The gentleman who makes the engines is Russell Stoltz....

He works out of his son's machine shop in Elk Grove Village IL

Here's the address and phone number:

Challenge Tool Co
(847) 640-8085 60 Joey Dr
Elk Grove Village, IL

Russ usually doesn't get in until after 9:00 am and may be out at the Doctor's, as his health hasn't been that great lately...

His work is top notch and not cheap...the only limitation I've found is getting mufflers, as he doesn't make them...so I think you'd have to go to Bennett or someone like that. I just posted 3 pics of the "big" inline twin in my gallery so have a look and let me know what you think....

Heard two of his 3.2 engines in Dennis Crooks P-38 at the St. Charles Rally of the Giants a couple of weeks ago.....what a sweet sound, almost like the full size engines...

Bill