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MG MGF Technical - Halfords air duct tubing

Who can help?
I have found the metal air ducting tubes in Halfords. I intend to duct cold air from the LHS vent up to the standard air filter box. The ducting is only about 20 cms long in the packet with no information as to the length it will stretch to.
Any ideas to the length when pulled?
Thanks all

The ducting from halfords does not extend very far. I tried to use it for replacing the airpipes for my KN filter from under the car to the filter. They only pulled out to approx a foot or so, so were not long enough for the job.

Before you connect up the pipe, first look through the archives here. You do not seem to get much air through these side vents so even though you can buy a purpose built pipe with fittings (approx 40) to go via that vent not much air will be fed to your airfilter. There definately is not enough to feed a KN filter anyway with the correct 'blast' of ram air needed.

Keith Williams

I bought a K&N from an Elise owner so had to use Halfords ducting for the cold air feed. They extended fine all the way from the subframe to the filter, so you should be fine just to the side air vent. Maybe there are different lengths available?

Tim Jenner

Sorry Keith but I disagree. I ran a K&N with the normal air pipe arrangement (scooped up from under the car with a 4" gap to the filter) for several years.

Since then I have enclosed the filter and piped air in from the LHS vent.

The car has more mid range torque now than it did before, in fact this modification filled in a sizable gap in my torque curve.

You are correct that there is no RAM effect below about 120 mph from the side vents, but you gain a good supply of cold air with more than makes up for it. My understanding is that the induction of the engine creates a negative pressure, which in turn draws air in from the side vent, rather than the air being forced in.

I don't think that the Ram effect does a lot for the std K&N arrangement anyway. As air moving a speed will hit the side of the filter and be deflected off. However what the std arrangement does do is site the filter in a stream of moving air that is cooler than the surrounding air in the engine bay.

The ultimate I suppose would be to force more air in to the side vent thus increasing the positive pressure and assisting flow in to the filter.

The choice as they say is yours!
Steve Ratledge

So is there a site that shows the way to fit a pipe for 40 to the LHS vent and up to the filter?


The airpipe I mentioned can be got from Moss who have a catalogue and good web site. See below. It seems an expensive way to do it for a short length of pipe with a fitting but may be easier than designing a clamp etc yourself (cost approx 45)


My comments re: the KN and airflow were only what I have read on here. It seemed a good idea to me to feed air via the LHS vent as there is no risk of 'ripping' the airpipes off the car (again) when you cross too highere speed bumps but there seemed more info against doing it than using it as a method.

As you say, take your choice and see how it goes

Keith Williams

Keith, Steve,
Many thanks for your threads.
Keith, I agree the price is a bit high but to do the job without hassle sounds good. One can spend loads of time improvising and this costs money, but fun.
As you said, it is a case of cold air and not ram effect that is important as I understand things.
Thank you both

note, this will only work with an enclosed filter
Will Munns

This thread was discussed between 11/08/2004 and 13/08/2004

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