Aftermarket intake questions

Dana Rohleder wrote:

I would leave it stock if you like how it sounds and looks. The miata is
quick, but it will never be a fast accelerator without either adding
forced induction or swapping engines.

The improvement from things like headers, intakes and exhausts is so
minimal relative to the money spent that I consider them more for looks
and sound than anything, though the car will flow somewhat more freely
than stock if it is all done correctly.


What year is your miata?
I would put a Randall Cowl intake on a 1990 to 1997 model, not sure if
they offer one for the later models.
It helps some and is not that expensive, though it does require cutting
a hole in the firewall.


Lots of debate on filters. I won't run K&N's. My turbo setup requires an
aftermarket foam filter, but ultimately, I would rather use the OEM
paper ones, which the Randall system allows.


One of the few things I have not installed on a miata.
Chris D. has a nifty-looking one on his '99 model that makes a nice
"whoosh" sound. :-)


Not the unit from Jackson Racing Products, I hate everything about it,
especially the fact that I ever bought one.

They are in the way of any radiator removal, the intake box cracks from
the heat and the stress, often underneath first so that you don't know
that debris is being sucked past the filter unless you really watch it
almost daily.

In other words, if someone bought me one and offered to install it for
free on another, non-turbo miata that I owned, I would tell them thanks
but no way.

Pat

No cone filter or K&N panel will do anything but pass more dirt and make
more noise. The stock airbox is not a point of restriction on a stock
engine, and will flow more air than the engine can use, even with a
paper filter. If anything, most cone filters probably cost power because
they suck hot air directly off the exhaust header. That doesn't stop
folks from buying them, of course, presumably because they're shiny.

There is a small benefit to a true cold air intake like the Randall,
which draws air from outside the engine bay. I have one, and while I
didn't notice more power, I don't have any less, and the car no longer
pings using 87 octane fuel on hot days. That's all I was looking for.

I don't know how well the Randall works on an NB.

Bottom line: the most you can expect from intake and exhaust mods is
about 15 rwhp for $1000-1500, a very poor return. Do it for the sound or
because you like shiny things, but if you want more power, think
supercharger or turbo. Oops, there goes your mileage...  :-)

"Oops, there goes your mileage"
Only if you have a heavy foot. Highway mileage may increase by 1 or 2 MPG.
Local is usually about the same.
A properly installed turbo scavenges, which helps improve highway MPG.
My 99 with stock rear end, 5spd, and a fifth gear mod, usually runs 29-30
with A/C on (Highway)
A/C on does horrible things to local gas milage.
Major disadvantage is that 91+ octane premium is needed.


investment?

What logic?

Leon


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

Less restricted airflow to the engine; the same logic that supposedly
increases horsepower - by increasing airflow efficiency performance is
enhanced. I'm not saying it's true - that's why I'm asking. But the
manufacturers and many owners seem to think so.
--
Boreal
2001 LS 6 speed Silver/tan, Sport Suspension w/hard rear sway bar




What logic?

Leon

I don't know why opening up the intake would increase economy, less
restrictive exhaust might BUT either or both may result in  heavier
foot which will lower economy.

It's hard to increase performance w/o using it, I know every time I
clean my airfilter and change plugs I go looking for Vipers to drag
race..... ;-)


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

More restrictive airflow.   If you take in cooler air, it is denser.
Hence for the same performance, you need to increase the intake
vacuum.  That increases pumping losses.


Maximum airflow is increased, not efficiency with respect to viscous
power losses.


What manufacturers?  Mazda?

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

If the air is denser, don't you need less of it for the same performance?

miker

Exactly.  The problem is that for most engines, (the ones that cannot idle
a few cylinders,) the engine is still trying to take in the same volume.
If that same volume has more oxygen, the throttle has to work harder to
keep air out of the engine.  That gives a larger vacuum to work against
the moving pistons.

And of course, when you replace the intake, you lose any design fine tuning
that Mazda may have done.  But then again, such fine tuning might well be
to satisfy some EPA requirement rather than to save you a buck on fuel.  ;)

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

So are you saying, that makers of competition and high-performance engines
have been hurting themselves by removing stock air cleaner/filter assemblies
and installing ram-air systems, superchargers, etc.?



TO the engine, not IN the engine. The idea is, when the throttle opens
requesting more air to add to the mixture, a properly designed intake would
be able to provide it more efficiently than a restrictive, tortuous intake.
That's why we change air filters, to reduce the restriction caused by dirt
in the filters. Less restriction = more available air delivered to the
throttle when it is needed.


