Longevity HR3 vs HRG3

[Blister]

Which will longer, a HR3 or an HRG3?

Can an HR3 be run on straight wood gas? What kind of power loss would one expect using wood gas?

Thanks!

[dieselgman]

Both engines (HR3 and HRG3) share the same displacements and bottom ends. Given the right routine maintenance for both engines, the gas powered unit will be expected to far outlast the diesel due to much less oil contamination and lower compression ratios - in general less horsepower output and a much cleaner fuel burn equals a longer lived engine.

I have seen the HRG run on straight wood gas, but the quality of the feedstock is a huge variable and dry properly filtered gas is necessary. Sour or contaminated gas will quickly coke up and stop an engine. I have not seen one of the diesels augmented to run wood-gas, although I don't know why that could not be worked out since propane auxiliary fuel has been used. You would still have to run diesel to get the unit up to combustion temps and probably could not completely shut off the diesel feed for the ignition to remain consistent.

If you compare caloric values of the fuels, you will find that wood gas has a lot less btu capacity in the internal combustion application assuming the same displacement engine. Knowing exactly how much in actual practice... very difficult because there is such a wide range of variable gas qualities and actual chemical make-ups involved. Just as a wild off-the-cuff guess I would have to say something about 20% to 25% less actual horsepower output. I can get you the published specs comparing Natural Gas with Diesel fuel but that does not exactly translate to accurate values for wood gas.

dieselgman

[listard-jp2]

Both engines (HR3 and HRG3) share the same displacements and bottom ends. Given the right routine maintenance for both engines, the gas powered unit will be expected to far outlast the diesel due to much less oil contamination and lower compression ratios - in general less horsepower output and a much cleaner fuel burn equals a longer lived engine.

Totally agree with your assessment, but not having had any exposure to Lister HRG engines myself, could you comment on what you would expect valve seat wear to be like, when compared to the HR engine. As gaseous fuels such as LPG / Methane are known to be very unforgiving on valve faces and valve seat inserts.

However it may be different on the HRG engines as the crankcase oil vapours are vented into the inlet ports, which would have the effect of giving some upper cylinder lubricant.

[dieselgman]

The HRG uses specially hardened valves and valve seats as well as specially hardened nodular iron rings. These modifications allow them to handle the extra stresses involved, otherwise I am sure the failure rates would be quite high and engine life-expectancy low. Lister bragged pretty big about the longevity of this particular engine type. The parts costs are quite high compared to other Lister models.

dieselgman

[Blister]

Thanks for you very thorough replies!