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IO360 210+hp instead of IO390

Bernard Hartnell

Active Member
I am building and installing an IO360 angle valve with a couple mods to bring up and past hp of the IO390 at a much lower cost. Cost reduction comes both in the cost of a rebuilt 360 vs new 390, but also down the road in parts costs as the higher cost 390 ages and requires such things as cylinders. My Io360 will have the Lycon port & Polish & special valve grind with 3 angle seat grind. It will also have the special coated 10.1 pistons. Plus 1/2 mag 1/2 light speed E ignition. Thus producing well over the 210 specked for the 14.
 
I am building and installing an IO360 angle valve with a couple mods to bring up and past hp of the IO390 at a much lower cost. Cost reduction comes both in the cost of a rebuilt 360 vs new 390, but also down the road in parts costs as the higher cost 390 ages and requires such things as cylinders. My Io360 will have the Lycon port & Polish & special valve grind with 3 angle seat grind. It will also have the special coated 10.1 pistons. Plus 1/2 mag 1/2 light speed E ignition. Thus producing well over the 210 specked for the 14.

You are the first as far as I'm aware to post plans to do something other than an IO390. Glad to hear about other possibilities. Personally, I would like to do a diesel.
 
Welcome to VAF!

My understanding is the angle valve heads flow pretty well as they are and port, polish etc adds very little in terms of power. Sure a flow bench may show some gains but does that translate into more power?

I've done the piston coating tricks in racing engines (cars, motorcycles) and have to say noticed no HP gains on a dyno while tear downs seemed about the same wear wise. I'm not a fan. Your mileage may vary of course.

High compression angle valve, overhauled...I am a believer. I could have mine and a spare sitting in the hanger for less than a new 390. Overhauled vs new of course, we each must make our choice. I would save the porting and fancy machine work and put that money into something with a bit more bang for the buck if this is a money saving exercise.
 
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I am building and installing an IO360 angle valve with a couple mods to bring up and past hp of the IO390 at a much lower cost. Cost reduction comes both in the cost of a rebuilt 360 vs new 390, but also down the road in parts costs as the higher cost 390 ages and requires such things as cylinders. My Io360 will have the Lycon port & Polish & special valve grind with 3 angle seat grind. It will also have the special coated 10.1 pistons. Plus 1/2 mag 1/2 light speed E ignition. Thus producing well over the 210 specked for the 14.

A few comments....

Re the "much lower cost": I assume this is an apples-oranges price comparison, a used/rebuilt 360 vs a new 390?

Yes, cylinder costs currently favor the 360. Even then, the operative word is "currently". No telling what costs might be with many more 390s in the air ten years down the road. Right now the issue is single source and low volume.

Don't know details, but I seem to recall the Lyc kit 390s having case strength improvements. For sure they have roller tappets. Most good aftermarket shops rework valve seats; I prefer cut seats rather than ground seats. Either engine can have an electronic ignition.

The compression boost is not a free lunch. At the basic level you're pushing the smaller engine harder to get the same power. You'll also have smaller detonation margins and may bump into future fuel limitations. Barrett Performance created the first 390s specifically to get away from the exact thing you're doing; the idea was a more reliable, longer lasting 200+hp 4-cyl for the aerobatic customers. Obviously the idea worked out pretty well, even though all the original experimental 390s were case conversions.

Last, a standard 390 matched to a BA Hartzell means you have no vibration concerns and no operating restrictions. It's a fully vibration-surveyed, certificated combination.

Then there's resale. Oddballs raise eyebrows, and not always in a good way.

I suggest buying one less avionics toy. Put the extra money into a 390.
 
saving

I am planning and saving for the 390. Last flyer from Vans (OSH I think) had essentially the same price for the angle 360 as the 390 IIRC...apples to apples. Maybe evan a deeper discount when a number of us have the -14's ready to engine?
 
A few comments....

