Author Topic: Pods vs. airbox (RACING APPLICATION-take it easy, it's a hypothetical question)  (Read 1630 times)

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Offline RFogelsong

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I know this has been beaten to death, please don't flame, this is a specific question based around the application at hand, but my question about one vs. the other is specifically for road racing applications.  Basically, if you were to build a 500 or 750 vintage racer, which would be better? 

The only reason I ask is because it seems that all of the race bikes I see have pods but everyone seems to have a general consensus (coming from daily rider type application) that the airbox is better for optimum performance.  Is there some sort of regulation in the series everyone runs?  Are pods done mainly for weight savings?  I know a lot of guys run CR carbs for racing, can these not be run with a traditional airbox maybe?

Who's right and why? I'm an aerospace engineer, so feel free to get scientific if that works for you.  It seems like (in my head at least) the stock airbox with either no filter or a very high flow filter would be best because you get low speed, high density air that would be supplied to all carbs equally.  Everyone's input is appreciated.

Thanks guys.
-Rob

Hondas past/present:
SOHC1:'74 CB125, '78 XL125
DOHC2:'71 CB450K
SOHC4:'73 350F, '75 400F, '75 550K
DOHC4:'81 900F, '01 1100XX
V4:'85 VF1000R, '86 VF500F, '08 VFR800

Offline BLUE71TURBO

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 What about velocity stacks ??    ???   ::)
Remember; Before you can be old and wise, you must first be young and stupid !

Offline RFogelsong

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Good point, I didn't think of those.  I'd think those would be the most efficient from an "engine is simply an air pump" point of view, but would these present the same tuning problems everyone gripes about when talking about pods?
-Rob

Hondas past/present:
SOHC1:'74 CB125, '78 XL125
DOHC2:'71 CB450K
SOHC4:'73 350F, '75 400F, '75 550K
DOHC4:'81 900F, '01 1100XX
V4:'85 VF1000R, '86 VF500F, '08 VFR800

Offline Retro Rocket

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but would these present the same tuning problems everyone gripes about when talking about pods?

No, simply because the stacks smooth out the airflow as it enters the carb throat, pods {well most} don't have stacks and thats why they aren't as efficient {turbulent air}.
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
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Offline turboguzzi

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yep, you run the danger of starting another pods vs box endless thread....

both WSBK and Motogp motors run airboxes, so could stop there.... seen them with my very eyes, its a fact, no arguing with that (unless you think works race engineers know nothing 'bout motors :) )

main reason is that you can harness airbox frequencies to boost power which simply do not exist without it, shielding from hot air and turbulence are added benefits

but old habits die hard, open stacks look cool and certainly period and for many the gut feeling that an open carb "will breath freely and therefore better" is enough of a logic. its a bit like it used to be with exhaust pipes in the 20's, people taught that by chopping them right after the exit they'd get minimum resistance to flow, scientific evidence showed longer pipes of the right length increased power.

i race vintage with open CR + stacks, and I would definitely build an airbox if i had the time. quite bit of a project if you want to make the carbs easily serviceable, etc. Planning to implement one in my next racer build
« Last Edit: June 03, 2012, 01:10:04 AM by turboguzzi »

Offline RFogelsong

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Cool, thanks for the explanations, it was exactly what I was looking for.  I'm gonna try to lock this now so I don't start another endless debate thread.
-Rob

Hondas past/present:
SOHC1:'74 CB125, '78 XL125
DOHC2:'71 CB450K
SOHC4:'73 350F, '75 400F, '75 550K
DOHC4:'81 900F, '01 1100XX
V4:'85 VF1000R, '86 VF500F, '08 VFR800