N300RE wrote:In my opinion I would NEVER run any engine LOP. A lot of people out there swear you can, but I wouldn't gamble the life of my engine just to save a few extra gallons. It's just not worth it and if you can afford the 550 conversion than what's an extra couple gallons of fuel?

You can figure at least a 3 gal/hr difference in fuel flow between ROP and LOP and if you were truly running your engine where it needs to be on the ROP side to be safe, you can probably see 4 gal/hr difference. At our fuel prices of around $6/gal that works out to $24/hr. This savings will be reduced slightly when you figure in the slight speed reduction. I have put 200 hours on the engine at LOP operations so this has saved me around $4800 in fuel. Soon I will be in the savings realm where I could replace my cylinders for free even if you believe that I will torch them using LOP operations. But I'm not having any cylinder issues and will keep going LOP. Personally, more than the fuel savings at the pump, I love the safety factor of the extended range when out in remote Alaska.

Great thread, popcorn in hand.

ROP? LOP? It's all about managing temps. LOP is cooler, cleaner, and more efficient. Plus, a LOP mixture burns slower so peak combustion pressure is at a more efficient point of crank rotation.

Back to the popcorn.....

I have at least six friends that run 550's in 180's and 185's and a couple of them with turbos. It's a good combo. The only problem is SOME have had cly problems with the TCM clys. I should have installed one in my 185 when I did a TCM reman in 1998. Since I and my son's did the R&R under my I/A's supervision I decided it would be eaiser to do the 520. Not at all eaiser, we had to do a lot of changes to make it fit, not a quick bolt in, should have done the 550. The 550 powered 185's are about 6 knots faster and climb better. I had a friend ( Tommy Rose, died in a race accident in Reno 2002) that did a lot of work to his 185 and the 185 did 213 mph at Sun & Fun in 1998, not to shabby for a gear dragger. I have a friend that has a 550 in his 1953 180 and it flat moves. THERE IS NO SUBSTITUTE FOR CUBIC INCHES!
Ron

I need more speed.....my 185 flies like a dream, however i could do with it going a bit faster. It has a 520 and when that come to a end i'd be very keen on the 550, does anyone know what a 550 turbo is like, more maintence?? and more speed? Also i think one prob is it seems to fly a little tail down, i keep wanting to push forward and get her on the step....rigging? suggestions?

skywagon guy wrote:I have at least six friends that run 550's in 180's and 185's and a couple of them with turbos. It's a good combo. The only problem is SOME have had cly problems with the TCM clys. I should have installed one in my 185 when I did a TCM reman in 1998. Since I and my son's did the R&R under my I/A's supervision I decided it would be eaiser to do the 520. Not at all eaiser, we had to do a lot of changes to make it fit, not a quick bolt in, should have done the 550. The 550 powered 185's are about 6 knots faster and climb better. I had a friend ( Tommy Rose, died in a race accident in Reno 2002) that did a lot of work to his 185 and the 185 did 213 mph at Sun & Fun in 1998, not to shabby for a gear dragger. I have a friend that has a 550 in his 1953 180 and it flat moves. THERE IS NO SUBSTITUTE FOR CUBIC INCHES!
Ron

The early versions of the IO-550 in the 206 experienced many (as in almost all of them) cylinder problems, where the cylinders were stepped, and thus were junk, not rebuildable. A lot of operators got a bad taste in their checkbooks during this period. When the 206 I flew was being converted, I visited with a Continental tech rep I knew about the engine. He asked me the serial number of the (new) engine. I got that and sent it to him. His response: "Don't sweat it, that engine is in the new serial number range". Continental quietly changed something in the cylinder design of those engines, and all those cylinder problems went away. At the time, we had two 206s running that engine, identical conversions. Mine ran VERY cool CHTs, all in the low to mid 300 degree range. The other ran around 400 all the time, and in climb it was HOT. That engine stepped cylinders, mine didn't, until the aforementioned numbnuts operated it improperly, and used up two cylinders (leaning at too high a power setting down low). Otherwise, my engine ran like a dream and four of the six cylinders went to TBO. The other two would have as well, but....

An important point was made by another poster: Make certain the fuel flows are set REALLY high at takeoff power. That was a trick we learned from the same Cont. Tech Rep....29 gph minimum and 30 is better, REGARDLESS of what the STC says. I wanted to see that Cessna flow gauge (actually a pressure gauge, calibrated in flow) all the way over into the other side of the gage on takeoff. The good news is, that flow drops off really quickly when you pull the power back after takeoff.

Great engine, just run it as Continental says to run it (and they do approve LOP ops) and keep those takeoff fuel flows high and it'll serve well.

MTV

This brings up a good point about fuel flow on takeoff. I read what I thought was a good article on this. In it though, he points out that fuel flow should be redline or more at sea level...decreasing with altitude. What's your take on this? If you target the rough estimate of fuel flow as marked on the Cessna gauge by altitude, it will obviously be less. Makes sense to me but was wondering what your past experience is.

The article is part one of a four part series by John Deakin in his Pelican's Perch.

http://www.avweb.com/news/pelican/182179-1.html

As you go up in altitude, the engine makes less power. Power and fuel flow are directly correlated. So, yes, at higher altitudes the max power fuel flows will be lower. The point is that the STC specified fuel flows aren't high enough, and Continental instructed us to increase these flows.

MTV

So then, the question becomes, how much is enough for a given altitude? That is what I'm trying to figure out. As a guide, I'm just watching CHTs and keeping them cool with air and fuel...after an initial setting of max power for altitude using the the altitudes on the fuel flow gauge during the takeoff roll. As you have said, it seems to need more fuel than that though to help keep them cool.

What is your technique? This is my first exposure to seeing all the CHTs and EGTs. It's been interesting!

Thanks,
GSP