You’re a pilot, so you’ve said it at least once about every airplane you’ve owned: “It’s a great airplane, but it just needs a little more power.”
It’s different this time. You’re serious. You’ve had the flying machine for a few years and you’ve gotten the avionics where you want them, the airframe and systems are sound, but you want more performance. The climb rate on hot days leaves a lot to be desired, especially when you bump the speed up enough to keep the cylinder head temps below 400 degrees. Plus, and this is the big plus, it’s really and truly time for an engine overhaul.
You’re about to spend serious money on an overhaul. If there’s a best time to buy more power for your airplane, this is it.
OPTIONS
It’s time to explore your options—which is what we are here to do. First, historically, the financially smart approach to a power upgrade was to sell your airplane and buy one that already had the engine modification installed because, while a big engine mod usually increases resale value, the increase is significantly less than the cost of the mod. However, we’re hedging that as the best option because, in the current aircraft market, we’re not positive that’s true.
The second option is buying more engine via an STC-approved mod. We’ll insert here a caveat that the option of a big engine mod may not be available for your airplane. Power is destabilizing, so adding horses may have an adverse effect on stability and control and/or may generate issues with airframe integrity. Our research indicated that if engine horsepower is increased by 10 percent, a supplemental type certificate (STC) will be required for the mod because it is a major alteration.
Third, you can get a boutique engine overhaul that increases the power output of your engine.
There are a flock of engine overhaul shops that advertise specialized overhauls that increase your engine’s power output without needing an STC. You’ll see reference to porting and polishing, blueprinting, micro-balancing, special sauces for corrosion protection and paint colors that cause cylinders to shed heat better.
OUR THOUGHTS
We’ll put our conclusions up front. We think the most effective way to increase performance via more engine power is to drop an STC-approved, higher-horsepower engine in your airplane.
A close second is to have your engine overhauled by one of the shops that can do it pursuant to an STC that allows it to be modified to produce more power. We note that any time an STC for more power is involved, a new prop may be necessary and there may be some forward of the firewall changes to accommodate the changes to the engine.
Our third choice for an engine power upgrade is a boutique overhaul that is not per an STC, although we’re hesitant to make such a recommendation. Engine shops such as Victor (www.victor-aviation.com), Ly-Con (www.lycon.com), Penn Yan (www.pennyanaero.com), RAM (www.ramaircraft.com) and Zephyr (www.zephyrengines.com) have long had good reputations for their overhauls and have scored high in Aviation Consumer’s engine shop surveys. Nevertheless, we are hesitant because the cost of non-STC boutique overhauls starts at 10 percent above the standard overhaul and goes up rapidly because of all of the options offered.
We looked for evidence that non-STC’d engine upgrades provided measurable improvements in power output and longevity and could not find any. We spoke with Mike Busch, proprietor of Savvy Aviation (www.savvyaviation.com), an aircraft maintenance management company that has overseen the maintenance of several thousand piston-engine airplanes. He told us that he has “never been persuaded that porting, polishing, micro-balancing and blueprinting offer enough improvement in power or smoothness for most owners to notice. I don’t believe that this stuff has the slightest effect on engine longevity. The predominant factor affecting piston aircraft engine longevity is corrosion caused by disuse and environmental risk.”
We did some checking on engine overhaul prices—up, way up, and increasing—so we’re not going to go out on a limb and quote many prices here as they’ll be out of date before this goes to press.
After saying that, we note that we did some price shopping for a new-limits Continental O-470 overhaul for a legacy Cessna 182 and got starting prices on the order of $50,000. On top of that, we were told that the price could go up depending on the condition of the engine and what can be reused.
We’ll interject here that only the factory (Continental or Lycoming) can offer a “zero time” overhaul, where the engine comes with a new logbook. Field overhauls are either to new specs—all parts must meet factory-new specifications—or a “service limit” overhaul. In the latter, any part that falls within the service limits set by the manufacturer gets reinstalled. Yeah, what sort of owner would have that sort of an overhaul on an airplane the owner intends to keep? You’re right. That’s why it’s a sucker bet to buy an airplane advertised with a “fresh overhaul.”
