Aftermarket intake questions

XS11E wrote:
> "Richard Phillips" > wrote:
>
>> Usenet wrote:
>>> P.S. My 91 with over 210,000 miles doesn't use significant oil,
>>> still shows good compression, and drives just fine even though
>>> I've been using a K&N filter, which is cleaned and reoiled every
>>> 30,000 miles.
>>
>> Just out of interest, how many of those miles were with the K&N
>> filter? I've just bought one (Typhoon) so anything that makes me
>> feel happier about it's filtering ability is good
>
> K&N actually filters slightly better than OEM. There's a very large
> amount of FUD about K&N filters, one being that they allow dirt in the
> engine which is untrue and the other that they will give big increases
> in HP which is also untrue although if you have an unusually
> restrictive intake system (Miatas don't) the K&N will help.

(What's FUD?!)

K&N claim this:
The K&N will filter dust as fine as talc which is between half and one
micron

The Paper filter will only stop dust as big as 5-6 micron

"Richard Phillips" > wrote:

> (What's FUD?!)

Fear, Uncertainty and Doubt.

http://en.wikipedia.org/wiki/Fear,_u...inty_and_doubt

An interesting marketing strategy.

The best example used against K&N was a "report" widely circulated on
the internet showing a mining company in Utah (I think? Could have
been Nevada?) used K&N filters in their heavy equipment and found sand,
dust, grit, etc. in the vehicles oil and a lot of engine damage. K&N
responded that they had never made filters for that type of equipment
and it later turned out that no such company existed.

Never the less, the fake report hurt K&N to some extent and the mis-
information is probably still circulating around the internet, some
urban legends never die.... I'm a bit surprised it hasn't shown up
here, maybe it will later?



--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

XS11E wrote:
> "Richard Phillips" > wrote:
>
>
>>(What's FUD?!)
>
>
> Fear, Uncertainty and Doubt.
>
> http://en.wikipedia.org/wiki/Fear,_u...inty_and_doubt
>
> An interesting marketing strategy.
>
> The best example used against K&N was a "report" widely circulated on
> the internet showing a mining company in Utah (I think? Could have
> been Nevada?) used K&N filters in their heavy equipment and found sand,
> dust, grit, etc. in the vehicles oil and a lot of engine damage. K&N
> responded that they had never made filters for that type of equipment
> and it later turned out that no such company existed.
>
> Never the less, the fake report hurt K&N to some extent and the mis-
> information is probably still circulating around the internet, some
> urban legends never die.... I'm a bit surprised it hasn't shown up
> here, maybe it will later?

This guy uses the same term, (FUD), but to describe K&N's marketing
strategy instead.
He makes no mention of a mining company in Utah or anywhere else, though
K&N air filters are described here as "snake oil soaked cotton gauze".

http://mymiata.paladinmicro.com/K&NComments.htm

Pat

pws > wrote:

> This guy uses the same term, (FUD), but to describe K&N's
> marketing strategy instead.
> He makes no mention of a mining company in Utah or anywhere else,
> though K&N air filters are described here as "snake oil soaked
> cotton gauze".
>
> http://mymiata.paladinmicro.com/K&NComments.htm

Apparently he's one of the "faith-based" fundamentalists he talks
about.

http://cars.about.com/od/productrevi...g_knfilter.htm
================================================== ================
How well does it filter?
Several readers have responded with concerns about the K&N's ability to
effectively filter dirt out of the air compared to paper filters. After
all, engine protection is the reason engines have an air filter to
begin with. K&N insists that their filters are rigorously tested to
meet OEM filtration standards.
Expert opinion: Not an issue
I discussed the issue with the owner of a reputable engine rebuilding
shop. In his experience, the engines that suffered from premature wear
were those in which the filters were routinely ignored. He didn't see
any significant difference in wear in engines where the filters were
routinely cleaned or changed, regardless of type. (He personally runs
K&N filters in his own cars.)
================================================== ==================

We rebuild dozens of engines on off road motorcycles in the '70s and
noticed the same results, engines with neglected air filters had dirt
inside, those with maintained filters didn't. We sold a lot of K&Ns
and Uni filters and never noticed any difference.

Lots of links he http://en.wikipedia.org/wiki/K&N_Engineering,_Inc.



--
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The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

In article > ,
XS11E > wrote:

> We rebuild dozens of engines on off road motorcycles in the '70s and
> noticed the same results, engines with neglected air filters had dirt
> inside, those with maintained filters didn't. We sold a lot of K&Ns
> and Uni filters and never noticed any difference.

