Ii have a few 40-size engines, all ABC/ABN except a newly acquired FP40 whixh has an iron piston.

Do the iron piston engines run differently—bettor or worse—to the ABC?ABN?

There is a fuel issue but as the FP is new and the price was such that I am still ahead of the price of a new LA if I replace the piston and cylinder liner, I am wondering about that option.

What do you guys think?

Cheers, Geoff

Hi Capt. It has been our experience that the steel PC engines make more power. I found that filling the boost port was necessary. The engine "pop-corns" (miss-fires) without filling the boost. We use synthetic oil only as castor seems to interfere with combustion causing funny breaks and missfires that do not happen with pure ucon at about 18% with 10% nitro. The engine will easily swing an 11x6 but will run at any of the usual engine speeds associated with stunt. Our personal engines are still steel PC and have been running a long time. Good luck.

Big is planning to go. I'm up to some engine work. Dennis and Archie are working me to death.................

My steel pistion FPs run stock, my later model ones I modify the boost port on. Love em both. Though aside from the fuel consumption variations I am really liking my LA 46 better. Of course keep in mind I LOVE to run big diameter props, and the LA seems to be happy with that.