Thom,
1. Injection vs Carburated:
Primary advantages of FI over carb are fuel economy of about .5 to 1 gph in cruise due to leaning advantages. Ability for inverted flight. Lack of carb ice concerns.
Primary disadvantages of FI over carbureted are cost and lack of simplicity.
2. Updraft vs Fwd-facing sump:
Here are the differences between the vertical and horizontal engines. The vertically supplied 180HP engines IO or O without the fuel delivery system and fuel pump are exactly the same. The
difference between an 180HP experimental horizontal engine and the vertical engine is just the sump and intake pipes. The two common forward facing
sumps produce more power because they don't heat up the air going
through them, from the hot oil in the sump portion, as the vertical
sumps do. Our tests have shown the horsepower difference to be
approximately 6.5 to 7 HP more with the horizontal forward facing
cold air sump. The Superior horizontal sump is made of a composite
plastic the others are made of aluminum. Our tests were conducted
using the aluminum sump but I can't see why the plastic one would
yield different results. If fuel injecting the vertical sump, you
should be able to use the same cowl setup as the carbureted version
of the engine. The Bendix Fuel injector when mounted is approximately
1 inch shorter than the carbureted version. Installing a spacer
between the bottom of the fuel injector and top of the air box will
make the height difference non-tangible. The only possible problem is
that the mixture control on the fuel injector will need to be
anchored, on the engine end, in a non-standard fashion as the mixture
lever on the fuel injector is in a different place than on the
carburetor. The standard carburetor throttle mount bracing should
work OK as the throttle arm on the Bendix fuel servo is in a very
similar location when compared to the carburetor.
3. Lasar vs Lightspeed vs Slick mags (also Halls vs Crank sensing):
I guess the answer to that is your own personal preference. There are many, many, 360's out there running with just two mags. They work great and are reliable and safe. However, even when you have a good system, others will try to improve it, that's why there are alternative systems available. Do those alternatives make the engine more efficient? Probably. Safer? Maybe,maybe not. More reliable? Not necessarily. More expensive to purchase? Most likely. So when you take all the variables, into consideration, it comes down to whether you want electronic ignition or not, what type of redundancy you want, and what you want to spend for it.
If you want dual electronic ignition, each using the other as the back up you could use two of a system like Lightspeed or some of the others available. If you want 1/2 electronic ignition and 1/2 standard ignition, the only way to do that exactly, is to use a mag on one side and a system like Lightspeed on the other side. If you want to run dual electronic with dual magneto backup, then the LASAR system from Unison is the way to go. All of these systems, standard magneto ignition, full electronic, partial electronic and partial mag, LASAR, in my experience, work well and are reliable. Another possibility is the FADEC system, from Aerosance. This system gives you full double redundant electronic ignition but also gives you electronic fuel injection as well. So with that system besides getting the advantages of the electronic ignition, you also get a very precise fuel metering system that also performs all of the leaning functions on the engine( No more mixture control). The FADEC system adds considerable cost to the engine over standard carburetor equipped with any of the ignition options listed. In most cases about $7500.00 more than a standard O-360. The Lightspeed system adds about $350.00 to $900.00 per side additional, depending on which of their systems you want to use over the standard engine. The LASAR system typically adds about $1800.00 to the engine, over standard ignition. These costs assume that you are getting some sort of credit for not using the standard ignition system. If you weren't getting a credit you would add about 600.00 for each mag and harness, you weren't using to the costs and of course you would have those components as not installed spare parts.
There are also some new players on the block that offer an emag and also a P mag. New techonolgy and very hard to get yor hands on any, but maybe worth a look.
4. 9.0 vs 8.5 compression ratio (I want the option to run MoGas): No mogas with 9:1 as far as I know. Same with any electronic ignition systems mentioned.
5. Roller pushrod vs solid pushrods: Only benefit I know of is the change in wear characteristics that COULD be possible with the roller tappets vs. normal tappets. Camshaft wear is an issue on Lycoming style engines especially if inactivity is present. The roller cam set up should help with this. The only disadvantages that I see is the newness and untested situation you get into when anything new comes to market.
WE would love to build your XP for you..give me a call if you are interested in us assembling it for you. 1-800-624-668 ext.305.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at you own risk."