When I was racing dirt bikes (national enduro circuit), I used both K&N
and Uni until the bike manufacturers caught up and started providing
decent foam OEM filters. You're correct, rigorous maintenance was the
key. But no one expected a dirt bike engine to last more than a season
under the best of conditions--the real breakthrough from K&N was the
ability to keep the engine running even when the filter was caked with
dust, because the flexibility of the gauze and the rubber mounting
collar ensured that chunks of oily crud would fall off under the
pounding of off-road racing. We were more concerned with finishing the
race than facing an early rebuild. Piston rings were cheap and easy to
replace.

These filters did what they were designed for: keeping enough dirt out
of an engine so it could finish a desert race. Protecting automotive
engines on the street for 200k miles was not a consideration...until
they discovered that clever marketing and manipulation of magazine
content could expand their market past their wildest dreams.

Note that overoiling a foam or gauze filter can ruin a 1.8 Miata's mass
airflow sensor.

Alan Baker > wrote:

>In article >,
> (Leon van Dommelen) wrote:
>
>> "nosfatsug" > wrote:
>>
>> >There is simply too much obfuscation so, I'm starting with a clean slate.
>> >What I hear Leon saying is that at any given velocity of a car, lets say a
>> >Miata for interest of this group, the power output from the engine is the
>> >same, assuming all other external factors are the same (e.g., engine
>> >modifications don't change the profile and thus the drag of the car).
>> >Also, assuming similar fuel mixture in the combustion chamber (which is
>> >controlled by the ECU to meet exhaust and performance criteria),
>>
>> Yes so far.
>>
>> > the amount
>> >of air entering through the intake system stays the same (e.g., same power,
>> >same fuel to air ratio, and therefore same air volume).
>>
>> No, this misses the exact point. It is the *amount of oxygen*, not the
>> *volume*
>> that stays the same. By design a Miata engine wants to take in 1.8 L air by
>> volume every cycle. When it really needs only a fraction of that, during
>> highway cruise, say, the throttle keeps out the excessive air. That means
>> that the engine fights the throttle, which costs power, hence fuel. Now if
>> the
>> intake air goes down say 30 C in temperature, the volume that the engine
>> needs
>> becomes even smaller by about 10 percent. So the throttle must let the
>> engine
>> get even less volume, so they fight harder, so fuel consumption goes up.
>
>No.
>
>Because while resistance goes up, the speed of the flow goes down. And
>power required to overcome the resistance to the flow is proportional to
>the *square* of the speed of the flow, but only directly proportional to
>the friction.

No. This is an internal flow, not flow around a car. Speed is irrelevant
here, it is total pressure that counts. The total pressure loss must be
greater for the smaller flow volume.

And resistance is a meaningless term here also. The throttle is not trying
to move through the air. What counts is head loss, not force. (Although
the head loss of course finally shows up as a reduction in pressure on
the top piston surfaces.)

>IOW, double the density of the air, you halve the required flow by
>doubling the resistance. Thus you get an increase by a factor of two
>from change in resistance, but a decrease by a factor of four from
>change in flow, for an overall decrease in pumping losses by a factor of
>two.

Think of taking the Miata to Denver. If it takes in the same number of
molecules of oxygen, in Denver the throttle might be wide open, and there
will be no real pumping losses. In Florida it will be partly closed at exactly
the same produced power. Pumping losses, here we come.

Then consider the fact that for *the air resistance of the car*, your argument
above *does* apply. The air resistance in Denver will be much smaller too, and
you are probably going at a good clip on this highway if your throttle is wide
open in Denver. We in Florida suffer.

But then, we do not freeze to dead in winter as they do in most of the rest of
the country. But then we freeze to dead in Summer. But you can always
go outside to warm up some in your Miata. )

Leon
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas

"nosfatsug" > wrote:

>
>"Leon van Dommelen" > wrote in message
.. .
>> "nosfatsug" > wrote:
>>
>> No, this misses the exact point. It is the *amount of oxygen*, not the
>> *volume*
>> that stays the same. By design a Miata engine wants to take in 1.8 L air
>> by
>> volume every cycle. When it really needs only a fraction of that, during
>> highway cruise, say, the throttle keeps out the excessive air. That
>> means
>> that the engine fights the throttle, which costs power, hence fuel. Now
>> if the
>> intake air goes down say 30 C in temperature, the volume that the engine
>> needs
>> becomes even smaller by about 10 percent. So the throttle must let the
>> engine
>> get even less volume, so they fight harder, so fuel consumption goes up.
>>
>Leon,
>
>You are right, the important variable is mass of oxygen not volume of air.
>I was being lazy in my analysis and basically assuming the conditions were
>similar enough that the density didn't change signficantly. I also
>understand that the same mass of oxygen requires less volume of dense air.
>How significant is the reduction in fuel efficiency with lower intake air
>temperature?

