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MG MGF Technical - Induction kits

I am looking to fit an Induction kit to my F (VVC) and have a couple of Qs.

I was going to fit a K&N inside the Rover 820 airbox. I have now bought a Montego Diesel airbox which is the same as the 820 airbox but usefully has 4 bolts around the outlet, should make it easy to make a bracket.

My Q is this: If the inlet to this box is 76mm (3") will enough air get into the box/engine. I know the outlet to the engine from the K&N is 76mm (the filter I want to buy) so I would have thought the inlet is sufficient.

I was going to buy the 57i Induction kit but at 90 it is expensive when the filter is under 50 and ducting is cheap from somewhere like B&Q. I am just wondering if the airbox robs the engine of air?

I know everyone says the K&N filter is great for the VVC and adds a useful increase in power but, compared to a panel filter in the standard airbox, Why? or should that be How? My son asked me why I was fitting it and although I can quote figures and proof I can't actually give him a reason. Can anyone help?
Kevin s

I believe it's as simple as the restrictive design (for sound reasons on a new car) that make the OEM air box a bit restructive.

All after-market airbox designs are less restrictive and sound louder (thus wouldn't be acceptable as OEM on a new car).

Then you can get into the art of tuning the inlet length etc. Try attaching the KnN directly onto the throttle body and see how the car drives. Very intersting. :-)

Paul Nothard

The inlet diameter (3") is the same as the narrowest point on the ITG air filter, so no worries there Kevin.

Regarding the filter you insert inside the airbox, you need not use a K&N. I did, simply because I already had one on the car! But you could use any cotton/oil matrix or foam filter. One of the filters sold by Pipercross is a perfect fit and only costs about 20 quid.

Actually, I suspect that K&N may actually sell a filter element for the 820 airbox that you could use instead...

I'd recommend something like a Samco 80mm- 70mm (check these numbers - details on website) reduction pipe to attach the filter box directly to the throttle body if you are planning the replacement element route for the airbox.

Why are you bothering with an airbox? Because it is all down to cool air.

The K&N 57i is great - especially if you are cruising along, and the cool air scoops are helping to cool the engine bay in the area around the filter. The problem is at slow road speeds: the air around the filter heats up, and you LOOSE power. The airbox erridactes this problem :o)

If you compare the expensive ITG with the 820airbox solution, you'll see that the power curves are practically the same - until right at the top end, which is where that extra couple of hundred quid earns you 2 bhp...
Rob Bell

This thread was discussed on 26/07/2004

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