I liked Quarter Midget .15 but the high performance engines were getting expensive.

In England they had Formula-20 which was about the same size as QM but used inexpensive plain-bearing .19 or .20 engines. I think the Fox .19 was one of the hot setups and the engines were much cheaper than a Nelson or Rossi .15.

I've often wondered if you could squeeze an OS .25FX in the nose of a QM. If not, maybe an Irvine.