* via thermostat is [i] steel-piped next to & heat is transferred into
rocker cover's breather hose
, this heated air is then sucked through PCV valve & into intake
manifold.chamber [ii] rubber-hosed into bottom of throttle body
, & heat flows into the air passing throttle.
Both designs make air intake & cylinder head unduly hot
www.circletrack.com/techarticles/1822/ : whenever intake manifold
heats up ( esp in long trips ), torque drops & warm-starts are difficult
, both because hot air cannot expand much when heated. Ideal
temperature of air to receive injectors' spray of petrol is just 40°C 104°F ( www.turborick.com/gsxr1127/gasoline.html para 10.2 ).
Intake manifold where injectors spray petrol ( near cylinder head ) &
chamber already get heat from manifold's contact with cylinder head,
EAC & Fast Idle valves ( both heated by * ), certainly do not need
more heat. If designer wanted manifold to heat up fast, then throttle
body must have a thermostat to stop * inflow when throttle is heated
to 40°C. These 2 designs make steep hill climbing slow & weak ; *
& air intake will both be @ their hottest, & torque will be lowest (
ironically, when torque is needed most ).
After I disabled these 2 designs, in 28°C air, [i] chamber, manifold
& cylinder head are cooler, benefits are many e.g. 1 can use ( cheaper
) mineral oil & lower viscosity [ii] torque ( 5% > before ) does not
drop after * heats up [iii] warm-starts are easier.
There isn't supposed to be much air flowing through a PCV system.
Maybe the thermostat for your throttle body, if it has one, is faulty.
It's supposed to keep it warm, not hot.
Maybe you fixed a symptom, not a problem? Your posting is hardly clear.
TE Chea wrote:
you need to stop drinking the "cold air intake" coolaid there guy. it
may be fine for you kidz in the nice warm county of l.a. to run about
with disabled de-icing equipment, but anywhere else in the country, it
becomes a bit of an issue when your car sputters to a halt because of
as an aside, i had my air intake cover off the other day, and forgot to
screw it on tightly. the screws worked their way out after a few
hundred miles, and the air intake cover popped off. it was noticeable
by two things:
1. increased noise. ok, ho hum.
2. big /decrease/ in power. the "ultimate" cold air intake, i.e. no
intake at all produces /less/ power???!!! yep, you better believe it.
now, it's possible that some aftermarket manufacturers of air intakes
know what they're doing and understand airflow resonance dynamics and
the effect it has on engine air induction, but somehow i doubt most of
them do. but hey, most of this stuff is not for performance, it's just
Uh,the air intake is still from the hot under-hood air.All you did was
shorten the intake runner length,which reduces torque.
If you don't believe cold air enables more power,then explain why racers
put scoops and ducts on their race cars.It wouldn't make sense,adding more
drag to get cold air that doesn't produce more power.
uh, i understand how it works thanks. what i'm saying is that it's not
so simple as most of the "cai" crowd believes. if the intake tubing is
tuned correctly, i.e. resonances are set specifically, it enhances the
air charge entering the engine. done right, it flattens/broadens
power/torque curves. otherwise you're stuck with huge flat spots in the
engine's performance, exactly what i was experiencing.
"tuning" the air charge has /way/ more effect than the minor density
differences made by a few degrees of ambient air temperature.
If Honda Tuning Magazine still has the article,they did flow bench and dyno
tests on an RSX for several different brands of short rams and two cold air
intakes.They did a reference test on the unaltered vehicle,then tested each
intake system.Both CAIs got 20HP and modest torque increases.The short rams
only got 5-7 HP gains. They included their graphs in the magazine
article.They also discussed the effect of intake air temperature WRT making
It was a very informative article.Maybe you can get a back issue.
i appreciate what you're saying jim, but did they drop a thermistor into
the air stream to measure the difference in air temperature between the
two? i'll be surprised if they did because i can't say i've ever seen
one of those "dyno graph" articles that ever has. without that, they're
simply measuring the dynamic air charging effect differences - what i
was talking about before. you're right, temperature /can/ make a
difference to power yield [an 80 degree difference in air temp gets you
roughly 10% difference in air density] but again, have you ever seen
temperature reading differences quoted? and what difference does it
make for a *moving vehicle* with & without cai? airflow under the hood
is, well, you get the picture... just questions to ask.
you need to re-phrase that one dude. radiated heat, by definition, is
not retained. and a sensor inside the manifold is not going to
experience much radiated heat from anything other than the manifold itself.
i think what you mean is that air drawn form under the hood i.e.
downwind of the radiator, is warmer, which is true. but in these pics
in all these cases, the cai's are /all/ downwind of the radiator, so i
don't see what the "cold air intake" is achieving in the thermal
department, unless it's on a static vehicle with the hood open. and i'd
love to see numbers on air temp for a /moving/ vehicle, especially as
oem intakes all draw air from up front of the radiator. if all these
kiddiez were serious, they'd cut through the fender and/or hood and put
a real cold air scoop to the outside world, but i've never seen that on
a cai'd civic.
scan it and send it to tegger.
again, i see dyno differences mostly attributable to air charge
resonances, not actual air temperature.