Common sense says that it should be very small. 30 degrees Centigrade
is about 50 or so Fahrenheit, and that changes the density, so the pumping
losses, by about the same percentage. That limits it to just a few miles
per gallon, and then pumping loss is only one item for which fuel is used.

I was not saying it is something to worry about, just responding to
suggestions that common sense says an aftermarket intake would improve
fuel mileage.

> Do cars get lower gas mileage in the winter in cooler
>climates?

I have no clue. There must be lots of much more important variables.

>I still do not understand your point for the case when the temperature is
>the same and the only change is a less restrictive intake leading to more
>restriction across the throttle plate. I do understand that fuel efficiency
>is impacted by pumping loses, which a greater at low power when the throttle
>is closed, and by friction loses which increase with engine speed. I also
>understand that more restriction across the intake system (e.g., closing the
>throttle) results in more pumping loses. What I don't understand is why it
>matters where the restriction is in the intake system. I'd think that what
>would matter is the restriction across the entire intake system not just the
>throttle. What am I missing?

I am somewhat mystified what you are asking here. Did I not already note
in another post exactly the same that you are saying here? Your final
sentence seems to be exactly what I said there. If the intake air temperature
is the same, the effect of the intake should be the same, except for effects
that would take a fanatic to measure.

Leon

>Gus
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas

In article >,
(Leon van Dommelen) wrote:

> Alan Baker > wrote:
>
> >In article >,
> > (Leon van Dommelen) wrote:
> >
> >> "nosfatsug" > wrote:
> >>
> >> >There is simply too much obfuscation so, I'm starting with a clean slate.
> >> >What I hear Leon saying is that at any given velocity of a car, lets say
> >> >a
> >> >Miata for interest of this group, the power output from the engine is the
> >> >same, assuming all other external factors are the same (e.g., engine
> >> >modifications don't change the profile and thus the drag of the car).
> >> >Also, assuming similar fuel mixture in the combustion chamber (which is
> >> >controlled by the ECU to meet exhaust and performance criteria),
> >>
> >> Yes so far.
> >>
> >> > the amount
> >> >of air entering through the intake system stays the same (e.g., same
> >> >power,
> >> >same fuel to air ratio, and therefore same air volume).
> >>
> >> No, this misses the exact point. It is the *amount of oxygen*, not the
> >> *volume*
> >> that stays the same. By design a Miata engine wants to take in 1.8 L air
> >> by
> >> volume every cycle. When it really needs only a fraction of that, during
> >> highway cruise, say, the throttle keeps out the excessive air. That
> >> means
> >> that the engine fights the throttle, which costs power, hence fuel. Now
> >> if
> >> the
> >> intake air goes down say 30 C in temperature, the volume that the engine
> >> needs
> >> becomes even smaller by about 10 percent. So the throttle must let the
> >> engine
> >> get even less volume, so they fight harder, so fuel consumption goes up.
> >
> >No.
> >
> >Because while resistance goes up, the speed of the flow goes down. And
> >power required to overcome the resistance to the flow is proportional to
> >the *square* of the speed of the flow, but only directly proportional to
> >the friction.
>
> No. This is an internal flow, not flow around a car. Speed is irrelevant
> here, it is total pressure that counts. The total pressure loss must be
> greater for the smaller flow volume.

Internal flow follows the same laws of fluid dynamics as external flow
does.

>
> And resistance is a meaningless term here also. The throttle is not trying
> to move through the air. What counts is head loss, not force. (Although
> the head loss of course finally shows up as a reduction in pressure on
> the top piston surfaces.)

No, but the pistons are trying to draw air through the throttle. In
doing so, they must use power.

>
> >IOW, double the density of the air, you halve the required flow by
> >doubling the resistance. Thus you get an increase by a factor of two
> >from change in resistance, but a decrease by a factor of four from
> >change in flow, for an overall decrease in pumping losses by a factor of
> >two.
>
> Think of taking the Miata to Denver. If it takes in the same number of
> molecules of oxygen, in Denver the throttle might be wide open, and there
> will be no real pumping losses. In Florida it will be partly closed at
> exactly
> the same produced power. Pumping losses, here we come.

In Denver, the resistance will be less (not none, BTW), but the air must
be moving much faster to make up for the change in density. Power
expended goes up in proportion to resistance (which has fallen) and up
in proportion to the square of the velocity (which has risen).

