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O-360 necessary?


ekisbey

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Can someone give a comparison between the performance of an O-360 and the O-320 as far as suitability on a MkIV? I've seen lots of data on both engines, and the more I look into it, the more I find myself considering the O-320 over the O-360. I know there are/were MkIV's flying with the 320, and I'd appreciate opinions. Factors such as cooling efficiency, fuel burn, wieght and balance issues, maintenance costs, and reliability are highest on the curiosity chart.

 

I ask this because during a recent discussion my wife and I decided that while cruising at around 200 knots was tempting, anything that'll get us over 150 satisfies our needs adequately. Especially since we're generally talking about distances less than two thousand miles.

Evan Kisbey

Cozy Mk IV plans # 1114

"There may not be any stupid questions, but I've seen LOTS of curious idiots..."

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Originally posted by ekisbey

Can someone give a comparison between the performance of an O-360 and the O-320 as far as suitability on a MkIV?..... Factors such as cooling efficiency, fuel burn, wieght and balance issues, maintenance costs, and reliability are highest on the curiosity chart.

I'm sure you're aware that both engines are acceptable per the plans. There are no substantive differences in cooling, maintenance, or reliability between the 320 and 360, AFAIK. You'll burn a bit less fuel, but you can do the same thing by throttling back on the 360, and running at 60% power instead of 75%. W&B is not a big deal, as the weight difference is maybe 20 lb., depending upon version.

 

Originally posted by ekisbey

I ask this because during a recent discussion my wife and I decided that while cruising at around 200 knots was tempting, anything that'll get us over 150 satisfies our needs adequately. Especially since we're generally talking about distances less than two thousand miles.

OK, I assume you realize that no 360 is going to get you a cruise speed of 200 kts - 191 kts is the most anyone has seen in a 180 HP COZY MKIV. The issue with the 360/320 isn't really top speed - the difference in the 20 HP will be 5 - 10 kts, as you surmise, and you state that's not important to you. As you also know, even a 320 powered COZY MKIV will way outperform an equivalently powered warrior or C-172. Where you will see a larger difference is in climb rates, although it'll still be a lot better than the spamcans. What you're losing, especially at high DA's, is excess power, which is what provides climb rate. If you don't fly at high gross weights, or don't fly at high DA's, maybe it'll make no difference to you.

 

I do know that at least one of the 320 powered MKIV's has a CS prop on it to optimize climb and cruise.

 

I don't know what the 2000 mile range implies - you're not going that far without stopping in ANY COZY. At 190 kts, that's a 10.5 hour flight time - at 150 kts, it's 13.3 hours. 2.8 hours is a big difference....

 

Personally, unless you get a great deal on a 320, I'd go with the 360 and just throttle back during cruise, if speed isn't that important to you. Either that, or get a Glastar :-).

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Originally posted by Marc Zeitlin

I'm sure you're aware that both engines are acceptable per the plans. There are no substantive differences in cooling, maintenance, or reliability between the 320 and 360, AFAIK.

That's the kind of info I was looking for. While I was aware that the 320 is also reccommended in the plans, I also noticed that there seems to be a shortage of Cozys flying with one. It struck me as somewhat odd, even taking into consideration that the 360 is not much more expensive and of a roughly similar weight, with greater power, and wondered if there were another reason.

 

I don't know what the 2000 mile range implies - you're not going that far without stopping in ANY COZY. At 190 kts, that's a 10.5 hour flight time - at 150 kts, it's 13.3 hours. 2.8 hours is a big difference....

 

Actually, I wasn't really "implying" anything, or perhaps I didn't supply enough info. Yes, I am aware of the range limitations at cruise, and have some idea how long it'll take me after stopping for fuel to travel the said 2000 miles or less. I meant that we plan on traveling distances less than 2000 miles, meaning one or perhaps even two stops for fuel if the winds aren't cooperating. Considering that we've always taken the asphalt to our destinations, driving for two or sometimes three days (well, a day and a half straight through, but soldiers aren't supposed to do that-- against the rules, y'know :) ), the thought of doing the whole trip in one day and arriving in time for dinner is appealing. Getting there three or four hours later is not a big deal.

 

I visited Nat in December prior to purchasing plans, to see the "as advertised" model firsthand, and to get a feel for the designer himself. I was also concerned about whether my 76 inches (and hence, greater mass) would be too large and wanted to try the Cozy on for size. We hit on the engine subject, I even asked about the Franklin, but nothing he said helped to make up my mind. It was one of those "you can probably go either way, just move the battery or something heavy if the balance isnt right" type discussions. That was the gist of it anyhow. I'm concerned about the engine because it's the one part of the plane that I can forsee myself stalling on (funds, availability, etc). I plan on getting the engine purchased early in the contruction process so I'll know it's waiting for me, not the other way around, and I'll have no excuses.

 

Okay. I'm about to reveal just how deep my ignorance runs here:

I'm curious about was a reference I saw to fuel type. The document stated 80/87 for the 320, and 100/130 for the 360. Was this accurate? And what is the difference in price and availability for these fuels in the US?

 

Thanks again.

Evan Kisbey

Cozy Mk IV plans # 1114

"There may not be any stupid questions, but I've seen LOTS of curious idiots..."

