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MG MGF Technical - Cold Air intake
|Last week i went to a tunnig expert, and he took me out one of the air filter boxes and placed an induction pipe collecting the air in the left side air intake. He also told me that it would work like an heat shield so a much better solution than K&N 57i. He also removed the catalytic converter. After those mods the benchmark was 136.7 hp. After this is was 148.2 hp. The torque raised from 159 nm to 169 nm. (VVC). My question is : Is realy 57i a better value solution than the present one?|
I have one of these things on my 1.8i. It works very well, but there are pro's and con's for both the 57i and panel units. I would like to get some graphs (Rob) for my car. Perhaps we will explore this some time this year.
|This is a really sound modification IMO- as it guarantees cold air intake into the engine. And that is definately a good thing.|
The standard inlet tract is long- which encourages good torque characteristics at the expense of top end power. This modification would really suit the 1.8i - perhaps less so the VVC...
I think if I were to undertake a modification of this type, I'd want to get rid of sharp turns and smooth the airflow tract as much as possible. Loosing the flexi-pipe between the airbox and throttle body would be a priority!
I would be very interested to hear of alternative installations- and would be happy to host the power curves (very interesting!:o)
I think Rog has a similar modification on his car at the moment- have you got any power curves for this Rog?
Home of the air filter results! http://go.to/mgfgallery
|IŽve got the power curves...and iŽll scan them. IŽll send them to you Rob but only tonight because now iŽve got to go work!|
|Thanks Bruno! Could you also send me a quick out-line of the mods you've done? Thanks!|
PS If you have the ambient temperature, barometric pressure etc. data, could I have that too? Ta! :o)
|Ok Rob the mail itŽs on his way....please post a thread or give any kind of opinion about those mods.|
Dieter will get a copy too if he is interested.
|I'm still pleased with the noticable increase in throtle response from this mod, which i did on the recommendation of Roger. I'd also recommend it|
|Forgot to say that iŽve stil got the standart air filter element, and the oil temp readings droped about 10% as Dirk anounced. Maybe more 30-40 km/h in the speedo for the same oil temp reading.|
Thanks, I have recieved the curves. I'll post them on a temporary web page for all to see and comment upon. Dieter, if any translations are forthcomming, I'd appreciate it! Otherwise, I'll laboriously do it... ;o)
URL to be announced- whatch this space :o)
|Bruno's results... http://www.zyworld.com/brooklands/filters.htm|
Bruno, what do you mean by a cone in the left hand grille?
Also, were both tests done in the presence of you modified cat?
|I mean that the all area of the left hand grill was used. Not just a pipe placed there. The larger part of the cone was in the left hand grill and the small one was conected to the air conduct pipe. Those tests were made with the standart air intake + standart cat = 136.7 HP, and then with the modified air intake + modified cat = 148.2 hp. The values on the page are not correct. Those values are in bhp not kw Rob. Soon or later iŽll go to the same guy for chip tunning and then iŽll send you the graph and by that time iŽll have the high performance filter element fitted too... maybe by the end of the month when my wallet allows it! :0) .Is there any kind of heat shieldig tape? I want to isolate the pipes and the airbox from the heat of the engine.|
|Okay Bruno- thanks for clearing up my confusion. I'll make the alterations to the temporary page :o)|
When I'll get a chance, I shall also make new graphs like the one already on the filter page, and do a direct comparsion with data we have already collated (the atmospheric conditions would be helpful for this). Do you know how much power is lost through the transmission?
136 bhp is a little low for a standard VVC- which will make comaparsion with P9 VLS a little difficult (which had a cat bypass and a double S exhaust at the time...). Maybe high ambient intake temperature is responsible. I shall check.
Hopefully more VVC figures soon!
