Home | Jeffrey Ozier-Mixon: I really like the Sierra. It is as comfortable as our family car, and cabin access makes all those one-hole planes (Pipers, Mooneys, even Bonanzas) feel claustrophobic. Even the Cardinal feels a bit cramped to us, which is wh

Jeffrey Ozier-Mixon: I really like the Sierra. It is as comfortable as our family car, and cabin access makes all those one-hole planes (Pipers, Mooneys, even Bonanzas) feel claustrophobic. Even the Cardinal feels a bit cramped to us, which is wh

Jeffrey Ozier-Mixon:

I really like the Sierra. It is as comfortable as our family car, and cabin access makes all those one-hole planes (Pipers, Mooneys, even Bonanzas) feel claustrophobic. Even the Cardinal feels a bit cramped to us, which is why we bought a Sierra in the first place.

For a similarly comfortable cabin and more speed I could buy a used Cirrus or Diamond, if I had $250k. Or build an RV-10, if I had a couple of years to spend on the problem. Neither of those are an option for us. If were willing to do without my pilot’s side door I would go with a Mooney 201 or Debonair, but I’m not.

What I really want is a Sierra that can cruise at 145kt or better, and/or go up to 16k MSL, and I don’t mind paying a little more in gas to do it. But not at the expense of reliability. My Sierra had too many issues with reliability as it was.

So I guess the question is, what can be done to a Sierra to make it go faster and higher, legally and reliably and with the most pay-back, dollars vs. knots? The most I would be willing to spend on these upgrades is $20k. Ideally I would be starting with a stock C model.

The answers seem to be:

– PowerFlow exhaust (Mike, what’s the latest?)
– balancing, blueprinting, port/polish etc (dubious legality)
– port/polish w/o size changes
– turbocharging (expensive, no STCs)
– improved air filter (gains?)
– improved ignition system (gains?)
– new roller cam from Lycoming ($$??)
– airframe cleanups – any available?*

* One potential airframe cleanup for A and B models is to install the fairings from the C model. I have heard that several people have done this and effectively gained several knots, comparable to a C model.


The following is from the MML Archive Search on BAC. I wish more folks would try out the BAC MML Archive Search. I think you’ll be pleasantly surprised at how easy and fast it is, and how easy it is to view all the results. You can search in titles only, in text only, or in both. I have added some new comments after this older post.

Date: 2003-08-27 17:28:50
Mike Rellihan

For two years I tried to work with Bill Sandman (M20 Turbos, and his air-oil separators), and with an outfit (RCM Normalizing) that does an STC’d turbo for the IO360 in the Commander 112’s. This included flying the plane to Sandman (Boca Raton, KBCT) to take photos and measurements. At the time, the price for the Mooney package was quoted as being around $35,000, and the RCM 112 package was around $32,000.

What happens is that as soon as they find out the very limited fleet size, and that there isn’t much commonality with other installation layouts, they drop it like a hot potato (for understandable financial reasons). I also received one comment from another guy (who turbocharges Bonanzas), that if I found a good aerospace welder and had about $60,000, I could probably get a one-time STC. In other words, I thoroughly struck out on the turbo possibility.

I have since concluded that the Powerflow Systems exhaust offers a much more reasonable possibility to get a modest performance increase at a much more attractive price (perhaps around $3,500 to $4,000; about the list price of a new standard exhaust). Based in Daytona Beach, they are only a 15-minute flight from my home base (KSGJ). I offered my plane as a test bed, including temporarily putting it in Experimental status, and even offered my time as an A&P to cut their development costs. Of course, the fleet size issue again rears its ugly head. I have been corresponding with Robin (the owner) at Powerflow Systems since January of 2002. They are currently working on the 200HP IO360 in the Mooney and Arrow airframes, in order to get something certified and bringing in revenue. Robin has been telling
me “about six months” for a while now, and just recently told me (with apologies) that the Sierra could be a year away. When it comes to mods and STC’s, we pay a price for having our wonderful airplanes.

PFS has already put systems on the market for the Lycoming O320 and O360, in quite a few airframes. Here is their link: http://www.powerflowsystems.com/
I’m hoping that I can get my Sierra on their plate next year. If someone with an O320 and O360 mouse wants me to volunteer them to get in line, I’ll be glad to do that. I have a commitment from Robin for a break on the cost of a prototype system.

If you haven’t been keeping up with these systems, I can tell you that I have been quite impressed with their results. Most speed mods actually have so-so results, with a mixture of anecdotal “It seems faster” comments. In contrast, these engineered exhaust systems have well-documented data, along with many glowing testimonials (almost no
nay-sayers or “maybes”), and including very favorable findings by Aviation Consumer. Some airframes in particular have dramatic improvements. The exhaust system is usually the airframe manufacturer’s responsibility and design, with many compromises, and some are incredibly poor.

When Lycoming certifies an engine for 200 horsepower, it is on a test stand with stub stacks and minimal accessories. A fair chunk of that power disappears when the airframe installation occurs. A company like PFS can legally recover that lost power and obtain STC’s, with no beef from the FAA, as long as they don’t try to exceed the
certified horsepower rating. If I could get one of these systems tomorrow for my Sierra, I’d be down there putting it on. It’s almost a certainty it would be good for an effective 20-30 horsepower increase at a 2500 RPM cruise, full throttle at 7,000-8,000 feet, on my IO360 (as compared to the stock exhaust system). It would also likely help climb quite a bit. Every added horsepower goes directly into climb performance at low speeds; that’s why twins have such great rates of climb (while both engines work!).

