- Joined
- Jan 12, 2020
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This is what I’ve been working on for last 4 years.
I’ve been Pylon Racing (F3d) for over 40 years and have used quite a few different engines throughout those years.
This engine is the culmination of maybe all those years of thinking.
I must thank Rob Metkemyer for his advice regarding bearing interference and fits and also his cylinder and cylinder head.
The case is sand cast alloy AA 601.
The crank shafts is a superb machined and nitride hardened shaft by Gabor Dobrocsi from Hungary, a tethered car engineer.
Otherwise all other machining done by me.
The rod and drum rotor is of 7068 T6 alloy.
7075 is ok for the drum but 7068 superior.
Piston is of RSA 444 (30%Si)
The drum runs on 2 x 26x17 x5 C4 clearance hybrids. C4 clearance throughout.
The concept of the induction drum in its design allows the alloy drum to be fully balanced. C4 clearance is extremely important as the 20 micron interference allows At running temperature achieves a loose and free rotating mass with zero crowding of the outer race. Bench running i see around 45-50 c temperature at the case (much more at the cylinder) at 32000 rpm.
I’ve built 9 with some failures early on.
Any way this project may be interesting to some.
Barry Murphy
murfb
I’ve been Pylon Racing (F3d) for over 40 years and have used quite a few different engines throughout those years.
This engine is the culmination of maybe all those years of thinking.
I must thank Rob Metkemyer for his advice regarding bearing interference and fits and also his cylinder and cylinder head.
The case is sand cast alloy AA 601.
The crank shafts is a superb machined and nitride hardened shaft by Gabor Dobrocsi from Hungary, a tethered car engineer.
Otherwise all other machining done by me.
The rod and drum rotor is of 7068 T6 alloy.
7075 is ok for the drum but 7068 superior.
Piston is of RSA 444 (30%Si)
The drum runs on 2 x 26x17 x5 C4 clearance hybrids. C4 clearance throughout.
The concept of the induction drum in its design allows the alloy drum to be fully balanced. C4 clearance is extremely important as the 20 micron interference allows At running temperature achieves a loose and free rotating mass with zero crowding of the outer race. Bench running i see around 45-50 c temperature at the case (much more at the cylinder) at 32000 rpm.
I’ve built 9 with some failures early on.
Any way this project may be interesting to some.
Barry Murphy
murfb
