Fat 50 Johnnyrude vs 50 hp looper

[Texasmark]

Mind was wandering the other day and got to wondering if anyone had compared the performance of a late '50's 4 cyl 50 hp with a later loop charged 2 cylinder.

Just thought it would be interesting to know the results. Several huge differences:

Cubes were 70 on the fat as I recall; don't know on the looper
Being 4 cyl, engine had to be very heavy for the hp
Engine hp was "brake hp" rated, not prop rated so there is some difference there
Prop and lower unit were less than stellar when compared to the lower unit and SS props available for the looper.

Thanks,

Mark

 

[Chris1956]

Re: Fat 50 Johnnyrude vs 50 hp looper

I owned two Fat-Ffities. In my opinion, If you put both on a barge, the "Fatty" would push much better and actually rev up quite a bit. I expect the looper would just idle fast.

if you put them both on a light boat, the looper would run rings around the Fatty.

My Fat-Fifty would only push my 14' runabout about 27MPH, but had great acceleration and low end power. I would think a 50 looper would easily hit 30+ on that lightweight boat.

 

[tashasdaddy]

Re: Fat 50 Johnnyrude vs 50 hp looper

power per pound, the 2 cyl hands down.

 

[EricR]

Re: Fat 50 Johnnyrude vs 50 hp looper

Though the fat fifty just looks cooler, in a big 1950's chrome excess manner.

 

[gwhaling]

Re: Fat 50 Johnnyrude vs 50 hp looper

Glad I read this post. My dad has a fat 50 rude 59 model. That did not work out as a replacment to his melted down 70hp rude. Did not work due to being a short shaft. Was considering it as a motor for my 14 foot vhaul. It can take a short shaft. Probably not now. Shame it's a good motor. Even with the prop to high in the water it had a lot more surge on start than the 70 hp rude. Just would not plane off with the short shaft. How well would a fat 50 push a 24 foot pontoon around? I ask due to my dad also having problems with his 80hp mariner and pontoon. Been a long summer of broken boats.
Glen

 

[tashasdaddy]

Re: Fat 50 Johnnyrude vs 50 hp looper

short shafts don't work well on toons. but it would push it very well, though a bit gas hungry.

 

[EricR]

Re: Fat 50 Johnnyrude vs 50 hp looper

Unless it's a very old pontoon with the engine mount that is adjustable vertically with a long lever like the old steel pontoon'ed Weeres my nieghbors used to have in the 7o's- the railing looked like chain link fencing, it had this kewl SS minnow style wheel with wood spokes!

 

[jimmbo]

Re: Fat 50 Johnnyrude vs 50 hp looper

I have an old magazine artical from 1979 comparing the 1958 50hp, a 1968 55hp (3 cyl) and a 1979 55hp (2 cyl). I'll find it and report the results. Just from memory I recall the newer the engine the higher the top speed and the better the fuel economy. The tests were on 14 and 16 ft boats.

 

[Texasmark]

Re: Fat 50 Johnnyrude vs 50 hp looper

jimmbo you hit upon the reason for the thread. I'll bump this till you get your answer so we all can enjoy.

Thanks,

Mark

This is a bump.

 

[jimmbo]

Re: Fat 50 Johnnyrude vs 50 hp looper

Sept 1979 Powerboat Magazine

Test boat was Starcraft 14' Holiday (alum)

Motors, all crank rated
1958 50hp V4 70.7 cubic in. 205 lbs, engine tilt adjustment
1968 55hp 3cyl 49.7 cubic in. 190 lbs, engine tilt and height adjustment
1979 50hp 2cyl 44.99 cubic in. 180 lbs, power trim and engine height adjustment, SS props.

Tops speeds
1958 50hp 32 mph
1968 55hp 34.5 mph
1979 55hp 37 mph

Fuel consumption

At 17 mph the 2 cyl 55 was 31% better than the V4
At 24 mph the 2 cyl 55 was 28% better than the V4
At 32 mph(top speed for the V4) the 2cylinder was 21% better

At 17 mph the 3 cyl 55 was 17% better than the V4
At 32 mph the 3 cyl 55 was 11% better than the V4


They also compared the 1968 100hp with the 1979 100hp

15' starcraft Holiday

Top speed

1968 100 hp 40.5 mph
1979 100 hp 43.5 mph

fuel economy
Running 40.5 mph the 1979 100hp was 9.1% better than the 1968


1958 50hp versus 1979 140hp on an 18ft boat

Speed - The 140 was 82% faster

Acceleration - The 140 was 27% faster with 1 man and 32% faster with 5 men

Load carrying - The 140 could plane the boat with 8 men versus 5 for the 50

Fuel economy - The 140 trolled on 42% less fuel. It also used 10% less fuel cruising at the same speed as the 50 running wide open. When buring the same amount of gas it was 41% faster.

 

[Texasmark]

Re: Fat 50 Johnnyrude vs 50 hp looper

Thanks man for the article.

So now we are getting back to one of my rememberances about engine technology and that is newer engines are much more fuel efficient so how can you say that moving the engine hp decimal point over one place gives you the WOT fuel consumption, regardless of everything that one would consider to effect it including where the engine hp is rated.

It's just not that simple. I know reputable folks disagree, but I'm hard headed and it's just not that simple.

Mark