I always get confused reading some American books or articles where they list the HP of an engine as a different size to the UK/Europe, can anyone list the equivalents for reference?

Thanks :beer:

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All i know is that 16.5cc = 1 cubic inch :wink:


Andy W

It's also 16.5 ML, and 16.5 grams of water.

The way I've always understood it is that the Americans measure HP with the fanbelt off, and the Germans measure (DIN) HP with it on.

So, the Yanks always seem to have more powerful cars as there's no big fan to spin.

German-----American

25 horse = 25 horse (never seen it quoted higher?)
30 horse = 36 horse
34 horse = 40 horse

And so on...

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UK 25 = US 25
UK 30 = US 36
UK 34 = US 40
UK 40 = US 50
UK 44 = US 53

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1 DIN PS = 75 kgm/sec ( DIN : a weight of 75 kilogram to be lifted 1 meter high in 1 second)

1 SAE HP = 76,04 kgm/sec

SAE HP rating is always more than DIN HP for the same engine.
It has to do with the power of an engine measured with all its surplus aggregates like waterpump, fan, dynamo, fuel pump, oil pump, air filter and exhaust. This is the real praxis or DIN way.

SAE way is the power of an engine without these parts attached.

100 SAE HP is about 85-90 DIN HP (10 to 15%)

And then some.....

Do I make myself clear?:rofl:

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OK, next question... what are the cc's of these engines?

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UK 25 = US 31 - 1131cc
UK 30 = US 36 - 1192cc
UK 34 = US 40 - 1192cc
UK 40 = US 50 - 1285cc
UK 44 = US 53 - 1493cc

Some books say 31hp for the US output of the 25hp...but I think most of the Vintage crowd in the US call it the 25hp too.

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Wasn't there a 998cc engine as well?

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Can't find a 998cc but the pre-war prototypes were 985cc.

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I'm sure I've seen references to Kübels with 998cc engines?

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