Overwhelmed by engine choices
 

I'm completely overwhelmed by the choices for engines. Tappets and cams and induction direction, oh my! I don't even know where to start. I see spec-sheets on the manufacturer websites and a few of the choices that were made on builder websites. But I'm still super confused. Everyone in this forum section seems to know what they're talking about. I'm clueless.

Where do I learn all of these terms and how they'll affect my engine choice?

Can somebody please point me to a getting started guide for Lycoming-like engines?

Don't feel bad, I'm in the same boat. I haven't really started to dig into engine choices yet--still have an airframe to build! Engine choice seems to be one of the easiest places to get lost down little roads that diverge at subtle choices.

You came to the right place. We have a variety of opinions, just ask.

Building an RV8? What do you plan to do with it? What is you mission profile?

Engine choices
 

You may want to start with Vans.http://vansaircraft.com/cgi-bin/stor...duct=lycoming2

Choices
Constant speed vs fixed pitch. CS must be specified when ordering and which governor.
Horizontal vs Vertical induction. One uses the traditional cowl. Other requires a modified cowl. Horiz is standard. I think.
Compression. Lower is less HP but also less wear. You can burn lower octane fuel. Higher is HP but requires higher octane. Overly simplified.
Parallel vs angle valve. Higher performance with angle at greater weight and cost
Injected vs carburated. FI is easier to balance injectors for LOP and inverted ops. Carb requires heat. Overly simplified. Also which fuel injection and if so which fuel pump and does it require return line plumbing.
Roller tappet vs non roller. Lycoming added the rollers to eliminate the wear point on the cam. On Lyc engines a cam or tappet problem requires a complete tear down for replacement. The jury is still out as to the success. Most engine builders don't use roller. Lyc rollers are standard.
Mag vs EFI. Traditional mags or PMags. Pmag is basically a mag with the capabilities of electronic ignition. EFI is more like auto ignition.
Spark plug bosses. You can specify auto plug bosses if you want to use auto plugs.

I'm getting edumicated but not quite there yet.
For now
IO360, low compression, parallel valve, p-mags, Airflow Performance FM-150 FI and pump, auto plug bosses

This or that for all the other stuff, but roller follower cam actuation is 4x longer life than a slipper, at least. That is based on data seen in the lab, first hand. Anything can be poorly done, but a mediocre roller is better than the best slipper.

Roller
 

That's one choice easier to make. Thanks.

It is you.
 

There is not a good answer here with out knowing what you want, need or can get, for what type of aircraft and flying you will be doing. I can tell you that both the two after market suppliers in Texas have very good web sites that do answer a lot of what you are asking for. A lot of picking out a power-plant is what that person likes or what they see as their dream engine. Some guys like a 10,000 Hp. dragster and others like a Mo-pad engine.
It can and dose take many years, in some cases two or three generations to pass down most of what you ask for. Just don't get frustrated it may be slow in coming, but start with what your expectations are out of your pick of aircraft and what you want it to do. Then call some of the good engine builders and tell them what you want. Call and talk to as many as you can, not just one or two. Then be realistic with yourself. Do you need a fire-breathing dragon to do a humming birds work? Most every thing we get in our little toys is a compromise. The ideal is not often what you get. Keep asking question and looking up parts tell you are comfortable with your knowledge of the facts. You too may be a gear head in the making. Good luck. Yours as always. R.E.A. III #80888

I know what my mission profile is right now but I'm not quite sure what it will be in 5+ years when I finished with the plane.

I'm still years away from needing to make a decision on anything firewall forward, but what I'd like to do at this point in the build is become educated about engines and their options. As a renter I never really got to know much about the engine underneath the cowling. I want to understand.

I want to read. But my googling and amazoning hasn't turned up an obvious place to start.

How did y'all learn about these engines?

Should I start with the powerplant book in an A&P course or is there something more specific for Lycomings that would be a better start for me?

27 years of the RVator
 

The book "27 years of the RVator " has a lot of info in the first few pages of the firewall forward section. It's far from a comprehensive guide but has much of what you may want to know in one place.

Just curious, what lab did that data come from and was this some kind of "predicition"?
Real world numbers have not proven that to be the case to my knowledge, and I've never heard an engine builder (the guys who see this stuff everyday) make any such statement.