1E080667
Other than the LU's and solid mounts is there any difference or is it the same motor?
1E080667
Other than the LU's and solid mounts is there any difference or is it the same motor?
Not many others... decals, gearcase choice, mounts, PCM calibration seem to be the main ones.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Last edited by 21xTriton05; 12-01-2019 at 06:51 PM.
The 300R has oil cooler but not the 250R.
When you have time can you eloborate?Originally Posted by EuropeanAM
Not much to elaborate (other than using more words to say the same thing). Keep in mind I simply don't have time to compare every part number of one serial number and another "assumed model number"... but I did take the time to compare the main/common differences.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Not asking for other differences. was hopeing you could explain in laymans terms what difference performance wise "PCM calibration" could make ?
Not many others... decals, gearcase choice, mounts, PCM calibration seem to be the main ones
PCM info is no longer published in the Parts Catalog- the PCM itself (and calibrations) are available through Mercury Warranty Service.
Any differences I might list would be pure speculation as we're just not privy to the engineering details.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
If you’re asking if the cals are identical I don’t think it’s easily answered. But are you asking if they are calibrated for the same power and torque?
Yes sir.
The reason for asking in the first place was trying to determine if there is any performance advantage between the powerheads.
When comparing apples to apples are they basicly the same ? Could my 250R powerhead just as easily be placed on the same model of 250XS
Always before there was some distinct advantage to having a motor from the racing division.
Case in point the 300R is lighter, turns more RPM, oil cooler, and has a different intake mannifold than its counterpart the 300XS
From the ARB filings, it looks like the 250 posXS and R have identical factory power and torque ratings (275 hp 312 ftlb) at identical engine speeds (5500 and 4500, respectively). Interestingly, some of the 300’s have the exact same power rating as those two engines as well. You are keen to ask, as the 300’s come in at least 3 different power ratings (275, 295, and 315). There is a prestige factor but the biggest performance difference is going to be due to the lower unit.
Even then its dependent on the boat if the sports master lower unit helps or hurts the performance.
I just missed a great deal on a slightly used SM . Was taken off a new 300R and replaced with a TM.
Those horse power numbers suggest lot's of room for performance upgrades on the V8.
Mike- we've been through this several times with others in the past. Numbers found in California Air Reforces Board filings are for emissions filings- they often do not reflect real "where the prop meets the water" Propshaft HP and Torque that can be attained at WOT. For this reason, we do not rely on that information (and really prefer it not be used here in the forums, especially since "4500 and 5500 respectively" are not ratings that anyone posting about a 300R in these forums are going to be significantly interested in comparing.
Every one of them should be looking at or very close to 6350 RPM's.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
The 5500 and 4500 was in reference to the 250r/250 proXS power and torque peak rpm, which both engines share. The stated figures for the 300r are 6250 and 5000, respectively.
Last edited by engineermike; 12-08-2019 at 03:12 PM.
The HD SM lists for around $9000 so if you run across a deal on one id jump on it. I don’t know if the v8 and L6 lower units interchange, but if they do and enterprising person could also use it to upgrade a 350 or 400m.
Even then its dependent on the boat if the sports master lower unit helps or hurts the performance.
I just missed a great deal on a slightly used SM . Was taken off a new 300R and replaced with a TM.
Those horse power numbers suggest lot's of room for performance upgrades on the V8.
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