Rotax 582 enhine RPMs and EGTs

[kszaronos]

Hello, I am a new Sport Pilot and new to Forum. I bought a Kitfox III with a Rotax 582. It only has 118 hours on engine and plane. Engine seemd to be running fine however the plane hasn't flown much in last 10 years so I had the engine torn down, looked over and rebuilt with new seals by a certifed Rotax repairman. Engine is running now but the RPMs won't go over 5,000 in test w/o the EGTs up near 1,100 and redline. Rotax mechanic can't figure it out and he has adjusted the prop pitch also. Any thoughts would be appreciated as the billed hours are getting up there. Feel free to cal my cell @ 317-506-2854. Thanks Keith

[jrthomas]

Hey Keith, it sounds like you're pretty close to me. I've found out that factory jetting with the jet needle clip in the stock position is pretty close. Some props seem to pull a little harder on static run up than others. I would go fly it and see where the temps and rpm's go. The rpm's will definitely go up and with stock jetting temps should be in the safe range. I think 1200 degrees is max. Keep us posted, James Thomas

[t j]

I'm not sure why you think there is a problem with EGts of 1,100. Red line is 1200 degrees.

Also, the EGT gages are calibrated at an ambient temperature of 70 degrees F. At lower ambient temperatures the gages will read higher by the same amount ambient is below 70. Example is with outside temperature of 20 degrees F the EGT gauges will read 50 degrees higher than actual.

[Monocock]

Interesting subject.

I think there has been a bit of misunderstanding in a couple of the above responses though about the rpm. What he is saying is that the rpm CAN go higher than 5,000 on the ground but that he doesn't want to go any higher as he is worried about seeing 1100 degrees on the EGT. Am I right or have I read it wrong myself? If so, I am sorry.

Either way, I wouldn't be too concerned about 1100 degrees at 5,000 rpm, especially bearing in mind TJ's final comment. If you go and fly it I think you'll find they won't go above the max of 1200 degrees by the time you get a few hundred more rpms and the aircraft is flying.

Other questions:
What are your outside air temps like?
Is the prop coarse enough (ie what can you get as a max static rpm on the ground)?
Have you checked the gauge accuracy?
Are you using premix or injection? If it is the former, what ratio are you using and if it is the latter, what kind of setting is the idle marker showing on the calibration?

[jrthomas]

You're probably right MC. 1100 degrees at 5000rpm is not a problem. The egt at this time of year are as hot as they will get if the jetting is as the factory set them. As the air temps get warmer the egt's will get cooler. I'm anxious to find out if he flew it and how it did. James Thomas

[Monocock]

kszaronos,

A couple of months on, I was wondering how you were getting on with this?

[GDN]

Hello, i'm new about Kitfox. Yesterday, i flew with very cold weather in France ( 35° F). When i took off during the climbing at high angle full throttle my EGT increase tu 1300-1400 ° is it normal, due to cold ambiant air ?
When i'm stabilized at 5000 rpm they goes down to 1200 .

If my oil injection pump is bad, not enough oil, can the EGT increase ?

Other question i always have to push the left rudder when i flight with no roll. I have a model 2, and i heard that the vertical fin is too small so we have always right yaw due to engine couple effect. Am i true and if i'm right is somebody made a higher vertical fin ?

Thanks a lot and excuse me for my bad english i'm french.

[Monocock]

Hi GDN,

I am not the most knowledgeable person but have learned fast about these aircraft and engines in the past 12 months. So, please accept that there might be more useful advice out there than mine!

I am surpirsed that your EGT's are higher in a steep climb than when you are level. Normally the higher fuel flow at high power settings means the EGT's are lower due to the cooling effect of the throughput of fuel. At full power I see 900 degrees and when I level out it is around 1100.

I do know that when the outside air is cooler that you will see a higher reading. However, 1400 does seem quite high to me.

Out of interest, what is your static rpm on the ground? If your prop is not coarse enough you might find that this will increase the EGT's as the engine is not working so hard. This is why the EGT's normally go up quickly as you push forward on the stick with no adjustment to the power setting. The engine becomes less "loaded" and the EGT's can shoot up quite fast if you are not careful.

Someone once suggested that the oil mix ratio can also have an effect on the EGT temps. However, I expect there is someone out there with more knowledge on this than me!

Finally, it might be that your carbs need adjusting.

Don't try and make lots of changes/adjustments all at the same time as you will never know what had caused it if it cures it!!!

On the yaw issue, have you got a rudder trim tab? It is not normal for any aircraft to need rudder input to maintan straight and level flight so it might be worth checking the rigging and the setting on the tab if there is one.

[GDN]

Thanks for that quick response.

My pitch propeller is too low, i know it because i tested yesterday full throttle without climbing and it goes to high 6800-6900 rpm.

So i'll first set an higher propeller pitch and after looking about that oil pump setting.

But for the rest it's a intense pleasure to fly it's own aircraft and a kitfox

[Monocock]

GDN,

I think you will find the propeller change will make a lot of difference - and you will get a much better airspeed in the cruise too. I bet she climbs well now though!

Good luck.