Well it is a bigger picture than just fuel. With a 180HP will burn about .6-.8 gal/hour more. You will use a little less runway (25-75ft), climb faster (250-300fpm) and cruise 8 MPH faster. However you can burn less gas with the 180HP.nturner said:Can anyone share some light on what fuel consumption they are getting from either types. Thanks
Not sure that is at me Dan, but that is not what I said. I give an example of a high flying 180HP RV (65%) Vs. a Lower flying 160HP RV at about 75%. The 180HP will be flying faster and burning equivalent fuel or even less by 0.5gal/hr.dan said:You can't just say a 360 burns more fuel than a 320. It's not that cut and dried. Your mileage may vary!
)_( Dan RV-7 N714D
nturner said:Thanks eveyone for your input. I was going to use a 0-320 and f/p prop but now I may switch to the 0-360.
GMCJETPILOT says he gets 7.8 GPH at 55%. My 160hp O-320 gets 6.4 GPH at that setting.
At current Houston fuel prices ($3.20), that means a two hour weekend burger run costs me $40.96. An O-360 would cost $49.92 to get to the same burger. The difference pays for the burger.
Kent,kentb said:There is a standard formula that I have been told: 1 gallon of fuel will convert to 10 hp per hour. If you have a 180hp engine and ask it to produce 180hp then it will cost you 18 gal/hr. If you ask the engine to produce 160hp the cost goes down to 16 gal/hr....
There is a standard formula that I have been told: 1 gallon of fuel will convert to 10 hp per hour. If you have a 180hp engine and ask it to produce 180hp then it will cost you 18 gal/hr. If you ask the engine to produce 160hp the cost goes down to 16 gal/hr.
RVbySDI said:Another issue is the engine noise and wear and tear. An engine running at 49% has got to be quieter than one running at 55%. There also has got to be less wear and tear on the internal components of that engine running at a slower rate. Granted it may not be of a significant difference but the difference must exist however small it may be.
Just my humble opinion,
Steve
RVBYSDI
RVbySDI said:I have a question for Johnbakerok on your post. You wrote:
What I am reading here is that you are comparing fuel burn and RPM % between the 160hp O-320 and the 180hp (I)O-360. But the other factor that you are leaving out is the MPH of the two airplanes and engines while flying at that 55%.
You mention the price of that $100 hamburger flight:
The question is the difference in how fast you are able to fly to point B from point A for the extra $8.96 in fuel cost. I may be missing something here, Someone please correct me if I am totally off base with this thought, but running an O-320 at 55% means that the airplane will not be flying as fast through the air as the (I)O-360 running at 55%. That extra $8.96 is buying you more speed equating to less time in the air.
My thoughts are that if you wanted to use the 360 engine to get to your favorite hamburger place at the same cost and speed that you use with your 320 engine you would slow that 360 down to whatever the RPM % would be for that engine that equates to a 320's 55%. At that setting you would essentially burn the same amount of fuel and be flying at the same airspeed.
Steve
RVBYSDI
It really depends on the (I)O-360 used. I believe the -A1B6 has no restrictions because of the harmonic balence on the crank. I obviously have no proof of my observations, just what would appear to be logical to me. I've also never noticed a difference in the smoothness of the O-360A1A I fly on the Cardinal and the O-320H2AD or E2D's that I've flown on 172's.kentb said:osxuer,
I think that the bigger pulses are there. If not why would there be rpm restriction with 360 engine and certian props? Also when you add electronic ignition there are more restrictions on rpm with the 360, but not with the 320.
Marginally at worstYou have the same number of power pulses per minute and are getting more power. You will have bigger pulses of power with each ignition of fuel.
steve,
I know of someone at Indepence, Or. that put a 360 in an RV9A. He justified it, because he would give up the CS prop and the weight would be the same.
He has sense stated that he wished he had stuck with Vans recomindation.