POWER VERSUS SPEED
Before we go further, we need to address the reality of performance increases with power increases. When it comes to cruise performance, there’s a hard aerodynamic reality: Airspeed increase is proportional to the cube root of the horsepower increase. If you want to go 10 percent faster, you have to have 33 percent more horsepower. So, that 20 percent boost from 150 to 180 HP in your 172 will only increase cruise speed from 110 knots to about 117 knots. It will also increase fuel burn, which may significantly hurt endurance because that 150-HP 172 doesn’t exactly have big fuel tanks.
Where the performance increase with the bigger engine pays off is in rate of climb. Climb is a function of excess horsepower—if your 172 requires 100 HP to fly level at Vy, a 150-HP version has 50 HP available to pull you upward. With the 180-HP mod, you now have 80 HP available for the climb—a 60 percent improvement. That’s significant.
In the turbocharged world we observed that a number of the engine mods didn’t increase horsepower by a significant percentage, but they did allow the engine to take sea level power up to higher altitudes and included more effective intercoolers that got rid of the need to carry extra airspeed in the climb, increasing climb performance. Plus, once at high altitude, the extra available power did pay off in measurable cruise speed improvements.
In no particular order, we’ll give a thumbnail sketch of many, but not all, of the STC’d engine power upgrade mods that, in our opinion, have stood the test of time. We will not quote many prices as the reality is that there are too many variables to give an accurate quote. Shops tell us—and we’ve certainly seen it—that the condition of the airframe can radically drive up the cost of an engine upgrade mod as serious hidden problems, notably corrosion, are uncovered when the shop dives into the airplane for the mod.
Nevertheless, we think that if you approach an engine power upgrade mod by planning on spending at least twice the installed price of a good, new-limits overhaul, you’ll probably be in the ballpark.
TEXAS SKYWAYS
Boerne, Texas-based Texas Skyways (www.txskyways.com) has been offering engine power upgrades for various Cessna singles since 1985. It currently offers a number of power upgrades using new, zero-time factory rebuilds or overhauled Continental engines—along with bumping TBO to 2500 hours on legacy Cessna 180s and 182s.
For the legacy Cessna 180s and 182s the offerings are a 285-HP O-550-F/TS, 280-HP O-520-F/TS and a modified O-470-U/TS rated at 250 HP. Texas Skyways will drop a 300-HP IO-550 engine into a Cessna 185, 205, 206, 207 or 210. It also has an IO-520 upgrade for the Cessna 205 that is rated at 300 HP for five minutes and 285 HP continuously.
According to Texas Skyways, the mods do not require changes to the airframe or cowling.
D’SHANNON AVIATION
Regarded as the world’s largest STC holder and manufacturer of upgrades for Beech Barons, Bonanzas and Debonairs, D’Shannon Aviation (www.d-shannon-aviation.com) offers a series of power upgrades, scimitar props and tuned exhausts—as we’ll as drag reduction gap seals. The engine upgrades include a 260-HP IO-470N, 285-HP IO-520BA and BB and 300-HP IO-550B and C. Notably, all of the engine upgrades can be done at D’Shannon or are available as an STC kit for your shop to install.
BOLD-WARRIOR
Griffin, Georgia based Bold-Warrior (www.bold-warrior.com) offers an STC’d 180-HP engine upgrade for Piper PA-28 series airplanes with 140-, 150- or 160-HP engines and Citabria 7ECAs, 7GCAAs and 7GCBCs. It will do the mod at its facility or sell you STC approval (currently $950) for your shop to do the installation.
The mod requires a Lycoming O-360-A4M, -A4A, -A3A or -A4N engine and a Sensenich 76EM8-0-60 or 62 propeller and a change in the airbox. Bold-Warrior has partnered with Penn Yan Aero to supply new or overhauled engines and prop packages to its customers.
VITATOE AVIATION
Former drag racer and all-around gearhead Larry Vitatoe worked with Tornado Alley Turbo’s turbonormalizing gurus George Braly and Tim Roehl to turn the Cessna T210 and P210 into the airplanes we always thought that they should be by replacing the TSIO-520 engine with an IO-550 mated with the airplane’s original turbocharger and turbonormalizing the engine. The Vitatoe (www.vitatoeaviation.com) mods to the T210 and P210 allow them to carry 31 inches of manifold pressure and 310 HP up to 23,000 feet and turn the airplanes into honest 200-knot cruisers.
