Anyone on BCP owned or spent time in a straight tail 172 with Avcon 180hp / CS prop conversion? Downside is no Auto STC and on a 57 172 there is not a gross weight increase (not a big deal for me). Oh and Avcon seems to no longer be around.

What do you plan for fuel flow at 65%?

I was a regular renter of one several years ago. Excellent all around performance. Why no mogas? If 8.5-1 compression should be fine for 91+ E0. That is what I run in my 180hp Cub. At 2400 rpm I burn 7 gph. 2300 rpm 5.8 gph. I run slightly rich of peak. I have electronic ignition which helps with economy.

Bugs66 wrote:I was a regular renter of one several years ago. Excellent all around performance. Why no mogas? If 8.5-1 compression should be fine for 91+ E0. That is what I run in my 180hp Cub. At 2400 rpm I burn 7 gph. 2300 rpm 5.8 gph. I run slightly rich of peak. I have electronic ignition which helps with economy.

I believe it has to do with the fuel pump that is added on.. Petterson had an issue and discontinued tests and EAA doesnt list it. I would fly this for a bit and add on a 220hp Franklin --- **if** the new Franklin USA brings it out in 6-12months.

Do you recall what you flight planned for fuel burn in the 172 with 180hp/CS you rented?

I fly a 170b with the Avcon 180hp conversion, so the numbers should be fairly close. I plan fuel burn at 8.5 gph, and usually burn closer to 8. That's at 2350rpm/17" at around 105 true airspeed.

Yeah, the 8.5 gph sounds safe for your application.

Thanks all! I have seen speeds from 120mph to 145mph for 180hp conversions... cant be that much difference between planes??

8-9gph with 800-1000 climb is perfect for my mission.

Been looking at 182's but this plane seems like a great option for the price that is listed.

have 175 with avcon 0-360 constant speed. 8 to 9 gph seem right. I am able to lean back somewhat. Doesn't like low power setting. vibrate and runs rough. It is nose heavy and will run out of trim with one and full fuel. Nothing that is hard to deal with but have to stay on top of. Fun to fly and vx will get 1200 fpm climb. Speed is 120 mph at 65%.
Need to sell due to rv 4 is getting closer to looking like an airplane. And I don't need a 4 place with lots of power, room for stuff and only fly by myself anymore.
Did put new prop on due to prop AD.
ML

29 Singlespeed

I have had long conversations with Harry Delicker of Delair in Porterville Calif.
Then one can only have loonngg conversations with Harry, mostly listening, but an excellent education.
The FAA would not allow any gross weight increases for the early 170 / 172s with a FLAT firewall. They would allow a weight increase for the later 172s with a "step" on the top of the firewall, but then you were limited to only 30* of flaps.

Even without the nose wheel my 170 was also nose heavy. Would leave about 1500 rpm on until touchdown with Hartzel 80" and the dampener, (another 14lb.). Went to MT prop to improve that (-29lbs). All new ball game learning how to handle the power adjustments with the MT which is more sensitive and quicker to react to power adjustments - gotta be smoother on the throttle.

Old dog having new trick syndrome!

Chris C

I have a slant tail '67 T-41 Avcon with CS that was down-converted from the IO360 Continental. Horton Stol, big tires, VGs. Climb rate is about right. I get about 110 knots TAS around 4500 MSL, which ends up being where I cruise most of the time, and burn about 9 GPH. The 180 HP plane is absolutely the way to go. 172s should have had the O-360 from the beginning.

jcadwell wrote:I have a slant tail '67 T-41 Avcon with CS that was down-converted from the IO360 Continental. Horton Stol, big tires, VGs. Climb rate is about right. I get about 110 knots TAS around 4500 MSL, which ends up being where I cruise most of the time, and burn about 9 GPH. The 180 HP plane is absolutely the way to go. 172s should have had the O-360 from the beginning.

I'm surprised that someone spent the money & time to downsize from the IO-360 Continental. A friend of mine has an IO-360 powered T41 & it seems like a great performer. Although if I was upgrading from a smaller engine I'd prefer the Lycoming, I don't know why anyone'd switch a T41 to one.