I want to be able to go as fast as I can, use the least amount of fuel and do it with the lease money spent. You don't always get to do what you want, but I think that going with the largest engine (wieght/hp) that is recomended for the airframe is as close as is reasonable to do.
I am putting an IO320 with Hartzel CS prop and an electronic ignition in place of one mag. This will be a little on the heavy side for RV9A's, but the combination will get me off the ground quick (even at high airports out west), let me set economic cruse (fuel useage) and will have no prop rpm rescrictions.
This setup is traditional enough that I will only have 25 hour fly off, and resale value will be highest. I think that if you have that does not fall with in the recommendation of the designer you will decrease your resale value.
Happy building,
Kent
I am not sure how you can make the comment, "A high percentage (RV-9's) are built that way ((I)O-360). I suggest the golden rule: Build it per plans. Van's aircraft has designed the RV-9(A) airframe around the (I)O-320 engine and a max 160HP. I would not exceed Van's recommended, weight, HP. If you want an (I)O-360 build a RV-7. As the builder you can modify your kit as you like, but unless you have experience as an aircraft designer you can get your self into trouble, exceeding airframe load factor or speed limitations.osxuser said:I don't think that putting an (I)O-360 in a RV9 would hurt the value at all. I think a high percentage of them are built that way. That said the 320 is a great engine as well, and I think that the CS prop is a must either way. So if I had to choose between a 360 FP or a 320 CS I'd have to go with the 320 too. But this is coming from a guy who wanted to built his own crossflow Lyc IO-360 out of TIO540 Cylinders and high comp pistons, I just like power I guess. Now I'm going for IO-360 turbo normalized.
I must point out the delta weight between an O-320 to IO-360 (200hp) is more like +40lbs, and finished RV's using these two engines have delta empty weights in the order of 70-118 lbs. The engine and installation of an IO-360 (200HP) is heavy. Weight is an issue, and if you have not flown a RV before or have much experience with them, you can tell the difference between a light one and a heavy one.osxuser said:I must also point out however, the 30LB difference you speak of is between a O-320 and a ANGLE VALVE IO-360 which is a difference of at least 40HP.
You may want to build a Lancair or Glasair. RV's are well suited for lower altitudes and for local flying in and out of short strips, fun aerobatics as well as occasional cross-country flights (where you can still see the ground). If you want to climb to altitude and suck O2 for fun, than by all means get a turbo charger. However the RV is designed for a "Total Performance" mission, as Van would say; A normal aspirated engine is well suited for the RV mission, fun. Sucking O2 at altitude is not fun for me. I fly enough at flight levels at work; down low is where the fun is. Even with normal aspirated engine you can fly well in the O2 altitudes with a RV. (I have been to 17,500 in my RV-4, but it is most happy in the lower teens solo and 8,500-12,500 at gross.) Have you ever owned a turbo charged engine? There are a few turbo RV's. It has been done, but it is crowded under the cowl. Also flying freight and charters years ago in turbo twins, I can tell you turbo chargers are a big maintenance issue. I always heard the mechanics talk about it. However if that is going to float your boat go for it, but I think a turbo charger is a better match in a Lancair if you are going to fly high long distance from one super slab runway to another, most of the time. The RV is for fun, flying just for the sake of flying, so it lends itself for formation flying, aerobatics, local dog fights and short X-C fly outs, as well as the occasional long X-C flights. A turbo is a waste of money, but if you just want to motor along straight and level at altitude with O2 than a RV will do that, but there are better airframes for this kind of flying. If you want to just fly along with Lancairs, get a Lancair. With a turbo the RV will do a OK job keeping up with a turbo Glasair or Lancair at altitude, but you will have a hard time. That is not what the RV is about.osxuser said:My current problem is deciding between a TNIO-320 or TNIO-360 for my yet-to-be-acquired RV-7. Also because the guys I'll be flying with all have Lancairs or Glasairs, and I need the little bit of edge that 180HP will provide. My main reason for deciding on Turbo Normalized power is my constant desire to go HIGH....