Re the "much lower cost": I assume this is an apples-oranges price comparison, a used/rebuilt 360 vs a new 390?

Yes, cylinder costs currently favor the 360. Even then, the operative word is "currently". No telling what costs might be with many more 390s in the air ten years down the road. Right now the issue is single source and low volume.

Don't know details, but I seem to recall the Lyc kit 390s having case strength improvements. For sure they have roller tappets. Most good aftermarket shops rework valve seats; I prefer cut seats rather than ground seats. Either engine can have an electronic ignition.

The compression boost is not a free lunch. At the basic level you're pushing the smaller engine harder to get the same power. You'll also have smaller detonation margins and may bump into future fuel limitations. Barrett Performance created the first 390s specifically to get away from the exact thing you're doing; the idea was a more reliable, longer lasting 200+hp 4-cyl for the aerobatic customers. Obviously the idea worked out pretty well, even though all the original experimental 390s were case conversions.

Last, a standard 390 matched to a BA Hartzell means you have no vibration concerns and no operating restrictions. It's a fully vibration-surveyed, certificated combination.

Then there's resale. Oddballs raise eyebrows, and not always in a good way.

I suggest buying one less avionics toy. Put the extra money into a 390.

I totally concur with Dan's statements.

Lyc. has already given indications that they want to phase out the angle valve 360. This will have some level of effect on future parts cost... to what degree remains to be seen.
Lyc. has also implied that the OEM price though Van's might end up being cheaper than what the IO-360 currently is. We will of course have to wait and see how that plays out.
 
My IO360 210+ hp engine thoughts now completed

Was at Oshkosh and finally able to order fuselage! Yippy!! That much closer. Had a chance to pet the IO390 210hp Vans had at their tent. Cool choice. Vans has been working to adjust the temps on it and is planning an upgrade with the sizing of the oil cooler. Like all former engine applications, engines must be tuned into place over time. Vans dinner talks also mentioned alternative choices. So my choice was actually one of theirs, putting aside the notion about the IO360 being some kind of resale issue or odd duck. The price a Vans has put together along with the prop makes the 390 a more viable choice than in the past. A choice worth consideration. But tuning it's cooling and other issues will be the same tasks as all other applications. My choice and overall approach is well tested throughout time and does not make this engine a hotrod short run engine, based upon factual history. It's a choice that actually has many thousands of test time in real aircraft over the 390. However, that would not stop me from purchasing the 390. Neither or in fact any engine choice for this aircraft will require high Oct. Av gas not auto gas engines. Anyone looking for those thoughts should think about other aircraft choices and models where lower hp requirements are appropriate. I love this plane and can't wait to fly it!!!!
 
Port polish and balancing

All you have to do, is stick your finger inside a jug to feel the profound shape and smooth or roughness difference between a jug that was done by Ly Con and the std issue jugs from the factory, to tell the difference. Next see the flow test data differences. Then the Dino testing results. This hp increase improves performance as well as fuel burn efficiency with no cost to engine life. Payback comes over time but performance is immediate. Raising compression to this level is moderate and is standard helicopter issue with same TBO. E ignition saves fuel while reducing the chance of predetination. Small hp improvement too. Ever try to run your plane one one set of plugs vs both? Now think about even greater efficiency!:D
 
Almost done now with FWF

almost all FWF Kit parts fit up to my IO360; exhaust, hoses etc. etc.. The block and jugs are a match to the IO390. My sump does not have the boss for mounting the throttle cable just aft of the servo. So had to work with my EAA tech counselor to build a bracket. Installed today and works well. Baffles fit perfectly with no mods. Prop governor- front, same hardware as 390. Bottom line is that an overhauled, modified like mine or a stock low time IO360 is a good option, as long as you use a forward mounting governor if you use a CS Prop & you use a forward facing sump & servo. Check out Vans comparative performances between the IO360 & the IO390. Your performance is not a factor with this choice. If you buy new through Vans, go the IO390. If you want to save significantly, and have the skill or have a friend who does to build you an IO360A, this is a clear cut alternative to consider. Jessie at Colorado Air Parts has been a very good company to acquire cost effective certified or non certified parts, both used, reconditioned or new!
 
