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Super M Motor vs. a 450 motor

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Skip Nelson

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Ok all Letter series Doctors. I have an opportunity to purchase a Super M w/f with a 450 motor in it. Would you say I would be better off with a Super M or this changed out one. Will I notice a difference in the Hp or not. I am a Super M nut but was wondering if their are any real advantages of this swapped out Super. No other mods are on it. The cost is relatively the same for either tractor. Thanks for your Red opinions!!
 
If you are looking to build a collector (since you say you are a SM nut) it should have a SM motor.

If I'm not mistaken you can build a 450 motor out of a SM block.
 
You can put the 4 1/8" "450" pistons in a C264 (Super M block) but there are other differences as well. The cam, carb, and head are all better versions then the Super M. Super M is around 48ish hp and a 450 is 58ish hp. If you were going to just use it then it would be ok, as a collector tractor id shy away. But im a purest.

Andrew
 
How do you mean "better off?"

If you want a running, useful tractor, this one's good, and the price is right, you're no better or worse off with this one.

If your goal is a "numbers matching" original, then you're better off with a "pure" Super M.
 
My SM was biult up to 450 specs. when I OHed it.It did give it quite a bit more power.If your a member of the 'Correct police',then you probably wont like it.Other than that,go for it,You will enjoy the extra power.BTW,a local fellow has a 248(M motor) in a 450.Makes a weak/sick 450!
 
By now about all SM engines have been rebuilt to the same cubic inch as a 450. If both used original gasoline heads the 450 would have more compression with standard pistons and its original camshaft and manifold also gave it a little more power. Lots of combinations of parts that could be put in over the years results in no clear cut answer to the question of performance. Also up into the 1960 tees IH sold replacement blocks with C281 on them that got used in SM tractors. Several around that just have the block changed with all SM parts used with the block. If thats what the tractor is you probably have the same setup as a SM with a replacement block hurting originality.
IH tests with fire crater standard altitude pistons used show only a 1.5 horse power increase with the 450. They recomended a 400 camshaft be used for more power in the SM and I think they used it testing the SM.
Also interesting was the fuel use at 1450 RPM. 450- 4.8 to 5.2 a hour.
SM-4.5 to 4.9 a hour.
 
Dave, i think you have the same serviceman's handbook that i do. did you ever notice that the 450 has .5 less horsepower and uses a little more gas and 3 less lbs. of compression with the replacement fire-crater pistons instead of the original flat pistons?
 
Thanks for all the replies. I should have said I am not interested in the authenticity of this particular purchase but more interested in the HP difference (noticeable) between the two: Super M vs a 450 in the Super M chasis. From the last two replies it looks as if the Super M has more hp then the 450. I would venture to say that a Standard Super M would have it over the 450 swap?
 
No. I think some people are confusing 400 and 450.


As tested by Nebraska:

M 33.1 HP drawbar, 36.07 PTO
SM 44.23 HP drawbar, 47.07 PTO
400 48.12 HP drawbar, 52.36 Belt (PTO)
450 51.28 HP drawbar, 55.28 Belt (PTO)


Go to external_link for more details
 
Randy don't have the same info you do. What I have shows both equiped with the recommended fire crater pistons should have the same cranking PSI.
But some other early info printed shows the 450 having a lower cranking pressure. Don't know if it was due to the different cams or not.
Course this is all just discussion now from years ago. In the real world now I have had a couple of M tractors with M blocks that would put it all over a lot of SM and 450 tractors.
Like autos that are supposed to be the same but some just run better than others.
Can't remember for sure without looking but think M&W claimed more power out of a early block with there parts than a 281 with there parts.
 
No you are talking original and we are talking about what maybe now. I'm guessing a fellow couldn't find on average one M or SM engine in 10 to 50 with the original bore now. Only original differance between a lot of 400 and 450 gas engines was 1/8 inch smaller bore in the 400 and a different manifold used on a 450. Most 400 were soon rebuilt to 450 specs and then it was a matter of the best tuned engine wich one made the most power.
 
Dave, i think you are referring to a m+w add showing an old looking m with their hi-t crankshaft and pistons next to a new looking 450 and the add states which tractor has more power? of course the m did. even the regular m+w overhaul with their turbo-dome pistons mw claims 53.8 horsepower from a straight m tractor, 55.2 for a super m, 58.3 for a 400 and 57.2 for a 450 useing their pistons.
 
I scanned the responses and there was some things I either missed or people did not mention. A C-281 engine has a better cam, better flowing head, and a higher compression head. So yes you can take a C-264 to 281 cid but it will have a few less horse power than the same pistons in a C-281. I have a C-281 with comformatic pistons in an M that has 67 hp at 540 PTO with stock high idle of 1600. The advantage a Super M has over a 450 is there is no live hydraulic pump to spin. So when you place a C-281 in a Super M it will make more horsepower on the Dyno than if the same engine in a 450. A C-281 will simply make more horspower with the same pistons as a C-264. I should add that my 67 HP engine is wihtout muffler, oversized venturi in the carb, port matched gaskets, polished intake runners, multi angle valve job. And a couple other little things I have learned along the way. The engine, head, cam, manifold are all stock except for those pistons with the tiny little dome. Oner more thing. My comparisons are assuming the C-264 has the 8060 head on it.
 
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