Small Indian diesel engines, the kind Rajkot is known for, commonly run from a few horsepower up to roughly 20 to 25 hp with one or two cylinders. Above that, you move to multi-cylinder engines, which larger Indian plants build into the hundreds of horsepower and beyond for gensets and industrial use.
The exact range differs by maker, so treat any figure as a starting point and confirm the model list with each factory.
Read the rating, not just the number
A horsepower figure means little until you know how it was measured. Ask the factory which of these it is quoting:
- Continuous power, which the engine can give for long hours without harm.
- Intermittent or maximum power, which it can give only for short periods.
- Power at a stated speed, because the same engine gives different power at different rpm.
- Power under stated ambient conditions, because heat and altitude reduce output.
Standards and units
ISO 3046-1 is the usual reference for stating the power of reciprocating engines and for derating them for site conditions. Ask the factory to state power to that standard, or to explain the basis it uses.
Also check whether the quoted figure is in metric horsepower, imperial horsepower or kilowatts. The difference between metric and imperial horsepower is small, about 1.4%, but kilowatts are clearer. One kilowatt is about 1.34 imperial hp.
How makers build their ranges
Small engine makers usually offer a ladder of models within one or two engine families. Each step up in power comes from a larger bore, a longer stroke, a higher speed or a second cylinder. Engines in the same family often share many parts, which helps you keep a smaller spares stock.
When you compare ranges, ask which models share parts and which are one-off designs. A range built on a common family is easier to support in the field. Also ask which models sell most in India, because these are usually the best developed and the easiest to get parts for.
Match power to the load
The engine must cover the shaft power the driven machine needs, plus losses in belts or couplings, plus a margin. For a pump, the shaft power comes from flow, head and pump efficiency, as explained in reading a pump curve. For a genset, see genset kVA ranges, because electrical output is lower than engine output.
An engine sized right at the limit will run hot and wear fast. An engine sized far too large will run lightly loaded, which in diesels can cause carbon build-up and oil in the exhaust. A sensible margin sits between the two.
Next step
We compare model ranges across makers and check that rated power is backed by test records. To shortlist engines for your load, book a free sourcing review.