If you think there is anything easy about installing a 6 cyl Continental engine where a 4 cyl Lycoming was intended to go, my guess would be that you haven't ever built an airplane yourself.
 
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Shucks, Scott; did you read the 2nd line?
{insert obligatory ;-) here}

Charlie
(Flying a purchased -4; RV-7 Mazda Renesis FWF in progress)
 
Check out Vans comparative performances between the IO360 & the IO390. Your performance is not a factor with this choice.

Where is the comparative performance info from Vans? I'm pretty sure Vans hasn't done true comparative perf testing...they have a -14 with a 360 and older model Hartzell that according to their website is a bit faster than their -14A with the 390 and newer 'blended airfoil' Hartzell. It's well documented that the stock 390 produces about 15 more HP than a stock angle valve 360, and also well documented that the blended airfoil Hartzell is a few knots faster than the older blade profile. My takeaway is that the nose gear on the -14A is a pretty significant drag penalty compared to the nose gear on the other 2-seat RVs, otherwise the taildragger 14 with smaller engine & less efficient prop should not be faster than the trigear 14A. Take a look at the -7 with 180 hp vs -7A with 200 hp (really 195 hp for a stock IO-360), or the same comparison on the 8 series. In each case the A model with the 15 extra hp is about 5 mph faster than the taildragger. Big difference for the -14 series where the A model with 15 extra hp AND better prop is still a couple mph slower than the taildragger :( I know the -14A has a bigger nosewheel and more robust gear leg, but I'm still surprised the drag penalty is so significant.

It would be nice to have true comparative perf numbers for the different engines on each airframe so we could know just how big the difference is for each.
 
Personally, I am not bothered about a knot here or there, but if Scott can give us an insight to the pro's and con's of substituting an IO-390 with an IO360-A1B6 variant with a rear governor, I would be interested.

At S n F last year, a few of the aftermarket engine vendors were already speccing motors for the 14.

We are a couple of years away from a motor. The initial cost of a Vans deal 390 outweighs the cost of a new 360 but with possible future penalties re spares etc etc.

390 is sensible, fits, designed for, but if the resale goes soft because of potential spares costs, is it worth it ?

Other 360's are a chunk cheaper.
 
The small amount of side by side testing that we have been able to do showed that the two prototypes, as currently equipped, have pretty much exactly the same speeds (I flew the tail dragger for this test and the two airplanes were dead even while in loose formation). When I fly them cross country I get 171-172 knots TAS with both airplanes at the same fuel flows.
So if the tail dragger did have an IO-390 and blended airfoil prop it should be a bit faster... probably by about the same difference that there is between an RV-7 and 7A.

Where did you see the info implying that the A model prototype is slower than the tail dragger?

I think either engine is a great choice depending on what deal someone is able to make (but the IO-360 must be a variant with a Fwd. gov., not a rear one. The two engines use the exact same FWF kit... all the parts work for either one. The weight difference isn't enough to be any issue.
 
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The small amount of side by side testing that we have been able to do showed that the two prototypes, as currently equipped, have pretty much exactly the same speeds (I flew the tail dragger for this test and the two airplanes were dead even while in loose formation). When I fly them cross country I get 171-172 knots TAS with both airplanes at the same fuel flows.

If you're flying them side-by-side at the same fuel flow then you're probably making about the same horsepower on each engine. In that case I'd expect the taildragger to be a few knots faster since it has less drag. If you were instead flying the same percent power (for example, wide open throttle at 8500' and using the same leaning procedure to get 70% power on both engines), the 390 has got to be burning more fuel and making more power than the 360.

