Ask anyone who knows what makes motors run, and he’ll tell you the name of the game is getting as much fuel over the piston as possible and burning it as completely as you can at just the right moment. How much fuel you can burn depends on how much air you can get flowing in and out of the engine. And since you can’t flow more air through the motor than what the air cleaner will allow in, it’s easy to see that the wrong selection up front is going to hurt you big time. That’s why we’ve been doing a number of air cleaner installs in American Iron; this easy-to-do garage upgrade can reap you a nice increase in power. And if your bike is a 2007 or later model, like our test 2007 Softail Deluxe test bike, you don’t need to install a fuel adjuster. Unlike on earlier models, the 2007 and later machines have an O2 sensor in each exhaust header pipe. This enables the stock ECM to sense how the engine is running — too lean or too rich — so it can make the needed fuel setting changes. Of course, the ECM will keep the air/fuel ratio at the EPA-mandated 14.7:1 (14.7 parts air to one part fuel), so the engine will run just as it did before the air cleaner installation, but with more power. How much more power is what we wanted to find out, so we also put the bike on a dyno, but we’ll get to all that in a minute.
The latest in our quest for higher power brings us to Wimmer Performance Triflow air cleaner assembly. The Triflow design is as simple and unrestricted as you can get and still actually have a filter element in the equation. Made of CNC-machined billet aluminum, the Triflow comes in two versions, Stage I and Stage II, and fits all EFI-equipped H-Ds, including 2008 models. We opted for bolting on the Stage II unit, which comes with a slightly wider air filter element and an internal velocity stack. Wimmer claims these upgrades increase air flow over the stock air cleaner element by 70 cfm. That much of an increase should show up as a power increase on the dyno. We also went with the chrome outer trim option, but passed on the rain sock.
As for who would do the installation — though this air cleaner job is simple enough for a home garage — we went to see out buddy Mark Fabrizi at Marquee Customs. Mark has done many an installation story with us, as longtime readers know. We also asked our buddy Rob of Rob’s Dyno to do before and after runs, so we could know exactly what power increases we realized with this installation. By the way, it was about 95 degrees Fahrenheit that day: not the best for performance output. Thankfully, the humidity was low. The accompanying dyno chart tells the tale!
–Chris Maida, as published in American Iron Magazine, the world’s best selling Harley magazine.
3/16″ Allen Wrench
5/16″ Allen Wrench
5/32″ Allen Wrench
Marquee Customs & Classics
72 Siemon St., Dept. AIM
Bridgeport, CT 06605
Rob’s Dyno Service
Gardener, MA 01440
11690 Highway 17 Bypass, Dept. AIM
Murrells Inlet, SC 29576843/492-0412