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MG MGF Technical - Air Induction Kits - now not so sure !!

Following the earlier thread on "Improvements" to your F, I had decided to install a K & N Filter with Air Induction kit and mentioned this to a respected Engine Tuner who said it was a waste of time, the "mickey mouse" air inlets wouldn't do anything and may in fact drag up moisture/water as they were fitted so low causing all sorts of possible engine problems.The only one he recommended cost three times as much !!
My point in all this is that I have just looked at where the bell shaped air inlet for the filter already exists on the car (2001 F 1.8i)and am wondering if anyone has extended this by adding either a further single or twin tube to a position where it wouldn't seemingly be drawing in the hot air from the engine ?
Are there any modifications that could be done to the existing filter box ? (apart from changing the filter itself)
Any thoughts would be appreciated.
John Mac'

Changing the filter for a K&N panel filter,

Yes, moving the air intake may help some, we think it was moved there to help with noise problems.

Also some elise guys (IIRC) have added an extra huge intake by cutting a hole in the bottom of the normal box and feeding that to the side intake for cool air -IIRC they kept the normal one too, but I'm not sure if they moved it to a high position to stop water being sucked in.
Will Munns

I had a K&N induction kit on for years with no problems at all. You need to keep the filter clean and waterproof by following the instructions. As long as the pipes are the correct distance from the filter there should not be any problems.

The main problems are keeping the pipes intact and in position under the car mine lasted less than a month before designing the bracket which is recommended quite a lot on the BBS.

If interested in a barckets email for further details, they cost 12.

As for what you engine tuner said about being a waste of time I disagree as for value for money against BHP gain then the K&n wins hands down. I replaced my K&N for a ITG maxogen filter which is 3 times the price but hardly any difference in performance except maybe different torque curve.

Tom Randell

John, the respected engine tuner makes some valid points - the K&N 57i has some significant design weaknesses as a way of improving performance. For starters, it is an exposed cone air filter, that sits inside a metal box that is warmed up by the presence of the engine.

Hot air = less power.

The cold air ducts do improve the situation however - as Graeme Bishko's measurements demonstrated: but it only works while the car is on the move.

The comment regarding water ingestion is not warranted however - the chances of any water entering the engine via those ducts is very remote, and the K&N is pretty water resistant (and hence is used on water jet-skis!)

What many people buy the K&N for is the fantastic noise. It sounds brilliant. However, you can enclose the filter for a few pennies (flower pots are one option, I used a Rover 820 airbox for my car). Doing this really does work - and does very nearly as well as filter kits that cost 300+ quid...

Regarding using the standard airbox, a panel filter doesn't add much unless you can attend to the intake system. The intake system is much better on post 2001 MGFs - but even then, if you can route a large air intake duct from the LHS engine bay grille to the airbox, so much the better. Bruno, Roger Parker and others have shown terrific results by doing just this - and again, the results are seen for peanuts investment...


if you want noise and extra performance but with compromises, go for the K&N 57i
If you want a cheap filter up grade, go for a panel filter in the standard air box and run a bigger cold air intake from the LHS air intake
If you want the noise and the performance, enclose a cone airfilter in an airbox, and draw air from the LHS air intake.

Hope this helps!
Rob Bell

Thanks chaps for some very interesting and valid comments.
The "ITG" filter Tom mentioned was in fact the type "my man" named, but at about 300 compared with K&N's 100 that's a massive cost difference for little change in performance IMHO.
For a few pounds I think I will try the Filter change and more air in route. The existing intake measures 44mm dia. almost exactly the same as a Plumbers plastic or copper "Y" piece, inserting this and then routing two 42mm dia ali. flex tubes to the side air intake may be worth having a go at. It would be interesting to have had a rolling road test before and after but with a difference of only about 3-4 BHP as an expected gain, I doubt if it would be worth it and even accurate under test conditions (with all the variables etc.)
Anyway I will have a play and in due course report back as to what happens !!
Incidentally Iv'e heard the "difference in sound" mentioned before when fitting K&N, is this purely air intake roar ? how "noisy" is this behind the passengers head with the roof off, at the moment the hardtop is on (coward)- (its the wifes idea - honest !) so I don't suppose sound level inside is greatly affected ?
Thanks again.
John Mac'

John, for some real noise, fit the K&N 57, remove the sound deadening material from the parcel-shelf and put the hard top back on :-)

Did this for about a month last year, its not quiet !!!
Neil Sutton

Yeah I've actually found the car louder with the soft top up rather than down for engine noise. Can only be resonating from the engine bay with the top up. With the top down the parce shelf is covered and obviously deadens any noise (sound) from the engine bay.

