Mar 13


Over the last few years, Kirby and the Team seem to get lots of questions about the race engines. Everyone wants to know, “What is in that engine that makes that airplane so fast!” Well, some things we can tell you and some we can’t! We will talk about some of the details, but everything combined makes for an incredibly powerful engine. If the Team found that they could gain 1 horsepower by changing a part or modifying, then they would in a heartbeat.

Tim Hess owns Unlimited Aero Engines and is Kirby’s engine guru. He is a perfectionist and works his magic on all of Kirby’s engines. He starts with a Lycoming IO- 540 narrow deck and modifies the case for solid lifters. Tim uses custom made “high ratio” rocker arms and custom made pistons that are 500 grams lighter than competitors. Wow you say, such a minuet difference in weight.

I am sure you are starting to get the idea, it’s the little things that make all the difference?

Heat barrier and anti-friction coatings are used on critical surfaces. The cylinders are ported by hand to provide proper intake to exhaust flow ratios, as well as, the intake and exhaust valve guides being custom made. Tim likes to use “Blueprinted” Slick magneto’s and metric 1.2mm low tension compression rings. Modifications are made to the internal oiling system for thrust bearing surfaces along with “priority oiling” to the prop governor. One last note of interest, cold air induction systems are used rather than the stock induction systems.

Now, those are the things I can talk about and there is a big list of the things I can’t talk about…darn!

Tim is working away on the research and development of his engines, looking forward to the future, making his engines faster with every passing year! Lucky for us!

When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.  ~Leonardo Da Vinci

Unlimited Aero Engines

537 Crawford Street

Fitchburg Municipal Airport

Fitchburg, MA 10420

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