1st Gen Durango 1998 - 2003 Durango's

intake questions

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Old 03-22-2007, 12:52 AM
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mtgrady1
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Default intake questions

i just bought a 2002 durango and was wondering if putting on a cold air intake system was worth the extra horsepower better fuel mileage. also which brand is the best buy for your money.
 
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Old 03-22-2007, 02:31 PM
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Default RE: intake questions

Before spending considerable money on a cold air intake,
read what the volunteers found independently testing
KN Air Charger, KN drop in, Volant, Mopar and Airaid 360
aftermarket air intakes against the stock factory airbox
on 5.7 V8 Hemi's in Chrysler LX's

http://www.lxforums.com/board/showthread.php?t=14140

Keep in mind that the factory airbox
on a Ram pickup 5.7 Hemi engine is even
bigger and less restrictive than the factory box on a LX.

To save everyone some math
the average of three runs
of the stock factory airbox and paper filter dyno'ed:

280 HP with a standard deviation of 3.75
(corrected to standard pressure and temperature)

The only cold air intake testing better
was the KN Air Charger at
281 HP with a standard deviation of 4.15

Since the average of all 18 dyno runs
where an air intake design
was tested after a standard PCM reset was:

279 with a standard deviation of 3.24
(runs number 4 to 6 plus runs 10 to 24)

you really can't say with certainty that the
extra 1 HP for the KN Air Charger was 'real'
because even a well designed wheel dyno
that is well maintained
and has a great operator
can't be depended upon to repeat that close.

279 HP with a standard deviation of 3.24
means in simple terms
that if you ran exactly the same engine exactly the same way
100 times, then
98 of the runs would 'scatter' between
a high of 285.5 and
a low of 272.5
(which is 279 plus and minus two times 3.24)

1 HP gain for the KN Air Charger versus
280 for the factory air box
is below 1% difference
and this rear wheel dyno
seems to be varying over a range of 12.96 hp
which at a bit less than 5%
is actually admirable for repeats on a wheel dyno.

What can you say with certainty?

You can say:
1) they have fancy colorful paint jobs

2) they make more noise than the factory intake

3) 50% of the buyers who check their next tank of gasoline
will 'by chance' find a higher MPG than the last MPG they remember.
Of the other 50% who 'by chance'
find their next tank of gasoline's MPG is lower,
a considerable number will think something like
"the computer is still learning" or
"I must have been driving with a heavy foot"
and will go on to give the CAI another chance
and watch future tanks of gasoline
for their wishes to come true to justify their purchase.
Since MPG improves on vehicles as they age,
(because their pistons' ring tension wears looser
and their tire tread depth wears down and gives lower rolling resistance
.....the well known 'break in' effect)
these buyers will eventually find their MPG has gone up,
and they give the credit to the intake for the increase.
Very few will ever take the CAI off for awhile to check to
see if the MPG stays the same, or goes down.
 



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