BTW the VVC with cat bypass, exhaust and 57i K&N got 150 bhp, so still a potential gain from this set up- and also not that the power curve is totally linear to the red line... Still advantage 57i?
|So a VVC with a cat bypass pipe, a sport exhaust, a 57i kit got 150bhp? IŽve got a standart exhaust (without cat) and a standart filter (only with modified intake). I wonder if when iŽll replace the stadart element by another high flow one if it will give anything. Otherwise i think that a sport exhaust + the high flow element would give at least two more bhp, or not? . Since iŽve got no access to the magazine "MG WORLD" or what its her name, could you tell me wich is the best sport exhaust?|
note: Last friday i called the tunnig expert and asked him about rechiping? He told me that the final output would be around 160 bhp! IŽve also asked him about an oil cooler because the oil temp readings realy get me worried.
|Sports exhausts don't release a huge ammount of power, sadly. The best from the power perspective is the Mike Satur Daytona exhaust- 5 bhp on the 1.8i. Useful 4 lb.ft increase in torque too. But not huge gains, and your existing filter arrangement exceeds this already.|
A panel filter replacement may give an improvement- and there is little to choose from the various choices on the market (as you have probably already seen from the power graphs on my web page).
The car tested had a double S system fitted. As we now know, this liberates very little in the way of power or torque- so any gain is likely to be from the filter+ bypass. I am not sure how good these bypass tubes are (may be able to find out soon though) so all the gains I think were down to the filter. Time and investigation will tell though.
BTW the oil cooler sounds like a very sensible idea to me!
|I remember reading a thread where it was not recommended to duct the cooling to the side intakes as there was very little air coming in. Also the K&N 571 also draws cool air from the underbody ducting tube. As you drive along this would force the hot air out of the boot vents so the K&N would get cool air circulating around it. I believe the only way to really test this is to have some kind of air flow meter and tempreature gauge near the filter. Otherwise we are all guessing.|
The cat bypass is surpossed to give only 2bph. However, a guy a Moto-build recons it is more than this. He states that you have only got to look through it to see how restrictive it is. To add another slant to this, In a recent CCC magizane test one Lotus Elise owner had 194bhp with the CAT on.
>>I remember reading a thread where it was not recommended to duct the cooling to the side intakes as there was very little air coming in.<<
This is true. The 57i kit is not a sealed system, so would not be able to suck air in through the duct. Bruno's (and Rog's) system differs in that the duct is sealed to the filter intake, and thus is able to suck ambient air though the grille.
>>Also the K&N 571 also draws cool air from the underbody ducting tube. As you drive along this would force the hot air out of the boot vents so the K&N would get cool air circulating around it.<<
Yes, absolutely. The cooling ducts use ram air principle to deflect air into the engine bay and around the filter itself. The filter has no influence upon the amount of cold air being drawn in. This is purely regulated by road speed. The limitations of this system are obvious.
>>I believe the only way to really test this is to have some kind of air flow meter and tempreature gauge near the filter. Otherwise we are all guessing.<<
I totally agree. In fact both Graeme Bishko and Paul Sharpe have employed temperature probes to investigate the efficiacy of the K&N ducts. Graeme's figures are particularly convincing demonstrating that there is a notable temperature drop in the vicinity of the filter using the cooling ducts under 'real' road conditions.
No one has tried to employ an airflow meter, but the temperature recordings are sufficient proof of efficacy. The original report of these findings are in the archives.
The one limitation of the ducts is that one side of the filter is cool, whilst the other tends to be warm. Strategic positioning of the ducts will get around this problem...
>>The cat bypass is surpossed to give only 2bph. However, a guy a Moto-build recons it is more than this. He states that you have only got to look through it to see how restrictive it is. To add another slant to this, In a recent CCC magizane test one Lotus Elise owner had 194bhp with the CAT on.<<
That is interesting isn't it? Personally I am not convinced by cat bypass modifications (legal/environmental issues to one side). We need more independent comparative tests with clean/ fresh cats to determine the reality.
The simple fact that the pipe is directly connected to the outside world means it gets all the cool air it needs, regardless of air flow. The engine sucks cool air in rather than relying on air flow through the engine bay. An analogy; On a cold winters day, if you put your face outside and open window and take a deep breath you get a lungfull of cold air even if the wind isn't blowing! wheras if you're sitting by your desk with the window open and the cold wind blowing in. Then take a deep breath i think you'll find that the cold air has already mixed with the warm air in the office and it won't be as cold.
I am beginning to see a devide between hardened 57i enthusiasts and Panel users.
