Bad ass pipes

Status
Not open for further replies.
Bad ass pipes


Here it is waiting to do some runs in the 1/4 mile to shake everything down on track. You can see the pipes and the new 17" wheels and 17.0" x 4.00" Goodyear Landspeed Eagles (same part number as Goodyear Racing Frontrunnners). Footpegs have also been moved up 3" and forward 1" from last year.
 
Bad ass pipes


We had an aerodynamic survey done, using a 3D scan procedure with me on the bike, by STAC performance here in Ontario, and the foot peg adjustment and helmet recess in the tank where both recomendations from STAC. They provided a written assessment and gave us an estimate of ~160mph @ 100hp given our surface area and drag. It seems we do not have excessive drag, but I (my frotnal area, anyway) create a lot of surface area pressure. Moving the pegs up puts my shins more in line with my elbows and gets my quads out of the wind.
 
That’s some clever aero dynamic analysis sir!

I’d have thought a bigger seat hump would help. I think Peter Williams was the first with this in his idea that it made a smoother line from the riders back to the rear of the bike and thus reduced turbulence (he also had not emblems or writing on his back to ensure the smoothest flow over his back).

You have a clear bit of turbulence coming off your ass that you might be able to eliminate this way perhaps?
 
very cool . how does their package recognize air pressure? using a smoke generator or pitot tubes>>?
 
STAC uses computer generated simulations, based on years of data taken from the University of Waterloo wind tunnel. A 3D scan is taken, then run through software developed by several UW Engineering grad students and the UW Fluid Mechanics Research Lab. I inquired about an actual wind tunnel session, but these sessions are far out of my budget. STAC was very reasonable and at least gives us an idea of where to focus. In their conclusion, STAC felt that flow separation dominates our total drag, so reducing area will reduce drag. Cleaning up airflow behind may effect cD, but will not reduce area. So, we should see more gains by focussing on reducing frontal area than we would trying to clean up unsettled air behind the rider (me).
 
And to bring it back to the thread topic, the aero survey is why the pipes curve in towards the center of the bike as they do; to keep them tucked in and out of the wind.
 
Eldo said:
And to bring it back to the thread topic, the aero survey is why the pipes curve in towards the center of the bike as they do; to keep them tucked in and out of the wind.
Click to expand...

Now that's a clever idea. I might have to copy that on my bike. Thanks.

Ken
 
Thanks Edo. Any plans for Bonneville this year? Also, for the techie in me, do you know if STAC is using FLUENT Computational Fluid Dynamics (CFD) to process the scan data? Some interesting ideas on their website pertaining to bicycles. I presume you can't use aerodynamically valanced rims for that "extra edge" because it would bump you into another class.
 
Andy,
Did you happen to run the bike with the new motor and the old pipes on the Dyno to compare the gain from the stepped pipes?
How did you come up with the step lengths and over all length?
Did you play with the step lengths and overall lengths to get the peak HP and Torque?
 
Did you adjust the cam timing at the same time to get the 'best' performance for the intended purpose of the bike ?
 
if my memory is still working; the JPN fairing doesn't look all that aerodynamic because of the size and bulk, but it works becuase all the smaller fairings allow to much loose (leather, body parts etc) to flap in the wind which really hurts the Cd.

spent some time in a wind tunnel and what channel studying von Karmann vorticies it is still really coool stuff, and now we are truly off topic...
 
95 HP with a 920cc, 480 sifton cam, welded & ported squishband head with huge valves, 44mm carbs, custom pipes & pistons - Herb Becker doesn't mess around.
 
Dances with Shrapnel said:
Thanks Edo. Any plans for Bonneville this year? Also, for the techie in me, do you know if STAC is using FLUENT Computational Fluid Dynamics (CFD) to process the scan data? Some interesting ideas on their website pertaining to bicycles. I presume you can't use aerodynamically valanced rims for that "extra edge" because it would bump you into another class.
Click to expand...
Not sure what program STAC is using; I believe it is software they developed in conjunction with the UW Fluid Mechanics department. I own a bicycle shop here in Waterloo, so I know STAC from the bicycle side of things. Rims and wheels are pretty controlled. I can use a disc or covering on the rear wheel, but the front wheel has all sorts of measurements I need to conform to. I will be using a modified Huyabusa front fender, but I need to have 210º of wheel visible from the side view when installed. I don't remember, off the top of my head, exactly how much area of the front wheel needs of be "open", but there is a specified amount. There is also a measurement from the outside circumfrence of the tire to the inside of the rim, I believe, but I'll have to consult the rulebook to confirm.
 
Son of Siredward said:
Andy,
Did you happen to run the bike with the new motor and the old pipes on the Dyno to compare the gain from the stepped pipes?
How did you come up with the step lengths and over all length?
Did you play with the step lengths and overall lengths to get the peak HP and Torque?
Click to expand...
I answed some of this in our DM converstation. Overall length comes from Herb's direct experience building winning VRRA and AHRAM bikes. No, we have not played with step lengths. There could very well be more power in there with some length tuning, etc, but we had to start somewhere; funds and time are limited, so it is difficult to build all sorts of pipe lengths and step lengths and still be on schedule to actually get the bike finished. Herb builds these pipes from scratch, rolling the reverse cones on his wooden buck, and gas welding all the joints with a torch. It's a ton of work. Maybe we'll try some different lengths in the future. We do feel that given our flow bench numbers and our intake/exhaust parameters, we are approacheing peak power, mathematically.
 
acotrel said:
Did you adjust the cam timing at the same time to get the 'best' performance for the intended purpose of the bike ?
Click to expand...
No, we are running the same cam timing we ran last year. I believe it is 50º.
 
jseng1 said:
95 HP with a 920cc, 480 sifton cam, welded & ported squishband head with huge valves, 44mm carbs, custom pipes & pistons - Herb Becker doesn't mess around.
Click to expand...
Sorry Jim, hope I'm not "hijacking" this thread too much...
 


Our peak HP run; 95rwhp @ 7500rpm. It's all over with pretty quick!
 
Son of Siredward said:
What's the digital readout on the side of the oil tank?
Click to expand...
That is my electrics box, and the digital readout is the real-time air/fuel ratio. I'm running a Daytona Sensors WEGO III system with Bosch 4.2 lambda sensors in the pipes. It records the data, which we download after each run. WOT at 7500rpm we look for around 14.0:1. Stochiometric for the VP C12 gasoline is 14.87, but that ratio creates a lot of heat, so we try to go a tad rich to control temps. I also have a real-time cylinder head temp digital readout that was not hooked up during that session.
 
Stochiometric ratios don't tell you what the mixture should be to reliably get the best power output. In the end, I cannot see any way to avoid fine tuning on practice runs on the day. Can you do that at Bonneville ?
 
Status
Not open for further replies.
Back
Top