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Upgrading to a larger engine a big deal?

Duncannon

Active Member
Ok, in the world of certified aircraft, the general rule of thumb when it comes to buying is to get the airplane that already has what want. For example, you should buy the airplane that’s already IFR equipped, has glass cockpit, autopilot, etc. if that’s what you want, vs. buying and then having it installed yourself. The same would be true for engine conversions (180 hp Skyhawk, C150 or AA1 with 150 hp, etc), best to purchase an existing one, assuming you can find one.

Is the same true for the engines on experimental aircraft, and more importantly, Vans RVs? If I wanted an RV (6-9 models, also maybe a 4) and preferred 180 hp or better, but the only ones for sale were those with 150-160 hp, would it be ok to purchase one of those and have it upgraded later? In my case, I’d probably just fly it until the engine reaches TBO, then have the larger engine installed. (I once saw a cheap RV 9 for sale, but it had the 115 hp O-235. I’d definitely want to upgrade to an O320).

I’m not a builder or have any mechanical skills, so I’d have to hire someone to swap the engines. I know that swapping engine brands can be a big deal. I read that if buying a Zenith and you want one with a Rotax, don’t buy one that’s powered by a Corvair or VW, etc. I wasn’t sure if simply upgrading or downgrading is a big deal.
 
You can switch motors. There is some FAA paperwork and a period of time to fly off in the "test area" you will need to submit to the FAA and have apply to you. Unless you live in the same area as the builder.

Stay with what Van's recommends and you will be fine. And relieved of some unneeded cash.
 
Depending, it can be a big deal requiring a new engine mount, which can lead to new landing gear legs that match the new mount. Plus you may have significant cowl and induction modifications. There’s also the likely need for a new prop

So it can be a pretty big deal. Also, you’d have to put the airplane back in a phase 1 fly off condition for a few hours.
 
Hmm. As I understand it, changing from one engine to a similar engine does NOT require Phase 1, but I'll defer to a DAR.

However, changing from a fixed pitch prop to constant speed did require five hours of Phase 1.

When I put on the constant speed prop, a few of those required five hours were well spent getting a new feel for the plane. The airspace restrictions were annoying, however.
 
From a work standpoint, it can be easy or hard, depending on the engine you find to put on versus the one coming off. It’s always easy at the overview level - the devil is ALWAYS in the details when you find that the O-20 is a half inch wider than an O-235, and the O-360 a half inch wider than the O-320. So baffles change, fuel and oil lines might change - cowling might or might not fit quite the same.

And then there is the “while I’m in there….” Syndrome.

Anything is possible, but there are too many variables to generalize on if it is worth it or not.
 
From a work standpoint, it can be easy or hard, depending on the engine you find to put on versus the one coming off. It’s always easy at the overview level - the devil is ALWAYS in the details when you find that the O-20 is a half inch wider than an O-235, and the O-360 a half inch wider than the O-320. So baffles change, fuel and oil lines might change - cowling might or might not fit quite the same.

And then there is the “while I’m in there….” Syndrome.

Anything is possible, but there are too many variables to generalize on if it is worth it or not.

Doesn’t Vans sell different cowls for 320 vs 360? I thought the scoop might have been different.. a good fiberglass person could modify it though.
 
If you are not going to do the changes yourself, it would be much cheaper to find a plane with the desired engine already installed. Everything on an airplane takes a lot of time, usually about 3-4x longer than I first estimated.
 
Any change that alters the flight characteristics of the aircraft requires a phase I flight test of at least 5 hrs. A change of power, a significant change of weight & balance, etc. are examples.

The additional requirement when changing to or from a controllable prop is to submit a new 8130-6 to update information in Oklahoma City.
 
I have a 6A with a 320. Got a screaming deal on the engine, so made the compromise. I love the plane. Climbs just fine and cruise at 160 Kts TAS on 8.1 GPH. You will not get a whole bunch more cruise out of a 360 - maybe 5+ knots and climb will not be radically better. T/O will be a good bit more fun, but that is only a few seconds.

Think about how you fly. I could go 5 knots faster if willing to go ROP and throw more fuel at it, but I don't as it burns more gas. Doubt I would be flying any faster if I had a 360, especially with today's gas prices. A stronger climb rate would be nice, but don't feel left out.

