Trial flight: IO360/390? Nosewheel or tailwheel?

I'm contemplating an RV14 project (which would have to be a taildragger) and a trip to Aurora for a trial flight. I have done some 1500 hours in other RV models. Really I need to see in the flesh what these RV14 aircraft feel like in terms of performance, ergonomics, etc., also in this case whether the space/load increment over the RV7 justifies the extra cost. Usually trying out a new type I know pretty quickly whether or not I like its overall usability and feel.

So then, I need to decide whether to try the RV14 with IO360 (although I probably would use an IO390) or the RV14A with IO390 (although I would definitely not use a nosewheel so ground handling would not be representative). Or, I suppose, try both.

Are there any folks here who have flown both models and can comment on whether the different engines make any material difference to performance in the air or any other aspects of flight?

Mr Dye from Kitplanes said previously that there would be a comparison but I haven't seen it published.

As you said - I have flown both models, and found a negligible difference between the two airplanes in terms of speed. The factory has not yet done a wing-tip to wing-tip drag race between the two airplanes, but the discussions I have had with them seem to indicate that there will be very little difference.

For what its worth, my thoughts are that a rebuilt 360 would be a whole lot cheaper than a new 390 (there aren't any used ones), and the speed difference in the real world (unless you are racing) is likely to be very small for a typical trip.

Does Van's have a FWF kit for the IO-360 for the RV-14 or are the engines basically the same fit wish?

There is a document that Van's published regarding engine choices for the -14 but I could not find it on Van's Aircraft website. Hopefully, someone else can post a link to that document.

As best I recall, if you do an IO360, it needs to be an angle valve engine because the -14 needs the heavier engine for W&B. It also needs to have a front mounted governor. There is not enough room between the engine and firewall for a rear mounted governor.

Actually the interference of an aft gov. would be with the nose gear (A model) or oil cooler (tail dragger)

Yes, an IO-360 will work fine on an RV-14 as long as it is an angle valve version and it has a fwd mounted prop gov.

As Paul already mentioned the performance diff between the IO-360 and IO-390 is small.

The two demonstrators (trike and tail dragger) are about exactly the same speed in their current configurations. That is with 210 HP and a Hartzell blended airfoil prop on the tri-gear, and 200 HP and the old school Hartzell on the tail dragger.
If they both had the same engine and prop, the tail dragger would be slightly faster (as is the case with all the RV models)

It seems then there is no way currently to compare in action, an apples-to-apples RV14 versus RV14A with same engine/prop?

1mph

Wingtip to wingtip drag race with a 1 mph difference means bragging rights for the winner (aka taildragger) and humiliation for the 1st loser (training wheel).
Sorry, couldn't resist. In realty, both are better than nothing.
Who cares about 1mph anyway?

Bluebeard said:

It seems then there is no way currently to compare in action, an apples-to-apples RV14 versus RV14A with same engine/prop?

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What info are you searching for.
People that have flown both (my self included) have told you that the performance difference is very small.
The published performance data for all of the RV models that can be built in both gear configurations shows the tail dragger just slightly faster.
That is the case with the RV-14 also.
So the fact that the trigear with a slightly bigger engine and blended airfoil prop is the same speed as the tail dragger with the lower HP and a standard prop, we can assume that the tail dragger with the bigger engine and blended airfoil prop will be just slightly faster that the trigear.

Now if you are wanting to know whether slightly mean 3 MPH, or 4 MPH, that is pointless. There are often bigger speed differences from one equally powered airplane to another just from differences in fit and finish quality (alignment of fairings, etc.) and how people operate their engine, than there is from what gear configuration is hanging below.

Well, Scott, I think you have answered my question: there is no significant performance difference (a few knots here and there I would not consider significant) between the two engine/prop configurations.

Which makes me wonder why the factory fitted the RV-14 taildragger with the smaller engine? It seems to rather go against the philosophy of standardization. As someone else observed here, where there is an RV engine choice more power seems to attract a premium. Does the IO360 angle-valve engine use the same engine mount, cowling etc as the IO390?

Bluebeard said:

Well, Scott, I think you have answered my question: there is no significant performance difference (a few knots here and there I would not consider significant) between the two engine/prop configurations.

Which makes me wonder why the factory fitted the RV-14 taildragger with the smaller engine? It seems to rather go against the philosophy of standardization. As someone else observed here, where there is an RV engine choice more power seems to attract a premium. Does the IO360 angle-valve engine use the same engine mount, cowling etc as the IO390?

Click to expand...

From the experience of another kit aircraft where there is a well-supported IO-360 and equally-well-supported IO-390 installation, the marketplace has spoken very clearly. The IO-390 is chosen by an overwhelming majority of buyers. Now these folks are laying down big bucks for the kit and its assembly, so the cost difference between a factory-new 360 and 390 is getting lost in the weeds. The real differences that owners perceive are, as pointed out earlier in this thread, slightly better cruise speeds, and, importantly, slightly better takeoff and climb characteristics. In cruise flight the two engines turn in similar fuel specifics.

Watch this video from Kitplanes for a more detailed review.
https://www.youtube.com/watch?v=rr1u80fN5sk

Bluebeard said:

Does the IO360 angle-valve engine use the same engine mount, cowling etc as the IO390?

Click to expand...

Yes,
And pretty much all of the rest of the FWF kit is the same (baffling, induction system, etc.) so there is no down side to it being offered as an additional engine option to builders. Particularly those interested in it from teh standpoint of installing a used/overhauled engine as a way to reduce the cost of the build (since as already mentioned, there is little to no cost difference if you purchase either engine new. In fact I think the OEM price through Van's is slightly lower on the IO-390)

So there is primarily two reasons the IO-360 was installed on the tail dragger prototype/demonstrator.

1. We had one.

2. It provided an opportunity to proof out the installation and confirm it was fully compatible with the FWF kit and instructions.

Thank you for this information - useful food for thought.