Cruisie rpms vs wot rpm's

[Darrendude]

I have a 77' mercruiser 120 ser # 452******x, what is a safe max cruising rpm? WOT rpm sez 3900-4300 in the manual.Is it 70-80% of wot rpms?<br /><br />Thanks

 

[tommays]

Re: Cruisie rpms vs wot rpm's

D<br />there is no 100% answer for you question but personaly on my 3.0 LX which has a WOT of 4800 i dont like to run above 3800 for long periods<br /><br />i could probaly run higher but its the highest i feel will give a long motor life<br /><br />tommays

 

[cmyers_uk]

Re: Cruisie rpms vs wot rpm's

My WOT is 4600 rpm , I do long cruises at 3000 rpm which for me gives the best balance between speed and fuel economy. I figure its the same as me driving my car along the motorway at 70.<br /><br />Regards<br /><br />Chris

 

[Darrendude]

Re: Cruisie rpms vs wot rpm's

Does anyone know what the manufacturers recommend as far as cruising rpm's are. Seems like a pretty pertinate question. They certainly could mean its ok to drive at WOT all day.<br /><br />Another question ....is my engine a ford or a chevy? I think its a chevy, but not sure.<br />Thanks again

 

[Dunaruna]

Re: Cruisie rpms vs wot rpm's

"Cruising' is a relative term. Every boat has a 'sweet spot' - the place where RPM, speed, fuel economy and comfort all come together for a not to loud, comfortable ride. Some cruise at an RPM that is just before the secondaries open. Some people back of full throttle until they are just on plane. Its different for everyone. <br /><br />The manufacturer cannot give a 'cruise' RPM, they don't know how much weight you have on board, they don't know what conditions you are boating in. <br /><br />Generally speaking, anything between 2000 & 3500RPM is cruising. <br /><br />Aldo

 

[Don S]

Re: Cruisie rpms vs wot rpm's

Generally speaking, anything between 2000 & 3500RPM is cruising.

To add to the above statement, as long as you are up on plane. On many boats operating at an rpm just below planing speed takes more gas, more power, is slower, and the bow is way high making it hard to steer and see.<br /><br />Do Some test runs and get used to the boat. It won't take you long to find out what rpm you like the best. <br />It's a Chevy engine.

 

[Darrendude]

Re: Cruisie rpms vs wot rpm's

Thank Don and Aldo you have been very helpful. I had the boat on the water today for the first time , seems to run pretty good for a $200 boat. Still cant seem to get the tach to work. When I turn the key on the tach pegs the needle. All the wiring looks to be connected right. Its the factory tach in the dash.