ST, SR and LD series differences?

[Bablitz]

I am looking for information about differences between the ST, SR and LD series such as rpm range and injection type. I am going to visit a fellow this weekend that has about 20 of the SR1's he says, some with genheads on and some without in various states of repair, but I suspect that he may have a mixed bag of these types. I am looking for the best type of these series to mate up to an Utterpower PMG and utilize various fuel types. any info would help.
Thanks in advance
Bud

[SHIPCHIEF]

I have an SR2 powered genset, it's rated @ 6.5 Kw @ 1800 RPM. It's a US Govt contract 'Long Run' generator, so it might be a little under rated, it does have a 10 KVA alternator attached.
You can extrapolate from there...

[listard-jp2]

The LD engine is the lowest powered version of the three types you mention, it was a common fitting in cement mixers in the UK (typically about 3 BHP). The ST is the more desirable engine (upto 10 BHP / Cylinder), and can be recognised by having the lower half of the cylinder head cast in Aluminium.

The ST is a very good engine, but has a weakness in the cylinder head, as they will crack between the injector hole and exhaust valve seat if the injector holding down nuts are wound up to tight.

Second hand heads are very sought after for this reason, but the Indians are now casting these items in either Aluminium or cast iron.

All of these engine are direct injection, but the LD uses a pintaux stlye nozzle (which is unusual for a direct injection engine). These engines will run on veg oil, but the SR and ST require frequent injector cleaning when running on anything but diesel oil.