K&N Filter choice ?

[Scott89TTA]

I've been looking at universal K&N filters for my car and found this model RX-3990-1. It has the X-Stream top/end instead of the solid end. Since we are trying to get some cold air from the fender well this filter should do a better job then the 8" (RE-0910) & 9" (RE-0810) universal filters most have been using. I have read where some get the longer filter and smash it down a little to get it in the fender well opening. It looks as if this may not be necessary with the RX-3990-1 ? The only thing I'm not real sure about is how much CFM is required on modified TTA's and GN's?

Here are the CFM numbers I got from the K&N tech's...

1. RE-0910 8" Universal ~725 CFM
2. RE-0810 9" Universal ~901 CFM
3. RX-3990-1 8 11/16" X-Steam Universal ~850 CFM

http://www.knfilters.com/search/product.aspx?Prod=RX-3990-1

Cost is around $62

http://www.ajusa.com/cgi-bin/knfilt...0-1&ajr_skey=02cbedea141a523ce920cebd9589842e

Anybody use this filter...if so what are you opinions?

Thanks,

 

[jpratt]

If using a cold air kit, wouldn't a cylindrical filter be better than a cone shape?
I like the looks of the cone with that top, but cant see it being better that a cylinder shaped one.

 

[UNGN]

The Stock MAF with the screens in place flows about 600-650 CFM.

I went 11.53@118 in a T-type through a 6.5" K&N and factory aircleaner elbow (though with a screenless LT-1 MAF)

 

[Scott89TTA]

Not sure...no cold air kit available for us TTA guys. This may not really pertain to the GN guys ? Just thought I'd include the GN's for some more opinions. I would be using this mounted directly to the end of the MAF and the end would be very close to the fender well opening where the stock airbox was.

 

[1BADDAM]

The only thing I'm not real sure about is how much CFM is required on modified TTA's and GN's?

Here are the CFM numbers I got from the K&N tech's...

1. RE-0910 8" Universal ~725 CFM
2. RE-0810 9" Universal ~901 CFM
3. RX-3990-1 8 11/16" X-Steam Universal ~850 CFM

Are those #'s for a NA engine ? I've seen a Viper at the track trapping 140 mph and all he had was a 4" cone K&N on his paxton NOVI. So I would venture to say 8" or 9" are plenty.

 

[Jicaju]

You need to get in touch with Grumpy. He has the mass air flow pipe you need.

 

[Scott89TTA]

Are those #'s for a NA engine ? I've seen a Viper at the track trapping 140 mph and all he had was a 4" cone K&N on his paxton NOVI. So I would venture to say 8" or 9" are plenty.

The numbers...if I understood the tech I spoke to on the phone where just approximate flow numbers (CFM) for the filters mentioned. They were not for a particular engine type...they came off a chart from test data.

You need to get in touch with Grumpy. He has the mass air flow pipe you need.

I already have one ...just ordered all new silicone couplers and S/S t-bar clamps from http://www.racepartsolutions.com/categories.asp?cat=90 they had pretty good prices. Just trying to decide what filter I want now.

 

[Jicaju]

I have a RE-1910 8-inches long 3 inch inlet. You might be able to use the RE-1810 but it will be a tight squeeze.

 

[Scott89TTA]

I have a RE-1910 8-inches long 3 inch inlet. You might be able to use the RE-1810 but it will be a tight squeeze.

You mean RE-0919 not RE-1910

 

[Joe Lubrant]

Just a Comment:

K&N 3x9's I know are rated to 600hp

I still see Turbo Cars runing the 9" filter with 66mm thru 76 type turbo's--700hp thru 950hp....Big Restriction!

Joe

 

[Scott89TTA]

Are those #'s for a NA engine ? I've seen a Viper at the track trapping 140 mph and all he had was a 4" cone K&N on his paxton NOVI. So I would venture to say 8" or 9" are plenty.

I found some more info...

K&N ENGINEERING AIRFLOW TESTING PROTOCOL

K&N Engineering performs all airflow testing on a SuperFlow Corporation SF-1020 flow bench. The SF-1020 is a computerized flow bench capable of measuring airflow rates up to 1020 cubic feet per minute (cfm) at test pressures of up to 50 inches of water.

The procedure K&N has developed for performing airflow testing is as follows:
here http://www.knfilters.com/testmethod.htm and here http://www.knfilters.com/powertesting.htm

 

[Scott89TTA]

Just a Comment:

K&N 3x9's I know are rated to 600hp

I still see Turbo Cars runing the 9" filter with 66mm thru 76 type turbo's--700hp thru 950hp....Big Restriction!

Joe

Very true...most people don't do the math, they just follow what they see everyone else us so they think it is sufficient. In most cases it is but some definitely not as you have stated in your post.

From K&N facts...

Filter Selection
If maximum horsepower is the objective, the size and shape of the air filter element is paramount. http://www.knfilters.com/facts.htm#SELECT

 

[Jicaju]

No, I mean RE-0910 not RE-0919. See even you can make a mistake also.

 

[Scott89TTA]

No, I mean RE-0910 not RE-0919. See even you can make a mistake also.

oops :redface: