The MMI K-27 and K-28’s have a very similar wheelbase length for the drivers. The pilot trucks have very similar travel. The K-27 has less lateral travel but this limitation really only affects the On30 models. The K-36 and K-37 have a longer wheelbase for the drivers and will not go as tight as the 27s and 28s. I can barely squeak my On30 K-36 through a 28” radius but my 27 and 28 will handle it like a champ.
I don’t think you will encounter these issues with On3 models though. The wheelbase is the same for On3 and On30 models. The only reason that the On30 models can push the envelope on turning radius is because of their blind center drivers. The On3 models should all have the same minimum curvature (unless there is a limitation on lateral travel with certain models). I believe PSC advertised a minimum 34” radius for the MMI K’s. I would bet with careful track laying and using transition curves, you might get that down to 32”.
Joe, I haven’t seen anyone convert On30 to S however converting S gauge equipment to On30 is a popular thing. Some of the AF rolling stock adapts really well when On30 trucks are installed. I have a tank car that someone made by using a postwar AF gulf tank car and installing On30 trucks. It was then custom painted for Conoco. It looks really nice and the proportioning is great; on my first inspection I didn’t realize it was made froma Flyer car.
