Equipment Name: Airflow Inlet System
The Airflow System consists of 2 parts;
a) A reshaped, short, carbon fiber velocity stack that fits in to the stock throttle body and,
b) A sealing ring to seal the stack to the throttle body.
Test bike: Buell XB9R (03 model) - Stock motor (just less than 1700 miles), Wileyco exhaust muffler (Basically straight through), Stock Induction system, Buell Race ECM.
Theory of Operation
The Airflow System is shorter than the stock stack by approximately 5/8” (15.8 mm). At its inlet it is dramatically reshaped compared to the stock unit. Using the theory of short length with a large inlet radius, we would expect to see some power improvement and hopefully some improvement to the midrange.
The fit and quality of the stack is good and being made or carbon fiber its looks too good to hide in the air box. The stock rubber velocity stack gets re-used. It must be cut (or trimmed!) at both top and bottom to leave just the sealing ring to form the new seal between the Airflow System stack and the stock inner air-box lower
The kit comes with clear fitting instructions. Using a seal off a Buell X1 to seal the stack to the throttle body, you simply push the stack in. The stack is a tight fit into the throttle body. Carbon fiber gives the look of not being particularly strong and considerable force is needed to get the stack down in to the throttle body. I was convinced I was going to break it, even having lubricated it before hand to help ease it past the seal. However, as we know carbon fiber can be very strong and it eventually went in.
Like all other systems tested, the vendor instructs you to then ride the bike between 3000 and 4000 rpm for at least 20 minutes to allow the ECM to adjust the air/fuel value for the new conditions you have just fitted. Personally, I would give it more time especially if the bike has not been used recently and there are big ambient (Temperature, humidity etc) differences between now and the last time you rode it.
At the Dyno
I’m deliberately avoiding giving final HP/Torque values in this report. The reason for this is that there are many variances that can effect overall dyno results. To start with, everyone’s bike has different output characteristics as a function of build tolerances, wear, maintenance state and so on. Temperature, pressure, humidity and even the dyno itself all impact the final numbers. The important thing is the change in the relative performance values between the systems compared to the baseline stock set-up.
Looking for repeatability from the test method, my test criteria desired that the bike make 5 back-to-back dyno runs with less than 0.5 HP variation between all 5 runs if possible. The Airflow System satisfied these criteria. The Airflow System gave a 2.2 HP peek increase and improved the hole in the midrange torque/power curve to a level line not a dip. Most of the power increase was from 6000 rpm to rev limit.
The Ride Experience
I rode with the Airflow System carbon stack at Texas World Speedway at a track-day in July. The change to the midrange hole seen at the dyno, was also felt on the bike. The improvement in the midrange helped pull the bike out of a slow to medium speed corners better than with the stock system.
A modest boost in power and the hole in the torque characteristic almost plugged is not a bad outcome for a simple piece of technology that you can fit yourself in less than 30 minutes. I believe that a this stack combined with cool air induction (a heat shield using say the stack air box lower and some heat reflective material) and a better breathing air box (cut or perforated) + a good pipe, that reasonable gains in HP could be achieved with this stack on a very modest budget.
Comments from Adrelenin Moto
Thanks for the very interesting and very comprehensive results. We are certainly pleased with the performance of the airflow inlet, particularly given it's simplicity and cost. As you suggest in your report, we are sure that when used in conjunction with other parts such as the XB12 airbox or a complete 'airbox eliminator' that the results would be even better.
I will pass on a copy of your report to the manufacturers HSA in Germany.
Thanks once again for what has been a very interesting experiment that has given me much food for thought
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