No, the manufacturers of the after-market intakes, and people trying to get
more performance/power from their engines. Stock intakes nowdays are
designed with acoustic chambers to reduce ambient noise, as well as small
air intakes feeding rectangular filter chambers that again feed round and
oval-shaped intake tubes, eventually feeding into a round intake at the
throttle. It is generally accepted that these transitions from one shape to
another with various diameter and direction changes tend to disrupt the flow
of the air making the airflow less efficient and slowing the velocity of the
air delivered to the throttle.

It may be "generally accepted," but on Miatas it's generally wrong. Most
aftermarket intakes result in a power loss, since the OEM intake flows
better than the MAF (1.6) or MAS (1.8). But by all means replace your
paper filter if your goal is more dirt in the engine.

Bruno wrote:

I'd be very interested to see the results, if you could post them up!

I've just got myself a 2nd hand (6 months old) Typhoon for my 2002 1.8,
hopefully I'll be fitting it in the next couple of days.  I'm not expecting
anything spectacular but I was curious and I got it much cheaper than new
price, I just had to scratch the itch, you know?!

R.

Richard Phillips wrote:

Here is an appetizer: http://users.cybercity.dk/%7Edsl45720/rulle.JPG

It's the test before any changes so we are talking a 1999 1.8 with
aprox. 60,000 miles on the clock and no alterations to Mazda specs
except it has a Remus exhaust.



Supposedly it's real easy to fit so if you got it cheap there certainly
is no reason not to try. Just make sure to keep the original parts in
case you don't like the new sound (or performance somehow suffers).

Kind regards
Bruno

Bruno wrote:

Interesting, it's what I expected, only more so!  Although that is a torque
graph, I'd be interested to see the BHP equivalent (although I would expect
similar curves).
My car is a 2002 1.8, approx 59,000 miles on the clock, no alterations
expect for a Racing Beat exhaust.  This test might as well have been done on
my car...


I'll try it and see, may well be standard again next week though  :-p

Cheers,
R.

Richard Phillips wrote:

Actually the graph is showing horse power as well the scale is just not
part of the photo I took. The unit is in metric horsepower meaning the
top at 7095 rpm is 142.5 BHP. The missing scale gives 60 HK at 90 Nm, 80
HK at 120 Nm and so forth.


I have put the kit on my car now and I do like the difference.

There is a little more "omph" in the exhaust but mainly at higher revs
and during acceleration so when taking it slow it does not make me feel
like a noise terrorist. Also there is a sucking noise from the new
filter which can be heard at idle and even a second after the engine is
turned off.

As for power I think there is a slight improvement but it could well be
wishful thinking.

The rolling road I used in the test without the kit is closed for the
holiday but I have booked a time for August 8'th so by then some hard
facts should be available (I want to use the same place to ensure the
most accurate result).

Kind regards
Bruno

Bruno wrote:

Looking forward to seeing the results.  Sounds like you had the same
experience as me!  It's when you put your foot down the filter change is
most obvious...

Cheers,
R.

Lanny Chambers wrote:


Lanny, I don't disagree with EVERYTHING that you say....  :-)

Even after that tire debate, I am probably going to go with the Toyos on
my 16X7 SSRS, complimented by your alignment specs of course. I imagine
that it will handle well.

I have gotten pretty used to these alignment settings over the past 7 or
8 years, though they did do too much toe-out in front last time and I
never bothered to take it back.
Pretty fun, but it was little, (ok, a lot), darty and it ate the tires
extra-fast.
I also had to watch that steering wheel on the highway, a little bump
would put the car over almost one whole lane.

Pat

No I am not.  As I tried to explain, admitting cooler air in the intake system
will reduce the flow efficiency, since the throttle is further closed,
increasing fuel consumption by increasing pumping losses.

The reduction of explicit flow restrictions *at given performance* does nothing.
If you reduce the flow restriction elsewhere in the intake system, you will
need to close the throttle more to keep the performance the same.

*Supposedly* these devices are to increase *maximum* performance, i.e. power
with the throttle wide open.  But Lanny may well be right in noting that most
just reduce maximum performance too.  As I noted in another post, if you mess
around with the intake, you lose any design optimizations Mazda may have done.
In particular, acoustics is a confounding factor, since the speed of sound
does not cooperate and go up proportional to engine speed.

Leon


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

 rammm@REMOVE_THIS_TAGdommelen.net (Leon van Dommelen) wrote:


So admitting warmer air would then *increase* flow efficiency?

Sorry, Leon, you're just wrong.


Or leave the throttle the same to get more performance...


...which is what we're after, right?


Do you really understand what you just said?

--
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."