Serowbot wrote on 04/15/13 at 09:31:13:"Primarily" for performance... but, that huge hunk of billet looks wicked beefy...
...
Yeah, I wanted it to look solid and beefy. Something sleek and elegant would not look right on a Mean Streak.
Now, if you don't care about reading technical stuff then read no further. You will get bored.
Regarding performance- the skull and crossbones design worked out great because I wanted the cover bolts to be on the outside to minimize structures inside the filter. I couldn't do the usual 5 external bolt custom setup because I think it only looks right when a bolt is centered on top (12 o'clock) and I didn't have the tank clearance for that. I've never really been into or done the skull thing on any kind of vehicle before, but it lent itself well to what I was trying to accomplish on the performance side which was to improve low end and midrange.
The longer intake tracts provide 20% more air per side. This is air that doesn't have to be pulled into the intake tracts (less resistance, less energy used in moving the air from a turbulent parallel plane thru a perpendicular orifice). This is also air that can be directly affected by intake flow momentum and can be influenced by positive intake waves that rebound off the back of the cover. My motor redlines at 6K. Honestly I never go past 5200 rpm. This design works for this particular application and the way I ride. Do the same setup to a motor that redlines at 12k and the elongated intake length will begin to actually increase resistance to airflow. For 40mm throttle bodies like mine with my increased intake length, it would start to negatively affect flow around 5500-6000 rpm and cause progressively more resistance as rpms increased from there. At those higher rpms, cylinder filling would benefit from a much shorter intake. Considering that, this setup doesn’t increase top end horsepower (max rpm) but instead improves torque in the low to midrange rpms where I spend nearly all of my time at.
The dyno torque peaked at 95 ft lbs. But that’s not what’s important to me. It’s where it is and for how long that is important to me. I now have over 90 ft lbs of torque available from 2600 rpm to 4000 rpm where, except for take-offs, I spend my riding time. At 5250 rpm, which is the hardest I have ever pushed this motor, I am down to what a stock Mean Streak does for peak torque. So to me it is all useable power on tap, not just what it can do at redline. I have tuned the intake to maximize power at the rpm range where I ride at the expense of power at the motor could make in the rpm range that I don’t ride. You can see evidence of this top end restriction on my dyno chart.
http://i1343.photobucket.com/albums/o794/Russell_Rodgers/image_zpsf5b69d2b.jpg The design also highlights what Paul, my buddy who owns the CNC shop, can do. He has an interest in expanding from just industrial products and into custom motorcycle parts. I certainly have never been a big skull fan but form followed function in this case, rather than the other way around. And everyone out there seems to have a boring single centered bolt cover with simple, repeating geometric shapes (swirl pattern, triangles, cross, etc.).
Pine wrote on 04/15/13 at 11:22:35:Did you do your own CAD?
I think its cool and good looking, and it looks like a lot of detail went into the design for performance as well as looks.
I really want to learn CAD.
I'm learning. For most of this project it was me making prototypes out of various material and a lot of explaining to Paul. A lot of it was me saying, "That may indeed work but for performance it has got to be just like this (size, shape, contour, etc.)!
RidgeRunner13 wrote on 04/15/13 at 10:39:13:That is sweet. Very unique.
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