I know of someone at Indepence, Or. that put a 360 in an RV9A. He justified it, because he would give up the CS prop and the weight would be the same.
He has sense stated that he wished he had stuck with Vans recomindation.
I want to be able to go as fast as I can, use the least amount of fuel and do it with the lease money spent. You don't always get to do what you want, but I think that going with the largest engine (wieght/hp) that is recomended for the airframe is as close as is reasonable to do.
I think Van could answer the question best since they designed the kit and have been doing it for 30 years or so. My guess is with more than 160 hp you can exceed placard airspeed limitations. There are many planes out there (including the jet I fly) that can easily exceed Vne/Vmo in level flight.RVbySDI said:If you know any more specifics on your acqaintence's complaint about the 360 I would like to hear more.
Is it possible that there is a mentality out there that believes that "Since I have a bigger engine I can therefore haul a bigger load, so I don't need to worry about total weight?" As such, there is less attention paid to keeping overall weight down.gmcjetpilot said:As far as engine weight I did a survey of over 115 completed RV's with all kinds of engines and props. Empty weights are always less with (I)O-320's than (I)O-360's (comparing like props). Obviously you can save weight and make up difference in engine weight in other areas (prop, avionics, paint, interior, lights), so weight of the engine may not be a big factor if you don't go crazy with other items.
gmcjetpilot said:I must point out the delta weight between an O-320 to IO-360 (200hp) is more like +40lbs, and finished RV's using these two engines have delta empty weights in the order of 70-118 lbs. The engine and installation of an IO-360 (200HP) is heavy. Weight is an issue, and if you have not flown a RV before or have much experience with them, you can tell the difference between a light one and a heavy one.
You may want to build a Lancair or Glasair. RV's are well suited for lower altitudes and for local flying in and out of short strips, fun aerobatics as well as occasional cross-country flights (where you can still see the ground). If you want to climb to altitude and suck O2 for fun, than by all means get a turbo charger. However the RV is designed for a "Total Performance" mission, as Van would say; A normal aspirated engine is well suited for the RV mission, fun. Sucking O2 at altitude is not fun for me. I fly enough at flight levels at work; down low is where the fun is. Even with normal aspirated engine you can fly well in the O2 altitudes with a RV. (I have been to 17,500 in my RV-4, but it is most happy in the lower teens solo and 8,500-12,500 at gross.) Have you ever owned a turbo charged engine? There are a few turbo RV's. It has been done, but it is crowded under the cowl. Also flying freight and charters years ago in turbo twins, I can tell you turbo chargers are a big maintenance issue. I always heard the mechanics talk about it.
Kent, no offense, good choice, I am building my second RV and it is a RV-7.osxuser said:First of all, I'm building a 7, not 9. So this whole conversation is scholastic in nature for me. (snip) I'm an professional A&P mechanic, so I know aircraft systems very well. I've seen the way the RV is built, and thats why I choose to build it over the plastic airplanes. Turbo normalizing is a very smart way to go because it keeps the engine within it's operating pressures, as well as keeping the specific fuel consumption high.
I am sure that George has had an extensive amount of training to be able to correctly manage his overpowered jet. Far beyond what most of us spam can/RV drivers have had. I am sure that with enough experience and training we could all learn to handle most any plane, but what about the next guy that gets in the plane you build?
6th issue 2004.keen9a said:Vne can be given in either IAS or TAS depending on the limiting factor at a given altitude (it can vary with other factors too). However, Van's sets Vne based on flutter testing which is a function of TAS, probably because even at sea level, flutter occurs before any structural issues.
Flutter = TAS
Loads = IAS
A few issues back, there was a discussion of turbo's and Vne in the RVator. I'm not at home right now, so I can't tell you the exact issue.
