rpms ??

[hoytultratec]

i have a mercruiser 488 3.7, does anyone know what my safe max rpms is.

thanks

hoyt

 

[Bondo]

Re: rpms ??

4200/ 4600rpms I believe,.....4800 would be Straining her.......

 

[hoytultratec]

Re: rpms ??

thank you, i havent gone over 4100 yet so i will keep it at that.

thanks again

hoyt

 

[180shabah]

Re: rpms ??

thank you, i havent gone over 4100 yet so i will keep it at that.

thanks again

hoyt

Was that WOT???

If so you are still strainin' her.

 

[hoytultratec]

Re: rpms ??

no that was not w.o.t still had more to go....still straining it at 4100 rpms????

that doesnt sound to high i thought i read some post a while back that it was like 4600 rpms???


hoyt

 

[laurido92]

Re: rpms ??

I have a Mercruiser 5.0L 260 MPI and it says that max RPM is 4800-5000.

 

[180shabah]

Re: rpms ??

I have a Mercruiser 5.0L 260 MPI and it says that max RPM is 4800-5000.

And????

 

[180shabah]

Re: rpms ??

no that was not w.o.t still had more to go....still straining it at 4100 rpms????

that doesnt sound to high i thought i read some post a while back that it was like 4600 rpms???


hoyt

Had 4100 RPM been your WOT RPM, it would have been too low

 

[hoytultratec]

Re: rpms ??

at 4100 fully loaded all lake michigan gear full tank 2 people speed was 32 mph im going to take it to 4500 see what the speed is thanks for the help.

oh yeah i have a 19 pitch aluminum prop.

thanks

hoyt

 

[180shabah]

Re: rpms ??

Actual speed in a boat is irrelivent, you need to fill the boat with a normal load(people, gear, fuel, etc.) then open it up and find out what your MAX RPM is at Wide Open Throttle. This will determine if the prop you have is correct. Your boat only has a single speed transmission, fine tuning is done by matching the prop to the boat/load/engine. If you are overproped, then you will be constantly lugging the engine, if you are underproped, then you will have great hole shot, but bad cruise economy and you run the risk of over-reving the engine.
I am not sugesting that you need to run WOT all the time, but you need to periodicaly to stay on top of your boats condition. FYI, I run two different props, a 21" for cruising, tubing and some skiing, and a 19" for larger skiers and slaloms.