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An O-470 on am RV-14?

Bad-Andy

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I hope this is not a stupid question (or at least not one with a glaringly obvious answer). Has anyone looked at putting an O-470 on an RV-14? I’ve searched for the answer and can’t come up with anything that would prevent it. It would only be 60ish pounds heavier, but would give a few HP more. And more importantly, could run auto gas all day long. I’ve done some “bar napkin” w/b calculations and it looks like it could work. So, the question is — what am I missing? Thanks.
 
couple of things;

What does that do to your fuel burn? Maybe I'm wrong, but I can't imagine you'd have much more than 2.5 hours + IFR reserve with that setup.

I think it's a mistake to get hung up on the Avgas vs Mogas thing. I get wanting to save money and I just went through the same exercise on my engine selection for the RV7. AvGas vs Mogas is about $1 per gallon right now around here. If I fly 200 hours per year (a big assumption) that works out to be an extra $2000 for avgas (I'm assuming 10 gph, your numbers would obviously be different). That's not nothing, but it's actually less than my family pays for cable TV or a cellphone plan. As far as Avgas going away, I've been hearing that for over a decade and it hasn't happened yet.
 
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Wt & Balance effects?

Find posted data from "standard" build as weighed on scales.
Run W&B for range of loads from fully loaded to minimum. Note fwd & rear center of gravity limits.

For a quick look, add #30 to right and left main gear weight as recorded.

Re-calculate W&B, CG, gross weight effects.
 
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You've probably had better ideas.

1. The weight increase is a killer, right there, and that doesn't include the added weight of the larger prop further forward.

The O-470 is a physically longer engine, too, as well as being heavier.

2. As mentioned, you'd need to come up with your own engine mount, FWF and engine installation kits, and probably a modified cowling, too.

3. One of the advantages of the RV-14 is its complete integration and relative ease of construction. You'd lose most of that and add a couple years to the project, ending up with an airplane with much lower value than you should.

4. I fly an O-470 and it's got approval for auto gas. I find that on trips, it's mostly illusory. While the advent of the Rotax-powered airplanes with their auto-fuel requirement is changing this situation, you can't really count on the availability of auto gas at just about every little airport you stumble into as you can with av-gas.

And after considering the fixed costs of owning an airplane, the small difference in fuel cost is honestly not something I notice. It's just lost in the overall cost.

Bottom line, I've got to recommend that you not do it.

Dave
 
You've probably had better ideas.

1. The weight increase is a killer, right there, and that doesn't include the added weight of the larger prop further forward.

The O-470 is a physically longer engine, too, as well as being heavier.

2. As mentioned, you'd need to come up with your own engine mount, FWF and engine installation kits, and probably a modified cowling, too.

3. One of the advantages of the RV-14 is its complete integration and relative ease of construction. You'd lose most of that and add a couple years to the project, ending up with an airplane with much lower value than you should.

4. I fly an O-470 and it's got approval for auto gas. I find that on trips, it's mostly illusory. While the advent of the Rotax-powered airplanes with their auto-fuel requirement is changing this situation, you can't really count on the availability of auto gas at just about every little airport you stumble into as you can with av-gas.

And after considering the fixed costs of owning an airplane, the small difference in fuel cost is honestly not something I notice. It's just lost in the overall cost.

Bottom line, I've got to recommend that you not do it.

Dave

Thanks Dave. I had not thought about the heavier prop aspect and about the engine mount. That will take a lot more than back-of the-napkin calculations. As for the mogas, it’s more of an issue of availability than it is money. I take a couple of trips a year into the Caribbean (in the Cherokee 180 I have now), and twice I’ve had to go a little farther than I like because intermediate stops didn’t have avgas available (although I’m pretty conservative on reserves over water...). Having the ability to use mogas would open up more options for fuel stops. That’s all. The only options I saw for mogas in an RV14 is a low compression O-360 (underpowered) or an O-470 (too heavy).

Back to the drawing board......
 
Anyone have any idea how many RV-14’s have something other than the factory recommended engine?

Curious if others have found value in improved performance with alternate engines.

-David
 
For as common as the O-470 is, it is a bit surprising to me that it has not seen the same after-market hot-rodding that the Lycoming O-360 has. In standard form, it has dismal Hp/weight, owing to the CR=7:1.

Putting IO-470 cylinders (CR=8.5:1) on an O-470 (can that be done?) should give something like 250--260 Hp which would be a nice bump up. But why not put 10:0 pistons in a O-470 like people do on O-360's and O-540's? That would get the power/weight ratio up where it starts looking like an attractive option.
There is an STC retro-fit fuel injection that would make GAMI tuning a possibility. (otherwise the stock induction distribution is so poor that LOP is hopeless)

With the magnetos above and in front of the accessory case, the motor mount can be shorter (although there is still the alternator on the back that needs some room). But the short motor mount partially offsets the c.g. effect of the added weight. Does having the magnetos where they are on an O-470 result in a larger frontal area or a lower thrust line? I don't know.

Another question/issue is the RPM limit. The O-470 has METO limit of 2500 RPM, and 2600 RPM for take-off. In principle I don't see why one couldn't run one faster.

It seems like this might be worth exploring in more detail.
 
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I looked at the 470 / 520 possibility back some years but decided it too much of an up hill climb to get it sorted out.
Weight was the main detractor, but also the challenge of a rear induction interfered with the 7A gear situation on the project of that time.
Another issue, & may be a detractor to employing higher compression, is the 470 / 520 susceptibility for case cracking.
Considering the IO-360 6 cylinder if it could be hot rodded was another pipe dream, nice smooth running engine. But same issues would probably nix that one too. Turboing it would be sweet though.
 
Putting IO-470 cylinders (CR=8.5:1) on an O-470 (can that be done?) should give something like 250--260 Hp which would be a nice bump up. .

PPonk or Skyways O-470-U is a 470 case modified with 520 cylinders for 260-280HP. Common mod for the 182s flown higher elevations and backcountry.

470 is a good motor, but probably not any net gain over a hot rod -390 even if somebody got it figured out. Lycoming 540 models of 230HP would probably be a more realistic bet - but you're just adding as much weight as HP at that point. Several Super-8s and Super -7s out there with a 540, surprised we haven't seen a -14 with a parallel valve 540 yet.
 
There is an STC retro-fit fuel injection that would make GAMI tuning a possibility. (otherwise the stock induction distribution is so poor that LOP is hopeless)

Another question/issue is the RPM limit. The O-470 has METO limit of 2500 RPM, and 2600 RPM for take-off. In principle I don't see why one couldn't run one faster.
.

As a long time 182/O470-S owner, I can confirm that the mixture distribution is hopelessly bad, especially at full throttle. But I don’t recall any METO limit. Another issue may be clearance with the standard Vans nose gear. IIRC the 182RG went to a Lycoming specifically to make room for the nose gear.
 
As a long time 182/O470-S owner, I can confirm that the mixture distribution is hopelessly bad, especially at full throttle. But I don’t recall any METO limit. Another issue may be clearance with the standard Vans nose gear. IIRC the 182RG went to a Lycoming specifically to make room for the nose gear.

My C-182 (1959) has an O-470-L which has the METO limit. We tow at 2600 anyway. The POH says that when maximum performance climb is required, the take-off power settings may be used. We figure towing qualifies.

For an RV-14, I would think a IO-540 parallel valve would be a great choice. Use a lot of RV-10 stuff.
 
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