I was thinking about my 40 size stick. I originaly was going to put an OS AX .46 on it, but I was thinking why not try a 4-stroke?

What size 4-stroke would give me equal HP/Performance (or close to it) as a .46 AX? The HP/RMP ratings kind of confuse me. This will be plane #3 for me but I have been looking at a bi-wing for #4. And I could move the 4-stroke over to it. Then put any old .46 on my stick.

.63 to .70 four stroke would be near the same.

70 slightly more performance.
60 marginally the same performance.
Don't listen to the people that say a 52 is the same.

The .46-Ax is on the high performance side so I would say at least a .70-.72 4-stroke.

Some options are:

http://www3.towerhobbies.com/cgi-bin...?&I=LXHSL2&P=0

http://www3.towerhobbies.com/cgi-bin...?&I=LXEXP5&P=0

http://www3.towerhobbies.com/cgi-bin...?&I=LXGRP4&P=0

http://www.horizonhobby.com/Products...ProdID=SAIE072

http://www.horizonhobby.com/Products...rodID=SAIE082A



I just ordered this one for my World Models Rambler 45 to replace a .55-AX:
http://www3.towerhobbies.com/cgi-bin...?&I=LXSZW5&P=0

I've owned magnums, OS's and Saitos. All work well but the OS's run better right out of the box in my opinion with less break-in and are a little less finicky. I also hear that some of the new Thunder Tiger 4-strokes are nice.

Don't compare engines with the BHP ratings. There is no standard as to how exactly to obtain those numbers. It's like MPG for a car. The only good way to compare performance is to compare RPM with identical props.

I say go with a saito 82....

Steven

An 80ish engine is overkill. If you can still find one, get an OS 70 - I still can't believe they stopped making them. It's one of the best engines ever.

My second choice would be the Magnum XL-70RFS

The OS FL-70 runs pretty good and is still available. It does have a couple drawbacks though in my opinion. For one, you can't flip the carb around so that can make the throttle linkage difficult. Number 2 is the air bleed carburetor. Mounted upright or sideways, it works fine but upside down can be a nightmare. There is no way to adjust fuel on the low end, just air. Unless the tank is positioned just right, it will tend to run very rich so you have to open the air bleed screw to compensate. That in turn leads to a high idle.

I agree that the .80 size engines are probably overkill for a lot of 40 size planes but it looks like that's the way the manufacturers are going.

Traski indicated the engine would go on a 40 size Stik. I wonder how OS's new .56 would do? I've seen the older .52's fly a 40 size plane around pretty good. Not quite equal with a .70 but still respectable.

I find the Thunder Tiger .75FS an excelent value for a 4S. Hey, I think the TTPro .46 is a great alternative to OS as well. It seems to me that OS has gotten way out of line with their pricing.

If you can find a good used O.S. 61 it would be your best bet. It is almost the same weight as the 52 but with a bit more HP. A 70 is a good choice, I fly a Mag 70 in a plane desigened for a 45 two stroke. It way overpowers the plane. I initally had a 52 on it and it flew well but I needed 7 oz of weight up front to balance it out. The 70 weighed just shy of 7 oz more than the 52. My plane is about 6 lb, and if I punch it from a slow roll on the runway, I'm 15 ft up 15 ft down the runway. Way over powered. Now if I could just fly it

Don