Larry
 
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I have a 6A with a 320. Got a screaming deal on the engine, so made the compromise. I love the plane. Climbs just fine and cruise at 160 Kts TAS on 8.1 GPH. You will not get a whole bunch more cruise out of a 360 - maybe 5+ knots and climb will not be radically better. T/O will be a good bit more fun, but that is only a few seconds.

When I did the numbers, the O-360 would burn another gallon per hour over the O-320. That translates to 30 minutes reserve...

Your mileage will vary, of course.
 
Ok, in the world of certified aircraft, the general rule of thumb when it comes to buying is to get the airplane that already has what want. For example, you should buy the airplane that’s already IFR equipped, has glass cockpit, autopilot, etc. if that’s what you want, vs. buying and then having it installed yourself. The same would be true for engine conversions (180 hp Skyhawk, C150 or AA1 with 150 hp, etc), best to purchase an existing one, assuming you can find one.
Duncan I see you are fairly new and a RV8 interested member. I have to assume a lot about your time, finances, RV flying if any. First of all a RV4 or RV6 with 150HP is likely the hottest plane you ever have flown and may be ever need to fly (I am assuming). Going to 160HP is slightly higher compression O320. Not a big jump in performance as you are already going lioke a scalded cat. 160HP to 180HP not a big difference and you will pick up 30lbs more weight. (BTW there are other options Carb vs FI, fixed vs CS prop). Going to 180HP is a 360 cubic inch Lyc. It is physically (bit much) larger and heaver. Is this a big deal? Well it will be work, just leave it at that. There is enough difference to make it interesting. AGAIN assuming you never built a plane, RV in particular and you will need a hanger, tools, and lots of time and some building talent. Is it like building whole plane no. WEIGHT is a factor if the plane is already heavy and has Fwd CG. You never get a higher HP engine that is lighter. The RV8 your are interested was the first Van's plane MADE for the IO360 angle valve 200HP engine and CS prop. However a 150HP fixed pitch will work. The early RV's 4 and 6 were focused on 160HP and fixed props. Again they are very nice flying, fast, nimble if you keep the weight down. I had a 150HP RV4 I built and I beat 180HP RV's in cross country races. Part of that was race tatics and airmanship but for the most part I was almost as fast or a handful of MPH slower than some 180HP RV's. Part of that it is fit, finish and again weight. I also had a CS prop and ran at 2900 RPM (for race day only). That gave me about 160HP.


Is the same true for the engines on experimental aircraft, and more importantly, Vans RVs? If I wanted an RV (6-9 models, also maybe a 4) and preferred 180 hp or better, but the only ones for sale were those with 150-160 hp, would it be ok to purchase one of those and have it upgraded later? In my case, I’d probably just fly it until the engine reaches TBO, then have the larger engine installed. (I once saw a cheap RV 9 for sale, but it had the 115 hp O-235. I’d definitely want to upgrade to an O320).
It sounds like you are telling not asking. Seems you got it all figured out. Just lets say again assuming money no object het a 180HP or 200HP RV. You will pay for it. Much more likely to get a RV4 with 150HP fixed pitch (again hottest plane you ever flew or likely to fly I assume) for a much much better price (10's and 10's and 10's of thousands). As I state above if you want a PROJECT RV you can rebuild in your dream image then it does not matter. However keep in mind a nice O360 or IO360 is going to cost a lot. The PROP that was ona 320 is not going to work fixed. If CS Hartzell you might be able to reuse on many models of engines and HP.

’m not a builder or have any mechanical skills, so I’d have to hire someone to swap the engines. I know that swapping engine brands can be a big deal. I read that if buying a Zenith and you want one with a Rotax, don’t buy one that’s powered by a Corvair or VW, etc. I wasn’t sure if simply upgrading or downgrading is a big deal.
OK good to know. Do not buy a project plane or one you want to upgrade engine and prop. Buy a turn key. Have fun, fly it, maintain and sell it. The exception is panel. If the bones are good, good engine and prop and has 1990's steam gauge panel then you can find someone to make and install a panel for reasonable (under $20K but can be done cheaper if you don't go over the top with autopilot and dual screens etc.).

