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MG MGF Technical - Considerations for the flowerpot mod.

feeling in a diy mood at the moment so am considering the "flowerpot" mod for cool air induction this weekend. any sugestions as to materials fo heat proofing, i was thinking of making the whole thing out of sheet aluminium, rivited, with 2 holes for the K&N pipes.
what do you think?
are other vent holes required in the "pot" or will the 3 do? (2 induction inlets (pipes attached) - 1 k&n pipe outlet)
will it be best to fasten it to something or let it hang off the k&n?

thanks for your input

Hi Kingsley. If you are going to do it, then do it right. The 2 pipes which hang down are ment to go under the car. All you have to do is contact Tom Randell and buy the bracket which clips to the under side of your car. With the bracket in place the 2 hoses point forwards, which is what you need them to do. The price is 10 all in. 5 mins to fix. Job done. Are you going to Stonely? (If you can find it... Ha Ha.) See You Soon. Paul...
Tom Randell. Forest View. Farnham. Surry. GU101LW.
Send the man a cheque.


If you are going for the enclosed system, I would remove the pipes from under the car and route them to the side intake. Better still replace them with a single larger diameter pipe as it will be easier to attach to your box.

Spyros Papageorghiou

I agree with Spyros.

Here's what I am going to do with my Rover 820 EFi airbox, bought for a tenner from a local scrappie...

1. Yes, the airbox will need to be rigidly attached. You don't want too much weight hanging off the end of the plastic throttle body; distortion of the throttle is likely if you do, and this is something that is best avoided at all costs.
2. Because the airbox will need to be rigidly mounted, the tube between the throttle body and air box will need some flexibility to absorb some of the movement of the engine. The OE flexi-tube is not efficient, but will do the job. Better is the tubing that comes with the ITG kit- anyone know where to buy this separately?
3. Totally agree with Spyros- a single large diameter tube is better than two small diameter tubes; resistance to air movement is significantly less and therefore air intake velocities can be be that much faster for improved high-rpm performance.
4. Again, in full agreement with Spyros- as you now have an enclosed air intake system, the nearside air vent is the best location to draw air from. Why? Because air in this area is practically stagnant. Still air= high pressure air. This requirement is completely changed from the air intake system for the 57i kit that requires a blast of cold air to work properly- this is because this is an open air intake system, if you know what I mean.

There are some other ways to improve high- engine speed power. Where you have the cold air intake entering the air box, if you increase the diameter of the pipe gradually, you'll have a situation that as air enters the airbox, it accelerates as it passes through this 'choke' - basically the pressure drops as the diameter of the air intake increases. This relative 'vacuum' acts to suck more air in- and thus you set up a neat 'ram-air' effect. This is the reason why the ITG 'box is designed the way it is.

good luck with your DIY Kingsley- I want to see the pictures of the finished work! :o) I plan to work the old Rover air box in the next few weeks or so... we'll have to compare notes!
Rob Bell


You could make the whole thing in Ali if you've got the panel-beating skills. Unfortunately I haven't, which is why I went the flowerpot route then covered it with self-adhesive Ali tape to prevent melting and this has worked well since around July last year.

While you're going to the trouble of making your own cover, why not replace the two little K&N pipes with one big 100mm diam pipe courtesy of Wickes? This will connect into the side vent avoiding all the clearance and dirt pick-up problems of the normal method. This big tubing is much smoother as well, so it should give better air delivery. The only problem is that the tubing doesn't bend very easily, so you need to make the air inlet in the side of the pot rather than in the end. You will also need to think about a connector onto the airfilter. The obvious solution would be a spigot placed between the air filter and the throttle body for the rubber tubing to fix onto. You can then weld a flanged disc onto this, which matches the inside diameter of the "flower-pot". The connection between the the flange and the pot needs to be robust, but if the fit is good, you would probably get away with just three self-tapping screws.

If you get the length of inlet pipe(s) right, you won't need any additional support straps, (not that there is much room anyway) and you certainly don't need any additional vents.

I doubt if you would need any insulation in our climate, because the residence time of air in the pipe is too short, but this is another factor to play with later.



I will work out some designs tonight and see if i can find some larger bore pipe tomorrow evening..
I shal make notes and take digital pictures throughout the make for reference.

This is gonna be fun!

Hi Kingsley

In case it helps the dimensions of the flowerpot I used are

inside diam of large end: 190mm

inside diam of small end: 140mm

length along axis 165mm:

This size of pot only gives a clearance over the K&N of around 25mm, but a larger pot would not fit in the space.
Even so you need to assemble the filter into the pot before wangling it into place. The next job is to rotate the K&N tubing to get the optimum clearance and the last part is to rotate the pot to get the best angle for the 100mm tubing to the side inlet.
I use the inlet tube to support mine, mainly because I couldn't find a convenient place on the engine to fix a support strap to.

Good luck


MS is now doing a closed box induction system the PiperX Viper at 230GPB. He may be able to supply individual bits.


Gaz, Kingsley

I'm a bit out of touch with where MS has reached with his filter-casing, but last summer he had a superb prototype in carbon fibre which looked like it would take either a K&N or a Piper X. This was very expensive so he was looking around for a metal spinner to reproduce it in aluminium.

The quality of Mike's parts is always excellent It's probably worth giving Mike a ring to check on price and availability. I'd be interested to see how he solved the support problem as well.


Chris, >my support problem!< I told you not to mention the truss ;-)

truss you to let the secret out...

This thread was discussed between 29/01/2002 and 30/01/2002

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