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Evan,

Here's an email that a friend posted about his O-320-powered Cozy. Terry

 

There have been a lot of questions coming my way about my cozy Mark 4 with an

O-320 160 hp Lycoming for performance data. I have never done a thourough analysis like I have planned to do. There has been too much wind and turbulence in Lubbock and I prefer to fly places everytime that I fly.

 

Basics: Nearly exact to plans built. Plans #90, cut off 3" each side of the canard after completion with micro fill, prepaint. Wheel pants (own construction). Clark Lyddick Performance prop 68 or 69 inch, his determination of pitch that would be needed for a 160 hp Cozy Mark 4. 1150 pounds originally, probably 50 pounds more by now. Unpainted or finished nose after gear up landing at 6 hours of flight testing. (I got the infamous gear up landing out of the way early, no big deal) One year of flying with Jack Wilhemson nose lift. Ellison throttle body. B&C starter and alternator. Alex Strong pitch trim. Full IFR panel.

 

Usual Cruise: 6000 - 10,000 feet 2600 rpm, 8.0 gph (peaked per VM 1000 engine monitor. 155-160 kts at 50 gallons, 2 adults, 2 big kids, 50# baggage stowed in all areas. 13,500 ft, 150 kts at 7.3 gph, 2600 rpm. I usually get 165 kts at 2700 rpm. At 4500 ft, I maintained 2840 rpm for 45 minutes and held 171 kts. My prop is under pitched for cruise. My longest leg was after leaving Oshkosh this year. We did 4.7 hours on 3/4 of a tank of gas at 150 kts ground speed from Peoria, IL to Grand Prairie, TX (Dallas) with 12-15 kts headwind and a detour to see the St. Louis Arch (very cool).

 

Takeoff in 1500-2000 ft at 3280 elevation and 90 degrees F (no wind, rare for here in Lubbock). Ground rpm is 2300 and take off rpm is 2320. Flying at front edge of CG envelope and as much as 1.5 inches foreward of foreward limit on some flights. Shortest takeoff was with 5-10 kts headwind, 1/2 fuel, 200 pound pilot, at sealevel and I estimated 700 feet with a 1500 fpm climb out at 100 mph.

 

Climb out: 700 fpm at 80 mph (estimated Vx), 1200 fpm at 105 mph (estimated Vy). 12.5 gph fuel flow. At fully loaded weight. Heavy weight flight testing done with suitcases filled with every book and heavy thing in the house. It was interesting when one shifted onto the co-pilot stick and rolled the plane.

 

Landing: Light weight, 100 mph downwind, 90 base, 80 final, touchdown at 70. Canard stall with power at 63 mph, without power at 68 mph. Overloaded front seat, 110 downwind, 100, base, 90 final, touchdown at 85 mph. Usually roll with mild braking for second half, 1500 -2000 feet. Able to stop with light load in 1200 feet and no wind. I love to roll on the mains for 500 feet til below 65 mph before nose wheel touch down, just for fun. Speed brake is handy for final and roll out. I deploy the speed brake at 1/2 mile final.

 

At Oshkosh this year, I noticed that the climb out was only 500-600 fpm and the takeoff roll was at 2000 feet at high weight and foreward limit CG. I then realized that I had left my nose ballast of 3 coke cans filled with molten lead (shotgun pellets) at 8.2 pounds each for 24.6 pound total. I am afraid to do the calculations on CG from that screw up. The cans went home in a car. The ballast was perfect for my solo flight home from Florida last month with 4 stops in Oklahoma to visit relatives. All of that flight was done at 2500 rpm to conserve gas and at 1000 - 2000 agl for fun.

 

Comparing to Nat's plane at Copperstate 2 years ago, his is quieter and has less vibration. The intercom system is professional versus my RST homebuilt. The 3 blades made a difference. The take off was more hardy, and climb out was faster. It would be much nicer for long cross country flights than mine, but I wouldn't give up on my plane.

 

I hope that this helps with engine decisions. I love my O-320 but like most men, I would love to have even more POWER.

 

Kevin Funk M.D.

Cozy Mark 4, plans #90

N871F, Foxy-Lady

Flying since 6/00

Terry Winnett, Capt, USAF

Cozy MkIV #792

RAF Lakenheath, U.K.

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As I'm revving up towards purchasing an engine, I'm beginning to realize just how much I don't know on the subject, especially in the used engine market. I'm finding that a lot of the things I thought I knew were inaccurate, and VERY little of what I know of automotive engines seems applicable. This is new territory, for me.

 

In particular, I'm having a hard time determining just what exactly a "good deal" on a engine is. For example, I don't know what a yellow tag implies, unless it's the same as the military uses, and how it affects engine value. I don't know what to make of replacement parts offered for sale, such as crankshafts, since I'd always believed a bad shaft meant a bad engine, period.

 

Where do I go (besides a school) to learn these things, or get some advice on the subject?

 

Also, I've noticed a retailer on a couple of the want-ad pages named premiumaircraftparts.com that seems to have a pretty wide selection of engines, parts, kits, and options available, at what sound like realistic prices. Anyone have opinions on them?

Evan Kisbey

Cozy Mk IV plans # 1114

"There may not be any stupid questions, but I've seen LOTS of curious idiots..."

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