Your Zenith Rotax to Auto engine conversion is not relevant. We have been talking about Lyc to Lyc upgrading the HP (usually 320 to 360 or the 235 to 320). Yes obviously huge difference in engines Rotax to some auto conversion (not the least is the actual engine mount, cowl, systems, electrical, cooling, exhaust, intake). Second NOT a fan of any auto engine conversion. I guess they are getting better in the sub 120HP range for slow flying planes. Anything in the 160HP and above Lyc dominates. However auto engine conversions are not significantly cheaper and generally ALWAYS under perform the purpose built aircraft engines. Auto engine conversion reliability is always a question mark, especially PSRU. Weight? Auto engines tend to be heaver. All true.

Yes to answer you buy a Zenith or RV for that mater with the Prop and Engine you will fly for the duration of your ownership is the wise decision. HOWEVER do as you like. With your admission you would have to pay someone to do this work... No don't buy a project. People who work or modify on RV's are not growing on trees. EAB kit panes are not Certified. However some A&P's and shops are starting to cater more to kit planes, there is a regulatory grey area and liability working on these planes as a 2nd party. The ones that do work on RV's or EAB's will charge you a fair price and that is a lot $$$$, because it is so time consuming. They can't starve and will be charging shop hours like it was a Cessna. The point of EAB kit planes is learning not getting cheaper planes than Cessna and Piper. If you have no intent on learning and working on your plane (to your limits with supervision from say EAA Tech advisor) then get a Cessna and pay A&P's to work on it. Finding good independent RV mechanics to do major repair or mod work is not a down the street deal. There are only a handful of them. Again the idea of EAB kit planes is YOU learn.

You really need to research the cost of owning a plane. Hanger, insurance, fuel, oil. An experimental or any GA plane ownership does rely on owner/pilot maintenance to keep cost down, oil change, plugs, brakes, inspectiion, minor repair or replace as needed. Bottom line a 150HP fixed pitch RV (if built light) is a fun high performance time. Good luck. RV prices are through the roof. A nice 180/200HP CS prop glass panel, panted upholstered RV (any model 4 through 14) is going to be well into 6 figures, even mid to high 6 figures today. If you have that money go buy an RV you like, an RV8 with all the bells and whistles and HP you think you need. It should hold the value unless the economy crashes.
 
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One thing not mentioned which might be applicable --- Lycon does cylinder work that would add about 20 HP to a stock engine via porting. So it is possible to take a 160 HP O-320 and get more HP out of it --- without changing to an O-360. So then the baffles and everything will still fit.
 
If you only added a CS prop, that would help the climb with a smaller engine. Top speed would be about the same.
 
Duncan I see you are fairly new and a RV8 interested member. I have to assume a lot about your time, finances, RV flying if any. First of all a RV4 or RV6 with 150HP is likely the hottest plane you ever have flown and may be ever need to fly (I am assuming). Going to 160HP is slightly higher compression O320. Not a big jump in performance as you are already going lioke a scalded cat. 160HP to 180HP not a big difference and you will pick up 30lbs more weight. (BTW there are other options Carb vs FI, fixed vs CS prop). Going to 180HP is a 360 cubic inch Lyc. It is physically (bit much) larger and heaver. Is this a big deal? Well it will be work, just leave it at that. There is enough difference to make it interesting. AGAIN assuming you never built a plane, RV in particular and you will need a hanger, tools, and lots of time and some building talent. Is it like building whole plane no. WEIGHT is a factor if the plane is already heavy and has Fwd CG. You never get a higher HP engine that is lighter. The RV8 your are interested was the first Van's plane MADE for the IO360 angle valve 200HP engine and CS prop. However a 150HP fixed pitch will work. The early RV's 4 and 6 were focused on 160HP and fixed props. Again they are very nice flying, fast, nimble if you keep the weight down. I had a 150HP RV4 I built and I beat 180HP RV's in cross country races. Part of that was race tatics and airmanship but for the most part I was almost as fast or a handful of MPH slower than some 180HP RV's. Part of that it is fit, finish and again weight. I also had a CS prop and ran at 2900 RPM (for race day only). That gave me about 160HP.


