Difference between aero-and car-engine
 

Hi all,

I want to buy a small pylon racer and fit a 25size two stroke.

There is a big difference in rpm between an aero engine and a car engine.
Aero engine 17000-18000 revs
Car engine 30000revs

Why do car engines rev so much faster?
Is it possible to use a car engine in a plane? (The car engine has a prop driver fitted)

Any info would be appreciated.

Ulrich

RE: Difference between aero-and car-engine
 

The car engine revs faster due to a flywheel (low rotating mass) being fitted. These engines do have more advanced timing. I have converted a Thunder Tiger .12 buggy engine to airplane use. I basically turned the heat sink head down on a lathe to reduce the height. It now has a head two fins high instead of eight fins high. This engine spins up to 18,000RPM with a 7X6 prop. This is low compared to using a flywheel spinning at 28,000 - 30,000 RPM.

RE: Difference between aero-and car-engine
 

I have an Irvine 15 , that came from JUST Engines It was shipped with an extended prop nut and the head was already "chopped' , milled off fins for aircraft use, rear exhaust, carb is the same/ It runs great but not in the 20K range. HAVE YET TO PUT IT IN A PLANE martin
It was offed in both configurations do not rembember the prop it got 16K, most likley a smaller one would increase revs iIt was converted to diesel
with a custom head also

RE: Difference between aero-and car-engine
 

Put an r/c car flywheel on your airplane engine and watch it spin up to 30000 rpm! :D

Car engines do not stay at full power all the time. They are revved up and down continuously. A car engine also wears out very quickly, due to the high rpm and other stresses. Trying to run even a car engine at peak rpm for an extended period of time, such as an airplane flight, would most likely wear it out or destroy it in short order.

As a side note, in the early days of r/c cars they were powered by airplane engines that had extra clamp-on cooling fins. They also revved much higher than when used with a propeller in airplanes.

RE: Difference between aero-and car-engine
 

Car engines have slightly higher timing than most plane engines to get max power at somewhat higher revs but not excessively higher, maybe around the 20-25K range. My son's car engine is timed very near the same as my ST S45 but I've measured his revs at 36,000 on a short straight so all those extra revs is just the engine doing what's basically a shaft run. As Kmot said, put a flywheel on a plane engine (or throw the blades off a prop :)) and they'll rev just as much. Car engines though have a stronger rod than plane engines to handle those shaft run revs.

RE: Difference between aero-and car-engine
 

AMB, does this Irvine .15 you have got a blue head? I had one of their first versions they made for freeflight. This engine was clocked at 39,000 RPM with a 7 inch prop on FAI fuel. Although it did have a glow button for a combustion insert, which I later exchanged for a more convenient one that I manufactured, machined to accept a turbo style plug. The glow buttons became hard to get.

RE: Difference between aero-and car-engine
 

Oil Content.