ash_on_mtb wrote:what about the old slr5000 toranas with the huge bonnet buldge, designed to allow the low pressure air that pillows up against the windscreen to be sucked into the engine, kinda like a crude snorkel, just backwards and on top of the bonnet...? They must have worked okay, as didn't brockie go alright in one of them, before the flux capacitator or whatever chrystal thing he had?!
Hmm good point Ash but then why do the later model Brocks have those cold air trays that run under the bonnet and forward? Also my VC Brocky has an extension on the std air cleaner that allows it to suck air from the front ... but maybe that is more about "cold" air than ram feeding air. I'm not sure what the intention of the A9X's rear facing scoop was .. but it looked tough
I recall when racing 125 GP bikes in the early 90's, we experimented with fairings that pressurised the air boxes and they were successful to the point we had to jet up the motor to avoid it running lean at Phillip island where we were reaching max speed of 220 kph. We got that idea from the aprilia 125 that Gary McCoy was allowed to bring back into Australia when he was signed to the AGV Attack team.
I think also some of the more modern superbikes have "ram air" type systems although that may be more about marketing than performance. Anyway, I stick to what I felt when running one on my Rangie ... now I know it never had much horsepower anyway but when the reverse facing snorkel impacted on the little power it had it was noticeable.
And to those that are concerned about crud getting into your snorkel, a simple mesh over the inlet will stop that (ala plastic mesh arrangements on safari's etc) even though you would be struggling to get anything that big into it in one go unless a mate sticks an empty tinnie in it
Think about it this way ... do you see any manufacturer building an exhaust pipe that faces forward? Probably not because that would hinder the exhaust gasses getting out of the pipe ... reverse that and think about what one of the advantages a snorkel represents ... cool air "forced at speed" into the air cleaner ... it can only help.
Sure snorkels do raise the height of your water proofing (but only if you ensure you block up all other avenues for the water to get in and by that I mean stuff like the standard water valve in landcruiser air cleaners) but they can also provide a benefit to the motor by creating a "forced" (when moving forward) cool air charge.
Chers
Simo