230sl Horsepower

[John Betsch - "SADIE"]

I'm a bit confused  Everything I read always notes 150hp for my 230sl but my owners manual lists horsepower as 170hp.  Whats the difference between SAE and DIN numbers

[dirkbalter]

DIN measures the power with all standard accessories installed, the way the engine is used.(if power steering or AC is option, than this is not installed, if standard, it should be hooked up).

SAE meaures the power without many accessories (alternator, water pump [basically anything belt driven], air filter, muffler etc) to get the max value engine can produce, leaving the way this is utilised to the imagination of the end-user.

[paults1]

I always thought that the 150HP was at the rear end, the 170HP was at the flywheel. Guess I have been wrong?.

[Benz Dr.]

150 HP would be very optimistic even on a good day.

[neelyrc]

Whats the difference between SAE and DIN numbers

Very little! DIN HP= 735.5 Watts vs. 745.7 Watts for SAE.  DIN is the German Standards Institute, SAE is the Society of Automotive Engineers. European vs American standards.  The difference is a result of a different calculation method.  Practically, they can be used interchangeably.  I haven’t read the standards but I understand both are measured at the flywheel.

By present European regulations horsepower units can only be used as supplemental information.  Power must be stated officially in Watts.

[John Betsch - "SADIE"]

Thanks to all who solved my dilemma  JB

[MikeSimon]

dirkbalter is correct. The difference comes from the variation in specification for engine test. Result is taken at flywheel in both cases, but DIN considers all accessories necessary to have the engine run by itself, e.g. alternator, fan, water pump. Power steering or a/c is never included, however. SAE allows engine to run w/o accessories, e.g. ignition by battery, remote cooling etc. The old DIN spec to measure horsepower was 70020

Don't let anybody tell you there is a formula to convert from SAE to DIN or back. Due to the difference in specific accessories, this is not possible in general.

Also, the tolerance rating for internal combustion engine output is generally +/- 5% from blueprint, e.g. an engine with nominally 100hp could be anywhere between 95 and 105hp, in 98% of the cases it is lower.