Turning my Johnson 9.5hp into 20hp

[cmuman]

I have recently obtained a 1964 Johnson 9.5 hp.

The guy I got it from said that the powerheads were the same between the 9.5hp and the 20hp for that year. He said that the 9.5hp had a more restrictive carburetor.

Is this true?

Can I just get a 20hp carb and swap it on this motor? It seems to easy.

 

[F_R]

Re: Turning my Johnson 9.5hp into 20hp

That's just so much BS. Not even in your wildest dreams!!

 

[ezeke]

Re: Turning my Johnson 9.5hp into 20hp

Wish that were even remotely possible. Don't think nitrous oxide could get you there.

 

[MarkV_Deep6]

Re: Turning my Johnson 9.5hp into 20hp

I got one of those....could that guy hook me up? NOT!!!

 

[cmuman]

Re: Turning my Johnson 9.5hp into 20hp

That is what I thought, but with the wealth of knowledge on this site I thought I'd ask. Did the 9.5 share powerheads with any other models from that year?

 

[wavrider]

Re: Turning my Johnson 9.5hp into 20hp

what F.R, said times 2.

 

[jay_merrill]

Re: Turning my Johnson 9.5hp into 20hp

The 9.5 powerhead is very unique and, as far as I know, is not common to any other OMC motor at all.

 

[jasono2l]

Re: Turning my Johnson 9.5hp into 20hp

Yeah that is just crazy, umkay. But that would be pretty cool if it was a possibility.

 

[WTL]

Re: Turning my Johnson 9.5hp into 20hp

Improving an engine's power over twice its rated hp of course is absurd, but this raises a good question....

Is there anything that can be done to pick up a horse here or there? I for instance just picked up a 28 SPL Johnson, is there anything that can be done to say, get 30 ponies out of her?

 

[-1boat]

Re: Turning my Johnson 9.5hp into 20hp

From what I understand the 28 SPL is the exact same as the 30 only without a VRO pump.

 

[wbeaton]

Re: Turning my Johnson 9.5hp into 20hp

From what I understand the 28 SPL is the exact same as the 30 only without a VRO pump.

That's my understaning too. You just gained 2hp! Actually, the lower unit may be different as it may not have through hub exhaust. However, I'm not too familiar with those motors.

 

[tashasdaddy]

Re: Turning my Johnson 9.5hp into 20hp

the SPL designation motors were originally work engines, not pleasure motors. now the are basic premix model or the next higher model, 28-30,48-50,88-90,112-115. the difference being the fuel pump.

 

[wbeaton]

Re: Turning my Johnson 9.5hp into 20hp

On second thought, neither the 30 or 28 hp wouldn't have a VRO and the fuel pump should be the same as the 30 hp. I'm pretty sure the 28 SPL has the old style lower unit without the through hub exhaust. Possibly the difference in exhaust makes up the 2 hp or maybe there is no difference (that's probably closer to the truth). Either way I doubt you'd notice 2 hp on that motor.

Perhaps you should start a new thread with this question instead as we've just hijacked this one.