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RE: Cold Air Joy was Re: Engine mods and reliability

To: "'MGS'" <>
Subject: RE: Cold Air Joy was Re: Engine mods and reliability
From: "Wil Boucher" <>
Date: Mon, 30 Sep 2002 10:08:30 -0700
If I understand the description correctly...

Here are a couple of photo's taken from "MGB, The Illustrated History",
published by Haynes...

Pages 193 and 196  show how 'Cold air intake' was done on '8 DBL'

(one hose goes into the cockpit to keep the driver cool, and the other
one feeds near the carb.)

I apologize for the poor quality of the reproductions...


1969 MGB 

> -----Original Message-----
> From: [] On
> Of Eric
> Sent: Monday, September 30, 2002 7:33 AM
> To: MGS
> Subject: Cold Air Joy was Re: Engine mods and reliability
> Eric wrote:
> >
> > My big news was the difference that my 'sort of' coldbox made.
> > Pipercross filters and 'stub' horns on the SUs has meant that they
> > been sucking in hot air from the engine bay.  Without messing around
> > with a 'cold box' over the SUs I just made a 3" hole in the radiator
> > shroud and ran a 3" flexible tube from the grill to just in front of
> > filter.  What a difference it made.
> >
> Pardon the garbled nature of that description - I really was just
> rushing out the door at the time but felt I needed to tell my little
> success story.  I am sure many of you know what a "cold air box" is an
> what it does?  :-) but for the others basically I am now feeding lots
> cold, fresh air into the carbies instead of the hot stuff in the
> bay.
> The PiperCross filter and short ram tubes were fitted in an effort to
> get more air into the carbies as I felt the rather heavily ported head
> through to the extractors had a bottleneck in the breathing department
> with the 'standard' MG SU filters.  I didn't really think far enough
> ahead in that by solving that problem I would be introducing another
> ended up quite disappointed that I didn't get the power boost I was
> after.  In fact I really picked up the fact when taking off to work in
> the morning my car seemed to have more "get up and go" than it did by
> the time I was halfway to work - really!
> But I will leave someone else to better describe the theory behind my
> $20 modification that has brought me such joy and a noticable boost in
> horsepower, noticeable on and off the racetrack.  That is, a
> boost over the reduction in horsepower that my shortsightedness had
> caused.  Obvious to many but completely missed by me at the time
> me feel a little silly).
> From
> Cold Air Induction
> If you've taken chemistry classes, you've probably seen the ideal gas
> equation, PV=nRT. This relationship between the pressure, temperature,
> and volume of a gas indicates that if the gas is colder, it's denser,
> and denser air will provide more oxygen, allowing your car to burn
> fuel and make  more power. A common rule of thumb holds that
> air intake temperature by 10 degrees F will increase horsepower and
> torque by 1%. The converse is also true; a 10 degree rise in intake
> temperature will cost  you 1% of your horsepower. Some aftermarket
> "short-ram" airboxes for newer imports draw in air from under the
> which might work decently with an engine that's been sitting
> but once it warms up, the aftermarket "performance" airbox will
> power.
> --
> Eric
> '68MGB MkII
> Adelaide, South Australia

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