[thackney]

I would expect a difference between a gasoline engine running on propane and an engine built for propane.

[Eric in the Ozarks]

Schwann’s delivery trucks have been running propane for many years. SemGroupCorp of Tulsa is their supplier.

[Dusty Road]

I suspect your right! The conversions now should be allot better. I still think CNG will be the future but at my age I may not get to see it.

[garryowenartillery]

Yes, big difference. Gas/Dri-Gas flex engines allow use of both fuel types and performance will suffer on both fuels. A well designed dedicated dri-gas engine (low compression with turbos) will price and power out favorably against petrol at least to my experience. My cousin runs a Kintner Racing-built 302 Mustang bracket car on Dri-Gas, I hate Fords, but Lordy!, it's got 2 of the biggest ImpCo vaporizers I've ever seen and a great big turbo. Makes huge horsepower for weekend fun with little maintenance.

My wife's late cousin's daily-driver was a Silverado short bed with a Dri-Gas only 454, twin ImpCo vaporizers and twin turbos, he claimed 900+hp...it was never dyno'd but the combination made it possible I guess, what a ride it was!

I've also experienced a Ford Louisville L9000 Road Tractor total conversion to Dri-Gas, it also ran really well, only problems were melting the custom turbo exhaust systems off it!