Bruce – In the past 8 or so years, I have done considerable experimenting with many 4S engines, among them were 4 different 40s.
Here is a bit of a capsule review of the 40s:
SAITO .40 – a nice, smooth running engine that was overweight for its somewhat marginal power output. Good for low-key sport flying and not much more.
Long out of production.
OS Surpass .40 – an incredibly powerful engine that tends to be a bit temperamental
but when it’s on, the power will drag a very heavy plane around with authority. It pulls my 57-ounce Euclid with no effort. It hates props and will throw one at you every chance it gets.
I fabricated a special drive washer for mine.
Thirstier than any other 4S .40 I’ve tried.
I would compare the pulling power to that of a Super Tigre .46.
It presently swings an 11 1/2 - 6 1/2 prop.
SAITO .40A – I think this engine offers the best all-around combination of power to weigh, compactness, fuel economy and user friendliness. The interesting thing is how well it works in a variety of applications. I’ve had it on a Nobler, P-40 profile and the prototype ARF Cardinal. I’ve spoken to quite a few people who have tried it in other planes with good results.
OS Non-Surpass .40 – this is probably the most perfect running engine I’ve ever owned. Not up to the power of the Surpass .40 or SAITO .40A but its running characteristics are so smooth and steady that it’s an absolute pleasure to fly. I’ve had around 12 different engines on the prototype ARF Cardinal and this is by far my favorite. Swinging an 11-7 Master Airscrew plastic prop, it does the pattern on just under two ounces of 20/22/50-50 fuel. Without a muffler, it’s so quiet that the prop noise can be heard above the exhaust.
If you ever have the opportunity to score one of these at a swap, go for it.
ENYA .40 – I have not run this one yet but it is a very early version with open rocker arms. I have the plans for a Boxcar Chief – that will be its home.
Hope this helps.
Bob Z.
Topic: 4 Stroke .40 size engines (Read 623 times)