Lycoming Engines Codes

[mikeno]

Can anyone provide specific Lycoming engine codes for the IO-360 and IO-540 that are acceptable for the 4 place BH? Also, is there a specific 172 model (S, N, etc.) for the struts and windshield? Thanks Mike BearHawk #1250 KLXT

[jaredyates]

I think you may find the first question to be hard to answer- it may be a better approach to look into which engines are hardest to integrate and which are easiest to integrate. For example, my engine isn't in a configuration that Lycoming ever made, so it has no suffix, but it was very easy to integrate. The best way to narrow it down would be to decide if you are planning to use Mark's engine mount or make your own. If you are planning to make your own, then you could probably make about anything work. There is a 5-part article back in the early 2000s Beartracks where Bob gets into the details about mounting options, narrow deck vs wide deck, angle valve vs parallel valve, etc. As for the struts, you'll probably want to get them directly from Bob as he has them custom made at an extruding mill. I happened to be visiting one time when he was receiving a shipment of the minimum order, and it was a pickup truck load full. For the windshield, LP Aero Plastics has one that is specific for the Bearhawk. My understanding of the story behind that is that after lots of folks started with a Cessna 170 windshield and carefully trimmed it to work, someone sent his trimmed windshield (Jim C?) to them and let them take measurements so that they could duplicate it.

[mikeno]

Thanks for the feedback Jared. I'll hunt down the Beartracks article on the engines.

[Zzz]

There is a 5-part article back in the early 2000s Beartracks where Bob gets into the details about mounting options, narrow deck vs wide deck, angle valve vs parallel valve, etc.

I'm glad you reminded me of that. Do you know exactly which Beartracks issue it's in?

[mikeno]

The articles begin first quarter 2002 issue and continue through the 4th quarter. If anyone has them, please share. The early (pre-2005) issues were included in the plans package from Bob but I got my plans in a trade for my Patrol plans and they weren't included. Mike BearHawk #1250 KLXT

[Battson]

The narrow vs. wide deck is an issue with some common "old wives tales" and can be misunderstood, and I was taken in by that confusion. That is definitely worth understanding before you make your choice.

On a different topic - I found this website very helpful:

http://www.meyette.us/LycomingEngineNumbers.htm

[Zzz]

The narrow vs. wide deck is an issue with some common "old wives tales" and can be misunderstood, and I was taken in by that confusion. That is definitely worth understanding before you make your choice.

The use of "narrow" and "wide" is kind of inappropriate, if I understand correctly. It refers to the thickness of the cylinder base flange, right? Not the actual footprint.

[Battson]

Yes - the "deck" is the flange at the base of the cylinder, where the bolts pass through to attach the cylinder to the case.
The newer wide deck (WD) cylinders have a thicker flange and don't need the banana plates.
The change was brought about as Lycoming strived to get more horsepower from their existing engines, they needed increased strength.
Bob suggested the ND might be slightly lighter, and (unsurprisingly) makes for a slightly narrower engine overall. The ND seems to be considered older technology these days. An ND install (namely the baffles) is forwards compatible with WD, but WD is not backwards compatible with ND.

[alaskabearhawk]

You can mount anything you want on the front as long as you don't put on anything that is too heavy. The main consideration is weight.