The Little Things About Big Engines

The Little Things About Big Engines

The Little Things About Big Engines

There’s no substitute for horsepower.

Truer words have never been spoken. If you want speed, you need the engine that develops the greatest horsepower. Why? Try as you must, nothing will replace having more horses under the hood – not even leverage. You can move the world with a long lever, but you can’t move it far. Aerodynamic efficiency helps, but not enough to move the needle appreciably. Shrinking the size of the tube going through the sky isn’t feasible. So, if you want to go fast (and what twin and turbine owner doesn’t, right?), there’s simply no substitute for horsepower.

I’ve had the pleasure of flying every King Air version over the years, having managed (and flown) a C90, 200, B100 and a 300/350 for the last decade. I fly all the versions during training or on ferry flights each year. I’m a huge King Air fan. Which is my favorite? No doubt about it, the King Air 300 is the clear winner. Why? It has the biggest engines mounted on the same fuselage as the King Air 200, and it flat-out performs. 

I can load up full fuel, put a person in every seat, fill the luggage compartment with everything that comes out of an over-loaded suburban, roll a surprisingly short distance down the runway and climb out at better than 2,500 fpm on a standard day. It is simply an amazing machine, and that is because it has the biggest PT6 that Beechcraft could figure out how to bolt on the airframe. The King Air 300/350 is the true Ferrari of the King Air world, undoubtedly due to its power. 

But wait…there’s something even better than the 300/350? 

Blackhawk Modifications, based in my home state of Texas, has built an entire business around the knowledge that horsepower is irreplaceable. They’ve figured out how to remove big engines from great airframes and up the ante by upping the horsepower even higher. Owners can now upgrade to the XP-67A engine and make their King Air 350 climb quicker, cruise faster and look cooler. I suspect the XP-67A STC for the King Air 350 will be very successful as the years go on. Why? Well, you know the answer already – there’s no substitute for horsepower.

Photo courtesy of Blackhawk Modifications

If buying or selling an airplane, the biggest engine variant will always demand the premium price seeing as the market loves horsepower too. In the MU2 world, the Marquise and Solitaire will always outsell the other variants because they have the biggest engines. Similarly, the King Air 90 with the biggest engine will sell first. Piper Aircraft moved from the 310 hp Malibu to the 350 hp Mirage for the benefits of horsepower. More horsepower equates to more demand.

And, when the chips are down with that unexpected engine anomaly on one side, you want the good side having horsepower in reserve. My biggest argument against low-power multi-engine airplanes is the lesser performance when an engine emergency occurs. Would you rather have an engine failure at night in bad weather over inhospitable terrain with icing at MGW in a King Air F90 or King Air A90 (with less available horsepower)? If things go awry, I want the stable with the most horses. 

I get this question often when working with clients who want to buy a PA46: “Should I get a super nice piston version or go for a turbine?” That’s an easy answer for me. My answer is always, “If you can afford it, always go for the turbine.” Horsepower changes the game. The Piper Mirage is a fine airplane, but it is a relative pony with an anemic climb rate that has trouble getting up the highest flight levels or handling icing
conditions. But bolt on the -35 JetPROP conversion, and you’ve got a true thoroughbred that’ll use half the runway both in takeoff and landing, gain 1,500 fpm during climb, and cruise 50 KTAS faster. The airframe is the same, but horsepower makes all the difference.

I can vividly remember when taking my instrument rating check ride many years ago, A.L. Johnson (longtime DPE from Nacogdoches, Texas) asked me, “What determines the rate of climb?” I stumbled, hemmed and hawed, and convinced him that I only knew enough to be dangerous. My poor response prompted a good discussion that I remember to this day. The answer to A.L.’s question is, “excess horsepower.” I never forgot A.L. Johnson and never forgot that question. In fact, I now ask that question during almost every checkride I administer. The amount of excess horsepower will determine the climb rate. So, when a bigger engine is mounted to an airframe, all of that additional horsepower goes directly into the rate of climb. That is why the Beechcraft Duke with a turbine Duke conversion will out-climb most jets, and the piston Duke has performance more equal to the Piper Mirage.

Is the largest engine version of an airplane right for you, or should you go for the small-engine variant? 

That’s an easy question to answer in a practical sense. All you have to do is lease the type of airplane you want to buy with the largest engine and then see if you can pull the power back. Most cannot do it. For example, if you are considering whether to buy a -21 JetPROP or a -35 JetPROP, fly in a -35 JetPROP and pull the power back to match the ITT of a -21 JetPROP. The -21 JetPROP has an ITT limit of 680F, and the -35 has an ITT limit of 740F. So, if you can fly the -35 JetPROP around with a max ITT of 680F, you’ll be flying a -21 JetPROP effectively. Most pilots cannot resist the urge to push the power lever all the way forward. 

This same test can be used with other airframes, too. Can’t decide between a King Air F90 or a C90?  Find someone who would be willing to allow you to take a test flight in an F90 and see if you have the wherewithal to pull back the power to the limits of a C90’s-21 engines. If you can do so, then you are motivated by efficiency, and you are in the elite club of owner/operators that know how to do the math.

Do math? Ouch! That hurt. Yes, there is no substitute for horsepower, but no one said that horsepower is cheap. You’ll pay more to acquire any big-engine version of an airplane. You’ll buy more fuel to feed the big-engine version, and every hour of operation will cost you more (engine reserve) in the big-engine version. Is it worth it? To most, yes, but it is a personal decision that has other variables in the equation, with the biggest variable being cost. Make no mistake, the bigger engine will always cost more.

So, do you buy the big-engine version of an airplane or the small-engine version of an airplane? The adage rings true, “The buyer with the most knowledge usually wins.” Do your homework and learn all you can. If you still struggle to make a good decision, be sure to hire a buyer agent who has your best interests at heart. But never forget, there’s no substitute
for horsepower.

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