I'm a little late to the party here. The only one I still have is the Bonanza RS-2000 with the single 820, but that's the best engine of all. Fully modified, latest rod, piston, dual GEM V-12 manifold with dual alky cars.......and it's a stroker. Around 150cc. I have only run it for a couple of laps because the first time I ran it, it has a bad condenser and I didn't get it fixed until the end of the day.....it's a rocket.