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Re: BJ8 Projects - never 'seal' a cold air box & use it as a

To: "Healey List" <healeys@autox.team.net>
Subject: Re: BJ8 Projects - never 'seal' a cold air box & use it as a
From: "Chris Dimmock" <cd3000@bigpond.net.au>
Date: Tue, 3 Aug 2004 08:46:20 +1000
Just in case - can I just add that you should NEVER make a cold air box
which is sealed, and try to 'ram' or 'force' air into your carburettors.
Many people have tried this in the past - hoping that fresh air being forced
into the carbs will give a 'poor mans supercharger' effect & improve
performance.

It won't.

If you 'force' air into SUs at greater than atmmospheric pressure, there
will be one result - melted pistons from running too lean, usually resulting
in a complete disaster. A supercharger compresses the already mixed
air/fuel - i.e. the carb is first, then the supercharger, then the engine.
Forcing air into the SU at higher than atmospheric pressure just makes the
car run lean - too much air, not enough fuel. Remember the discussions on
richening SUs before Lake Tahoe because of the altitude?

A cold air box should have holes at the back to ensure it isn't pressurised.
This is critical.

Modern motorcycles that benefit from 'ram' effect have computer controlled
ignition/fuel injection systems to prevent the engine from running too lean
at high speed - ie they change the air/ fuel ratio depending on air
volume/pressure.

Best regards

Chris
www.myaustinhealey.com


----- Original Message ----- 
From: "James Sailer" <heliskier@direcway.com>
To: <rusd@velocitus.net>
Cc: "Healey List" <healeys@autox.team.net>
Sent: Tuesday, August 03, 2004 2:49 AM
Subject: RE: BJ8 Projects


> Hi Dave..  thanks for the input ...
>
> Re: cold air box ..  I am designing a box to draw air from the heater hose
> and bring it across the top of the valve cover and between the two HD8s.
I
> will re-route a heater intake to down the inside of the fender ..... Am
> planning a cylindrical air filter to be positioned over the distrubutor ..
> who knows .. It may even work!...
>
> Jim

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