Merc 2.5L on Seafari?

[McGillicuddy]

I noticed the 2.5L Mercury from the 90s weighs in at about 350#. Seems very light for a 245hp motor. Can I put one on the Seafari 20 or is that suicidal torque on the transom... And did they make lower horse (> 115) in that weight class?

[Blue197320]

i think the 200 is also a 2.5L ive got a 2.4L and its great. i think the 2.5 is fine for it

[Fr. Frank]

The 2.5L is fine for a solid transom. My '72 Seafari has the original metal decal saying it's rated for 240 hp. Most say 175hp, or 140 hp. There's a '71 CC locally with Yamaha 250 2s mounted on Porta-bracket.

[Bigshrimpin]

2.4L mercs were the lightest (Late 70's 339lbs)
Mid - 80's 2.4L 200's were 363lbs
92 - later 2.5L (150 - 260) were about 390.

I don't have the specs on the race motors
245, 260, 280 . . . They had a different trim setup with the HUGE single ram pistons like the 84 and earlier Mercs with an external pump.

After messing around with the motor height . . . I can just touch 50mph with my seafari and an old old Merc Vertical Reed 2.4L 200 (really 175ish) with a 19Pitch Mirage plus.



2.5L Mercs are pound for pound the meanest motor out there. These motors have a LOT of bottom end torque and they pull HARD all the way up to WOT. I like the 2.4's b/c of the economy, chrome bore cylinders, and light weight. a 2.4L 200 has better fuel economy than the 2.5L 150 EFI Or Carb.

[Bigshrimpin]

2.5L 280
http://www.youtube.com/watch?v=RT1N6...eature=related
2.5L 260
http://www.youtube.com/watch?v=wy8mz...eature=related
2.5L drag => 348 on a Dyno
http://www.youtube.com/watch?v=mM9l774zLo4

[Blue197320]

big, is 5800 rpm too much for a 2.4L? the prop im looking at has been used on here with a 20sf and 200 merc and gave 5800 rpm and 58mph. its a 13.75x21 stainless. they make the same size in aluminum that i was going to get.

[clb33fyxj]

http://www.youtube.com/watch?v=RLbV1hoeQ1s

twin 2.5 race O/B's. gotta love the sound of 7500rpm. the boat in the vid will do over 100

[Bigshrimpin]

5800rpm is what I prop mine for . . . 5800 is the max recommend RPM in the factory manuals for the 2.4L motors. Without the spark advance/idle stabilizer module and the oil injection they're good way above 5800rpm.

[Fr. Frank]

Blue, my target RPM for my 2.4L on the back of my '72 Seafari was 6000. I actually turned 6050 at WOT, trimmed out, 1 person and 30 gallons of fuel with my reman'd 2.4L XR4. Originally 150hp, it dyno'd right at 190hp after the rebuild. I was turning a custom made 15.25"X16.5"P PowerTech OFS 3 blade. (still have the prop, the motor was sold)

Fully loaded, with 7 persons, 30 gallons of fuel, fishing gear and a full live-well, I could still turn 5700-5750 rpms. I wanted to be able to turn the maximum of the reccomended maximum rpm range with the boat a maximum load. I call that running "max of max at max" That way I'm never over-propped so that I cannot take advantage of the full power of my motor in an emergency.

BTW, Tim, on a cold day, after I had about 20 hours or so on the motor and my new prop, I once ran downwind in a light chop, 2 guys on board, and about 10-15 gallons of fuel, and ran and maintained 46 knots on the GPS, or about 53 mph for more than 10 minutes with that XR4 on the back of my Seafari. Had a nosecone and LW pickup, too. Threw one heck of a rooster tail for a Seafari, had to be 8-10 ft high. And yes, that's right on the edge of chine-walking for my boat. Actually fell into a chine walk a couple of times before re-stabilizing.

The reason? Trying to get in off the Gulf of Mexico from 20 miles out before the really nasty squall hit. We made it, too.

[Bigshrimpin]

http://www.youtube.com/watch?v=5b90Fq7Cmvk

http://www.youtube.com/watch?v=5UG61hdwxjg&NR=1