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MG MGF Technical - Airbox Mods
|I've recently been working on some airbox mods on my m/c, and wondered if I could do something similar to the box on the mgf. I've recently installed a panel filter in the mgf, (because I, or rather the other half!,doesn't like the noise from cone filters), and noticed what appears to be a fairly restrictive intake. I thought about cutting the bottom half of the airbox away,exposing the filter to the elements,and by keeping the 'lid on' get the performance without the noise!Has anybody else tried this? what do the technical boys think to this idea?|
|Have you looked at shortening the intake. if i rmember correctly it seems to go all over the place. Would it be possible to use the origibal box but have the intake come straight from the side intake.|
Just opening the bottom of the box would result in the engine breathing hot air from the engine bay so probably wouldn't work to well, cold air is the key.
I was discusing this with somebody the other day, what was the best solution. and my mate asked what the cup cars did, i didn't know, i assume somebody here does.
Apparently at present the best method is a closed air box attached directly to a side intake so the engine can suck in cold air.
|The MGFs we saw at Spa have special air filters which go into the boot space and breathe through the boot lid. they also have a dry sump with the oil resevoir being in the boot.|
|Paul, the best solution is instead of cutting the lower half of the airbox away is to replace the intake system from below the air box with a pipe to the engine bay vent to draw more cold air into the engine. Roger Parker has some experience with this with extremely encouraging results on his own car- as indeed did Bruno on his VVC.|
Matt, the Cup cars use a completely different inlet/fuel injection system- four throttle bodies infact with a filter that sat in the boot compartment that sucked air in via the boot lid vent! Not sure how appropriate this would be for a road car though!
|I shall get on with butchering my car sharpish then....or maybe not.|
|What about this for subtle air intakes - on my favourite car....|
Carl, from Sweden had some good ideas on an airbox and also on mods to the rear side airintakes.
See this one:
The airintake mod isn't online currently, but tomorrow. I'll add this night the pictures he sent the other week.
Also Andy Gilhooley has got the modification from Mike Satur to his car. (See his webside)
Never read from him any measures.
Andy, how does it work ?
Any temperatur change to report ?
|Following discussions with Roger Parker i diverted the pipe from the base of the air box into the side air vent below. This cuts out the resonator box and the inlet at the back of the engine bay. Conbined with a K & N panel filter i've found this gives better throttle response and a pleasant noise on acceleration (this is a good mod if you don't want the full K & N cone filter noise as i didn't).|
thanks to Dieter for hosting my pict. on his site. I can really tell You all that even if the extension isnīt a "beauty " in showels in fresh air into the engine bay and to air-filter box ! Attached taped red wool-strings on the rear lid outlet was standing in 45 deg even at 100 km/h. Without the extensions they hardly lifted from the lid.... Backside is a lot more dirt, both on filter and in engine bay in general.
Regards , Carl.
|I guess that a more aesthetic solution would be Mike Satur's chrome engine bay inlet covers- it'd certainly be interesting to see whether they'd be as effective as your simpler cheaper mod Carl- nice work, and lovely idea for the vent streamers :o)|
Carl, can I ask you how the filter/filter box assembly is attached to the car? A rigid tube to the filter? How is the mass of the airbox supported? Or is the plastic sufficently light not to require an additional bracket without putting undue stress upon the throttle body?
|Must make a different sound as well I'd have thought?!|
to make enough space for the box the following was made: All of the old air-box was removed. Donīt rely on what the manual says - it is possible (with some force!) to take away the whole box downwards when the wheel is off. There is a heavy blacksmith-type bracket used for attaching the old box and fuel-filter. This bracket is taken away and the fuel-filter is mounted slightly sideways with a small alu-bracket. This is more easily done than described here,when the old bracket is taken away it is obvious how to place the new bracket and fuel-filter ! The home-made box can now be fitted, no real attachment needed as the box rests nicely on parts of panel and fuel-filter. The remaining 10 mm space left when refitting the engine -lid is filled with one-sided self adhesive soft rubber.
This takes away any rattle and fixes the box nicely.
Tubing from airbox to throtle-body is half the original rubber-tube. The old fastener is used at throtle-body side , at air-box end it is a press fit over the box extension. This reveals all possible stress from box to throtle-body.The Makrolon is a lightweight material so weight is of no concern here.
There is still a nice deep sound - but not so loud as when there is a "original" KN/ Pipercross instalation.
All in all it gives huge amount of cold air to the filter , also at a slight over-pressure and still a sporty sound. The modified air-inlets are spare ones I got from a dissmantled car,they really only come on when doing track-days ,slalom events etc.