Where did you see the info implying that the A model prototype is slower than the tail dragger?

http://www.vansaircraft.com/public/rv14perf.htm Note that the specs show the taildragger to be faster on the smaller engine at the same percent power settings...
 
390 is sensible, fits, designed for, but if the resale goes soft because of potential spares costs, is it worth it ?

The worrisome 390 penalty was cylinder replacement cost, formerly up in the $3k bracket. However, that changed last summer. A major price reduction zoomed by under the radar; I missed it and I suspect a lot of other folks did too.

A recent survey:

Lycoming list is $1909.63, Air Power is $1712. http://www.airpowerinc.com/productcart/pc/cylinders.asp?catid=70&subcat=0&prodid=466972

Spruce is $1834 http://www.aircraftspruce.com/catalog/eppages/lycoming07-13900-46_07-14111.php

If you would like new blueprinted cylinders (dimensional checks, port cleanup, seats recut with a Serdi, etc), Barrett is $1997

Still not priced down there with parallel valve cylinders, but believe it or not, 390 cylinders now cost less than 360 angle valve cylinders from Lycoming:

http://www.airpowerinc.com/productcart/pc/cylinders.asp?catid=70&subcat=75
 
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If you're flying them side-by-side at the same fuel flow then you're probably making about the same horsepower on each engine. In that case I'd expect the taildragger to be a few knots faster since it has less drag. If you were instead flying the same percent power (for example, wide open throttle at 8500' and using the same leaning procedure to get 70% power on both engines), the 390 has got to be burning more fuel and making more power than the 360.



http://www.vansaircraft.com/public/rv14perf.htm Note that the specs show the taildragger to be faster on the smaller engine at the same percent power settings...

Mark,
I think you are "picking nits" (as some would say it).
I don't know how much experience you have doing detailed speed flight testing, but when you start talking about performance numbers and attempting to measure down to the difference of 1 or 2 kts it is a challenge.
Not impossible, and at Van's we have always strived to give honest confirmed via testing performance #'s, but that level of accuracy is difficult. I think the thousands of customers that state that their airplane meets or beats the published #'s substantiates that we at least got it close.

I agree that the larger displacement engine, at the same exact percent power setting should burn a little bit more fuel and have a little higher power output. The difference between the 360 and 390 would be less than 10 HP.
It is simple physics that shows that small changes in HP have relatively small effects on speed
(A good tutorial I found a few years ago is this one previously published in an EAA chapter news letter http://www.eaa691.net/images/technotes/Tech_Note_5_Aircraft_Performance.pdf)

A less than 10 HP difference would result in only about a 2 kt theoretical speed difference. As already mentioned, that is getting into the realm of difficult to measure.
So if you want to argue theoretical vs actual, go ahead. If you want to question the data published for the 14 and 14A, that is also your prerogative.
I can't explain the reason for the data currently posted, but I don't believe it is because there is a larger speed delta between the tri gear and tail dragger 14, than there is with the RV-7 and 7A.
As mentioned previously, I flew in one flight test where both airplanes were configured at the same MP, RPM and mixture (as much as possible, mixture is a difficult one to match) setting and the airplanes were dead even speed wise at a DA of about 3000'. There are a lot of different factors that can have little influences on the actual power output (the 390 engine had 600 hrs, the 360 was brand new, etc) and there are numerous other things that could account for a couple kts one way or the other (I don't think both airplanes were washed just before the test :rolleyes:) so I believe that there is not much more speed difference between a 14 and 14A, than there is between a 7 and 7A... if there is, I don't think it is more than a couple kts.
In my mind, considering the many other influences that builders can have on actual speed performance, a couple kts is just a couple nits.
 
Mark,
I think you are "picking nits" (as some would say it).
I don't know how much experience you have doing detailed speed flight testing, but when you start talking about performance numbers and attempting to measure down to the difference of 1 or 2 kts it is a challenge.
Not impossible, and at Van's we have always strived to give honest confirmed via testing performance #'s, but that level of accuracy is difficult. I think the thousands of customers that state that their airplane meets or beats the published #'s substantiates that we at least got it close.

