Lycoming easing their position on LOP?

[nomocom]

LOP operation Item 10, I notice a change in tone....

http://www.lycoming.com/news-and-eve...e-fuels-fa.pdf

[rjcthree]

Is it time to track fuel in a never ending thread? Many of us using high compression engines. . . . Nothing short of 100oct will do. Thoughts?

Rick 90432

[shuttle]

Thanks for posting the link. The doc referenced Lycoming Service Instruction 1070P. I'd not seen this before. It's been superceded relatively recently (16th July 2010) by SI 1070Q.

Here's a link to 1070Q: http://www.lycoming.textron.com/supp...fs/SI1070Q.pdf

SI 1070Q lists Lycoming engines and the fuels approved for use in them.
I do not fully understand yet everything the SI is talking about. I'll need to study some more. It does contain some useful background info.

There is a short table towards the end of the document listing Lycoming engines approved for use with automotive fuel of AKI 93, where AKI is the average of RON & MON (read the doc for definitions).

I was interested to see that no (I)O-320 engines are in the 'approved for use of automative fuel' list but there are some (I)O-360's.

The (I)O-360 list includes:
O360 series A, C, F, G & J engines
IO360 B1B, B1E, B1F, B1G6, B2E, L2A, M1A, M1B

Anyway, I think SI 1070Q is worth knowing about.

[Ron Lee]

Originally Posted by rjcthree

Many of us using high compression engines. . . . Nothing short of 100oct will do. Thoughts?

My reading of the 100LL replacement fuel issue is that 100 octane is a replacement requirement. No dual/multiple fuel solution. Obviously other requirements.

Hence I am not worried about the alleged demise of 100LL.

[rjcthree]

The problem is that Continental has thrown in behind a 94UL as the successor to 100LL. They have not stood up and said 100 octane is required. The manufacturers are split, halving (or more) the voice!

Seems like something those two (and maybe Rotax too) should get together about!

Rick 90432 (read most of the 100octaneformyplane.com site waiting for the dorctor this morning).

[nomocom]

Originally Posted by rjcthree

Is it time to track fuel in a never ending thread? Many of us using high compression engines. . . . Nothing short of 100oct will do. Thoughts?

Rick 90432

When you read about the fuel testing, the octane demanding phase for engine operation is high chts and high power. My thoughts are with modern engine analyzers we don't need the octane as dearly as before. Sure, it's nice, but......these days when we can see when we are getting a cylinders close to 400 f, we do something about it, either immediately with a power reduction or mixture change or more permanently improve cooling via mods done in the shop.

I'd like to see a high octane remain available, but it seems like there isn't financial incentive for two tanks of piston fuel at airports, so my vote would likely go for the lower octane if there were a significant cost difference between the say 94ul versus a 100 replacement.