3.6l 54 hp Super Major/Trader rpm under workload

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RBack
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3.6l 54 hp Super Major/Trader rpm under workload

Post by RBack »

Having a 4 cyl 3,6 L Trader/Super Major 1962 in my boat (made the same year).
Parsons Pike Marine is the name of the motor in its marine version.

A new propeller is to be fitted and in the process of adjusting its (the props) size I've, been checking different rpm and boat speed with the old prop.

If I've understood everything correctly, this engine should normally run with maximum 1600 rpm under load (according to the Super Major Handbook I've downloaded).
Maximum torque is at 1200 rpm
Unloaded it should reach 1900 rpm according to the same papers.

My aim is to have the new propeller adjusted so that the motor can run with its most efficient revs at the boats cruising speed (hull speed - it's a full displacement hull)
with efficient I mean the most fuel efficient and the most efficient in terms of engine sustainability under constant workload (driving a boat is constant workload).

Would this be at 1200 rpm or is it something else?

And by the way... When checking the rpm without workload, the motor revs far beyond 2000 rpm. I wasn't too keen on letting it do so, but curiosity took over and for a short brief second I had it running with 3000 rpm. Curiosity killed the cat but not the engine.
Does that mean anything in regards to the theoretical numbers mentioned in the handbook?

yann1967
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Re: 3.6l 54 hp Super Major/Trader rpm under workload

Post by yann1967 »

This means that full power is reached at 1200rpm.

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RBack
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Re: 3.6l 54 hp Super Major/Trader rpm under workload

Post by RBack »

At least in theory - which I suppose is the only thing to follow as long as the engine hp and torque isn't measured.
However it's quite recently restored, so it should be in fairly good shape.

So in terms of theory... then the most efficient (also fuel efficient) rpm is 1200? Am I correct?

Emiel
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Re: 3.6l 54 hp Super Major/Trader rpm under workload

Post by Emiel »

Hi,

Although engines are basically the same, there are differences between industrial and agri specs. These are in the type of injection pump fitted and governor. The combination injection pump and governor "make" the character of the engine. The numbers you state are correct for an agri engine. You should find industrial manuals and parts lists and compare these to the tractor spec engine and you will see differences.

I would never recommend running these engines in the 3000 rpm area. My options would be: 1. cut of fuel supply; 2. find my trainers and run

rgds

Emiel
Best regards

Emiel

N 1937, E27N 1948, 8N 1948, E27N 1950, E1ADKN PP 1956, Dexta 1959, NH Clayson M103 1964

RBack
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Re: 3.6l 54 hp Super Major/Trader rpm under workload

Post by RBack »

Thank you for the confirmation!
I've forgotten about the matter over the winter, but the new prop is now being adjusted according to the mentioned rpms.

No surely it won't be run at such high revs. I was kind of surprised it wasn't (technically) limited. So I promptly eased off the throttle when it kept building speed.

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