Scott, I do appreciate that good performance testing is difficult and measuring a couple knots difference is in the noise, but I?m talking about more like a 7 mph difference (the -14A with 390 should be ~5 mph faster than the -14 with smaller engine and less efficient prop, but it?s 2 mph slower instead, so it?s 7 mph slower than I would have expected based on published numbers for the other 2 seat models with different engines and gear configurations).

The difference between the 360 and 390 would be less than 10 HP.

Actually the stock angle valve IO-360 only makes 195 hp. Lycoming was able to get away with a rating of 200 hp under the rules that existed back when they certified that engine, but I?ve been told by Lycoming employees and several engine shops including Barrett and Aerosport Power that it will only dyno out at 195 hp. Whereas the stock 390 makes a true 210 hp, so the difference between the two is 15 hp.

A less than 10 HP difference would result in only about a 2 kt theoretical speed difference. As already mentioned, that is getting into the realm of difficult to measure.
So if you want to argue theoretical vs actual, go ahead. If you want to question the data published for the 14 and 14A, that is also your prerogative. I can't explain the reason for the data currently posted, but I don't believe it is because there is a larger speed delta between the tri gear and tail dragger 14, than there is with the RV-7 and 7A.

I?m assuming Vans published data is correct for all of the RV series. So to my point, if you look at the specs for the -7 series at http://www.vansaircraft.com/public/rv7perf.htm, a 160 hp RV-7 at 75% power cruises at 192 mph, and the same airframe with 180 hp is spec?d at 200 mph. So the engine rated with 20 more horsepower gives you an extra 8 mph at cruise. I won?t repeat all the math I put in my previous post, I?m just saying it seems like the -14A with an extra 15 hp and more efficient prop than the -14 should be a bit faster, not slower. My assumption is that the nosegear on the -14A has a greater drag penalty than I anticipated and that is probably the main reason, but like you mentioned there could be a variety of other factors conspiring to achieve these results?

Anyway, what I?d REALLY like to know is what the performance numbers will be if I put a stock IO-360 on my RV-14A. Guessing I?d see cruise numbers around 190 mph (comparable to a 160 hp RV-7A or -9A).
 
Actually the stock angle valve IO-360 only makes 195 hp. Lycoming was able to get away with a rating of 200 hp under the rules that existed back when they certified that engine, but I?ve been told by Lycoming employees and several engine shops including Barrett and Aerosport Power that it will only dyno out at 195 hp. Whereas the stock 390 makes a true 210 hp, so the difference between the two is 15 hp.

For years I have been aware of the IO-360 only producing ~195HP.

No one flys their RV continuously at max. rated power so comparing the differences in actual max HP when talking about cruise speed is pointless.
I was speaking in terms of cruise power setting at 70% power at 8500 ft or so as you previously quoted. In that case the difference is only about 10 HP.
The speed difference with 10 HP is very small. Not low enough to get lost in the data scatter but starting to get close.

The only difference most people will be able to notice in the two engines will be take-off and climb performance, and even that wont be all that big.

If you do try the IO-360 report the results. If you build a nice clean airplane I think they may surprise you.
 
The small amount of side by side testing that we have been able to do showed that the two prototypes, as currently equipped, have pretty much exactly the same speeds (I flew the tail dragger for this test and the two airplanes were dead even while in loose formation). When I fly them cross country I get 171-172 knots TAS with both airplanes at the same fuel flows.
So if the tail dragger did have an IO-390 and blended airfoil prop it should be a bit faster... probably by about the same difference that there is between an RV-7 and 7A.

Where did you see the info implying that the A model prototype is slower than the tail dragger?

