We got started with a run on the dyno. This bike is a stock Heritage; the only thing done to it at the time was a set of aftermarket fishtails-no aftermarket mods like a Power Commander or Race Tuner. The bike was brought up to temp, ran a pass, and sported 54.28 hp and 67.88 lb-ft or torque.
As soon as the bike was cool, shop tech Mike Rupp got started by removing the stock air box and filter, along with the backing plate.
Here is the new TP air filter, cover, mounting plate, and hardware. This kit retails for around $410.
A comparison look at both filters: The top filter in this photo is the stock H-D, and the other is the new TP high flow. You can see that there is more surface area for air to be filtered and fed to the motor.
Mike got started by installing the mounting hardware to the filter cover. To keep this cover clean-looking the TP cover is mounted from the back through the mounting plate, giving it the appearance of no bolts holding it on.
Then the breather bolts were installed in the heads. Mike placed a little bit of thread sealer to help keep any oil from misting past the filter.
Next, the backing (or mounting) plate was installed. Mike placed the gasket on the plate, then placed the mounting plate on the EFI body.
The kit comes with all-new hardware. For this part the three black 1/4-inch Allen heads were treated to some thread locker and torqued to 35-inch-lb.
Then the new High Flow filter was installed.
Mike placed the cover over the filter, lined up the bolts to run through the backing plate, and installed the bolts from the back along with some blue threadlocker.
Here you have it: A clean-looking air filter and cover installed in less than an hour. If you don't like the look of the stock H-D filter, this is an alternative for you to gain some power.
OK, one more run on the dyno. After the TP high flow air filter was installed, we picked up 5 hp-not bad for a bolt-on part that anyone with a few tools can install-and it looks good.
We all know the more air you can feed your motor-mixed with the right amount of fuel-the more power you can find from that motor. So if you were told that something as simple as an air filter could give you more horsepower, would you try it? Well, we tried it for you.
The Scramjet air cleaner from TP Engineering features a machined billet-aluminum backing plate with an integral velocity stack and chromed die-cast cover with a unique air scoop that aids breathing for added performance. Each kit includes a washable air filter, backing plate, mounting hardware, and breather kit. The kits are available for all top-breather Evo and Twin Cam engines with CV, S&S;, Mikuni carburetors, and Delphi fuel injection; other kits are available for 45mm Mikuni carburetors as well. TP claims that this air cleaner kit-a simple bolt-on part to your carb-can gain up to 5 hp, and on an EFI unit, the same if not a bit better. We have a few bikes at our disposal for testing, so we headed over to our go-to shop Horn Cycle Works in Pomona, CA, to install the Scramjet air cleaner kit on a stock '06 Heritage Softail with fishtail pipes and ran a few passes on the dyno.
TP Performance **
Horn Cycle Works