Some PFS installations look better than others to me. On older airframes the collector is external, mounted below the cowling. Some people like the “hot-rod look”, and PFS says they actually get some thrust from the rear-facing exhaust. Some newer installations have the collector at least partially concealed within the lower cowling. As long as it still works as intended, that approach looks better to me personally. At any rate, I’ll keep the List updates as events
unfold. Once PFS has the heavy hitter airframes and core engines out of the way, with steady revenue coming in, they should be better able to address our birds at a minimal additional development and STC cost. Just an expanded market and more gravy in their pockets at that point. They have dramatically increased their product offerings
just this year. Apparently it is the engine survey (vibration, HP output, noise, etc.) that drives the highest cost relative to the FAA requirements, with the airframe aspects being secondary. The larger-fleet airframes should have covered most of the engine-related development costs, by the time PFS gets around to any Aerocenter craft.

November 10, 2004, Update:

I have been compiling the Power Flow Systems Interest List, and I’ll soon be approaching PFS again with the new list of names.

There are many small things you can do to the airframe to reduce drag. Newer IFR GPS-Comms can let you get rid of the long-wire and pancake ADF antennas. A new canoe-style marker beacon antenna can let you eliminate the old sled-runner style. If you have old unused antennas, like an old Loran antenna, get rid of it. Make sure your doors fit snugly, with good seals. Airflow around doors causes a lot of drag. The same thing happens from any bad seals, like wing root seals. Check your fairings; are any missing? Broken, flapping in the wind? Do you have a standalone strobe sticking up from the tail, three or four inches higher than the original beacon? Are there more or better fairings on later models, that you could install on your earlier airframe?

Bob Steward previously reminded us not to “tanker fuel”, and not to fly around with 100 pounds of tools and spares. Many people appear to need baggage-compartment ballast. See if that would still be needed, if you installed a lightweight Sky-Tec starter. If you have major avionics work done, and have made other changes like a lightweight starter, have your plane re-weighed. You may well find that you have gained payload, and no longer need ballast. When you fly, slide your front seats as far back as you can, to reduce trim drag. To the extent that it is safe, load the baggage aft-heavy, as long as you stay within limits. In most of our planes, the 3rd and 4th seats can be removed in a minute or so, using the knurled thumb-screws. It is especially easy if you have the large rear door. That leaves you with more payload, and a flying pick-up truck, if there are usually only two of you.

If you have a constant-speed prop, and are facing replacement, think twice before switching to that sexy 3-blade. It may actually cost less (at first), but you’ll lose 30 pounds of payload. You’ll also have a more forward CG, increasing trim drag, and the 3-blade is less efficient. There is a reason why the piston Malibus have two-blade props.

Check the aircraft rig. Instead of bending trim tabs for fixed yaw and roll trim, try to do it correctly by adjusting the nosewheel steering link (yaw) and the flap stops (roll), based on the instructions for your airframe.

Do most of your traveling between 7,000 and 8,000 feet. That may let you use full throttle, on both constant-speed and fixed pitch props. A wide open throttle minimizes engine pumping losses; that’s one reason why most diesel engines have no throttle plate. With a CSP you can take it a step further, using WOT while controlling power with RPM.

All the above things can eventually add up to five to ten knots. That’s like adding twenty to forty horsepower. One of the first things you’ll notice, following cumulative drag reduction efforts, is that the plane will accelerate faster, and to a higher speed, when you lower the nose for a descent. That helps you regain time (groundspeed) lost in the climb. Not only is drag reduction largely free (or one-time cost) horsepower, it will also create even more favorable results if you are eventually able to install something like a Power Flow exhaust system, perhaps in conjunction with a Challenger intake filter..

The IFR GPS install makes it easier to get direct clearances. A straight line give the plane a higher effective ground speed. Learn to properly use lean cruise, and to run one tank to empty or nearly empty. Saving a 45-minute fuel stop, on a flight with four or five hours of air time, nets a significant increase in effective ground speed.

All these speed-related comments assume that another ten to twenty knots makes a big difference. It seldom does on flights under 400-500 miles. Even on longer flights, for our kind of flying, getting there without the hassles of traffic, and with the ability to pick and choose intermediate points of interest that we can reach without parking in an interstate highway wreck, make the speed a non-issue. It is only when you are trying to get 1,000 miles on a deadline that speed can matter; particularly under problematic weather conditions that force route changes. Of course, those are the same circumstances that have killed a lot of pilots and their passengers, over the years.

If you have to reach altitudes of 15,000′ plus (Rocky Mountain flying) on a regular basis, the only thing that will do it (assuming a certified piston-engine plane) is turbonormalizing or turbocharging. TN is a lot easier on the engine than TC, since the manifold pressure doesn’t go over 30 inches. Any kind of supercharging is going to be expensive to put on, expensive to operate, and expensive to maintain. There are very few choices for a supercharged plane with the room and multi-door access that we enjoy in our planes; and any of those choices will cost far more than we pay for our planes.

Thank you for adding to the resources available for your Fellow BAC Members.