1988 classic fifty 4 cyl. rpm question

[verado7]

i want to hear your guy's thoughts on the max rpm for this motor - it's the same block used for 44xs builds and the best year to use - my motor is bone stock and the rec. rpm range is 5000 - 5500 rpm - however this motor makes a great deal more power at 5600-5700 rpm and i dont see any lean conditions - i know you can push some motors more than others and want to know if this safe to do on this motor or how high one would go - i have pushed it to 5800 but that seems to be the end of the power curve - i use xd50 oil ( syn. blend ) anything i should consider if i want to run at these rpm's ? i only go short trips out to fishing ( 20 minutes ) . but i like the speed - LOL .

[Tim Weber]

i want to hear your guy's thoughts on the max rpm for this motor - it's the same block used for 44xs builds and the best year to use - my motor is bone stock and the rec. rpm range is 5000 - 5500 rpm - however this motor makes a great deal more power at 5600-5700 rpm and i dont see any lean conditions - i know you can push some motors more than others and want to know if this safe to do on this motor or how high one would go - i have pushed it to 5800 but that seems to be the end of the power curve - i use xd50 oil ( syn. blend ) anything i should consider if i want to run at these rpm's ? i only go short trips out to fishing ( 20 minutes ) . but i like the speed - LOL .

The racing version easily turns over 7000 rpm. To do this, you need more oil than 50:1. In the ancient days of 55H and 30H Mercs we ran 2 quarts of oil to 5 gallons of gas. I would run at least 30:1. It might smoke a little but oil is cheaper than parts.

Tim

[Trident]

But to consistently run lots higher RPM, like a 44XS, the motors are NOT bone stock. They have plastic reeds and are generally set up looser than stock (all mine are, including the one I run on a shifting LU on a 16 1/2' Lund)

Having said that, with good fuel (no ethanol), good oil and plenty of it, any of these motors can run safely to 6000 rpm all day...

Hope this helps.

Jerry

[Mark75H]

But to consistently run lots higher RPM, like a 44XS, the motors are NOT bone stock. They have plastic reeds and are generally set up looser than stock (all mine are, including the one I run on a shifting LU on a 16 1/2' Lund)

Having said that, with good fuel (no ethanol), good oil and plenty of it, any of these motors can run safely to 6000 rpm all day...

Hope this helps.

Jerry


I agree

[verado7]

thanks guy's i appreciate the info - it sure does run alot better at the higher rpm's - i will add some extra oil to my main tank - i use one tank for getting to and from fishing grounds and a second for trolling - i ditched the autoblend when i got the motor - i could never get myself to trust those things . i have to say this is the best merc. i have ever owned - they've all been good but this one stands out for sure - it's mounted on a 1972 15'5 sangster -
again thanks for the info -i feel alot more confident running it higher now .