We reviewed a Vitatoe-modified P210 back in 2013 and found that in a cruise climb of 120 KIAS the rate of climb never went below 900 FPM all the way to FL220, which took just over 20 minutes from a 1000-foot MSL departure. We’d made that climb in a stock P210 several times and it generally took twice as long.
The mod, carried out at Vitatoe’s Chillicothe, Ohio, shop, includes a new prop and substantial work in front of the firewall and takes 14-16 weeks, including test flights.
RAM AIRCRAFT
For Waco, Texas-based RAM (www.ramaircraft.com), we are providing pricing as of August 2022 because it was freely offered to us and it reflects, in our opinion, competitive pricing in the engine mod world. The caveat is that this pricing does not include any work required due to the condition of the airframe—and, in our experience, in the world of aging airframes, extra work is the norm, not the exception.
Currently RAM offers three STC’d engine upgrades for the Cessna 340/340A—one bumps power to 325 HP and two step it up to 335 HP. RAM’s Thomas Dunn told us that a turnkey 325-HP “Series IV” mod is $195,000 performed at RAM. The “Series VI” 335-HP mod runs $210,000, while the “Series VII” 335-HP mod is $220,000.
The Series VII mod differs from the Series VI in that it uses a larger turbo, intercooler and airscoop, allowing lower manifold pressure and carrying maximum manifold pressure to 25,000 feet. RAM’s performance charts show a 260-HP cruise at 23,000 feet at 232 knots while burning 20.3 GPH per side. In our opinion, that’s closing on turboprop performance for a fraction of the cost.
RAM offers the Series IV and VII mods for the Cessna 414 and 414A.
For the Cessna T310 and 320, RAM offers an engine power upgrade from 285 to 300 HP. The $170,000 mod includes a useful load increase.
On the Beechcraft side of the house, RAM upgrades the older IO-520-CB or B3 engines in Bonanzas and Barons to IO-550s to modernize those airplanes and improve performance. Cost is $79,000 for a Bonanza, $155,000 for a Baron.
PENN YAN AERO
The well-respected overhaul shop Penn Yan Aero (www.pennyanaero.com) was one of the first to offer an STC’d engine overhaul boosting the power of a 150- or 160-HP Lycoming in a Cessna 172 to 180 HP. It’s available for 1977-1986 Skyhawks equipped with Lycoming O-320-E2D, -H2AD or -D2J engines.
For the mod, you schedule with Penn Yan when it can accept your engine and, assuming the crankshaft and crankcase are in good shape, Penn Yan turns it into a Lycoming O-360-A4M engine developing 180 HP.
Penn Yan claims an increased cruise speed to 151 MPH and takeoff roll decreased to 700 feet at gross weight. We clearly remember the first time we flew a 172 that had gone through the mod because we were impressed with the new takeoff and climb performance.
MIKE JONES
Based on the Murfreesboro, Tennessee airport, Mike Jones Aircraft (www.mikejonesaircraft.com) initially focused on service and renovation of Piper Navajos. It now offers a series of Colemill power increase STCs for Piper Navajos, Beech Bonanzas and Barons and Cessna 310s.
For Piper PA-31-310 and -325 Navajos, Mike Jones provides the Colemill Panther conversion that bumps horsepower to 350 a side using Lycoming TIO-540-J2B engines with four-bladed Q-Tip Hartzell props.
The Colemill Foxstar mod is available for Beech C-55, D-55, E-55 and 58 Barons. It includes 300-HP Continental IO-550 engines and four-blade Q-Tip Hartzell props.
For Bonanza models A-36, V-35, S-35, E-33A and F-33A, Mike Jones offers the Colemill Starfire engine mod. It includes a 300-HP Continental IO-550B engine and four-blade Hartzell Q-Tip prop.
For the normally aspirated Cessna 310 models I through Q, the Executive II conversion installs IO-550 engines, upping cruise to 200 knots and single-engine rate of climb to 400 FPM.
