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MG MGF Technical - K & N air filter yes or no?

Dear All,

My mechanic is encouraging me to fit a K & N filter, quoting improved performance and fuel economy.

Car is 1996 standard 1.8 - currently running perfectly. My questions are hopefully simple ones:

1. Full induction kit or not? If yes is making this conversion difficult and will the car need to be re-tuned?

2. Go for the one for one filter replacement?

3. Car is running very well at present - therefore either option not worth the effort?

Your thoughts & comments as ever are very appreciated.



E J Davies

Why not go for a cool air intake from the side vent you can easily fit a duct to the existing filter box and fit a K&N panel filter in place of the standard paper unit. See for how you could do it!
Mike Cunningham

pretty much you'll not notice any performance diffrence, but more engine noise will give this sensation :)

The K&N filter doesn't need replacement or regular cleaning (well it does, but not regular like "I'm a regular at the pub", more like every 5 or ten years).

you will have to declare it to the insurance and this might make it more expensive in the longer term.

No engine retune required
Will Munns

Sounds Grrrrrrrrrrrreat though!!!!
Sam Murray

No too noisy for me.
My route mgtf 160 air box which has much larger filter surface area than original F and with twin inlet pipes with proper bellmouth ends you will need the fixing bracket too as this is different. Fit this with a performance air filter ( I bought an ITG filter element ) and you get the airflow without the noise and you can pipe the cool air from the side vent using the standard inlet pipes.
Add a 52mm throttle body and the car now pulls 5th gear from 30mph.
You do have to cut away part of the plenum that the standard air box connects to on the early F.

Dave Karle Kar-Solutions
David Karle

I remember reading in Enjoying MG some time ago about a racing MGF fitted with K&N filter(s) and they found the engine was clapped out after a season's racing. Using a better filter during the next season the engine was then fine for another season. I believe the K&N has much bigger holes which let in more air - great but not much good at fine filtration. You takes your pick?
Pete Tipping

I have a K&N Cone Filter fitted to my 1996 1.8i and so far it has not suffered from "poor filtration" -- mind you I have only had it fitted since 1997!

What I can say is that it does allow the engine to breath much more freely than the original filter and of course they should be cleaned and re-oiled from time to time.

However do remember there are many different types of K&N!

Ted Newman

Getting old now - after all, I've had a K&N of one type or another fitted in my car since 1998 - but this may of some help:

The 57i kit sounds amazing, and with a standard exhaust, isn't really any louder on a cruise than standard. Blip the throttle though, and you'll be beaming like a mad man... ;o)
Rob Bell

Hi Elona

I fitted and ITG panel filter to my 1.8i and re-routed the air intake pipework to the side vent.

I spent 40 quid on the filter and another 30 quid on parts for the pipework and funnel and spent a couple of hours of time doing the work. To be honest, I noticed no difference whatsoever in terms of performance or noise.

I'm sure as Rob says the 57i kit will give you a smile or two with the increase in noise under acceleration, but, perhaps that's about all in real driving terms.

Money probably better spent with the increased flexibility the throttle body should give you - which, in addition, in the engine compartment is a very discrete upgrade compared to the 57i kit so on that basis whether you declare it on the insurance is, I guess, up to you.

M D Allen

MD ,

Thank you for your reply. However I do not understand what you are referring to. Are you recommending a new throttle body? Can you explain further in simple non mechanic language. What is it, what do I I change and why, will I notice it, what is the advantage is it a DIY job or do I need a mechanic?

Apologies for all of the questions non-technically minded female at this end.


E J Davies

The standard MGF 1.8i, MGF VVC and MGTF 135 have a 48mm diameter throat to their throttle bodies, MG Rover fitted a throttle body with a 52mm throat to the MGF Trophy 160, the TF 160 and the ZR 160, this 4mm increase in diameter makes for a significant increase in area of the throat. Fitting one gives a small increase in power to both a 1.8i and a 1.8VVC and also improves the engines flexibility. It is a simple bolt on replacement. The 52mm throttle bodies are also made out of aluminium, the early cars have a plastic throttle body which can distort resulting in a sticking throttle.
Dave Kar-Solutions
David Karle

I have fitted to both an MPI and a VVC 52mm TB plus K&N had an imediate increase in pulling power witout any loss of MPG. Unless you have a Trophy160 or any TF160 it would be a number one modification and one of the best for value for money.
Andrew Regens

Bear in mind that on a standard MPi or VVC engine the limiting factor is NOT the throttle body diameter. When MGR designers chose the 48mm diameter TB, they would not have done so if it wasn't capable of handing the engine's requirements. Fitting a 52mm TB simply 'adjusts' the point at which maximum airflow is achieved relative to amount of pedal movement - if with the 48mm TB the maximum flow arrives when the pedal is pressed to the floor, the 52mm TB reaches this point at approx 80% of full pedal travel. The remaining 20% of pedal travel to the floor becomes superfluous. There is certainly a benefit in having the alloy TB over the plastic version, and the car will 'feel' quicker with the 52mm TB because an inch of pedal travel results in more airflow than with the 48mm version. If you were to put the car on a dyno, the maximum power remains absolutely identical. Only when the rest of the induction path is opened up, i.e. ported head, more aggressive cam profiles, aftermarket ECU, will the aiflow get to a point where the extra throughput of the 52mm version is actually required.

The improvement that a K&N gives, i.e. removing the restrictions inherent to the standard airbox & convoluted path the incoming air has to follow, is the best value for money and definitely improves the 'sporty' feel of the engine. Power increase realistically is a few bhp, increasing to around 5 if you enclose the filter element to ensure only cold air goes into the engine.

I went for a Vadar induction kit with a 52mm TB and it's awesome, it's more expensive than a K&N but this is still relatively cheap power.

I removed my old air box and re routed the inlet to draw cold air from the LH engine duct and it works well and looks pretty cool too. I can throughly recommend a cold air induction system over anything that will be drawing warm air from inside the engine bay...

I fitted one and it made no difference apart from a more Jap sounding whine type noise. This is now almost completely drowned out by the mid-sport MIJ quad exit exhaust system I fitted after.
Martin Costin

Hi Elona,
I went for the K & N panel filter and it gives pick up just fine, little bit of grunt when you need it and sounds good too.
Initially when I was buying an MGF back in 1999, I took a demo model with a K & N cold intake induction kit on it for a test drive and didn't like the "buzz" noise but I prefer the noise of the panel filter in my MGF. I wouldn't change it for the world.
Cheers Sue
Sue Wilson

"You're having a laugh!", says I to the man at the insurance company recently (the one with Bulldog), when I told them that the F had a the K&N filter fitted by the PO and he wanted to charge me an extra 120.00 per year.

So it's either Bye Bye to the K&N or the the insurance company, not sure which yet.

Just be warned people, if you fit one and don't tell your insurance company, your policy may be void when you try and make a claim.

Chris Bond

Chris, you should check out a specialist insurer if you're undertaking any mods. The AA hit the roof when I said what I had in mind, but A Plan's specialist MGF branch only loads a premium for forced induction and nitrous, and they were cheaper, so happy days ;)

Hi Elona,
Which filter did you decide on.
Cheers Sue
Sue Wilson


With all of the contradicting advice - yet to decide.
Likely to go with K & N panel.


E J Davies

In the USA it is unlikely the insurance company will care about a 4mm larger throttle body. Here in Canada you could install a supercharger and the insurance company really could care less.
It really is a different ball game in North America.
(We Are Very Far From Brussels!)
Rich McKIe

This thread was discussed between 10/09/2010 and 04/01/2011

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