I think either engine is a great choice depending on what deal someone is able to make (but the IO-360 must be a variant with a Fwd. gov., not a rear one. The two engines use the exact same FWF kit... all the parts work for either one. The weight difference isn't enough to be any issue.

Hi Scott,
Please tell us at what rpm/mp, altitude, fuel flow, and percent of power you are getting the 171-172 knots.

Always appreciate your posts.
Thanks in advance.
Rich
 
Hi Scott,
Please tell us at what rpm/mp, altitude, fuel flow, and percent of power you are getting the 171-172 knots.

Always appreciate your posts.
Thanks in advance.
Rich

If you are interested in highly precise data I would also have to give you density altitude, OAT, etc. (which I don't have)

The 171-172 Kts is common for both the RV-14A and RV-14 prototypes at 9.5 - 11.5 K, full throttle, 2400 RPM and slightly lean of peak, with fuel flow typically in the 8.1 - 8.4 GPH (dependent on actual altitude and OAT).
I am not sure of exact % power. I never quote % power as a performance comparison data point because I have never confirmed how accurate the computation is. I prefer to only use it as an operational reference between one flight and another when flying any individual airplane.
 
Those are pretty impressive numbers. They exceed the published 'book' numbers by quite a bit, since speed is almost identical to 'book' 75% 8K feet numbers, but altitude is ~2K ft higher, fuel flow is ~3 gph better, & rpm is 300 under the 75% point. I understand the somewhat lower flow at higher altitude; is the wing that much more efficient than the 4/6/7, that you can give up a bunch of HP (300 rpm/3gph/2k') and maintain the same cruise speed by going up 2K feet?

Amazing.

Charlie
 
If you are interested in highly precise data I would also have to give you density altitude, OAT, etc. (which I don't have)

The 171-172 Kts is common for both the RV-14A and RV-14 prototypes at 9.5 - 11.5 K, full throttle, 2400 RPM and slightly lean of peak, with fuel flow typically in the 8.1 - 8.4 GPH (dependent on actual altitude and OAT).
I am not sure of exact % power. I never quote % power as a performance comparison data point because I have never confirmed how accurate the computation is. I prefer to only use it as an operational reference between one flight and another when flying any individual airplane.


Thanks Scott,
As a "hack" I don't need precise data. I've got about 70 hrs on my 14A and absolutely LOVE IT!!! No paint yet and just working on wheel pants and fairings and wanted to see the difference.
I'm flying mine at wot 8.5 to 10.5 k feet, 2300 and getting about 148 kts at 10 gph, peak egt. Looking forward to faster when complete.

ps
Shocked to hear about Joe Blank.
Joe took me for my first ride about 4years ago. Ordered the kit soon after. Would enjoy talking to him in tech support with my many questions this past few years. He was way helpful and a true gentleman. Sorry for the incredible loss to Joe's family and you all at his vans family.

All the best to you all,
Rich
 
Thanks Scott,
As a "hack" I don't need precise data. I've got about 70 hrs on my 14A and absolutely LOVE IT!!! No paint yet and just working on wheel pants and fairings and wanted to see the difference.
I'm flying mine at wot 8.5 to 10.5 k feet, 2300 and getting about 148 kts at 10 gph, peak egt. Looking forward to faster when complete.

ps
Shocked to hear about Joe Blank.
Joe took me for my first ride about 4years ago. Ordered the kit soon after. Would enjoy talking to him in tech support with my many questions this past few years. He was way helpful and a true gentleman. Sorry for the incredible loss to Joe's family and you all at his vans family.

All the best to you all,
Rich

Adding fairings will have a huge effect on speed.

Thanks for the sentiments regarding Joe. He is hugely missed.
 
If mentioned earlier in this thread I apologize but if your not reading about Cirrus, they just updated their engine choice on the SR20 to the Lycoming IO390. This will help volume some and hopefully bring down prices. Should most defiantly help parts availability.

My first post here. Dreaming about building a 14. I'm a current SR 22 pilot.

Later.

