Redline on 275 Merc

[RaceCarRobbie]

I was wondering if anyone knows the redline or max RPMs I should be turning on my 1993 275 Mercury. Thanks in advance.

-Rob

[cm21]

I was told 5500 when I had my 1991 275.

[LI SUPERBOAT]

yeah 5500 max rpm

[21eagle]

are these motors any good??? i know parts are hard to come by but do they produce decent power????

[mach351]

Big power and they will last if you keep them within thier design perimeters - i.e. NO high rpm!

[SPRKY01]

I have a balanced 3.4 300+hp at 150# comp with alu flywheel on a mirage with about 90 hours that i turn between 6,500 and 7,000 rpms with a 32 inch mazco four blade.Keep it below 6,000 rpms on a stock motor with good oil and you should be fine.

[AirRide]

I have a balanced 3.4 300+hp at 150# comp with alu flywheel on a mirage with about 90 hours that i turn between 6,500 and 7,000 rpms with a 32 inch mazco four blade.Keep it below 6,000 rpms on a stock motor with good oil and you should be fine.Good luck with that.

[21eagle]

i guess you mean this is way too much rpm's ?????

[LI SUPERBOAT]

yeha maybe he get away with 6000-7000 rpm ,becusue it on a miarge,weight to power ,it s like a 200 that revs 6500 -7000 on a lite hydrostream ,you dont get that out you fishing boat,better stay safe 5500 and the motor should live ,if not time bomb

[MODVP22]

Raceman has a good bit of knowledge of these engines.

[Capt.Insane-o]

Excelent motors if kept in their rpm range.

[SPRKY01]

I have owned eleven 3.4 300s and 275 hps the cosworth is a totaly redesigned and updated motor from the first 3.4s I have ran these motors on a custom built 32'sport fish center console. ON my 32' i would run 145# comp at 6,200 rpms with 93 octane at 40 to 1 pennsoil synthetic . I run offshore between 50 miles to 100 miles a day easly i have owned this boat for the past 10 years and have put thousands of gallons of fuel thru these motors . I have learned a lot about them thru daily use. I install holley fuel pumps to keep a constant supply of fuel always 93octane good oil and water seperators.They are a great torque motor for heavy loads but like with any thing you should always follow the merc manuals specs. LIKE EVERYONE ELSE.

[MODVP22]

I have owned eleven 3.4 300s and 275 hps the cosworth is a totaly redesigned and updated motor from the first 3.4s I have ran these motors on a custom built 32'sport fish center console. ON my 32' i would run 145# comp at 6,200 rpms with 93 octane at 40 to 1 pennsoil synthetic . I run offshore between 50 miles to 100 miles a day easly i have owned this boat for the past 10 years and have put thousands of gallons of fuel thru these motors . I have learned a lot about them thru daily use. I install holley fuel pumps to keep a constant supply of fuel always 93octane good oil and water seperators.They are a great torque motor for heavy loads but like with any thing you should always follow the merc manuals specs. LIKE EVERYONE ELSE.

Great info. Don't you have one of these motors on a lighter boat also?

[modvp]

Here is a little history I found on the merc 3.4 EFI: http://i61.photobucket.com/albums/h53/blkmtrfan/merc300/moth09.jpg

I've owned a 1985 3.4 and if I remembered correctly, my rev limiter (which I later disabled) was set at 5800 rpm and operation range for the engine was between 5300-5800 rpm.

[max200]

Saw these today you guys might be interested!
http://treasure.craigslist.org/boa/1401329152.html