NORTHPOINT AVIATION
NorthPoint Aviation (www.northpointaviation.net) took over the XP470 STC developed by P Ponk engines in which a stock O-470 engine is modified with larger cylinders and 7.5 to 1 compression pistons creating what is, in essence, a carbureted Continental O-520 engine with a horsepower increase of 35 to 45. The mod includes a new two- or three-bladed McCauley prop. One of the attractions of the mod is that it utilizes the existing engine mount, baffling, exhaust and cowling and the weight increase is only 4 pounds.
JOHN JEWELL AIRCRAFT
John Jewell Aircraft (johnjewellaircraft.com) offers power upgrades for Cessna 210s and legacy 182s.
For O-470-powered 182s Jewell modifies the engine to O-470U configuration developing 252 HP at 2624 RPM. It also increases TBO to as much as 2200 hours.
For K, L, M and N model 210s, the Jewell STC swaps the engine out for an IO-550L engine developing 300 continuous HP and installs a three-bladed Hartzell or McCauley prop. Jewell advertises an up to 20 percent increase in rate of climb.
Jewell will turn a turbocharged K, L, M or N model 210 into a normally aspirated model with an IO-550L engine. For those who do not regularly fly their turbo 210 high, going to the normally aspirated engine that develops 300 continuous horsepower rather than the 285 HP
of the TSIO-520 (it is rated for 300 HP for five minutes) means better performance up to 10,000 feet, a longer TBO and decreased maintenance costs.
AIR PLAINS
Trying to keep track of the power upgrade option STCs held by Wellington, Kansas-based Air Plains (www.airplains.com) can be daunting as the company has been in the more power business for over 40 years.
For the Cessna model 172B through R it will bump the power to 180 HP.
For the model 180, Air Plains drops in a 300-HP engine, boosting rate of climb a claimed 51 percent.
Cessna 182 models H through R are eligible for a 300-HP engine replacement STC. There is also an STC for S and T models bumping power to 260 HP.
All models of the 182RG can be modified to either 260 or 300 HP.
WIPAIRE
We’re still boggling at the Boss 182 conversion offered by seaplane float manufacturer Wipaire (www.wipaire.com) in which it takes a Cessna 182S or T and installs a Lycoming IO-580 engine developing up to 340 HP (stock power is 315 HP) after tuning by engine shop Ly-Con.
The conversion includes a tuned exhaust, several choices of propeller and an increased gross weight for the airplane.
PETERSON PERFORMANCE
While the mods offered by Peterson’s Performance Plus (www.katmai-kenai.com) involve more than an engine power increase, we’ve included them in this article because of the startling performance generated by their Kenai and King Katmai aircraft. Both replace the engine in a Cessna 182 with a 300-HP Continental IO-550D. What comes with the engine upgrade, including a new prop, is an airframe modification that installs a canard. That results in stunning short-field capability. The King Katmai is optimized for STOL ops in the backcountry. When we reviewed it some years ago we were able to easily land or take off in less than 400 feet.
The Kenai is optimized for cruise performance, and can cover 1000 NM at 150 knots while able to take off and land in less than 500 feet.
OTHER METHODS
Finally, especially if there is no STC’d engine mod for your aircraft, we’ll mention two methods for getting more power out of your current engine: the Power Flow (www.powerflowsystems.com) exhaust and replacing one mag with Electroair’s (www.electroair.net) electronic ignition.
We’ve reviewed each recently. The tuned exhaust from Power Flow gives an increase in engine power of approximately 10 percent. The computerized adjustment of engine timing performed by Electroair’s electronic ignition gives a rate of climb and service ceiling increase of approximately 10 percent.
CONCLUSION
When you’ve decided that you like your airplane, want to keep it, and want more power there are a number of options available to you. If there is an STC for more engine for your airplane, we think that is the best of the options.
If there is no STC’d drop-in engine upgrade we recommend looking hard at a Power Flow exhaust and/or Electroair electronic ignition. Finally, careful shopping for a “boutique” overhaul offered by a specialty overhaul shop may give you a little extra performance.
