I'm building a plane and I would like to know which motor is better the OS 46 FXi or the OS 46 AX


thanks

I am pretty sure that they are almost same engine. The only difference would be that the FXi is supposed to be broken already, and only came with the Nexstar RTF. There are a few cosmetic differences also, like the mufflers look different.

The 46 AX is a bit stronger than the FXi. But you probably won't notice any difference between the two of them if you had them side by side. Either one is a good engine and you'll do fine with them.

Ken

I believe the FXi is what came on the Nexstar (maybe still does?). The AX is a newer engine with a few design enhancements. Both are form a top notch manufacturer and will work well.

What they said so go for the best deal. If you can snag a new older OS such as the FS or FSR they were winners too.

Is there a difference in the needle valve? They talk about a limiter with the Nexstar ARF - is that just the plastic 'cap'?

The "plastic cap" is the limiter on the FXI.
I have 4-.46 Ax, 2-.46 Fx, 1-.46FS and the .46 FXi. All are great running motors with the power edge going to the FX, followed closely by the AX and FS with the FXi having the least power of the bunch but still pretty good.

Curt

I have both engines and they run about the same, both are very strong for their size. So either one will work just fine.

As you move to larger engines, you will find some differences in power levels with the AX engines. They have more and it becomes noticeable as you move up in size. I had an OS 61 SF on an aircraft, and put an OS 75 AX on a newer aircraft, of somewhat similar design. The AX pulled that plane around with more authority.

Minnflyer did a review on the Goldberg Protege a while back. He used the OS .55 AX engine on this plane, and it did very well. Read the review for yourself. I bought the Protege based on that recommendation but could not get the .55 AX because they were out of stock at the LHS and he didn't expect any new engines for a month or so, but he had the .75 AX in stock. So, I bought that engine. All I can say is WOW!! Awsome engine, performance, and ease of use.

Now, I do not have a .46 AX but do have three or three of different styles, FX, SF, and so on, plus an OS 50 SX I believe, and they all run fine and have great power, AND start very easy.

It comes down to availability, I guess. Either way, you cannot go wrong.

They are both great engines, cant go wrong with either.

I have both engine, I decided to put the FXi on the new Tower Kaos because the FXi only has 5 or 6 flights it FXi came on a nexstar so Im sure you know why it only has 5 or 6 flights

The 55 AX has the needle on the carb, and it runs right. The rear needle engines are a huge pain in the butt. I will never buy one again. I went through 5 91 FX engines and a couple of 46 FX engines and all went back to the factory and they finally just gave my money back.

I ran the new 55AX a few weeks ago and it ran like an OS used to. Right out of the box, flipped it, it started, adjusted the needle just a tiny bit and flew it a few flights. It ran like a top. The FX never produced power and quit every flight, over heated and had major fuel flow problems. I am sure the new ones are not much better.

Some have good luck with them. You can roll the dice and hope you get a good one, or get a 55 AX and not worry at all.

The 46AX comes with the rear mounted needle. Mine worked flawlessly right out of the box.

I bought the 46AX a little over a year ago to replace an aging 40FP. Great power, easy start. It's been on 2 different planes now. BTW, the 40 FP is over 20 yrs old and still flying. It's on my son's trainer.

The magnum .46 comes were you can change it from rear mounted needle to carb mounted needle. You can't do that with OS?

The needle on the 46AX is mounted to a support which is screwed in with the back plate. You can rotate the needle 90 degrees on the bracket, or you could mount the needle somewhere else if you wanted to, but it would remain a separate entity from the carb, attached only by a piece of fuel tubing.

That makes me like the Magnum engines that much more.

Thats one of the all time best engines built. I have a lot of FP engines. They still rock on.