Choosing an engine/prop

[iowaflyer]

First time poster here--so please be gentle. BTW, I have checked the archives but wanted to get some new opinions.

I've just ordered the empennage kit for an RV-7. I'm trying to finalize my choices with regards to prop and engine. I know I want a non-certified FI IO-360 (IO-360-M1B) and I THINK that I want the horizontal induction with the forward facing induction (cold air). For simplicity, I'm going to stick with good old mags.

My questions:

Who should I get the engine from? I've priced out Mattituck and Aerosport power for a new engine. They both tell me that only new engines are available; overhauled are very hard to find and the price difference isn't that great anyway. Anybody else to consider? Is there anyone that can provide an OH'd engine?

Is the cold-air induction worth it?

I'm a first time builder and want to keep things relatively simple. Is the above setup with a Hartzell blended airfoil CS prop going to generally work OK with the Van's-supplied cowl/mount/firewall forward kit without much modification?

Any other suggestions/modifications to my engine choice?

74" or 72" prop?

Thanks in advance--I appreciate the great advice that the forums provide and I'm sure I'll have plenty of questions later on.

[erich weaver]

If you go with horizontal induction, make sure to check with Vans on what, if any, fabrication is necessary to route your intake air from the filtered air box, which is typically placed just inside the cowling air inlet on the left side. This may add a complication that you wouldnt have to deal with using vertical induction. It will defintiely save time to use an engine that Vans has a standard kit setup for.

Are you sure you dont want to consider electronic ignition, at least on one side? There's really nothing complex about it, and it has definite advantages.

erich

[iowaflyer]

I've been told that use of autogas may not be possible with electronic ignitions--something about advancing the timing/higher peak pressure/risk of detonation. Any truth to this?

[airguy]

Originally Posted by iowaflyer

I've been told that use of autogas may not be possible with electronic ignitions--something about advancing the timing/higher peak pressure/risk of detonation. Any truth to this?

Compression ratio, octane rating of the mogas, and possible ethanol content have more effect than EI. Not saying EI doesn't change the game - but it's not the major player.

[Bob Martin]

http://www.attawayair.com/

Robbie does ECI engines
and as done the forward facing sump with cold air induction.
Check it out!

[agough277]

You can't go wrong with Van's recommendation: fixed pich and carburated. I installed two TMX O360 engines and am favorably impress with how smooth they run. Put Van's Sensenich props on. Haven't had to have a prop balance done on either. Help and service from Mattituck was excellent. Use the money you save on something else.
Al

[Caveman]

Originally Posted by iowaflyer

First time poster here--so please be gentle. BTW, I have checked the archives but wanted to get some new opinions.

I've just ordered the empennage kit for an RV-7. I'm trying to finalize my choices with regards to prop and engine. I know I want a non-certified FI IO-360 (IO-360-M1B) and I THINK that I want the horizontal induction with the forward facing induction (cold air). For simplicity, I'm going to stick with good old mags.

Great choice on the airplane! I don't fault the mags choice, either.

My questions:

Who should I get the engine from? I've priced out Mattituck and Aerosport power for a new engine. They both tell me that only new engines are available; overhauled are very hard to find and the price difference isn't that great anyway. Anybody else to consider? Is there anyone that can provide an OH'd engine?

Don't overlook Barrett, (BPE), they have an ad just to the left on this page.

Is the cold-air induction worth it?

I can't say, but I like the cowl shape and my engine puts out about 195 hp. (I have 9:1 pistons).

I'm a first time builder and want to keep things relatively simple. Is the above setup with a Hartzell blended airfoil CS prop going to generally work OK with the Van's-supplied cowl/mount/firewall forward kit without much modification?

Short answer is yes. I have this set up with the Teledyne Mattituck IO-360 M1B, (horizontal sump) Hartzell BA, but with one Lightspeed ignition. One caveat... I chose the SilverHawk fuel injection to avoid any cowling issues. It worked nicely.

Any other suggestions/modifications to my engine choice?

I'm very happy with my TM engine. It is smooooth. Barrett, TM, and Aerosport all have excellent reputations and support. For me, it came down to a bit less money when I started piling on the options. Prices have probably changed.

74" or 72" prop?

I went with the 72" but you can argue either way. Some say that the 74" gives you two inches to work with if you ding a tip. My thought was that if you didn't have that extra 2" on a taildragger it may keep you from dinging a tip in the first place. The prop performance should be about the same either way.

Thanks in advance--I appreciate the great advice that the forums provide and I'm sure I'll have plenty of questions later on.

Sounds to me like you've done some good research.

[RV7Guy]

You've got ECI and Barrett Precision close by. Either would be great. I have an ECI built by Robbie Attaway (mentioned earlier). My next engine will be an IO390 by Barrett Precision.

Props-I highly recommend the Whirlwind 200RV prop. It was designed for the RV airframe. The 200 is extremely smooth and efficient.

You've got lots of time before you need the engine. Things will likely change with improvements and modifications over time. Who knows, the prices might come down, yeah right!!!

[L.Adamson]

In regards to "fixed pitch"; there are a lot of us RV'ers that fly a 150 miles to brunch on Sundays.
Now we do operate out of higher altitude airports and have mountains to deal with. The fixed pitch versus constant speed, often comes up at the table discussion...........because I bring it up!

And the consensus is.................not one RV owner with a C/S would prefer to go back to a fixed. And most fixed owners, would prefer a C/S after seeing how well ours do!

So take this for what it's worth....

L.Adamson --- RV6A

[N941WR]

Originally Posted by iowaflyer

I've been told that use of autogas may not be possible with electronic ignitions--something about advancing the timing/higher peak pressure/risk of detonation. Any truth to this?

Funny, I wonder how my car operates on autogass and EI?

Seriously, they work just fine and many of the EI systems will alow you to tune them for 100LL, auto fuel, etc., if you want. That is not required to run auto fuels, so don't let that scare you off.

The two big EI vendors out there right now are E-mag and LightSpeed. Research both as they each have their good points.