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Air Filter test....Surprise!
the fabled K&N filter that is touted to increase power by 20-50hp but in current dyno tests will more than likely lose 1-3hp unless your mixture is richened up could be wearing out your cylinder bores because it emits large particles of dirt...read it here...http://www.mcagraphix.com/filter/test.htm
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I concluded that K&N was just snake-oil (pun!!) a few years back. Had one, won't have another...
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The most conclusive testing I have ever seen was done by David Vizard, well known and respected in racing r&d. In one of his books, How to Build Horsepower, Vol. 2, the first chapter was "Performance Filtration". Included in the chapter was a section with exhaustive testing on different filters. The K&N was the easy choice. The HP was up and the filtration was comparable to the best paper units.
David Vizard is well known for his comparative scientific testing and is used by many to perform such testing. There is a lot of pitfalls in testing done by others that are not allowed for. There are many manufacturers that offer factory high performance cold air kits that use K&N. I have used K&N in the past and will continue to do so in the future. |
Can't remember where I read it...
But I do remember reading that the problem with K & N and STOCK AIRBOXES (as in the test above) may be a matter of sealing at the rubber filter edges, in the stock box. This may be due to variations in airboxes (airbox changes for a new or older year than was used to design the filter?) which were not known or noticed by K & N, or it may be carelessness on their part... either way, use of a K & N with an oval type filter housing, it should be easy to verify leakage at the seal. The K & N element type is well proven to be generally superior in flow compared to restrictive paper elements. I have used them for many years on motorcycles, especially. So do a lot of professional racers
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I think the Corvette comes stock with a K&N?
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Interesting reading. I am sure that the filtering effect does have some real substance.
I do how ever use K&N filters on all my cars and trucks I changed filter on the Cobra from the 13" oval air cleaner assembly with factory paper element ( too small filter area) to an 11" K&N X-stream unit. Really made a big difference in performance. I think the key is the ram air effect that the top has in combination with the hood scoop. It is flowing enough air thru the top that I can hear the choke plate vibrating sometimes. I think the x stream unit was money well spent. Bud |
Hey Bart:
I wouldn't put a lot of stock in what Vizard says in his horsepower book. Look to other sources, too. Mr. Vizard had an office in the K&N shop when he wrote the book, so he may have exhibited a little favortism, which I've known him to do. Regardless, I still think the K&N filter is best after my experiences with it in desert racing. As for losing power because the mixture needs to be enriched, that's the case with most engine mods that are effective, such as headers, cams and such. Components must be installed with the system approach in mind to obtain optimum gains. |
I'll admit they will filter the air if installed properly and checked periodically. But those number they give for "added horsepower"? Ha!:LOL:
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I misplaced them but, someone posted (on the net) plans for a homemade air flow meter, it was far from high tech but good enough to test/read flow in various air filters. If anyone knows of these plans I sure would like to have them?.
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K&N are way to expensive for what you get.
I am sorry to say, the China version is about 20% of the K&N. I would like to see that airflow meter as well. Currently the Boss breathes through a standard looking cobra filter, but that may change. I would like to find a setup that will fit my 3310 and duct out to the front of the car. Just my $0.02 |
Vizard comparison chart
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because I live in the industrial N.E. I will continue to use Motorcraft paper filters on my vehicles, IF u are concerned about flow, just increase the size of filter. example 12" dia. to 14" dia..or if space permits 3" height to 4" height...also a tip most engines are running an air cleaner too close to the top of the (Holley)choke shroud...ordinarily milling this off will give an increase of only 12cfm...BUT if U were running an aftermarket unit because of hood constraints, milling the shroud off in this instance will yield up to 150cfm..the difference here is unbelievable!
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Ford428:
What pressure are you using to get the flow numbers you are quoting? |
Does anyone have a picture of how to mill the Holley choke shroud? My choke is acting up and I think I can do away with it anyway.
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On the subject of airflow, bought the Proform body from Summit or Jegs for around 95.00 for my Holley 3310, 750CFM. Got my moneys worth, excellent results with my 427, 500 HP engine. Had to go up with the primary jets and go to the yellow long secondary spring. Engine starts good, idles good and pulls hard up throught 6,000 RPM. In my book a choke is useless on a FE Cobra. The Proform Body is a quality piece that has to flow much better than the stock body. Easy to change out.
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Aumoore, a power band saw and a die grinder with a fine tooth carbide bit will produce these results.....
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Oh yeah, dip the bit in diesel fuel to keep the aluminum from sticking, every 30 seconds or so.
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