Turbo charging is great, but you have to pay for it. If you are making more power, regardless of how you make it , you are paying for it. There is something nice about flying at 55% power, if that is all you need. RV 's go very fast on little power, turbo or not. Clearly a turbo makes you go faster, but you have to pay for it in more ways then one.cobra said:GEORGE,
You get a big advantage with turbo charging at any altitude above sea level. Racers see approx 20% loss of power at 5000 ft without forced induction. High altitude performance is a plus.
With turbo charging, your contention (go slower at same power output) is only true because of potential weight increases, not for anything inherent to turbocharging. The advantage of turbo charging (over supercharging and natural induction) is that you can cruise without paying an efficiency penalty WITH the benefit of having significant up per end HP on tap when you want it.
Jconard said:QUOTE: There has been some discussion before elsewhere about Vne speeds. These are IAS on most aircraft I am aware of, not TAS.
WRONG, WRONG, WRONG, WRONG, WRONG!
QUOTE: Fuel flows are not always higher with turbo engines
misleading....fuel flow will be the same at the same power, but if the turbo is in fact helping to produce more power, it will be burning more fuel.
QUOTE: With modern turbos and wastegate systems applied to both air and liquid cooled aircraft engines, combined with proper engineering, design and materials applied to the exhaust and intercooler system, we don't see any significant increase in maintenance worries.
Who is "WE"? Virtualy every owner and mechanic of factory turbo aircraft report increase maintenance cost, and accelerated wear as a result of the turbo installation. Unless you think you can better engineer the system than could rajay, or Lycoming, or Continental..etc... this is simply a ridiculous statement. If on the other hand by "WE" you mean people who have turbo charged cars, and believe without support that their experience with those applications will be relevant to aircraft use, you may have an audience.
The water cooled alternate engine guys have an advantage with water cooling. Turbo technology in the auto industry is very advanced. If you are going with a Rotary or Subaru I think not using a turbo or supercharging is a waste, for these engines, because they are made for boost and in a way they need the boost. The size of these engines from a displacement stand-point is small. A Lycoming 360 is about 5.9 liters. A Mazda effective displacement is about 1.3 liters and the Subaru is about 2.5 liters. In other words these engines are 1/2 to 1/4 the Lycoming's displacement. This is not a put down, it is amazing they put the power out the HP they do, however they do it with high RPM's and turbo or supercharger's. This is fine, but the high RPM makes a reduction drive to get prop RPM down a requirement. The Lycomings direct drive has its advantages, as does it's simple air cooled design. The auto engines are well suited for turbo charging. It can be done on a Lycoming, but the small displacement and water cooled heads are more tolerant of higher compression.rv6ejguy said:With modern turbos and wastegate systems applied to both air and liquid cooled aircraft engines, combined with proper engineering, design and materials applied to the exhaust and intercooler system, we don't see any significant increase in maintenance worries. A poorly matched turbo, improperly mounted with inferior tubing and design, WILL certainly increase reliability concerns and maintenance.
I would stress that applying a turbo to your RV is an engineering exercise. You better have a good grasp of engines, materials, turbocharging, intercooling, fabrication and airflow if you want it to be successful and reliable. There is a lot more to this than bolting on a normalized Lyc and flying off into the blue.
gmcjetpilot said:6th issue 2004.
In the ref article above, by Van, the last sentence says something about: "If you must hurl your self thru the sky with a turbo charger he recommends you don't do it with a RV and use an airframe better suited for that purpose." This was my original suggestion the Kent who seemed like all he wanted to do was fly in the flight levels as fast as he could with a turbo RV to fly with Lancairs.
Cheers George
Sorry Kent, MID TEENS? Fly down low on the deck thru those mountain passes. It is a lot more fun, anyone can fly over the top sucking gas. Do you live in Denver? I get dizzy thinking of flying that high.kentb said:You seam to have me confused with another poster. I think that it is OSXUSER that has the turbo and Lancair buddys.
My almost completed RV9A will have an IO320, CS, one mag and one EI. I may carry a portable O2 so that I can fly in the mid teens while crossing the Rockies, but other wise will stay down lower.
Kent