There's a thread around here somewhere where the guy that did a lot of testing for me posted his results, I cant find it using the search. For all I know, it could have been deleted before we took over the site.
The tester (Kenny Brown) picked up about 30-40 horsepower on pump gas at the rear wheels. I forget the exact numbers. Most everyone that ran the system really liked it and found it to be mostly trouble free.
Dan, I must have been sick when you guys were testing propane. I remember Dan telling me that you were supposed to be coming down to test, Melissa's car blew up, you never came and no testing was done. Dan never mentioned to me you guys had a kit, I never heard any test results and would like to have had some input in tuning when you were testing.
Bruce (RIP) also had a propane kit which to my knowledge, was never installed or tested. He sent me tons of emails touting the benefits of propane over alcohol from a bunch of EFI gurus and was salivating at getting a kit. We ended up selling him a kit at bare cost in exchange for his promise that he would test the hell out of the kit and post results. To my knowledge, he never even took the kit out of the box. This was years before he passed away so I know it wasnt his health that kept him from doing the testing.
Last but not least, the reason the kit sort of faded away was mainly due to lack of a quality controller. We started working with another TR vendor who will remain nameless about building us a controller for the kit because Dan did not want to build the control boxes any more. This guy drug us along for over a year with promises of a controller "forthcoming" that never saw the light of day. Meanwhile, same vendor continued development of his own alcohol stuff while pushing our stuff off to the side and after wasting over a year waiting on a new controller, told us "too bad." At that point, Dan had lost interest and I had lost interest because we hadn't had kits to sell in over a year while we waited on this new controller that was "forthcoming."
Given the advances of alcohol, at this point Id have to say that alcohol probably have more advantages. Back then, not so much so. Either way, propane is a nice mod for a street car. It does increase power, the tank lasts a while between refills and it's relatively easy to tune.
Im actually contemplating doing a new alcohol controller for existing kits. I have some ideas on doing some things that havent been done before in a controller but Ive got too many projects going as it is and not enough time to oversee them all. Maybe next year once we get this header project squared away.