Engineering Myth Busters
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Joined: Jun 2011
Posts: 231
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From: London
Engineering Myth Busters
After three years owning an S2000 and reading these forums, I've decided to start a Myth Busting thread. Here are two of mine for starters. Feel free to suggest your own.
Myth 1: I've just fitted lighter wheels saving me 8Kg in rotational mass which is equivalent to saving 80Kg in regular weight.
Busted: Only fast spinning parts upstream of the gearbox have a 10:1 effect relative to non-rotational mass. For wheels a more realistic figure is 1.6:1 meaning that my new wheels which saved me a total of 8Kg of rotating mass are equivalent to about a 13Kg saving of non-rotating mass. (There will be a small, but welcome decrease in the cars polar moment of inertia as well).
Ref: http://stephenmason....nalinertia.html
Myth 2: My CAI/Snorkel is better than yours because is utilises the RAM air effect.
Busted: Oh no it doesn't. The RAM effect only makes an appreciable difference above 150mph, since at lower speeds the airspeed of your car is hardly any higher than atmoshperic pressure (which you don't notice, but it turns our that our atmosphere is quite heavy), which happens to be beyond the power (and red line/gearing) of (al)most (all) of our cars. Ref: http://www.f1technic...t=3656&start=15
Of course, IF you can get your filter to reliably sit in a cooler air stream than the regular intake or increase airflow with less restrictive piping and filters that helps hence the name Cold Air Induction (CIA).
Myth 1: I've just fitted lighter wheels saving me 8Kg in rotational mass which is equivalent to saving 80Kg in regular weight.
Busted: Only fast spinning parts upstream of the gearbox have a 10:1 effect relative to non-rotational mass. For wheels a more realistic figure is 1.6:1 meaning that my new wheels which saved me a total of 8Kg of rotating mass are equivalent to about a 13Kg saving of non-rotating mass. (There will be a small, but welcome decrease in the cars polar moment of inertia as well).
Ref: http://stephenmason....nalinertia.html
Myth 2: My CAI/Snorkel is better than yours because is utilises the RAM air effect.
Busted: Oh no it doesn't. The RAM effect only makes an appreciable difference above 150mph, since at lower speeds the airspeed of your car is hardly any higher than atmoshperic pressure (which you don't notice, but it turns our that our atmosphere is quite heavy), which happens to be beyond the power (and red line/gearing) of (al)most (all) of our cars. Ref: http://www.f1technic...t=3656&start=15
Of course, IF you can get your filter to reliably sit in a cooler air stream than the regular intake or increase airflow with less restrictive piping and filters that helps hence the name Cold Air Induction (CIA).
Joined: Mar 2013
Posts: 2,730
Likes: 38
From: Portland
People don't use the snorkel for a ram air effect, they use it as a source for a cooler air, and with that in mind, I am sure there is plenty of air flowing through the front bumper and through the ducting at 50mph. I may be wrong though...
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Joined: Jul 2004
Posts: 36,017
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From: Queen City, NC
You're not wrong - manufacturers picked up on the benefits of getting colder air to the engine long ago and all cars these days utilize "cold air intakes", its just a matter of efficiency.
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