>> respected Engine Tuner who said it was a waste of time <<

I had exactly the same experience after talking to an engine tuner. He pointed out that the excess dust, floods, and overall tropical climate of Cyprus are all no-no's when it comes to open air filters in mid-mounted engines. Needless to say, today i'm the more than proud owner of MS's enclosed Vader Cold Air Induction Kit.

Not only does it provide a subaru type sounding snarl above 4000 revs, but it's made the whole car so much more response and dare i say... FAST?! : )

Previous filter was wired up the wrong way (beleive it or not), and was just doing nothing but taking space... hence why it's now sitting in a box in the garage! :-D

JW Ioannou


I have just a question, what are you calling "LHS air intake"?

Hi Titou, i'm sure Rob is referring to the Left Hand Side air-intake.

JW Ioannou

Thank you for your answer.

I have got a vader cold induction kit too and I am very happy with it. I have draw air from the LHS air intake too, and JW I think that I am the second more proud owner of this kit.

Following on from that worthwile debate, I have seen an F, an MPi, with a chrome open cone shaped filter attached directly to the plenum chamber, jubilee clip attachment.
Casually asked the owner what he thought of it, said it was great, good roar when booted, cost 8 from E Bay.
How good is this, it obviously sucks in hot air from the engine compartment, short term/long term effects anybody ?

Adrian Clifford

I'm no engine diagnostics engineer but would have thought all that the owner was achieving was an impressive "roar" without any improved car performance, in fact probably the other way.
As I understand it the whole point of the "air induction kit" is to bring in colder air that is more dense, this contains more oxygen hence better combustion and performance - I stand to be corrected if I'm wrong.
John Mac'

The K&N with or without cold air induction kit aids the air flow to the engine as the original *F* system was extremely convoluted and so strangled the flow.

I found an immediate improvement in engine acceleration when I fitted my K&N about 6 years ago and was able to hit the rev limiter very, very quickly even before I installed the cold air kit.

BTW I have a MPi and I still think that the K&N is a worthwhile addition - OK it will not give a huge performance increase and no doubt that is why the insureres that I use, or have used, have never loaded my premium.

And as for the <respected Engine Tuner who said it was a waste of time, the "mickey mouse" air inlets wouldn't do anything and may in fact drag up moisture/water as they were fitted so low causing all sorts of possible engine problems> anyone with such an arrogant attitude should have their advice taken with a very large pinch of salt. To drag (or push) up water you would have to be going at a very high speed and if you hit water that deep at that speed I think you might just have other things to worry about.

All IMHO of course.

Ted Newman

I was trying to guage technical opinion as to benefits against deficits re cold air and hot air. I understand fully what you are saying John and Ted, is there a down side to this sort of filter, we all appreciate only a nominal bhp gain but the engine breathes better. Providing the filter is cleaned as prescribed, looked like a five minute job to take out, no engine comp cover to remove.
The colder, denser air is of course ideal so can we berate this simple system or are we (you) OK with it ?

Adrian Clifford

>> How good is this, it obviously sucks in hot air from the engine compartment, short term/long term effects anybody ? <<

How good a 'filter' is an 8 bargain bucket filter going to be? How much dust is going to be ingested by the engine? That's the sure passage to engine damage.

As for its location - I've done the RR tests: putting the filter straight onto the throttle body like that DROPS power by around 5bhp peak. Add in the losses due to hot air, and you are probably looking at a total 15bhp power LOSS unless cold air can be delivered to the filter...

However, without doubt, it would sound great... ;o)

Adrian, the 57i kit is a compromise. It sounds great when you're accelerating, but for constant throttle openings is barely any louder than standard. It does release more power, but cold air supply is absolutely crucial to see it.