It will be very interesting to hear abour Rogīs airscope and how that one showels in air. His aproach is of course a bit more unsighty and doesnīt change the style of the car.....
Regards , Carl.
|Thanks Carl, that is well explained.|
I've bought from a scrap yard an old Rover 800 airbox to achieve something similar to what you've made. But weight is much more of an issue- and TBQH I rather like your solution to the problem: it is a positive advantage to be able to look at the filter to observe cleanliness!
I'm a little unsure what this Makrolon material is- and even less sure as to where I can buy some! Is this stuff the same as perspex? Is it fire retardant?
Sorry for the barrage of questions!
|Its the same|
Makrolon and perspex or plexiglass is all based on polycarbonat.
> Is it fire ....
Yes it is HB, 'happy burning' regarding UL specs :)))
See stores who have construction material. In German it is a 'Baumarkt'.
Clear plastik screens for showers in bathrooms i.e.
PS going to get the spare air intake from the garage and try Carls mod also.... at any time :)
|Thanks Dieter. This stuff is readily available in the UK DIY stores like B&Q which sells it as an alternative to door glass, and can come in some particularly fetching floral leaf paterns. Very tasteful- NOT! LOL|
The stuff I've seen is of very narrow thickness- was is the thickness of Carl's material?
|I had a thought last night - what about just getting a very large tube (of the same type that is used for the induction pipes) that will go over the Conefilter all the way up to the rubber hose. At the other end, the two induction pipes coule feed into this large bore tube, and thus the cone filter would be shielded from the heat of the engine, and you would also get free flowing cold air to the filter. What do you think?|
|If I get this right, this air box is completely sealed, as was the original air box with panel filter (except for the filter of course). How can you make sure, that using the induction tubes, which provide more air than the original, the volume of air to the air filter is correct. Since thereīs no other way out for the air than throught the filter. Couldnīt this result in lean (if thatīs the right word) mixtures? |
|Sorry, I was talking about putting this tube over the K&N cone filter, rather than putting a larger feed to the panel filter. I wish I could draw it here! Basically, instead of the plastic cylinder that Carl used to enclose his cone filter, I thought that you could just place a flexible tube over the cone filter, and have the induction pipes feediing in to one end. That way you would have cold air rushing past the filter, without sucking in too much warm air from the engine.|
|Andy- I like your thinking there. The solution is fine so long as it broadens out around the filter itself to give at least an inch- and preferably more- clearance. Much less than this and the airflow around the filter will become restricted and turbulent which will loose you all the advantages you seek to gain. Also, if one hopes to use the off side vent as an air source, you'll need to seal the system around the filter.|
David, by not supplying enough air will reduce manifold pressure, reduce the charge entering the engine- effectively suffocating it. Therefore, use as big a tube as possible. A 100 mm diameter pipe will be more than adequate.
|Cheers for your comments Rob. I was not thinking of using the side vent, though this could of course work. Instead I was just thinking about using the induction pipes to provide a nice cold stream of air through the large flexible tube over the filter, in a cheap and effective manner. Rob, does your enclosed filter actually increase the pressure of air into the engine? Would you consider Nitro Oxide for when you really want to BLAT it? - assuming the Head Gasket could take it?!|
|Andy, the filter clearnace issue still stands- but by ducting air from under the car, the filter no longer needs to be enclosed. You might want to consider larger diameter cooling ducts for the best results though- but the standard K&N jobs do a pretty good job on their own judging by the filth in my car's filter!!!|
Nitrous oxide? A bit too scarey for me matey! LOL
PS still have the standard K&N kit for the present- but alternative solutions are being looked at. :o)
|Cheers Rob - I appreciate the clearance would be an issue, as effectively a tight tube would reduce the effective surface area of the filter. I fancy experimenting a bit on the weekend. Only mentioned the NO2 because it seems that it may be a logical progression from general talk about adding a little extra oooomph! I believe there are very cheap kits (less than Ģ300), with around 30% power increase at the touch of a button. However, not sure what the Engine management would do with regard to mixture! Imagine 200 bhp from the touch of a button though!|
|If I come to be wondering around a DIY store this weekend, I'll check out what diameter tubing there is available. Shower ventilator flexi-tubing is about 100 mm diameter I think, so may not be large enough.|
Anyone know where one might source some 150-200 mm light weight tube?
|Has anyone used the ITG airbox and filter??|
It's a carbon fibre replacement for the original which picks up cold air (it's sealed against the side vent I think) and has a free flow filter element inside. The delivery tube from filter to airflow sensor is a longer smooth bore pipe, so there might be a mild bit of ram charging going on.
