Airflow rates for Stock airbox???
10-05-2004, 03:16 AM
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Airflow rates for Stock airbox???
Does anyone have the rate of air flow for the stock airbox? Also, how it compares on average to an after market intake solution? Lastly, I would like to know the flow of the K&N drop-in versus others, ie. stock box and avg aftermarket.
Thanks in advance
Thanks in advance
10-05-2004, 06:33 AM
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Flow rates are how aftermarket confuses you into thinking a mod does anything.
The engine can only injest 214 ci/2......x rpm all divided by 1728 = 402 CFM @6500 rpm if it had 100% VE vs 280 CFM @4500 rpm.
By definition the torque peak rpm is the hight VE point [most air per cylinder gulp]. As the rpm goes above this point the restrictions from the intake valves and time for air to pass the valves starts a small but steady decline in efficiency.
By 6500 rpm the torque has fallen to 214 lb/ft/260 peak= 82% efficiency SO instead of ~~ 402 CFM the flow is 402 x 0.82=~~ 330 CFM @ 6500 rpm............at 6,000 rpm the efficiency might be 85-87%.
The correct way to measure the restriction of all the stuff in front of the throttle body is to tap a rubber line in front and read the pressure restriction from the atmosphere in inches of water with a MANOMETER. Typical HIGHEST readings are in the order of 11-13 " of water column [11/27.7= ~~0.397 psi negative or 0.4 x 6.8= 2.7% restriction to flow.
Air filter might be 1" water column and MAF ~~ 7".........the other 4" comes from air box and and air ducts from MAF to throttle body.
You can't do anything about 64% of the losses so you are playing with 1% [2-3 HP] that remains.
Other than the sound mods create there is little to be gained per $100 of expense!
http://www.bobistheoilguy.com/airfilter/airtest1.htm
The engine can only injest 214 ci/2......x rpm all divided by 1728 = 402 CFM @6500 rpm if it had 100% VE vs 280 CFM @4500 rpm.
By definition the torque peak rpm is the hight VE point [most air per cylinder gulp]. As the rpm goes above this point the restrictions from the intake valves and time for air to pass the valves starts a small but steady decline in efficiency.
By 6500 rpm the torque has fallen to 214 lb/ft/260 peak= 82% efficiency SO instead of ~~ 402 CFM the flow is 402 x 0.82=~~ 330 CFM @ 6500 rpm............at 6,000 rpm the efficiency might be 85-87%.
The correct way to measure the restriction of all the stuff in front of the throttle body is to tap a rubber line in front and read the pressure restriction from the atmosphere in inches of water with a MANOMETER. Typical HIGHEST readings are in the order of 11-13 " of water column [11/27.7= ~~0.397 psi negative or 0.4 x 6.8= 2.7% restriction to flow.
Air filter might be 1" water column and MAF ~~ 7".........the other 4" comes from air box and and air ducts from MAF to throttle body.
You can't do anything about 64% of the losses so you are playing with 1% [2-3 HP] that remains.
Other than the sound mods create there is little to be gained per $100 of expense!
http://www.bobistheoilguy.com/airfilter/airtest1.htm