>
> Then consider the fact that for *the air resistance of the car*, your
> argument
> above *does* apply. The air resistance in Denver will be much smaller too,
> and
> you are probably going at a good clip on this highway if your throttle is
> wide
> open in Denver. We in Florida suffer.
>
> But then, we do not freeze to dead in winter as they do in most of the rest
> of
> the country. But then we freeze to dead in Summer. But you can
> always
> go outside to warm up some in your Miata. )
>
> Leon

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling four feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect if you
sit in the bottom of that cupboard."

In article >,
(Leon van Dommelen) wrote:

> The air resistance in Denver will be much smaller too, and
> you are probably going at a good clip on this highway if your throttle is wide
> open in Denver.

if you're in a non-FI Miata, no. Your throttle will indeed be wide open,
but you'll be in third or fourth gear, engine gasping for breath.

We now resume the counting of pinhead-dancing angels, already in
progress...

Alan Baker > wrote:

>In article >,
> (Leon van Dommelen) wrote:
>
>> Alan Baker > wrote:
>>
>> >In article >,
>> > (Leon van Dommelen) wrote:
>> >
>> >> "nosfatsug" > wrote:
>> >>
>> >> >There is simply too much obfuscation so, I'm starting with a clean slate.
>> >> >What I hear Leon saying is that at any given velocity of a car, lets say
>> >> >a
>> >> >Miata for interest of this group, the power output from the engine is the
>> >> >same, assuming all other external factors are the same (e.g., engine
>> >> >modifications don't change the profile and thus the drag of the car).
>> >> >Also, assuming similar fuel mixture in the combustion chamber (which is
>> >> >controlled by the ECU to meet exhaust and performance criteria),
>> >>
>> >> Yes so far.
>> >>
>> >> > the amount
>> >> >of air entering through the intake system stays the same (e.g., same
>> >> >power,
>> >> >same fuel to air ratio, and therefore same air volume).
>> >>
>> >> No, this misses the exact point. It is the *amount of oxygen*, not the
>> >> *volume*
>> >> that stays the same. By design a Miata engine wants to take in 1.8 L air
>> >> by
>> >> volume every cycle. When it really needs only a fraction of that, during
>> >> highway cruise, say, the throttle keeps out the excessive air. That
>> >> means
>> >> that the engine fights the throttle, which costs power, hence fuel. Now
>> >> if
>> >> the
>> >> intake air goes down say 30 C in temperature, the volume that the engine
>> >> needs
>> >> becomes even smaller by about 10 percent. So the throttle must let the
>> >> engine
>> >> get even less volume, so they fight harder, so fuel consumption goes up.
>> >
>> >No.
>> >
>> >Because while resistance goes up, the speed of the flow goes down. And
>> >power required to overcome the resistance to the flow is proportional to
>> >the *square* of the speed of the flow, but only directly proportional to
>> >the friction.
>>
>> No. This is an internal flow, not flow around a car. Speed is irrelevant
>> here, it is total pressure that counts. The total pressure loss must be
>> greater for the smaller flow volume.
>
>Internal flow follows the same laws of fluid dynamics as external flow
>does.

One day you need to tell me all about it.

Leon

>>
>> And resistance is a meaningless term here also. The throttle is not trying
>> to move through the air. What counts is head loss, not force. (Although
>> the head loss of course finally shows up as a reduction in pressure on
>> the top piston surfaces.)
>
>No, but the pistons are trying to draw air through the throttle. In
>doing so, they must use power.
>
>>
>> >IOW, double the density of the air, you halve the required flow by
>> >doubling the resistance. Thus you get an increase by a factor of two
>> >from change in resistance, but a decrease by a factor of four from
>> >change in flow, for an overall decrease in pumping losses by a factor of
>> >two.
>>
>> Think of taking the Miata to Denver. If it takes in the same number of
>> molecules of oxygen, in Denver the throttle might be wide open, and there
>> will be no real pumping losses. In Florida it will be partly closed at
>> exactly
>> the same produced power. Pumping losses, here we come.
>
>In Denver, the resistance will be less (not none, BTW), but the air must
>be moving much faster to make up for the change in density. Power
>expended goes up in proportion to resistance (which has fallen) and up
>in proportion to the square of the velocity (which has risen).
>
>>
>> Then consider the fact that for *the air resistance of the car*, your
>> argument
>> above *does* apply. The air resistance in Denver will be much smaller too,
>> and
>> you are probably going at a good clip on this highway if your throttle is
>> wide
>> open in Denver. We in Florida suffer.
>>
>> But then, we do not freeze to dead in winter as they do in most of the rest
>> of
>> the country. But then we freeze to dead in Summer. But you can
>> always
>> go outside to warm up some in your Miata. )
>>
>> Leon
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas