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Omc '84 i/o 2.5 l 252sthrcra rpm

fishergirrl

New member
Hey, I'm looking to find what the RPM should be when the engine is wide open on an '84 OMC I/O 2.5L engine (model 252STHRCRA.) We bought the boat used and it didn't come with the owners manual. Right now we're specifically wondering about the RPM to replace a prop, (we don't know if the prop on it is the ideal, but we heard you can find out the ideal by using some equation with the boat's current RPM and the ideal RPM when it's wide open.) If anyone is an expert on this engine and has any other helpful advice, we'd love to hear anything you have to give us! This is our first boat, so we are soaking up all the info we can. Thanks!
 
Hey, I'm looking to find what the RPM should be when the engine is wide open on an '84 OMC I/O 2.5L engine (model 252STHRCRA.) We bought the boat used and it didn't come with the owners manual. Right now we're specifically wondering about the RPM to replace a prop, (we don't know if the prop on it is the ideal, but we heard you can find out the ideal by using some equation with the boat's current RPM and the ideal RPM when it's wide open.) If anyone is an expert on this engine and has any other helpful advice, we'd love to hear anything you have to give us! This is our first boat, so we are soaking up all the info we can. Thanks!

around 4000 rpm with a 13.75 x 19 prop
 
Ayuh,..... Yer luggin' yer motor,...... drop down to a 17" pitch,....


i get 30-32 mph on a 19p at 4000 -4200rpm with 4 souls on board....18.5' renken bowrider 995
2.5l omc 400 stringer its an 83 original dont really want max rpm 17p prop would raise rpms beyond 4000- 4200
 
FYI.... and for what it's worth....... the OEM WOT RPM rating for a given Marine Engine is a Test RPM ONLY...... it is not an RPM that is to be sustained for any duration (unless of course, you wish to drastically shorten the life of your engine).

The test is used to determine if your drive reduction and propeller size/pitch are correct for the engine and hull.




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