| Author | Message | ||
     Sanchez |
So I got this voltmeter thing that also has a temperature probe.  Theory: The airbox pulls hot air off the rear cylinder through the hole in the frame under the airbox cover. Test: I put the temperature probe in one of the airbox slots and went for a ride. The temp started about 76 F. It rose steadily as I cruised down the highway and reached 109 after a few miles when I stopped to turn around. It climbed up over 120 while I waited at a light with the fan off and then settled down to a constant 106 on the highway after the fan came on. When I stopped again for another light, this time with the fan on, the temp dropped significantly. It was down to 95 or so by the time I started again. To see what effect idling would have with the engine up to temperature but the fan off, I shut the bike off and waited for the fan to stop. As soon as I started it back up, the temps climbed. It got to 158, which turned out to be the maximum for my meter. After that, the meter just gave up and said "HI." Conclusions: - With the fan running and the engine drawing air in the 3.5-4k rpm range, the cylinder added about 30 degrees to the incoming air temp. - With the fan running and the bike at low RPM pulling less air, the cylinder didn't add nearly as much heat. - With the fan off and the bike at low/no speed, intake temps shot up over 100%. This explains behavior I saw Friday on my way home from work. I sat in line at an on ramp light for a couple of minutes waiting my turn, and the bike pinged as I left the line. It doesn't normally do that, and I just chalked it up to being a hot day. In hindsight, I know I hadn't been riding long enough for the fan to come on, and the engine must've sucked in a load of hot air. | ||
| Sanchez |
Also worth noting: I'm using a CityX airbox cover that doesn't have the air intake over the gas cap. I'll try this again tomorrow with my old Uly cover. After that, my next test will be to close off the frame opening with aluminum tape and repeat the experiment. | ||
| Ourdee |
The temperature probe should be reading 98.6 .  | ||
| Teddagreek |
Cool Experiment.... Thought the original Idea was good minus the snorkel.... I always though drawing the cooler ambient temperature was a good thing..  Now with the newer closed frames and way open airboxes we flow more but from hotter areas.. Hot air off the off the gapping hole to the rear cylinder, Hot air as the frame warms up.. We have the gas cap grill/vent but how much does it really draw compared to the rest... Maybe those hyper-mile guys are right and hot air intake is a good thing at least for MPG..  | ||
| Ourdee |
Hot air intake is part of the secret to high mileage. One of the things I did to get better mpg from my Jeep. | ||
| Sanchez |
I can see how hot air would improve mileage. Hot air is less dense, so the ECM needs to use less fuel to maintain the optimum air/fuel ratio. I wonder if Buell engineers deliberately put the airbox slots on the right side for that reason? If so, I guess they rethought it in 07 when they closed off the right side and opened up the front and left instead. (Message edited by Sanchez on September 06, 2009) | ||
| Electraglider_1997 |
Anyway you can hook that thing up to the rear cylinder temp gauge? | ||
| Sanchez |
> Anyway you can hook that thing up to the rear cylinder temp gauge? No, unfortunately not. It just has a plastic-covered temp probe on the end of a wire. | ||
| Sanchez |
Experiment #2: Ulysses airbox cover Result: No difference. The air inlet over the gas cap didn't lower the intake temp. Next I'll drill my 06 airbox out and cover the right side holes to make it match an 07. Just because it took me a long time to find these pictures, here's the difference between a 2006 airbox and a 2007 airbox (courtesy of Jmhinkle): 06 right:  06 left:  07 right:  07 left:  |