Radiated heat (from the engine) gets absorbed by other things under the
hood,including the underhood air.Thus,it's retained.
these are all SHORT RAMs,-not- COLD air intakes(CAI) ;BIG difference.
CAIs are longer,and run down through the wheel well to draw cooler air from
outside the engine compartment.(thru the original intake's passage.)
that is why HT's tests showed only 5-7 HP for short rams and 20 HP for the
CAIs,and torque increases for the CAIs but not the short rams.
Air temp was the big difference.
No need to;there's an opening available stock;the Honda/Acura intake is
quite complex,and convoluted.the resonator tank and associated plumbing is
unseen,hidden in the wheelwell in front of the wheel,you have to remove the
wheelwell liner just to see it.(personal experience!)
I have seen where some folks made their own ducting and air box to supply
the short ram with cold air.
I don't have the magazine anymore.
I haven't found it on HT's site anymore,either.
dude, the engine's at 78C. that's warm to the touch, but it's nothing
from a radiant heat standpoint. what you're feeling is convective heat,
primarily wafting around from the [very hot] exhaust and the radiator.
they're all /sold/ as cai's:
like every single item on that page.
respectfully, i disagree. the effect being observed is dynamic
supercharging. otherwise the length of the tube would make no
difference, it would be purely air temp. seriously jim, the effect of
airflow dynamics are huge. you're right, a lower air temp helps,
sometimes by a noticeable amount, but it's chicken feed compared to a
mismatch between a given intake tube's resonance and rpm's. that's why
you'll find variable-geometry intake manifold systems on a fair number
of modern un-turboed cars, but air cooling only on turbos where air
temps can increase significantly. and even then, intercoolers are more
to help reduce detonation effects of inducing hot air than they are to
increase air density.
i know about the resonator. my first civic had had it's resonator
removed for some reason i never figured out. performance sucked until i
sure. and integras take air in from under the front bumper. but that's
still better than the products sold as "cai" because they have nothing
to do with cold air!
well, i looked online and finding any article that mentions actual air
temp readings, let alone one from a moving vehicle, takes /way/ more
patience than i've got.
The following treats the rams but says the CAI modifications
weren't yet available. Maybe you can improve on the search
and turn up your article.
Of course as I'm sure you know, Jim Yanik, colder air means
more dense air, which means for the same volume of air flow
into an engine cylinder, more fuel may be admitted. So of
course engine power can increase and substantially. (OTOH,
as has been discussed here in the past, this does not
necessarily translate to more overall fuel efficiency for
the car. For one thing, if the air is cooler because of
lower ambient temperature, then the car sees more wind
resistance.) Certain industrial size diesel engines, for
one, have an air cooler built into them to increase power.
Whether these seemingly popular (according to the makers who
have plastered the net with their claims?) aftermarket CAI
devices do anything meaningful is still not clear without
more information. I see the ads claiming up to 15% more
I'm sure this subject is beaten to death on Usenet...
I do not see how leaving the screws loose on the air intake
cover affects air intake temperature in any meaningful way,
though. Maybe Beam has backed off this assertion.
What a laugh! I just read through some as well. I love this one: "Bonnet's
rubber seals & felt, front wheels' hub caps too can be removed, to help cool
Sounds like his problem is the loose nut between the steering wheel and the
| > Why do you own such a badly designed car?
So far all its design flaws ( 3 more & 2 inadequacies which I tell
friends & relatives ) can be corrected / mitigated. I love its 4ws (
saves time, very scarce now : no new model has 4ws ), perfect rust
proofing. No electric / hybrid / toyota's super 4ws on sale yet.
| "Bonnet's rubber seals
Removal of these let air enter & cool intake manifold & chamber
, & let out hot air produced by air con's radiator. Torque rose 3%.
| & felt
lets heat enter bonnet & escape via convection / radiation
| front wheels' hub caps too can be removed, to help cool engine.
My front wheels used to be too hot to touch, caused by this * flow
design flaw & cheapo exhaust manifold. Removal of hub cap will
let drive shaft & engine cool faster, unnecessary for well cooled
engines, but for desparate users with severe overheating, this can
help a bit, esp on original steel wheels with 15½" Ø plastic caps.
| loose nut between the steering wheel and the driver's seat.
Salesmen / dealers all deny flaws, & denigrate to deter exposers, to
protect their bread & butter, just like in 1 thread above ( 11-5-06 )
on ignition switch.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.