About a month ago, I told you about a company that could potentially spell the death of the gasoline engine as we know it. That’s good news for drivers — who have been feeling it at the pump lately — but it’s even better news for investors who can remain patient with this stock.

#-ad_banner-#In fact, when I first profiled this stock in my Game-Changing Stocks newsletter, it was around $24.11. Ten days later — shares rose as high as $29.63, for a short-term gain of 23%, before pulling back.

Like any game-changing, innovative company still in the early stages of growth, shares of this stock are going to be volatile. It happens. But I’m convinced that this company’s long-term growth potential outweighs the risks. After all, we’re talking about the death of the gasoline engine…

The company I’m talking about is Westport Innovations (Nasdaq: WPRT), which makes natural-gas engines for semi-trucks and other heavy-duty applications. 

The Canadian manufacturer’s engines were the star of recent trucking trade shows as the captains of industry and independent truck operators alike saw a way to dramatically decrease fuel costs, as well as to comply with ever-stricter (and costly) environmental regulations.

Some of the largest U.S. fuel retailers have pledged to add natural gas to their truck stops, and Energy Secretary Steven Chu has said the nation will soon have a natural gas filling station every 150 miles — easily enough to support national over-the-road routes. The engines have even drawn the support of President Obama, who likes that natural gas is cleaner than diesel, that it is domestically produced, and that new engines mean new “green-collar” jobs.

So with industry support, a push to upgrade fuelling infrastructure and a cheerleader in the White House, natural gas is a hot area, and Westport Innovations is clearly a company with game-changing potential. As these new engines begin to establish a toehold, then a footprint, within the trucking industry, Westport could see shares grow as dramatically as its revenue, which was up 53% in 2011 in comparison with the year before and is on pace to grow at least 40% this year. 

But let me be clear — with this outstanding growth potential comes a commensurate level of risk. That’s always true, of course, but investors in this space need to realize that they are dealing with emerging new technology as well as with commodity risk. Westport’s shares will be influenced by the price of natural gas. 

The good news for Westport is that the price of natural gas is likely to stay low, as increasing shale production has created a huge supply glut. I am confident in maintaining my recommendation on these shares. 

Action to Take –> Expect volatility with this stock. The beta on these shares is nearly twice the market average (meaning they are twice as volatile as the overall market). I think Westport is an extremely strong buy at any price under $37.50, unless the price of natural gas, currently at about $2.50, exceeds the $5 mark. Patient and watchful investors are likely to be rewarded with a lower entry point.

[Note: Andy is known for finding stories no one else is covering… and making bold calls. This includes a price spike for a key commodity (responsible for 10% of U.S. electricity), Warren Buffett making a major investment in Japan … and one of the most widely-owned stocks in America dropping like a rock. To get the full details on Andy’s predictions Andy for the next 12 months, you can watch this video, or read Andy’s report here.]