2610D Injector pump timing

[1danny]

The compression ratio for the 3T80 and the 3T84 are 21:1. Did you replace the complete injector assembly or just the nozzles? the fuel pressure should be 2275psi. The fuel pressure can be changed by adding or subtracting shims.

Danny

 

[rock2610D]

1st to Mech. I read what you said your manual states. I also have a manual that states my tractor takes 4.8 quarts of oil and it takes almost 7 quarts.

Doing some pressure, temp, and volume calcs I find in order for my tractor to reach a compression of 600 psi from standard temp and given a 1 cubic inch of combustion chamber, the temp of the compressed air would be at or just above 300 degree F. IE 26 cubic inches compressed to 1 cubic inch from about 32 degrees F, the compression alone would cause a TDC compressed air temp to be 300 degrees F. Seems a little high??? Even the low end of 568 psi implies a 272 degree F. TDC Compressed air temp. THE ONLY WAY YOU WILL GET TEMPS LIKE THIS IS IF THERE IS A TURBO OR BLOWER ON THE ENGINE. And that will be while running not while cranking. I feel your manual was in error.

On the other hand given 21:1 comp ratio and 400 psi TDC pressure... 26 cubic inches compressed to 1 cubic inch from standard temp and press I get.... an air temp of TDC compressed air to be 50 degrees F. So at about 32 degrees F the temp of the compressed air at TDC would be about 50 degrees. That sounds more reasonable.

Take all these #s somewhat lightly because of the thermal mass of the engine itself cooling/heating incoming air, plus other factors. But the jist of the matter is that from a engineering standpoint 600 psi on your tractor is probably not achievable with the starter on engine from factory. Given about 6 square inches of surface area on piston... 600 psi divided by 6 square inches = 100 pounds of force needed to push each piston up to TDC. 400/6 = 67 pounds of force 33% less. I bet our starters wont even crank an engine that has to have 600 psi of pressure.


1danny thanks for the info on the compression ratio, I did replace everything above and including the thermal washer. IE did not replace the copper washers or swirl chambers. Thanks for info on shims. Did that already I have a post on that issue. Shims change pressure which change the point(ADVANCED/******) at which the injector pops fuel into chambers.

 

[Mech]

Well I can't dispute your numbers but I did do a google search and found the following from a few different sites. In any case no matter what the actual temperature and psi my experience with two diesel tractors with Yanmar engines, one used and one new, at 8600 feet is that they need a warm engine or warm air to start easily.

Articles:
Air is drawn into the cylinders and is compressed by the pistons at compression ratios as high as 25:1, much higher than used for spark-ignite engines. Near the end of the compression stroke, diesel fuel is injected into the combustion chamber through an injector (or atomizer). The fuel ignites from contact with the air that, due to compression, has been heated to a temperature of about 700–900 °C (1300–1650 °F).

At the end of the compression stroke, the pressure in the cylinder can reach 500 psi or 34 atm and the air can be heated up to 1000° F or 530° C.

Diesel engines, by comparison, operate at compression ratios between 14:1 and 24:1. During the compression stroke, the temperature of the intake air rises to as much as 1400º F.

With the piston, having covered the intake ports, travels upwards, compressing the trapped air from its original volume to a fraction of it, generally anywhere from 17:1 to 23:1 (gas engines are about 9:1) to about 42 bars (~600psi). The air’s volume reduction crushes the air molecule together and as a result they build up heat.

Air is compressed to a pressure high enough for the adiabatic temperature to reach or exceed the ignition temperature of the fuel. Because this temperature is 1000°F (538°C) or higher, compression ratios of 12:1 to 23:1 are used with compression pressures from about 440 to 800 psi (3 to 5.5 megapascals).

 

[rock2610D]

Not quite sure how to intrupet the data you posted but on my diesel pick up with a EGT (exhaust gas temp) sensor 1600 degrees is the danger area(pistons, valves, head and such will melt), after diesel fuel ignites. I have to assume that when the diesel fuel ignites the mixture gets even hotter? That would mean 1600 degrees ++++ and metal I think would start melting. Data is intresting though. It could be true but a brief look at some of the language leads me to believe that this artical is talking about a detroit diesel which is a 2 cycle not a 4 cycle like we have.. 4 Cycles do not have holes that pistons cover up for intake and exhaust valves. 2 cycle detroits do I believe and I also belive they are supercharged, and since they do not persay have exhaust strokes and intake strokes seperatly they very well could have some of the numbers you quote... I personally would love for those #s to be true. Just cranking the engine would heat it enough to allow starting to occur.

It seems given your data that diesels do have EXTREMELY high comperssion temps. Diesel fuel probably has a pretty high auto ignite temp. other wise it would ignite when left out in the sun. Must be at least 200 degrees or better. To do this pressures must be quite high. Found this website that show ideal diesel cycle and auto calculator. Shows up to 1000 degrees!!

The Diesel Engine

At this point I am wondering what the addition of a diesel fuel heater woud do to help my starting problems?? Cant be a heater that goes over 200 degrees though, diesel will self ignite!!!