As someone who runs a factory V8 I have seen mine idling in the red when
stuck in traffic after a fast run in ambients in the high 90s. When the
standard rad split twice in quick succession I took the option of fitting an
uprated rad with an extra row of tubes, otherwise visually identical. It
did help some, but not as much as I was expecting, but since then other have
said that a 25% increase in cooling surface within the same external
dimensions will not result in a 25% increase in cooling, for when the air
passes over the last row it has probably absorbed nearly as much heat as it
can.
The biggest improvement in fan cooling came from investigating the
30-year-old electrics. I found I was losing about 3 volts to each fan i.e.
nearly 20%! This was a combination of less than perfect spade connections
and volt-drops inside the relay (causing it to get hot in use so easily
detectable). But the biggest problem was that although the fan system uses
slightly heavier gauge wires to carry the 12v to the fans, it only uses
standard gauge wires to ground! What's more this is common to both fans and
all the front lighting, and has a long run before it reaches the body. I
provided a local ground (in addition to the existing to help the lights) for
each fan at its mounting bracket, and even when the first ground was
connected there was still a noticeable increase in fan speed when I provided
the second. The final improvement was to run a thick brown from the spare
alternator output spade to the spare input spade on the replacement relay, a
distance of about 12 inches, and this gave another noticeable increase in
fan speed as well as boosting the voltage to the remainder of the cars
electrics as effectively it now has a 'ring main' with double the current
carrying capacity. Now I can almost suck the car along using just the fans
;o)
In recent ambients of 34C I shut the car in the garage and managed to get
the air temp at the rad intake up to 41 degrees, but the temp gauge was
still only reading 1/3rd the way from N to H. It was stuck there, and the
fans were never going to get it any lower, but it wasn't getting any higher
either (it did go all the way up to the red when I disconnected the fans
just to check the gauge).
When I had the temp probe immediately in front of the fans I noticed an
increase in intake temperature just by releasing the bonnet catch, and
unlike the 4-cylinder car there was never any foam sealing the top of the
rad to the bonnet when closed, so that is the next trick as even when fully
closed there is a gap of about 3/4". Also I have been thinking about
shrouding for some time as the standard fans are so inefficient.
PaulH.
----- Original Message -----
From: "Barrie Robinson" <barrier@bconnex.net>
To: "James J." <m1garand@speakeasy.net>; "James Nazarian" <jhn3@uakron.edu>
Cc: "Paul Willoughby's Home" <paulwillou@socal.rr.com>; "v8"
<mgb-v8@autox.team.net>
Sent: Friday, August 22, 2003 12:03 AM
Subject: Re: was timing, now Engine Compartment Hot Air Exit
> Many moons ago I sent a message out to the MGB V8 list asking for info on
> their cooling configurations and their results (Runs too hot most of the
> time, runs hot some of the time, runs hot in traffic jams, bloody perfect)
> but I only got 13 replies. One thing did stand out and that is the
> majority of almost perfect cooling was from people who used standard MGB
V8
> rads and the standard MGB V8 dual pusher fans - strange but true. I only
> wished more of our 179 members on the list had responded.
///
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