Hi all
I did a lot of reserch before buying my engine and here's what I found. Tohatsu builds all the 4 stroke Tohatsu, Nissan and Mercury engines below 40 hp. The 4-5-6 hp engines all weigh the same, 55 lbs for short shaft and 57 lbs for long shaft. The 4-6 hp engines all use the same parts, the difference being in carburator jetting and rated rpm.
I bought the 6hp version as there was no weight penalty for doing so. It was a bit more expensive. One thing I found out is that the market for these engines are little inflatables that weigh less than 1000 lbs and buzz around at 15 -20 mph. The props on the 4-6 engines are pitched accordingly. Hang it on a 2600lb + sailboat and it wont make full power unless going to a finer pitched prop. Basicly HP is a function of MP(manifold pressure) and RPM. 57lbs is a PIA to get on and off the tail end of a Tuna.
I've had both a strong 4hp and new 6hp engine on my Santana here in the Bay Area and preferre the safety margine of the 6 hp version.
Your mileage may vary.
Tom M cIntyre
Spitfire # 802
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