I'm with Bruno on this one!!
Don't take sides, combine them. :o)
If I could (I can't because of the sprinting regs) I'd corden off an area inside the
engine bay and feed it with the KnN pipes. The filter would pull air from this box.
Thus you get the cold air you are after *and* the ram air effect.
Surely the best of both worlds?
In fact, that is similar to how the cup cars get their cold air (it intrudes into the boot
and pulls air from above) and sound similar to what Roger has been doing.
|Paul, I am not sure if this is actually against regs is it? I would welcome clarification on this issue.|
Ultimately, I agree with your assessment Paul- a combination of both may be preferable.
It all boils down to what would comprise the ideal system- and neither the 57i or the enclosed system with side vent air draw are it.
Fact is, there is no evidence that I know of demonstrating the direction of air flow around the left grille. If there is a negative air pressure pocket at this location, then drawing air would be less than ideal. Therefore air should be drawn from another locatione- ideally a location that has positive pressure. The boot vent with the roof up could be that location- I don't know as I do not have access to the MIRA wind tunnel data.
IMO the perfect kit would be a cone filter enclosed in a sealed air box, with a high capacity air feed from a positive pressure location- possibly from under the car- ie. the system that Carl has created. I'd like to copy it, but I can only clear plastic I can find polystyrene which is too flammable for automtive use. Any suggestions anyone?
|I think that many bikes demonstrate the advantage of ram air, very few bikes suffer from the problem of heated air engine bays but they will all benefit from the fitting of a ram air system, the only proviso is that if the induction air intake at the end of the ram air pipes is a box then that box must of sufficient volume to allow a resovoir of air large enough to satisfy the needs of the engine when full throttle is applied. Most bikes using this system have very large collection boxes for just this purpose, my own bike has the funnel of the ram air tubes mounted in the nose of the fairing and finishing in a large air resovoir box in which the filter is also fitted.|
|Good point Ted.|
For a 4 cylinder, 1.8 litre K series engine, each cylinder has a capacity of 1796cc/4 = 449 cc (or mls depending on prefered units).
1.8i has a peak rpm of 6750, a VVC 7250 (add 250cc until the rex limiter cuts in).
For every engine revolution, one cylinder is drawing in air, so at 7,500 rpm, 449 x 7500 = 3367.5 litres per minute, or 56.125 litres per second is being drawn into the engine.
The air supply system would therefore need to be capable of supplying the engine with up to 56 litres of air per second... assuming 100% volumetric efficiency- ie. that that much air can actually be drawn into the engine (the actual figure is going to be far lower than this because of the diameter of the airways and the valve area). What is the volumetric efficiency of a K series head/ air inlet system? I suspect that Dave Andrew's K-series engine tuning site may have that answer, I'll have a look later.
Ted, what size relative to the deplacement/peak rpm are bike's displacement box? Bikes often have higher volumetric efficiencies than car engines.
|Rob what you have to remember is that the box is there to a/ iron out turbulence and b/ to give enough extra air for that first huge gulp when the throttle is slammed open.|
I haven't actually measured these boxes but on my bike, 1200cc and 8500 max rpm, I would say it is about 2 litres plus the air filter and is fed by a tube of about 2 inches diameter but on sports bikes it would be fed by two pipes and be about 4 litres.
|Yup, you are right Ted... just me rambling out loud... 56 litres per second of air if 100% volumetric efficiency- that is a bloody huge capacity- about a 1/3 of the boot space of an F... every second. Wow.|
Anyway, there must be relationship between engine capacity and airbox size? Maybe the standard airbox/ resonance chamber will give a clue to the minimum capacity of 'box required?
Food for thought!
|That would make it almost as dangerous as a jumbo jet if you were stand by the intake:-)|
|A couple of points:|
The inference that the ideal solution would be a cone filter in an enclosed air box is intresting because that is what PTP are about to launch - with air drawn from the underneath of the car through ducting. I'm hoping to get my hands on one in the next few weeks and maybe get it on a rolling road to test it against my K&N . Although the problem with rolling road tests is trying to simulate the forward flow of air.
