Sportster
611
It’s hard to find a stock clean unit these days…
Especially an AP1….and these motors are not rebuild friendly.
The good news is that they are so overbuilt that they will most likely keep going as long as you put good oil into them.
Mine has never broken even once - and that’s with multiple track days. Not the case with my 911 - especially the air cooled units. The oil leaks are not fun either….
Finest air cooled engines on wheels live with two brands IMO….HD and Ducati.
This is what an air cooled motor is supposed to look like 

S2000 vs Viper
By: Sportster : April 19th, 2023-22:06
My s2000 ap1 nose to nose with my friends viper gts at the track. Both are highly analog race cars - unique in their own ways and great track weapons. Viper - v10, relative lightweight, massive torque, great handling S2000 - 120 HP/litre, 9000 rpm redline...
Love the s2k
By: Sportster : April 19th, 2023-22:26
Wikipedia “The F20C produces the highest specific power output for any naturally aspirated piston engine in a car priced under US$100,000, at 125 hp (126.7 PS; 93.2 kW) per liter” “Honda's F20C engine held the record for producing the highest specific pow...