Hi Joe,
Thanks for the pictures of the new layout. Looks like I can continue to invest in our favorite DuctTape stocks
.
One thing I can not tell from the photos though is where the resonator attaches into your overall system? Also, where does the hot/cold bypass attach?
If we decide to use Honda's original design and keep the inlet diameters/lengths the same, then the bypass valve should be located at the effective end of the snorkel, where ever that may be located.
The spacing of the resonator 'tee' relative to the end of the snorkel provides part of the 'tuning' in the overall design of a resonate system that Honda has put together. The tube diameters and lengths, along with the resonator hose length to the resonator cavity itself, all act together to keep a tuned resonance in the 1300 rpm range. The resonance is probably tuned even lower than that based on a hunch, but I had no idea how low the tuning went before the testing, and did not consider this RPM, but have a strong suspicion it goes this low.
The end of the stock snorkel provides the function of an acoustic reflector, so placing your bypass valve there will still cause a disruption in the smooth surfaces of the piping and get the desired tuning back to Honda specs, if it isn't already. There definitely needs to be an abrupt expansion of tube diameter at the stock location of the snorkel away from the inlet filter box to maintain the inlet tuning. You can take a look at my former post for more theory on this. The trumpet flare would be an excellent choice here as well, which would then feed to the catalytic converter.
So to recoup a preferred design:
_ Using the stock Honda lengths/diameters, work backwards from the airbox to the resonator 'tee' connection. Measure the average length of this piece of tubing to the tee. Which ever way you decide to plumb the tubing, insure that this length to the tee is the same.
_ Make/fabricate a 'tee' of the same dimensions and place in the system at this point.
_ Measure the length to the end of the snorkel from the 'tee'. Create a stretch of tubing any direction you wish using this same length.
_ Place your bypass valve at the snorkel length measured above. If you attach the bypass with tubing to the snorkel location, then keep that tubing short, like under 1 inch if possible. A longer hose will again change the tuning of the acoustic circuit.
_ Also in the same spot, create a trumpet flared section that is let's say at least 3 inches in diameter at the largest part of the flare. The trumpet flare overall dimensions are 1.5 inches at the small end, 3 inches at the large end, and make the flare length about 5 inches long. Look at coronets, trumpets or trombones for inspiration on creating this shape. Ideally, you would want to 'tee' your bypass valve in the large portion of the flare (on the curved side-wall somewhere).
_ Orient the flare such that the large end faces the bypass valve and air box, and the small end faces the catalytic converter, where the hot air pickup is located.
_ To finish the air intract, connect whatever tubing you need from the small end of the flare to the catalytic converter. The length of this tubing is not critical as long as the flare in is place. If the flared section is deemed not important, then the effective end of the snorkel will end up being at the catalytic converter, and effectively change the resonant frequency of the tuned system.
I hope this information is not coming too late, as you have obviously put much effort into your system, so if I am late, I apologize.
Actually my own hot air intake has been functional for several weeks now, but when I redo it, I plan on 'modeling' the system by shaping hard foam insulation by gluing/cutting/shaping until I get the layout correct, then fiber-glassing over the outside of the foam, cutting the pipe into sizable sections, gutting the foam, then reattaching the overall piping with rubber hose and clamps (DuctTape??
). The fiberglass will be thicker at the hose connection points for stability. Worm-gear hose clamps have a tendency to D-shape tubing and distort it.
I will also, as you have, place a suitable insulating material on the outside of the fiber-glass to get the R-value up. It might be fiber glass batting or GreatStuff expanding foam. If anyone decides to try the expanding foam, just practice on something else first, as this stuff can get really messy for those who are not familiar with it.
I will take your idea of the air bypass, which does seem to be essential for the various temperatures through out the year, and probably simply run a choke cable into the cabin where I can 'roughly' estimate a setting for the various seasons. Not quite as elaborate as yours though
.
Hope this is not too winded, but the acoustics in this system are not admittedly simple.
Hope all of this lengthy discussion helps, Jim.
