Marathon, 7.8KW, 1800 RPM, Single Bearing, Pancake Generator End with AVR

[RJ]

Very bummed that I missed these!

Don't know when the thread got moved, but if it moved while they were still available, that is a problem imho.

Often, I skim the parts of interest thread very quickly and move on because I don't have time to read the whole forum.

HUGE bummer as I would have snagged a couple of them for my baby cat diesels.

Steve

Steve, I'm sorry you missed them. I mentioned them to Henry in a PM over a month ago when I noticed them first pop up on e-bay. We both have similar engines so I thought it might be a good match for his setup as well. I actually just saw this thread yesterday for the first time so I really don't have any idea when, or if it was moved. I wanted to get a few of them a well, but could only swing one at the moment.

[Henry W]

Hi Steve,

I moved and modified the topic aprox. three hours after they were sold out.
I believe there were 11 available when I first looked at the link that RJ sent to me over a month ago.

I forgot all about them until stumbling upon them on March 31st because I had another genhead in mind.

There were 8 available on april 3rd and I had no idea they would sell all in a short time.

My fault. I should of posted them when I stumbled upon them again on March 31st.

My apolagies,


I just stumbled upon something.

I will PM you about the find.

Henry

[RJ]

Hi RJ,

The Kubota D1005 is a 5 series three cylinder engine.
The bore is 4mm larges than the D905. The stroke is the same. Pretty much everything is the same as the D905.

The D1005 engine has an aprox net cont. Hp of 11.7 at 1800 rpm with aprox 34 ft-lbs of torque.
The D1005 engine has an aprox gross int. Hp of 13.1 at 1800 rpm with aprox 43 ft-lbs of torque.

It should be a pretty good match for the 7.8Kw genhead.

The D905 engine is rated only 2 or 2.5 Hp less with aprox 4 ft-lbs less torque. Not much of a differance. I feel it will also be a good match for the 7.8Kw genhead.

Henry

Henry I think you hit it on the nail, I stumbled on this publication from Kubota and it should give us a good idea for these engines. This states the D905 is good for 8.9 KW Standby and about 8kw con't duty. It states the D1005 is rated for 9.8kw standby and about 9kw con't.

[Henry W]

Hi RJ,

Thanks for posting the link.

Yes there is about a 1Kw differance in producing electrical power on the D905 and D1005 engines.

About Kubota's numbers, I feel they are high.

Most generator manufactures that use Kubota D905 and D1005 engines have more conservative numbers like:
D905:  7Kw continuous
D1005:  8Kw continuous

I feel the conservative numbers most manufactures use are still a bit high.

I would rate them:
D905:  6Kw continuous
D1005:  7Kw continuous

I feel it would be better to take the more conservative approach.

At least we know what these engines are capable of producing for standby power.

A word of caution!!! I spoke to an application engineer from Kubota about a month ago and he said he seen these engines on 1800 rpm generators have over 40,000 hours on them.

Back to the Marathon Genhead. I will start assembling it soon. I hope to have it ready to test run some time next month. I am looking forward loading it up and see how it does. I don't know what numbers we will be looking at but I think they will be pretty good.

Henry

[Henry W]

I just talked to Marathon tech support and gave them the model and serial number of the generator head I have and I just found out the Starting Current Surge on these Generator heads are 75 amps @ 240 volts . That works out to be 18,000 watts surge.

Henry

[Henry W]

I was given a Performance Data Sheet for this Generator head. The only differance is the head model number is for an OEM Genset manufacture. And the generator head is conservatively rated. So this Performance Data Sheet shows what this generator head is capable of producing.

Henry