[kuboman]

Kuboman, I'm glad you corrected that number. It's making more sense now. Ten degrees is the OEM spec for our EGR equipped 2.4 liter motor - and I agree that the performance could benefit just as you say with some more advance. Just how much to advance it is the question, and I'm not sure how to go on that. How are you measuring that angle?

For the non-mechanics out there, there are several different methods used to measure any kind of cam lobe timing...and just like the engine valves do, our injection pumps respond to a lob on the camshaft. But unlike engine valves or gas engine spark timing - both of which are easy to measure - the entire fuel injection process takes time for the fuel to move up from the pump and out the injector nozzle. So how we measure the injector timing makes a difference. Do we want to measure the timing when the injector cam begins to deliver fuel? (easier to do)....Or do we do it later when the spray actually happens? (more difficult). Due to fluid lag time, the different methods will give us different degrees BTDC.

In the shop manual, Kubota bases their 10 degrees BTDC on their own measurement method which they go into in good detail. I like their method because they are measuring the crank angle while the injection pump is in mid stroke and has just pushed fuel up to the level of the injector nozzle. By doing that, they are compensating for some of the injection lag.
rScotty

BTW, I'm still feeling a lot better about the soot my Kubota's motor makes when I throttle up. At least now I am beginning to understand why it smokes and what trade-offs were made to make it so. One big trade-off is the soot/N0x ratio which was mandated by the "interim Tier IV" emissions legislation back in 2007.

I actually pulled the figure off the engine spec plate. With shims it takes the guess work out of timing as each thickness of shim changes timing a specified amount. I think you could advance timing 2-3* quite safely. Maybe more, i haven't studied up enough to know if these engines have a mechanical advance built into the injection pump.

 

[caballero59]

I suppose this 10 deg timing will work if the tractor is operated at low rpm's. I would like to know how many shims for optimal operating between 1700-2300. I seldom wrap it out to max speed.