Jeff
 
If mentioned earlier in this thread I apologize but if your not reading about Cirrus, they just updated their engine choice on the SR20 to the Lycoming IO390. This will help volume some and hopefully bring down prices. Should most defiantly help parts availability.

My first post here. Dreaming about building a 14. I'm a current SR 22 pilot.

Later.

Jeff

Jeff, welcome to VAF. And yes I agree it's very good news about the SR-20 announcement. I doubt it will lower Lycoming's OEM pricing agreement with Vans, but it will certainly improve the odds that the engine will be supported far into the future and eventually increase the pool of serviceable cores and used parts.
 
I am currently investigating an aircraft to build and was attracted to the RV14a. I am based in UK and really want a plane that runs on mogas not 100LL... which costs around $9 a US gal here. Mogas comes in at $5.5 a gallon.

I was looking around for a 2 seater tourer kitplane that used the Rotax 915is engine because i think at 7000 feet and above it could give as good performance as an I0 360 or an IO 390 and use less fuel and use mogas. Also like the FEDAC etc. The RV14 with this engine would be perfect but it doesnt use the 915is

I just cant find such a thing in any kit manufacturer and i noticed that the I0 360 uses Mogas, is that true and UK moves to e10 in a year which means our 95 octane unleaded will be 10% ethanol, is that an issue with lycoming 360 engines?. As i understand it the 390's cant use mogas?

Any advice would be appreciated https://aopa.com.au/lycomings-quiet-mogas-admission/
 
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I am currently investigating an aircraft to build and was attracted to the RV14a. I am based in UK and really want a plane that runs on mogas not 100LL... which costs around $9 a US gal here. Mogas comes in at $5.5 a gallon.

I was looking around for a 2 seater tourer kitplane that used the Rotax 915is engine because i think at 7000 feet and above it could give as good performance as an I0 360 or an IO 390 and use less fuel and use mogas. Also like the FEDAC etc. The RV14 with this engine would be perfect but it doesnt use the 915is

I just cant find such a thing in any kit manufacturer and i noticed that the I0 360 uses Mogas, is that true and UK moves to e10 in a year which means our 95 octane unleaded will be 10% ethanol, is that an issue with lycoming 360 engines?. As i understand it the 390's cant use mogas?

Any advice would be appreciated

I think that you’ll find that the 915is is way to lightweight to work on teh nose of an RV-14 - and practically speaking, wouldn’t be very satisfying on power at lower altitudes.
 
Yes, thats why i am thinking of the 200 HP version of the IO 360 as it can use mogas. The 215 HP IO 390 cannot use mogas as i understand it? Mind you i read that Lycoming admitted that their engines actually do fine on Mogas in an AOPA article in australian mag, unfortunately the article is behind a paywall.

The whole engine thing is frustrating, lycoming engines are dinosaurs, LL100 and no FADEC, arghh. I see pipistrel is bringing out a 4 seater airplane with a 915is married up with an electric motor. The plane will do 212 knts. Faster than the IO 540 version of the same aircraft. Such a plane would be sipping fuel. I think we are on the cusp of a revolution in GA as powertrains change and the cost of running drops dramatically. Lycoming seems destined to part of GA history not its future

https://aopa.com.au/lycomings-quiet-mogas-admission/
 
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I totally agree with your frustration! I can't believe that Lycoming is still stuck in the past on this 100LL issue. I am being told that your can have a 390 custom built with lower compression pistons that "may" allow use of ethanol free 91 octane mogas. Not sure how much of a HP hit this cause..... Still years away from buying the engine, I hope this works itself out soon....
 
I swear I found a thread on here that talked about how Lycoming tried to make a lower compression IO-390 for mogas. But at the end of the day, the power loss made it an extremely expensive engine that would be outperformed by a much more inexpensive mogas 360.

Remember with RV-14s you need the 360 with the governor on the other end than most of the 360's out there.
 
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