What's Hot? • New Mike Busch engine webinar.

[Garfly]

 

 

[Bruce Tuncks]

Thanks for posting that Garfly. I wanted to see it but missed out at the time.

My son has an IO 360 in his Lancair so it was exactly relevant.

[Bosi72]

Regardless of Mike's suggestions about the temperatures, the Manufacturer's Engine manual should be followed. 

Still, great video..

Edited November 15, 2021 by Bosi72

[Thruster88]

Lycoming and Continental cylinder heads are made using fit for purpose metal.

[Bruce Tuncks]

Don't agree Bosi. Years ago, Jabirus lowered their redline from 200 C to 175 C. I agreed with this even before they did it. My personal aiming temp is 160 degrees C

I think manufacturers feel under pressure to come up with good numbers, like the 200 C was, and some naive people get into trouble by trusting them.

There was a woman who had terrible trouble with her Jabiru engine, and I think this was part of the problem.

[Bruce Tuncks]

Recent experience with the gen 4 engine on Avgas has also demonstrated that Mike Busch is also right about the too cool side. Some engines were clogging up with lead-looking deposits.

[Bruce Tuncks]

I just converted mike Bush's "sweet spot" temps which he has from 350 to 400 F. On my conversions, this translates to 176 to 204 C, which I reckon is 40 degrees  too hot for a Jabiru CHT.

Thruster points out that the Jabiru stuff is not as good as the Lycoming metal, and I agree. I think the gen 4 engine has different metal, does anybody know about the gen 4 head metal?

[Yenn]

Did Thruster mention Jabiru heads? If he did I didn't see it. You seem to be putting words into his pen.

[Bruce Tuncks]

Yes he did, he said that lycoming etc used "fit for purpose metal" therefore implying that Jabiru did not. I don't really disagree with thruster too much on this matter.

If you tap something hard onto a Lycoming head ( or even a volkswagen for that matter)  you get a sharper ring than with the old jabiru head. I am sure that a hardness test would also show a big difference. But I also suspect that the gen 4 heads are made of a different and harder material.

[Bruce Tuncks]

On rereading that post, I fear I have implied that the older Jabiru cylinder heads were no good.  This is not my real position, which is that the older cylinder heads must be kept cooler than those from harder alloys. Kept cool, they run fine for many years. I have two at 20 years old and going well.

[Yenn]

Bruce, you are sounding like Scott Morrison.

"Yes he did, he said that lycoming etc used "fit for purpose metal" therefore implying that Jabiru did not."

You could also imply that Rotax and all the other manufacturers did not and I still cannot see any mention of Jabiru in his post.

[facthunter]

There's a variation in different models of each make. The best heads are forged and then machined. They are shrunk onto threaded steel cylinders more or less permanently and some of them are nitrided and some are not. Heads for turbocharged models are much thicker in the walls. Most crankshafts are nitrided.  Some have dynamic counterweights  for Torsional damping.  Nev

[Bruce Tuncks]

Yenn, god forbid that I seem like Morrison to you. Please Thruster enlighten us here.

[Thruster88]

I guess I was having a dig. Also saying Lycoming didn't just pluck 260°C as maximum cylinder head temp from thin air, they use the right metal to make it so. 

[Bruce Tuncks]

I reckon 260 is too high even for a lycoming head. I think this was the gist of the webinar.

[facthunter]

I agree. The highest I've seen as a limit is 235 C.  The limit is related to the head metal losing heat treatment qualities. Hardness and tensile strength. Nev