Cooling

Archives of Posts to the NZ MX5 List back in 2003
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GrubbyMX
Keep calm, Forum Moderator here.
Keep calm, Forum Moderator here.
Posts: 67
Joined: Thu May 18, 2006 9:53 pm
Location: Christchurch

Cooling

Post by GrubbyMX » Mon Dec 01, 2003 9:57 pm

Its been the first decent hot day in CHCH since I added a pair of 3"
spotlights either side of the number plate which takes up a fair amount of
the space in the front air intake.
On the way home the temp gauge slowly crept up to within about 5mm of the H
while doing about 100kmh with quite a strong right three quarter tail wind.
Went out and did some tests hammering it both into a head and with a tail
wind two runs in each direction, one with number plate on and one with plate
off. Plate off the gauge sits right where it normally should. Plate on it
gets hot.

The radiator is full, has recently been flushed (at new cambelt time) and
has plenty of antifreeze.
The cores are clean
The fans are working.
Have I a problem or is the cooling system that marginal that the addition of
the spotlights is all it needs on a hot day to stop it coping?
91 1.6 V Spec Manual

Ralph the Dog
Keith

EricW
See my 5 and raise you.
See my 5 and raise you.
Posts: 95
Joined: Wed May 24, 2006 7:07 pm
Location: Whangaparaoa

Cooling

Post by EricW » Tue Dec 02, 2003 7:38 am

Your spotlights take up about 12.5% of the area of the intake, not enough to
badly affect cooling, but they will be causing some turbulence onto the face
of the radiator, this increases with the square of speed, (twice the speed,
four times the turbulence), but the increased airflow through the radiator
at high speed will normally cope with this, especially if the spotlights
have a streamlined rear face.

However, if your number plate also obtructs the intake, as I take your
comment to mean, rather than sitting above it, as it does on my 1.8, then
you might have got past the point of no return on a hot day! There are
plenty of MX 5s with spotlights in the intake, so I would be thinking that
the number plate is the prime cause of the problem.You were possibly getting
towards critical before you fitted the lights. A flat number plate will
produce a very considerable "stagnation point" behind it and will disturb
the airflow in a shaped chamber, such as the intake, to a most suprising
degree. I would move the plate before I moved the lights

Eric

jeff

Cooling

Post by jeff » Tue Dec 02, 2003 10:12 am

less antifreeze and more water will cool better... about 30:70 is fine. You could also look at sealing around the radiator to prevent air by-passing it. The undertray and radiator top panel are there for this purpose!

Since you have the top down ;) you can just turn on the heater for some additional (engine) cooling.

BTW - the "H" mark on the temp gauge is only around 110*C, not enough to damage anything :)

woof!


Ralph Dog <Ralph.dog@clear.net.nz> wrote:
Its been the first decent hot day in CHCH since I added a pair of 3"
spotlights either side of the number plate which takes up a fair amount of
the space in the front air intake.
On the way home the temp gauge slowly crept up to within about 5mm of the H
while doing about 100kmh with quite a strong right three quarter tail wind.
Went out and did some tests hammering it both into a head and with a tail
wind two runs in each direction, one with number plate on and one with plate
off. Plate off the gauge sits right where it normally should. Plate on it
gets hot.

The radiator is full, has recently been flushed (at new cambelt time) and
has plenty of antifreeze.
The cores are clean
The fans are working.
Have I a problem or is the cooling system that marginal that the addition of
the spotlights is all it needs on a hot day to stop it coping?
91 1.6 V Spec Manual

Ralph the Dog
Free Pop-Up Blocker - Get it now

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

Cooling

Post by Gary Morrison » Tue Dec 02, 2003 10:54 am

I think its obvious if you look at the design of the car and its cooling
system that there is a reason other than aesthetic for the "mouth". Its there
to let air cool the radiator... if you stick stuff like number plates in there
it will compromise the cooling. It only becomes marginal when you compromise
the design.


On Mon, 01 Dec 2003 21:57:31 +1300, Ralph Dog wrote:

Its been the first decent hot day in CHCH since I added a pair of 3"
spotlights either side of the number plate which takes up a fair amount of
the space in the front air intake.
On the way home the temp gauge slowly crept up to within about 5mm of the H
while doing about 100kmh with quite a strong right three quarter tail wind.
Went out and did some tests hammering it both into a head and with a tail
wind two runs in each direction, one with number plate on and one with plate
off. Plate off the gauge sits right where it normally should. Plate on it
gets hot.