Jr.CubBuilder wrote:...The lack of an auto gas STC for these is the result of the fuel pump system which can cause vapor lock when you are hot and/or high. Unfortunately the pumps are required by the FAA due to the size of the fuel line under the center tunnel, and there's no cost effective way of getting to this.

My C150/150 has an engine driven fuel pump and an electric boost pump. EAA sent me an 87 octane mogas STC no problem when I told them what I had. Works fine. I don't see why the fuel pump(s) would cause a vapor lock problem-- in fact, a pump & boost pump seem like they would be the way to overcome vapor lock if it ever should occur.
BTW as far as I know EAA just does 87 octane mogas STC's, Petersen does both 87 & 91. 180 horse Lyc requires 91 so EAA is out of the STC picture for that..

I have a 1963 P172D with the Avcon conversion to an O-360 CS. Great little airplane. With the money I've put into the engine, however, I would not even consider running mogas, and in any event there is no STC for it. Avcon is still in business so far as I know, but they have the lousiest customer service of any company on the planet, I think.

I run 115 knots as flight plan speeds, burning 9.8 gph at 2400 rpm/21" mp, and I usually come within 5 minutes of my plan on a 2-3 hour flight. I can slow it down, of course, and burn less per hour, but my observation is that I'll burn about the same amount of gas to get from A to B. It runs very, very smoothly at that power setting. At lower elevations it climbs like a scalded cat runs up a tree, and it has pretty good performance at higher density altitudes. But a 182 it is not. Max take off weight is 2350#, which gives it roughly a 1000# useful load. With 52 gallon tanks, that makes it a 3 person airplane, if you carry anything at all in the baggage compartment. I normally have a full survival kit there, and I have a backpack oxygen set, so generally I'm down to a 2 1/2 person. For those rare occasions in which I carry 4 adults, I do it with around half tanks, and I pull out much of my normal "stuff".

Cary

Cary wrote:I have a 1963 P172D with the Avcon conversion to an O-360 CS. Great little airplane. With the money I've put into the engine, however, I would not even consider running mogas, and in any event there is no STC for it. Avcon is still in business so far as I know, but they have the lousiest customer service of any company on the planet, I think.

I run 115 knots as flight plan speeds, burning 9.8 gph at 2400 rpm/21" mp, and I usually come within 5 minutes of my plan on a 2-3 hour flight. I can slow it down, of course, and burn less per hour, but my observation is that I'll burn about the same amount of gas to get from A to B. It runs very, very smoothly at that power setting. At lower elevations it climbs like a scalded cat runs up a tree, and it has pretty good performance at higher density altitudes. But a 182 it is not. Max take off weight is 2350#, which gives it roughly a 1000# useful load. With 52 gallon tanks, that makes it a 3 person airplane, if you carry anything at all in the baggage compartment. I normally have a full survival kit there, and I have a backpack oxygen set, so generally I'm down to a 2 1/2 person. For those rare occasions in which I carry 4 adults, I do it with around half tanks, and I pull out much of my normal "stuff".

Cary

Thanks! I think I have decided to continue to wait and look -- putting more pennies in the in the piggie bank. The fuel burn is not that much less than a 182.

Cary wrote:..... With the money I've put into the engine, however, I would not even consider running mogas.......

I'm curious what is meant by this? I don't feel that running mogas is tough on my engine, quite the opposite, no lead = no clinkers to foul the plugs. Petersen's literature describes running a 25% 100ll/75% unleaded mogas mix as being best for radials & Franklins, due to their need for a little lead for the valves. They otherwise recommend running a tankful of 100LL every 75 hours or so.
I guess with no STC available, it's a moot point for your airplane. But it is a viable option for others.

29singlespeed wrote: Thanks! I think I have decided to continue to wait and look -- putting more pennies in the in the piggie bank. The fuel burn is not that much less than a 182.

The 182 is probably more capable, and not much more expensive to run if you use mogas (most if not all O-470's have a stc available). There's some good deals out there these days-- not long ago, a friend of mine bought a nice straight-tail 182 for $30K.

hotrod150 wrote:

Cary wrote:..... With the money I've put into the engine, however, I would not even consider running mogas.......