It's reckoned to be at least as good as the K&N, but costs a bit more.
Steve Cox's Abingdon Challenge car has one, and I believe a couple of the other competitors do too.
When I was involved in the building/shopfitting trade we used to get various diameter flexible tubing from the builders merchants - used for ventilation purposes such as running to/from toilet blocks without outside windows.
|Thanks Ted, sounds just the ticket.|
Alan, I don't know anyone who has an ITG as at over 200 quid, it is significantly more (by about 100%) than a K&N. I doubt that it is 100% better than a K&N, but I am sure it has a number of advantages for all the reasons you mention- namely a fully enclosed filter system that probably does indeed include some clever detailing of air flow to optimise ram effects. I'd love one- and it comes as no surprise to hear that Steve Cox has one on his car!!! ;o)
|Quite frankly I would not be happy using a piece of tubing that might melt at the sort of temperatures likely to be reached in the engine compartment, so I would rule out PVC, (eg rainwater pipe) or PE, (eg sewer pipe). Both of these soften considerably at the temperature of boiling water and might change shape over time if used as a cover for the air filter, Salvador Dali eat your heart out!|
Plastics such as Perspex, (polymethylmethacrylate) have a higher softening point but burn too easily once they get going, however it might be a good choice to try different temporary shapes because it is easily shaped and glued. Polycarbonate has a higher softening point, but is not so easily obtained and is more expensive.
If you want to be safe, I suspect you are stuck with either a fire-retardent grade of polyester reinforced with glass or carbon, which is very easily worked if you can stand the smell.
The safest practical solution is probably to make your own shape from aluminium sheet. It may not be transparent, but it is not going to add to any overheating problems and it is cheap.
I suspect the biggest problem will be to find a suitable mounting point to avoid straining the manifold.
|Chris, I agree. But builders merchants usually hold ali tubing that would probably be ideal...|
|The London Building Regulations regarding fire are very strong and have been since 1666! As a consequence these flexible tubes were available in fire resistant materials - in those days such as asbestos but I expect they have equivalents today!|
|Spent ages on the weekend just looking at fabricating a decent heat shield for the filter and pipe. Ended up puting it back exactly the way it was after lots of playing. However, I did screw the pipes on to the bottom of the car onto the lip that you mentioned Rob. I did wonder whether just some decent heat reflective material on the pipe would reduce the expansion of the air, as this seems to get quite hot. Alternatively, what would look really sexy is some small fans of the boot vents to direct cool air into the filter area. I think the looks would be more important than any performance gains here!|
|I think you will find that the boot vents are for extracting hot air not inputting cold air - what the car needs is what Roger Parker is working on and that is the means of deflecting more cool 'under-car' air into the engine bay.|
|I would have thought that the draft you get underneath the car would be much better for drawing air out i.e. there is a greater opening at the bottom than the top. Creating some system that would draw air out from underneath the car would also help suck the car down. I belive there are lots of clever things that you can do with the underbody in this respect. Would be interesting to know whether sucking or blowing is best.|
|Airflow under the car is turbulent due in no small part to the rough and uneven surfaces. One of the characteristics is that when the air comes to a space above, i.e. the engine bay, then there is a movement of that air in an upwards and circular movement. This seems to me to create an air path that comes mainly up behind the engine and which is then encouraged to vent via the boot vents. |
In placing a scoop forward of the gearbox, which is also forward of the engine, but on one side only, I hope to divert an amount of extra air upwards into the front part of the engine bay where considerable heat energy is transferred from the exhaust. Hopefully this will see more heat energy transferred to the air with a greater flow through the engine bay and out through the boot vents. More air and more heat transferred means lower temps. Testing will hopefully provide a clear indication whether theory can be transferred to practice.
|I'm quite sure it has the likelihood of being successful. I wonder whether a smooth underbody would create better suction to the road if it were correctly sculpted, and with this suction, there would be suction through the engine area creating a flow in through the side vents and the boot vent. Just a thought. You could also attach a whopping great fan to the back and suck the car down like the Grand prix ground effect cars ;)|
As a footnote, is it so important to drastically reduce the hot air in the engine bay, when you can more effectively isolate the air into the airfilter and around it?
|>> As a footnote, is it so important to drastically reduce the hot air in the engine bay, when you can more effectively isolate the air into the airfilter and around it? <<|
...if you want to reduce the likelihood of an HGF then yes
This thread was discussed between 28/02/2001 and 11/03/2001
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