The radiator is full, has recently been flushed (at new cambelt time) and
has plenty of antifreeze.
The cores are clean
The fans are working.
Have I a problem or is the cooling system that marginal that the addition of
the spotlights is all it needs on a hot day to stop it coping?
91 1.6 V Spec Manual

Ralph the Dog

GrubbyMX
Keep calm, Forum Moderator here.
Keep calm, Forum Moderator here.
Posts: 67
Joined: Thu May 18, 2006 9:53 pm
Location: Christchurch

Cooling

Post by GrubbyMX » Tue Dec 02, 2003 12:32 pm

true, however a large number have it there and said
manufacturer did put a number plate mount there...
Keith

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

Cooling

Post by Gary Morrison » Tue Dec 02, 2003 12:53 pm

Hi Ralph,

But on my car the mounting arrangement put the plate above the mouth, not in
it...

Gary


On Tue, 02 Dec 2003 12:32:48 +1300, ralph.dog@clear.net.nz wrote:

true, however a large number have it there and said
manufacturer did put a number plate mount there...

Eric West

Cooling

Post by Eric West » Tue Dec 02, 2003 1:52 pm

I looked at a 1.6 parked in the street today and noticed that the plate is
attached to 2 brackets screwed into the top of the "mouth" and pointing
upwards. This places the plate above the mouth. If the brackets are on
"upside down" this would place the plate within the mouth and this would not
be good. Is this what we have with Ralph's car and is his solution as simple
as turning the brackets "right way up".

May be Ross could sell him a nice black plastic mounting which Ralph could
put his plate on

Eric

jeff

Cooling

Post by jeff » Tue Dec 02, 2003 4:05 pm

Tinker, a '96, came with the steel bracket which put the plate in the mouth also. Flipping it over put the plate in front of the bumper, but this was quickly bent (and snapped) by those park-by-touch types . Ended up screwing it directly to the bumper, which has a nice integrated look and is also unaffected by carpark nudges.

Naturally it now lives wedged behind the windscreen, no problems for 3+ months legally or cooling-wise ;)


Eric West <eric@mcsdigital.co.nz> wrote:
P { DISPLAY: block; FONT-SIZE: 11pt; MARGIN: 0in; COLOR: black; FONT-FAMILY: "Times New Roman"; TEXT-ALIGN: left}LI { MARGIN-TOP: 0in; DISPLAY: list-item; FONT-SIZE: 0pt; MARGIN-BOTTOM: 0in; COLOR: black; FONT-FAMILY: "Times New Roman"; TEXT-ALIGN: left}TD { DISPLAY: block; FONT-SIZE: 0pt; MARGIN-LEFT: 0in; COLOR: black; MARGIN-RIGHT: 0in; FONT-FAMILY: "Times New Roman"; TEXT-ALIGN: left}I looked at a 1.6 parked in the street today and noticed that the plate is attached to 2 brackets screwed into the top of the "mouth" and pointing upwards. This places the plate above the mouth. If the brackets are on "upside down" this would place the plate within the mouth and this would not be good. Is this what we have with Ralph's car and is his solution as simple as turning the brackets "right way up".

May be Ross could sell him a nice black plastic mounting which Ralph could put his plate on

Eric

xtr515758

Cooling

Post by xtr515758 » Tue Dec 02, 2003 4:25 pm

After a number of different arrangements for my front plate I have settled on bolting it direct to the bumper below the mouth, creased down the middle with the underhanging portion bent back about 40 degrees. Probably slightly illegal ('tampering' with plates) but still clearly visible and doesn't foul on judder bars and the like. I still find the concept of the top- hinged plate which hangs in the 'mouth' and swings back as speed progresses very appealing, but would need some clever device such as an electomagnet to hold it in place for police inspection at the roadside...
Tinker, a '96, came with the steel bracket which put the plate in the
mouth also. Flipping it over put the plate in front of the bumper, but
this was quickly bent (and snapped) by those park-by-touch types . Ended
up screwing it directly to the bumper, which has a nice integrated look
and is also unaffected by carpark nudges. Naturally it now lives wedged
behind the windscreen, no problems for 3+ months legally or cooling-wise
;)

Eric West <eric@mcsdigital.co.nz> wrote:

I looked at a 1.6 parked in the street today and noticed that the plate
is attached to 2 brackets screwed into the top of the "mouth" and
pointing upwards. This places the plate above the mouth. If the brackets
are on "upside down" this would place the plate within the mouth and this
would not be good. Is this what we have with Ralph's car and is his
solution as simple as turning the brackets "right way up". May be
Ross could sell him a nice black plastic mounting which Ralph could put
his plate on Eric

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