A bit about who we are

Okay, I know you all have been anxiously awaiting an update, so here it is. I also know that some of our followers are rather technically minded, and others just like the color, so I’ll try to make it interesting for both groups. Here goes…

I think it’s a good idea to start with a bit about who we are. Back in the early 90’s a group of friends and race enthusiasts decided that they wanted to build a Harley Pro-Stock race bike. They decided to take an old idea and modernize it. The idea was to borrow from the old school muscle cars, taking their powerful hemi combustion chamber but make it work on a Harley Davidson. After brainstorming and lots of R&D, a new design emerged.

Before we continue, let me back up and give a bit of history. To be accurate, this wasn’t the first time a hemi had been used on a Harley. In 1966 Harley Davidson replaced their “Panhead” engine with a new, more powerful design called the “Shovelhead”. (The name came from the shape of the rocker covers because they looked like old coal shovels.) This design was a true hemi and was more powerful than the old panheads but it also ran very dirty and wasn’t so great on fuel efficiency. Due to the energy crisis of the 1970’s and a few other factors, this engine design fizzled out and Harley stopped making them in 1984.

But some of you may be wondering, what the heck is a “hemi” anyhow? Well, you are sitting on one. No, I am not referring to your derriere, or that ratty old office chair. Think bigger. You are either in the Northern (that’s most of you) or the Southern (Let’s hear it for our followers down under!) Hemisphere. It’s simply a circle cut in half horizontally. Like I said, the old shovel heads were a true hemi. Picture a softball, cut around the center, or equator, making two equal halves. What is commonly referred to as a “Chrysler Hemi” is a segmented hemi. If you take that half of a soft ball and cut another third off of it, you get a segmented hemi head. This is what they used for their Prostock Sportster Racebike. (If you are wondering what the heck a combustion chamber is, well, that’s for another entry.)

What made their design different from the old Chrysler heads wasn’t the hemi head so much, but more the piston design. With a lot of trial and error the guys came up with a piston that matched the shape of the combustion chamber, and they were able to control compression by changing the flat of the piston. Surprisingly, no one had done this before. It worked really well, and the bike had a stellar first year on the circuit. In their class, They were number one in their region and number two in the country.

They decided to develop the hemi for commercial use and in the mid 90’s started Hemi Design. At the time they were modifying the D-port Evo heads, and when Harley came out with the new Twin Cam heads in 1999 they found that the application also worked on this bathtub style chamber as well. They continued to grow with Harley, taking whatever v-twin style head that they came up with and making it better.

A few years ago, Ron, my dad, left Hemi Design due to creative differences. In the aftermath, Hemi Performance Engineering (HPE) was formed. We went back to the drawing board and came up with a new design. Still using a version of the segmented hemi head we changed the piston design to better utilize the tried and true hemi chamber.

My brother Derrick’s bike, known as “The Lab Rat” has been blowing away bikes in his class with this new engine style. Three years running he took first place in the Wyotech Dyno shootout in Daytona, Florida. This past year he got the silver, but I would like to note his was the only bike in the competition that didn’t arrive to the shootout in a trailer. The Rat is fast, but it’s also Derrick’s rider. It’s street legal and aside from the flashy custom paint job and gobs of chrome it looks like a stock Deuce. After all, what’s the point of having a bike that you can’t actually ride?

In the first blog you were introduced to some of the characters in this story. In the next installment you will get the history of “The Lab Rat”. Derrick’s bike is our main character really, because it’s the bike we are taking to Bonneville.

Stay tuned for the next installment..