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The 320is, Porsche 944 turbo 2.5/2.7cc, M3 2.5 and 2.3 are exactly sized the same.
After the '86 they have also the same linear output, so they are perfectly switchable.

Hi,the reason I posted that question is because in the magazine(Total BMW I think)it said that the diameter of the one used in the 2.5 was bigger to help generate better air flow through it.On the eprom issue,I believe the 320iS has an unique one ,fitted specially for that particular car.

well...for the AFM intake and out port and i'm sure that is the same size cause i've seen other AFMs here in italy of the 2.3, 2.5 and also porsche turbo 2.5/2.7cc(!).
But, when in doubt...www.s14.net.

I'll be happy to learn something new.

For the eprom: i've taken off only 4 eproms from four different cars.
I've found always the same MAP of course, but NOT the same eprom.

In mine i've the 128kb eprom
In others i've found 256 or 128kb eprom.

In all of them stock eproms there's certainly only ONE MAP (the same for every car) and it is 32Kb large in the 256 eprom and 16Kb large in the 128 eprom (obvious!).

Well,if you´ve seen it then you´re right.I once tried to use a JR filter,intended for the 2.3 L engine and had to swap to a custom built cone filter(a much bigger one)cause it was flowing very poorly,with this filter I have now, the car breaths so much better,you really feel the power being developed and the induction roar is almost(so close it´s scary)like it´s using a group A Carbon fibe box.Guess I´ll just buy these second hand green injectors from a Escort Cosworth this friend of mine has laying around,take it to the rollers and see what power,( if any improvement)it makes.I´ll report it back to the forum.

for your interest.
I've a twin air cone 90-150 on my 320is (i dont want to tell you the make to avoid to be a sponsor) with a custom support for the AFM. I can say that before the transf. i was able to pull the 5th gear to 7000 rpm and now i can get it to the rev limiter.

Unfortunately i didn't find what i would have liked to!
In fact i was after a cylindrical filter with a BIG free volume into it (without the cone of the twin air system), but couldn't find the right dimension, here in italy.

In fact i'm under the impression, like you say, that the car needs a restrictions-FREE air volume againgst the inlet port of the AFM (that you can have with a very BIG filter) more than a straight intake option (like in the twin air type).

It is obvious that, the more you 'free' the intake, the more you lean the mixture, especially at low rpm.
At high rpms the leaning problem is less sensible cause you have a lot more fuel delivered.

i'm very interested in the injectors switching, cause you know, it is always somekind of critical!

I just got a reply from a tuner about a sc kit so I´ll problably have a go at the injectors.Regarding the filter,after the switch my car pulls to the limiter in EVERY gear.I´ve been told by a BMW mechanic,that used to own a 320iS that this a rare thing specially in fifth gear.Actually when I remap the thing on the rollers I´m planning to extend the rev limit to 7500 ´cause the car feels like it will keep on pulling up to 8000.I dare to say it feels and sounds almost like a V-Tech engine.I´ll post my results as soon as I get them.

For both of you... I'm quite interested in the air intake filter 'constructions' you made. I wouldn't want to use them in the 320iS, but in my 325i track car. So pictures, theories, suppliers... all more than welcome here!

I do know that there is an open intake KIT for the 325i (you can see K&N). Part of this kit (the metal adapter between filter and AFM) is what i've in my car.
The other part is simply a self made (hardware store components ) support of the AFM which was originally fitted on the stock air box that has been removed.

For bclemente...i've had a dyno test, and the fact of the power still increasing after the rev limiter is true (at least in my car). In fact i've made an eprom without rev limitations.

bye

As you can see on the picture below I already have something similar installed. But I'm wondering, because of intake vacuum, if I will benefit from a larger cone. Already opened up the closed parts of the front grille to get more air straight to it and that worked out fine.

....the more you increase the pressure at the AFM inlet port (supposing that all cones are made of the same material).
My cone is not larger than yours, only it is a twin air cone, so i can overcome the 'less volume' problem a little bit.

The most excellent cone i've ever tried was the JR 180lenght, 180 diameter and i think 80-82 the diameter of the rubber hose. i was really able to sense the difference.

But, given the fact that you have to get rid of the stock airbox to let more air into the engine, paying attention to the leaning issue...I think that with a larger cone the power increase is really small.

OK so if I stick to an air intake filter that's about the same size, that would be goodenough then? This one's so dirty... I will try cleaning it with compressed air first of course!

NOT the compressed air! The first thing that is written on the instruction manual of cotton filters is to avoid compressed air, cause it can damage the filter.

Use the cleaning kit.

OK! Thanks again!

Jeroen,for the filter I used one from a brand called Eagle,it´s supposed to be a cover for K&N so they can market them at lower prices.The one I use is cone shaped but the inside is hollow so that air flows through the outside and through the inner part of it,meets inside and goes through to the air meter(dual cone?)I´ll send a picture as soon as I can to your e-mail because I still don´t know how to post pics.For the cold air I used a bit plastic pipe used in sinks,L-shaped,painted it matt black and stuck it where the cold air feed used to be for the original airbox,looks factory fitted.(Even I was amazed after I fitted it).Francisco,the BMW mechanic I told you about,he told me that if you remove the ABS rellay,it shuts off the rev limiter.He didn´t know why just said it was so.Is this true,ever heard of it before?

dual cone is called TWIN AIR