Petersen's literature describes running a 25% 100ll/75% unleaded mogas mix as being best for radials & Franklins, due to their need for a little lead for the valves. They otherwise recommend running a tankful of 100LL every 75 hours or so.

A Franklin 220 will not like that recommendation.

hotrod150 wrote:

Cary wrote:..... With the money I've put into the engine, however, I would not even consider running mogas.......

I'm curious what is meant by this? I don't feel that running mogas is tough on my engine, quite the opposite, no lead = no clinkers to foul the plugs. Petersen's literature describes running a 25% 100ll/75% unleaded mogas mix as being best for radials & Franklins, due to their need for a little lead for the valves. They otherwise recommend running a tankful of 100LL every 75 hours or so.
I guess with no STC available, it's a moot point for your airplane. But it is a viable option for others.

It is all personal preference what to run, but I love having easy access to mogas. It is cheaper and my o-320 is quite happy running it. The occasional fill up of 100LL on a trip where mogas is not available gets a little lead through the system.

An update for anyone buying mogas here at LMO, a couple weeks ago Larry at Airwest told me that they lost their supplier of 85 ethanol free, so now they are selling 91 ethanol free.

mountainmatt wrote:

hotrod150 wrote: Petersen's literature describes running a 25% 100ll/75% unleaded mogas mix as being best for radials & Franklins, due to their need for a little lead for the valves. They otherwise recommend running a tankful of 100LL every 75 hours or so.

A Franklin 220 will not like that recommendation.

Petersen's brochure lists the 150 & 165 Franklin as approved for 87 octane auto fuel, no mention of the 220. I have heard that it is a 100LL only engine due to high compression. Is that what you're talking about?

I'm very happy with the 59 Avcon I fly, especially after the lighweight starter, alternator, and Selkirk extended baggage reversed the pig front end the Hartzell created. I keep at least 30 lbs at station 125 so that helps. No need for power on landings anymore.

The airframe is approved for mogas as is the A1A, but the combo not together. Who really knows why? It could have been a problem unique to that one airplane that was tested. I have trouble understanding how the slightly increased fuel flow of the Lyc, given 2 more fuel pumps over the O-300 that doesn't have a one, won't adequately feed mogas.

I said:

With the money I've put into the engine, however, I would not even consider running mogas, and in any event there is no STC for it.

My primary hesitancy in running mogas is that there is no STC allowing it. That means that my engine hasn't been approved for it. So I'm not going to go play games with running slightly cheaper gas and risk the $23,000 that my engine cost me, to save $1.50/gallon (the difference between Shell mogas locally and 100LL). The cost/benefit ratio just isn't there.

I average slightly over 60 hours per year (62 last year), and at 9.8 gph (which is accurate for cruise, although for just flitting around I burn less), I'll burn 588 gallons or so and it'll cost me $882 or so extra per year on 100LL. To save that amount, I'll have to find a source of unadulterated (i.e., no MTBE, no ethanol) mogas (hard to do in Colorado), arrange for it to be transported to the airport safely, and have the necessary pump, etc., to put it in my airplane. Guaranteed that I can't keep 100 gallons in my hangar without incurring the ire of airport management. I have no idea what a tanker trailer and pump, etc. would cost, but likely a lot more than what I'd save unless it were amortized over a lot of years--and then it would still cost me to haul the fuel from wherever I was able to purchase it.

Alternatively, I could fly down to Longmont, CO, to refuel with mogas at the airport at a savings of $.45/gal. Round trip I'd burn probably 6 gallons. So let's say I timed it right to buy 40 gallons, which means I'd save $18 on the fillup, but it would cost me $28.50 to fly there and back. Or I could go to Limon, CO, and save an additional $.80/gal. That way, if I bought 40 gallons, I could save $50 on the fillup, and it would cost me $56 to fly there and back. So far as I can determine, those are the only places around with mogas at the airport.

Bottom line is that there's either no savings but instead additional expense for me to burn mogas in my airplane, which has no mogas STC anyway.

Cary