My own solution to the "K&N problem" can be found here:
Rob Bell

Being a "newbie" to F ownership I didn't realise how much must have gone before on this subject of "air induction kits".
Rob - your article is brilliant and written so that even I can follow it, I think a visit to the scrappy may be on the cards for the Rover Air box !!
Ted - somewhere I had seen an illustration of the K&N air inlet pipes slung on the underside of the car and they looked extremely low. Having recently sold my TVR and changed it for the F, the last thing I wanted to do was to start losing pipes from the underside again !! as most probably know the exhaust system on the TVR "S" series was very low and speed bumps in my area precluded many a road to drive on.Where the K&N pipes appeared to be located they could I thought quite easily have scooped up water and certainly dust from certain roads that I as a necessity must drive on.
Anyway, its an interesting thread and I've certainly learnt a lot and it would seem now for a reasonable cost and some DIY I may get a little more poke - sadly I'm comparing perfomance with the TVR and I know I will never match it (Oh dear have I started another debate !!)
Cheers all.
John Mac'

John, comparing performance in different cars is all relative, I have a F (with K&N of course) and a Scooby and enjoy both, although point to point the Scooby is so much quicker.

Why did you sell the TVR?
Neil Sutton

I have had a K&N on my VVC for several years - a rolling road test showed it added about 15BHP. I fitted Tom's bracket and have never had any problem with the air pipes - despite the car being lowered.
Another benefit is that those cold air tubes keep other components - notably MEMS / ECU - much cooler.

Water has not been a problem - but I guess the filter needs to be cleaned more than once a year.

Hi i am thinking of bying a new filter but what one,on my list is the itg or the taipan what do you think thanks Mark

Neil - you asked "why did I sell the TVR" - two main reasons.(1)
The wife stopped going in it because it couldn't have a hardtop fitted especially for the Winter and she felt vulnerable with the top down. (2)they saturated the roads around here with speed humps many that I maintain were above the legal limit ( should be max 100mm on a Public road)I kept grounding out the car and in the end got really fed up with it.
Hence along came the F, bought a Hardtop (other half now happy), car rides higher, can now clear the humps.
Hasten to add the Hardtops shortly coming off and I'm yet to find out if I have a passenger !?
John Mac'

>> Anyway, its an interesting thread and I've certainly learnt a lot and it would seem now for a reasonable cost and some DIY I may get a little more poke - sadly I'm comparing perfomance with the TVR and I know I will never match it (Oh dear have I started another debate !!) <<

LOL! Well, you could always save up your pennies and fit a supercharger John... ;o)
Rob Bell

Rob -I used to have a Wade supercharger on a Special I built many years ago - but that's another story.
Supercharge an F ?- wouldn't that mean sacrificing the boot space !!?
John Mac'

Nope, just a lot of cash (6k!!!)
Will Munns

John, I can now understand why you sold the TVR. I have just have the pipes supplied with the K&N kit (I have Tom Randell's bracket but never got round to fitting it) and to my knowledge they clear speed cushions which they have around my way. I tend to keep my Hardtop on to about April, still a bit cold out !!!
Neil Sutton

Just to Add I had a K&N 57i on my 1.8 I then went for the Tiapan and for an untrained non tech driver I could feel the power difference immediately, I suppose thats the best test, just put it on and see if you feel the difference, but yeah the noise of the K&N is nice

Jon (NSE 81V )

I had a K&N 57i, great filter good for noise and performance I'd say. My main issue was that it suffered in warmer weather, and I could really feel a the differnce.

Had a ITG fitted recently, again drawing air from the Left Side Grill. Not a huge gain id say over the K&N but it does feel a lot more consistent if that makes sense, smoother and less flat spots on acceleration. Miss the K&N roar though I must admit but the daytona makes up for it! Im sure i'll notice its worth even more when the warmer weather comes into hopefully in the summer.

Hope this helps.

Thanks Rob, that sorted that one out. Hope the guy, who's F it was reads these pages !

Adrian Clifford
Will Munns

Sheer boredom this evening led me to this page

Quite impressed when their webpage detected where i live and actually displayed prices in local currency : ) not sure what rate mind you ; P

Interesting products for those interested...

They also claim to have the lowest prices for K&N (emphasis on the claim part)

Perhaps old news, perhaps not... just thought i'd share my find with you!
JW Ioannou

Will - the Pipercross kit on e bay is not suitable for the MGF (according to the seller).
Thanks anyway for the link.
J McvGregor

This thread was discussed between 14/02/2005 and 20/02/2005

MG MGF Technical index

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