When I did my temperature readings in the engine bay, I recorded much higher temperatures than Graeme did. Clearly my intake pipes are/were not working as well as Graemes. As far as I can tell my intake pipes are fitted correctly so it would appear that the positioning of them could be critical.
I've concluded that the cone has the advantage of free flow, but it draws air at very high temperatutres, particularly at low speeds, while the enclssed system has the advantage of drawing cool air, but the necessary plumbing restricts the air flow. As to which is better, its difficult to tell - and you'll proably find the enclosed system is better at low speed and the cone better at high speed.
|What iŽll try to do is to fit an"Y" in the intake pipe so that it can catch some air from under the car. What everybody seems to forgot is that the enclosed system also gets hot (Both airfilter box and pipes) warming the air... Is there any heat shielding material to isolate both pipes and airfilter box? IŽve seen 106 gtis and Saxos with dynamic air intakes...and both pipes and airfilter box are protected with some kind of gold/silver tape... any idea?|
|Roger has some interesting power figures from his cold air/air filter experiments taken on Peter Burgesses rolling road which he sent to me. Im surprised he hasnt noticed this thread up til now, but I know hes been snowed under with work. Maybe hes saving them for a paid article in Safety Fast!! - in which case I wont tresspass.|
|Roger mentioned details of these increased power figures in an earlier thread about a cold air feed about 6 weeks ago (which i guess is in the archive). Though it looks like he's not caught onto this thread yet. |
It was his previous posting that got me interested in doing a little 're-plumbing' as Bruno and others have done. I e-mailed Roger at the time and he was very willing to discuss all his findings at length which i found interesting.
As i mentioned earlier in this thread i've found the air intake changes to make a perceptable difference and the car is definately more pleasant to drive with sharper responses from low to mid revs. The ultimate test was when the wife drove the car for the first time after the mod (she is the only other person who gets to drive the car). She came back saying "the car is different, better,..what have you done?" Praise indeed...*smile*.
I guess this whole thread is irrelevant if you want to fit a 57i for the noise, but if you don't want that level of noise, (it still sounds better than standard though), Bruno/Roger's alternative is definately worth thinking about.
>The inference that the ideal solution would be a cone filter in an enclosed air box is intresting because that is what PTP are about to launch - with air drawn from the underneath of the car through ducting.
Carl did that two month ago, surly no measurements done, but I've still his pictures online.
BTW .. where is Carl ?? He wanted to send some more pictures.
According to temperure isolation materials, what about demon tweeks catalogue, nothing inside there ?
On other hand IMO any metallised thin plastic foil shoul do a good job in reflecting heat.
|If getting cold air is as good as it seems then why did K&N not incerase the pipe length so the cone is near the bottom of the engine where there is loads of cold air. This would be a simple thing to do and yet it has not been done. A plate would stop dirt hitting the K&N. On the Escort K&N have extended the pipe to the bonnet area before fitting the K&N 571. So the filter draws air from the front grille. Nice and cold. Rob would it be possible to contact K&N and ask why they did not do this, As I believe you were involved with the air filter tests and may have the right contacts.|
If getting cold air is as good as it seems then why did K&N not incerase the pipe length so the cone is near the bottom of the engine where there is loads of cold air.
My engine bay temperature recordings showed there was an area of the engine bay that was significantly cooler than anywhere else (not far from the pick up for the standard air box). The idea of siting a K&N in this area, on a longer tube, was investigated on my behalf by Techspeed but they found that the gains from cooler air were offset by the losses from the longer tube.
Back to square one :-(
|Steve, I understand that a longer intake path would be of benefit to torque but detrimental to power. It depends how you want to play the trade.|
The Montego EFi has a very long induction pipe to its filter, and it is of the same internal diameter as the K&N pipe. With this Spencer proposed to mount a cone filter in that left hand air duct to draw cold air in a similar way to the Bruno/Roger/Paul mod. He didn't do it as he sold his car, bought an Elise in leu of delivery of an Audi TT...
Maybe worth experimenting with, if you can gain access to 'cheap' rolling road time. And that is the tricky bit :o(
This thread was discussed between 09/03/2000 and 15/03/2000
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