The original conventional engine has been around for a good 100 years, and has only changed modestly in the last 50 years. Most of the improved fuel economy has come about recently, with the ability to have computers carefully administer the fuel, and turn it off when not needed. Most of the companies know we need a new and more efficient engine, one designed to somehow go that extra step to somehow give more economy without losing power.

But up to now, no one has been able to come up with a solution. Companies have billions invested in the current engines, its just easier to do more advertising then to really develop a new kind of engine. We are used to what we have, and perhaps we even love our trusted old friend that car, that engine that was a part of our life for so long! We really don’t want to let it go! And it’s a lot of trouble for a big company to commit to using a new and unproven product.

It takes years to just decide to go ahead. Maybe we are at a stand still. For the last 40 years Hefley Engine has worked and reworked its designs, always looking for that something new that will really work. and never quite satisfied until something near to perfection was created. 

You have not heard about us simply because we were never completely satisfied with our designs. In fact, we see others still struggling with many of the designs we once considered, then discarded. While we will always be improving our product, we now have a great solution.

We developed an engine that changes its size from a large engine to a small engine. The large engine is always immediately available for full power, but most of the time full power is not required, so the engine automatically adjust to being a smaller engine to give that same economy as we expect of a smaller engine. The adjustments are done as the power is required and it is done smoothly and efficiently. These changes are done inside the engine in a smooth simple fashion. We weren’t satisfied until we made it simple and easy to manufacture and maintain.

Several others are trying to do the same thing, but their machinery is seriously lacking a simple and efficient manner to effect these changes. If you look carefully at our website, you will see exactly what we can do. But we go one step further to explain how we do it.

 “The Hefley Workshop” This portion of our website, is generally produced for those who have considerable experience in engine design. We don’t expect everyone to fully comprehend it, but feel we needed to reveal our secrets or run the risk of creating doubters.

This variable displacement engine was originally made for gasoline, but we also found a great bonus, we need only add a few additional parts and it was able to change its compression ratio. This change makes it possible to run on gasoline, but also on most of the other suitable alternative fuels. That’s just a bonus!

We call the engine that can run on any fuel the "Hefley X2 engine".