Hib Halverson
Technical Writer for Internet & Print Media
The question posed on the Callaway Forum by CAC member "Jeroenvgfn" was not really a question specific to Callaway's cars. Its answer affects the owner of any C4--or any Corvette for that matter--interested in aftermarket, oiled-cotton air filters. Specifically, his question was about why Callaway chose to change vendors for its air filters.
"Jeroenvgfn" asks a great question . The thread languished, unanswered, on the Callaway Forum for months and there is no excuse for that. There's little doubt in my mind that the switch from Green to K&N is because of a "price issue". That's the only reason a vendor would change from a great product, such as the "Green Filter", to just an "average" product, such as the "K&N FilterCharger".
One advantage K&N has, due to its large size in comparison to Green Filter USA, its market share and because it uses an inferior design that's less-expensive to manufacture, is it can go to volume retailers, such as Callaway Cars, then convince them to buy filters for less which they can turn around and sell at the same price and know that their customers are getting a filter that is "good enough". From the retailer's perspective, that's a wise business model because it increases the margin on the product. From the user's perspective, it might not be so wise.
The differences between a Green Filter and the K&N are several, but the ones which are key to filtering performance and airflow are the ones Corvetters need to understand.
Yes, the two products share a key feature, the oiled-cotton filter media, but that's where the similarities end. As the Green is a newer design, it has some quality and performance enhancements which K&N has either chosen not or is unable to adopt. Why has K&N not kept up with current technology? Perhaps, since it has the lion's share of the market; it may see no advantage in updating its technology.
Green's filtering media is woven cotton rather than the cotton gauze used by K&N. Put a golf shirt next to a gauze bandage, examine and feel the two materials and you'll better understand that key difference. The benefits of woven cotton are: it's thinner, holds oil better and is stronger. Green Filter's cross-weaving one fine and one medium layer of cotton produces a fabric that is thinner and stronger than K&N's gauze but still has the ability to trap dirt particles of as little as 5 microns in size. That means, for a given level of filtering and filter size, a Green may flow more air than a K&N. Is this important? It can be if the filter you use it near its limit as to air flow and going to a larger filter is not an option. Woven cotton holds filter oil more consistently. Woven cotton is stronger than gauze. Unlike gauze, you can't wear a hole in woven cotton by rubbing it. Lastly, there is no way small bits of cotton can rip off since the woven cotton threads are interlocked with each other.
Some other filters, K&N included, use a simple, pressure-molded, injection process to bond the perimeter rubber to the filter's interior components. That method saves manufacturing time, but in the process, rubber can seep onto the filtering surface. When the filter rubber bleeds onto the filter media, not only does it have the look of shoddy construction, it can restrict airflow as much as 25%. Green Filter USA uses a more time-consuming and expensive, four-step manufacturing process which virtually eliminates seepage and insures maximum airflow through the filter. Green chose that method because it produces a higher-quality and better-performing product.
There are other differences and, if you're interested in the techie details, you can find more information at www.greeenfilterusa.com
Clearly the Green Filter is a superior product and that's why I moved all my engines in the five of the cars (three Vettes and two other Chevrolets) my Wife and I own to Green Filters starting several years ago. It's why "Jeroenvgfn" uses them. It's why tens of thousands of other performance air filter buyers have kicked the K&N habit and gone Green. It's, also, why I believe Callaway Cars ought to go back to using them.
"Jeroenvgfn" asks a great question . The thread languished, unanswered, on the Callaway Forum for months and there is no excuse for that. There's little doubt in my mind that the switch from Green to K&N is because of a "price issue". That's the only reason a vendor would change from a great product, such as the "Green Filter", to just an "average" product, such as the "K&N FilterCharger".
One advantage K&N has, due to its large size in comparison to Green Filter USA, its market share and because it uses an inferior design that's less-expensive to manufacture, is it can go to volume retailers, such as Callaway Cars, then convince them to buy filters for less which they can turn around and sell at the same price and know that their customers are getting a filter that is "good enough". From the retailer's perspective, that's a wise business model because it increases the margin on the product. From the user's perspective, it might not be so wise.
The differences between a Green Filter and the K&N are several, but the ones which are key to filtering performance and airflow are the ones Corvetters need to understand.
Yes, the two products share a key feature, the oiled-cotton filter media, but that's where the similarities end. As the Green is a newer design, it has some quality and performance enhancements which K&N has either chosen not or is unable to adopt. Why has K&N not kept up with current technology? Perhaps, since it has the lion's share of the market; it may see no advantage in updating its technology.
Green's filtering media is woven cotton rather than the cotton gauze used by K&N. Put a golf shirt next to a gauze bandage, examine and feel the two materials and you'll better understand that key difference. The benefits of woven cotton are: it's thinner, holds oil better and is stronger. Green Filter's cross-weaving one fine and one medium layer of cotton produces a fabric that is thinner and stronger than K&N's gauze but still has the ability to trap dirt particles of as little as 5 microns in size. That means, for a given level of filtering and filter size, a Green may flow more air than a K&N. Is this important? It can be if the filter you use it near its limit as to air flow and going to a larger filter is not an option. Woven cotton holds filter oil more consistently. Woven cotton is stronger than gauze. Unlike gauze, you can't wear a hole in woven cotton by rubbing it. Lastly, there is no way small bits of cotton can rip off since the woven cotton threads are interlocked with each other.
Some other filters, K&N included, use a simple, pressure-molded, injection process to bond the perimeter rubber to the filter's interior components. That method saves manufacturing time, but in the process, rubber can seep onto the filtering surface. When the filter rubber bleeds onto the filter media, not only does it have the look of shoddy construction, it can restrict airflow as much as 25%. Green Filter USA uses a more time-consuming and expensive, four-step manufacturing process which virtually eliminates seepage and insures maximum airflow through the filter. Green chose that method because it produces a higher-quality and better-performing product.
There are other differences and, if you're interested in the techie details, you can find more information at www.greeenfilterusa.com
Clearly the Green Filter is a superior product and that's why I moved all my engines in the five of the cars (three Vettes and two other Chevrolets) my Wife and I own to Green Filters starting several years ago. It's why "Jeroenvgfn" uses them. It's why tens of thousands of other performance air filter buyers have kicked the K&N habit and gone Green. It's, also, why I believe Callaway Cars ought to go back to using them.
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