Intake manifold has asbestos gasket to insulate heat ( from cylinder
head ), but the 9 nuts which lock manifold onto cylinder head have
no asbestos washer, so heat enters manifold via [i] these 9 nuts [ii]
the exhaust gas channeled to EGR valve [iii] * channeled through
manifold .[iv] manifold chamber via EAC & Fast Idle valves.
Designer seemingly assumed ambient air is never >20ºC ( can be
seen from exhaust manifold's front & rear covers
- meant to keep exhaust gas hot, unnecessary & bad in warmer
climate ), & users will use * to heat their seats' spaces, so * will
not be >40ºC.
To further cool air intake, I use polystyrene & rubber washers to
insulate chamber from these 2 valves, glued 3 heatsinks onto
chamber, fitted copper wires & hoses ( with water & surfactant )
onto chamber & throttle body. Then air intake is cooler : warm-
starts & hill climbing are easier, in even 27ºC ambient air, let
alone in hotter weather.
These 2 valves' insulations also make Fast Idle valve heat up &
reduce idling rpm sooner, & save petrol during idling / coasting.
I could not post here a photo of my F20A's chamber & valves, looks
like this NG bans any photo.
i. Yes, there are nuts holding the manifold to the head. This is not
a defect. If you put soft, crumbly asbestos washers on it, that will
be a defect.
ii. Yes, the Exhaust Gas Recirculating valve does tend to let hot
gases into the manifold. This is not a defect.
iii. what is channeled through the manifold besides air?
iv. It is hard to say whether the small amount of heat transferred
from the coolant to these valves is offset by radiant cooling from the
increased surface area provided by the valve body. What is certain is
that any effect would be so trivial that only you would consider it.
By golly the exhaust shield actually says, "Not for use in ambient
temperatures above 20C." No wait, let me put my glasses on. Oops,
I'm sorry, my bad. It actually says "HOT." It also has a hand icon
and an X so I guess the X is where you are supposed to put your hand.
Please try it Cheah and see if you can find another defect.
Seriously Cheah, It is pretty obvious you could get more power out of
the engine with a cold air intake. It might also ice up if the
ambient gets cool and damp. It also might emit more pollution, which
is something you can blissfully ignore, unless you get caught. (The
fine could be $50,000 in the US.) For these reasons, Honda like all
other manufacturers must control (i.e. raise) the intake air
temperature. Since you are already feeding warmed air into the
intake, there is no need to make heroic efforts to cool the intake
Honda engines work superbly under wide conditions virtually all of the
time. If yours has a problem, that is unfortunate. If it needs
fixing, I would start by restoring it to its original condition and
removing your modifications.
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