The first thing to understand about Dynamometers is the fact that they do not measure Horsepower.  That's right ! They never have, and they never will.  Dynamometers only measure Torque and RPM , and then calculate Horsepower.  The formula is: Torque X RPM /5252=Horsepower. Below 5252 RPM Torque numbers are greater than Horsepower numbers, and above 5252 RPM Horsepower numbers are greater than Torque numbers.  For the history of Horsepower and why we use 5252 click here.

The second thing to understand is that boat engines run in a stall condition. They run up to max RPM for the application and then stall.  Boat engines usually stall long before they reach max Horsepower.  For that reason it is useless to focus on Horsepower figures.  The engine will never reach that RPM.

When we test a boat engine we first run it at the lake to see where max RPM is reached.  For example lets say max RPM was 5200.  We then put the engine on our Dyno and make several test pulls.  This tells us three things:  At what RPM max Torque is reached, at what RPM max Horsepower is reached, and most importantly, how much Torque was being produced where the engine stalled.  In the case of our test boat, we want to focus in on how much Torque is being produced at 5200 RPM.  The max numbers may not be relevant to the application.  Usually the max Torque number is at a lower RPM than our boat test number of 5200 RPM and the max Horsepower number is at a higher RPM than the boat test number of 5200 RPM.  We then focus in on the Torque number at the 5200 RPM and we ignore the max Torque and Horsepower number.  For example, let's say the Torque was 520 Ft Lbs at 5200 RPM.  So if you're choosing a new cam or selecting a new set of heads or what ever, your main goal is to make more Torque where the engine stalled.  We would focus in on improving Torque numbers at around  5200 to 5500 RPM.

At LIGHTNING PERFORMANCE we are experts at choosing engine components.  Check out our test engines and see what kind of Torque and Horsepower you can expect.

Call us with your Max RPM and let us help you increase your Torque number.