It sounds like you are telling not asking. Seems you got it all figured out. Just lets say again assuming money no object het a 180HP or 200HP RV. You will pay for it. Much more likely to get a RV4 with 150HP fixed pitch (again hottest plane you ever flew or likely to fly I assume) for a much much better price (10's and 10's and 10's of thousands). As I state above if you want a PROJECT RV you can rebuild in your dream image then it does not matter. However keep in mind a nice O360 or IO360 is going to cost a lot. The PROP that was ona 320 is not going to work fixed. If CS Hartzell you might be able to reuse on many models of engines and HP.

OK good to know. Do not buy a project plane or one you want to upgrade engine and prop. Buy a turn key. Have fun, fly it, maintain and sell it. The exception is panel. If the bones are good, good engine and prop and has 1990's steam gauge panel then you can find someone to make and install a panel for reasonable (under $20K but can be done cheaper if you don't go over the top with autopilot and dual screens etc.).

Your Zenith Rotax to Auto engine conversion is not relevant. We have been talking about Lyc to Lyc upgrading the HP (usually 320 to 360 or the 235 to 320). Yes obviously huge difference in engines Rotax to some auto conversion (not the least is the actual engine mount, cowl, systems, electrical, cooling, exhaust, intake). Second NOT a fan of any auto engine conversion. I guess they are getting better in the sub 120HP range for slow flying planes. Anything in the 160HP and above Lyc dominates. However auto engine conversions are not significantly cheaper and generally ALWAYS under perform the purpose built aircraft engines. Auto engine conversion reliability is always a question mark, especially PSRU. Weight? Auto engines tend to be heaver. All true.

Yes to answer you buy a Zenith or RV for that mater with the Prop and Engine you will fly for the duration of your ownership is the wise decision. HOWEVER do as you like. With your admission you would have to pay someone to do this work... No don't buy a project. People who work or modify on RV's are not growing on trees. EAB kit panes are not Certified. However some A&P's and shops are starting to cater more to kit planes, there is a regulatory grey area and liability working on these planes as a 2nd party. The ones that do work on RV's or EAB's will charge you a fair price and that is a lot $$$$, because it is so time consuming. They can't starve and will be charging shop hours like it was a Cessna. The point of EAB kit planes is learning not getting cheaper planes than Cessna and Piper. If you have no intent on learning and working on your plane (to your limits with supervision from say EAA Tech advisor) then get a Cessna and pay A&P's to work on it. Finding good independent RV mechanics to do major repair or mod work is not a down the street deal. There are only a handful of them. Again the idea of EAB kit planes is YOU learn.

You really need to research the cost of owning a plane. Hanger, insurance, fuel, oil. An experimental or any GA plane ownership does rely on owner/pilot maintenance to keep cost down, oil change, plugs, brakes, inspectiion, minor repair or replace as needed. Bottom line a 150HP fixed pitch RV (if built light) is a fun high performance time. Good luck. RV prices are through the roof. A nice 180/200HP CS prop glass panel, panted upholstered RV (any model 4 through 14) is going to be well into 6 figures, even mid to high 6 figures today. If you have that money go buy an RV you like, an RV8 with all the bells and whistles and HP you think you need. It should hold the value unless the economy crashes.

Thanks for your reply, you told me what I needed to hear, even if it’s not what I wanted to hear. 😋😶

I am not IFR rated and have no intention of ever getting the rating, so I’d be happy with an aircraft with the old fashioned steam-gauge panel. I’m happy to use FF and a backup handheld for navigation. Non-IFR aircraft are definitely lower in price than the ones with glass cockpits.
 
non-IFR vs. glass

True, but these are not your only choices. :) A steam gauge IFR RV can be a super price/performance value, especially with an autopilot.

Non-IFR aircraft are definitely lower in price than the ones with glass cockpits.
 
When I did the numbers, the O-360 would burn another gallon per hour over the O-320. That translates to 30 minutes reserve...

Your mileage will vary, of course.

An IO-360 will burn about the same as a O-320 at the same power output. I can burn about 7.3 gph (21/21) putiting out around 120 hp. Can the O-320 put out 240 in a pinch?
 
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