Hi to all,
I'm going to start building a New Era 40 airplane. I have two unused engines that I'd like to install, as I believe they have sufficient power.
The engines are OS MAX 35AX and IRVINE 36 ABC.
I'd be interested in hearing from anyone who has used these engines.

Thanks!
Norberto

Although the AX series absolutely are decent, my choice would be the Irvine, as the Irvine has true Chrome, and the OS has not.

But that is just my personal preference.

Both will be good, but I think the OS is slightly more powerful. ABN or ABC does not matter when it comes to longivity or performance!

Thanks for your answers!
My question is mainly about the power output of each engine.
The OS 35AX is of Chinese origin. The Irvine is British. I've had problems with two Made in China OS 55AX engines. They had fuel leaks in the front bearing from the break-in period onwards.
I'd like to use the Irvine since I've never flown with these engines, but it always depends on its power output, as the aircraft is designed for a 40 engine.
The Irvine's manual doesn't specify what propeller it can use, but I think a 10x6 would be fine.

https://sceptreflight.com/Model%20En...0ABC%20RC.html

There are three Irvine .36 reviews at scepterflight.com

Thanks for the info!

Without question - the Irvine is the clearly better engine. True ABC will always be better than any OS ABN model.

I'll probably choose the Irvine. There are very good reviews about this engine. The Irvine is also lighter.

One of those reviews says that the Irvine is good for .5" larger props.

Hi!
As I said ...I think the OS is slightly more powerful as it is a more modern design. I have run several of these "new" AX engines and they are as good as any other OS has been or better. ABC or ABN dose not matter when it comes to how long an engine will hold up or how much power it will deliver.
suitable props for both engines are 10x6 ,11x5 or even 11x6 ( if using the OS). Best prop brands are Graupner G Sonic or RAM. APC props are good too but not as good as those first mentioned.

Given the known problems with OS engines going back to the SF series, I’d agree to disagree with you. The AX I series was notorious for rear bearings falling apart, and the peeling liners…. Yeah, no, the better engine is the Irvine. The AX might be a tick stronger, but knowing its potential catastrophic flaws, I personally would sell it and buy another Irvine. They’re usually cheaper than OS engines, so it’s a triple win. Some will still preach the OS is superior, but you won’t convince me any time soon.

I will 100% agree, that the AX series is with some distance the BEST "ABN" engine OS ever produced, and yes, it is more modern, therefore probably porting is slightly more refined.
But the power increases in regular Schnuerle ported sport engines in general, have been at best in the low single digit percentages.

But having said that, Chrome by its very properties simply is a different metal (duh) which is FAR more suitable for glow engines.

It is that simple...

And OS has a reputation, one that is IMHO carried over from the past, but not entirely justified anymore. Still good, no doubt, but by far not the "Rolls Royces of model engineering" that they once were...

The OS 35 AX turns an APC 10 x 6 at 10,470 rpm

The Irvine 36 turns it at 11,200 rpm, both with stock mufflers

If I have two engines that I’m picking from for a model, I like to run them open faced to see the real apples. It’s not always about the power, but if an engine turns your prop at an acceptable rpm and not have any tractability issues with open exhaust, then that is the better candidate. OS historically has made powerful sport engines, but with some caveats. Probably the worst one, IMHO, the giant carb and constipated muffler setup. Runs good on the muffler, but falls on its face without the muffler. Think “PowerBox”.

Good methodology

You guys not hindered by any noise regulation?

Over here running loud pipes or ineffective mufflers is unthinkable, so for us Europeans, an engine running good without a muffler is as useful as hooves on a goldfish.

Running a sport engine without silencer/muffler!!!! Why? They don´t throttle well without a silencer!
In our club here in Sweden (Väsby Modell Flygare) we have no noice regulations! I can fly my F3D pylon racers as much as I like! Think its the same overall in Sweden!

He did explain why

I test run engines at my house. Neighbors don’t care, especially considering it’s not for very long. If I’m going to slog a few engines and a bunch of props, I have a spot I go to that is free of people, buildings, or animals. I could burn a gallon of fuel and nobody would know. I know not everyone has a spot like that, but I’m sure a spot free of sound police could be found to run an engine for a few minutes.

On the bold - that’s Bovine Scatology. If a basic off the shelf sport engines doesn’t run well without muffler, there’s something wrong.

About 40% of the intake charge follows the exhaust out through the port and is wasted and reduces low and midrange torque. Then you automatically enrichen the mixture increasing fuel consumption.

The problem is not the "few minutes of testing".or "finding a spot for testing"... It's the fact that literally no club will allow anyone to fly like that, not even the few clubs that do not have an official noise limit (one of those I am so lucky to be a member of). A fair number of out clubs are so noise restricted that wet fuel is not allowed anymore to begin with, plenty others have noise limits of, for example, 80 dB or less.

As I understand it, that is exactly the type of shortcoming you seek to expose by way of your test method. Correct?

Thinking some more about that, I would be inclined to say the opposite is true: If an engine runs crap without its intended muffler, and well WITH, that does not indicate "something wrong with the engine", on the contrary, it indicates that both the engine as well as the muffler are extremely well designed as two parts that together form a "system". Similar to for example how a bike frame or car chassis and its suspension can be complementing each other,

Bert - please note I never said to fly the engine that way. I merely said to test an engine, or rather to compare two engines, to run them open exhaust to see the power it is capable of in the best way - apples to apples comparison. Reason being no two mufflers work alike; one may rob more power than another. If I have a performance level in mind, this is how one would truly compare the capability of the engines in the most equal circumstances.