Hello.

Anyone with information on operational temp on a os37 engine?

All model airplane engines are the same 200-220 with 240 and up too lean and below 200 too rich. Check on the back of the cylinder with a IR temp gun or use spit, does nothing too rich, bubbles just right, boils off fast or "jumps" off too lean. All in degrees F, sorry...

Generaly, you should be able to hold your finger on the backplate for 4-5 seconds after the flight.

I install it in a caliber 3 heli and cant reach the backplate on this one. Have a IR-sensor and measure on the head of the glowplug.
3 or 4 sec on the plate should be right, but I wondered what it would be on the plug.

Does your OS 37 cook? So does mine. I've got a hatori pipe and am using 12% nitro although now going up to 20%!!!

I can hold my finger on the back for 3-4 seconds but that was after a lot of playing around with the needle settings to get things cooler without losing too much power.

What needle settings/fuel/pipe are you using?

No cooking .. using low neede configuration as is say in the manual and high needle one turn out from fully closed.

I repeat....

All model airplane engines are the same 200-220 with 240 and up too lean and below 200 too rich. Check on the back of the cylinder with a IR temp gun or use spit, does nothing too rich, bubbles just right, boils off fast or "jumps" off too lean. All in degrees F, sorry...

Head or back of cylinder, hottest spot.... Checking backplate doesn't give accurate info and who calibrates their fingers? Low end setting, pinch the supply fuel tubbing at idle, should run with no change for 5 seconds. If it cuts out sooner you're lean, takes forever then slowly speeds up and dies rich...

The finger test is kind of useless on the 37 due to the design of the backplate.

Best is to get a Venom temp gauge and keep the max inflight temp below 220. Second best is to shoot the base of the cooling fins with an IR gun, after switching to normal, spooling down and taking a reading it should be below 195 or so (15 to 20 degree drop from max in that time)

to evan-RCU.

NO. I am not agree with you. There are different temperatures to different sizes. A 90 size heliengine is NOT so hot as a 30 size.
But thanx for answering. I got a 90 size and a 50 size. Both have different temp...

Sorry but the two do run at the same temps. for helos I have a .91, .50, and .32. For airplanes I have from .049 to gas and they all run the same temp. Even my motorcycles run at that temp, my car too. The bike and car are water cooled and the thermostat controls the flow of the water to about 195 but the head and cylinder temo is actually 200-220. You can disagree but I'm right. With internal combustion piston and cylinder engines they all run best at these temps.....

What do you think the temps should be? What are you running on the 90 and 50?

What do you run your car at? 95-100C? That's 205-215F water temp, head and cylinder are probably 100-105C....

BMW car says 90-100C, (195-215F) is normal (water cooled), Harley Davidson says 190-230F with 250F being safe (air cooled).

Evan you can't even compare water cooled engines to air cooled r/c engines. The fuel to air ratio is different, no oil present in the fuel. High CHT in autos are preferred so they can pass emissions, but my impala makes way more HP at 160 with a AFR of 12.9:1

Even-Rcu : You probably dont know so much about this subject. Comparing water-cooled engines with rc-model engines are way of...almost funny. A guy sas to me yesterday : 90 helis : you skuld be able to hold your finger at backplate all the time : 50 helis : 6 - 9 sec... and 30 helis - 3 -4 - go figure. Hope you learn something.. and if you still stick to your guns it is fine by me!!

Yes and you might have a 160degree thermostat but the actual head and cylider temps are higher than that, again 190 or 200. And the reason that it makes better power is the cooler fuel air mix burns better, but more power doesn't mean the best for the engine and there are draw backs to running your engine too cold just like too hot.

The ratios are not that much different between water and air cooled...

You guys obviously are not understanding physics...

As a person who recieved his BSME degree I feel I do understand physics. No my cht are not 200F they are 160 until I get on it and they will go up to about 180-190. The sensor is on the back of the head and my engine is a gen 1 sbc, so the head is the last thing to be cooled. I don't run a thermostat on this engine, just restrictors in the housing. Yes there are issues running too cool, mainly the oil, this is why I have a high quality sythetic, so it doesn't make acid like conventional oil. Colder air allows me to run more fuel, the more oxygen I can get in the cylinder the more fuel I can pump in, a stoichemetric ratio is 14.7:1 that will not however make more power due to the inability of the engine to make a perfect burn.

That is all off topic though, and still you cannot compare a fullsize water cooled engine to a r/c engine on temps, other comparisons yes, temps no. Fuel is the cooling factor for his OS 2 stroke, fuel has nothing to do with cooling on a 4 cycle water cooled engine, it is the oil and water that cools.

That OS should run about 200F, just as BH said.

agree... 200F - 220 F.. seems right for the os37. I am installing watercooling on my caliber 3 now... then it can run better.

Where's the smiley for beating a dead horse?

Come on, guys, let's all just walk away from this; it's not that big a deal.

- Chaz

Your right Chaz, I agree, I am done, but here is the emoticon you wanted

Why thank you, Sir! I knew they had that one at HeliFreak, but I hadn't seen one here.

Regards,
- Chaz

Nice smiley.

I had an OS32H in a Caliber 30. No matter how I tuned it I couldnt hold my finger on the backplate.
As I was concerned about this and wanted a little more power I upgraded to a OS37SZ. I still cannot hold my finger on the backplate no matter how I tune it.

I do live in the tropics with average OAT around 30-35C so I assumed that was why.
I run it as rich as I can, any richer and it bogs slightly. Still a hot backplate. So im not convinced about the backplate method.

OleC

Your running watercooled Heli in Norway. Must have had a hot summer there. It would run very cool in winter then.
How do you water cool your engine. Is there a marine cylinder head or similar you use.

Cheers

Planetheli : Yes, i could figure that you had to run it rich in the tropics. In the summer I have to do the same.
WE had a hot summer yes. We usually do in the south. today it is 25 C.
NO watercooled heliengines here. It was just a joke directed to the replies above, but it would be fun though...

Have a nice day.

OCF

So what temperature have you decided is best for your .37?

dunno yeat... I will tell when I find out.

What are you waiting for? I told you the temp in post #2. Others backed it up, I find it interesting you ask us what something should be then tell us, well at least me, that we're wrong. Then in post #16 you say 200-220 is right which is what I've been saying all along. Why do you belive there's a difference between engine sizes? Worse case is you fly it and make up your own opinion and let us know. It'll be between 200 and 220 though....