M3 airbox onto M20, rolling roaded today!

[Simon13]

Just wondering if anyone has done this, moved the alternator, i've been playing about with getting an E30 M3 215bhp airbox. Hoping it will give some more torque to my cammed 2.5 which is sadly a bit lacking in this department!

I've been playing with an aircon bracket and alternator this evening, which i can get to mount but you wouldn't be able to get the belt on!

I could earth it on to the chassis leg on the drivers side and extend the engine loom to it, which even i can do and run it underneath the sump to it.

So has anyone made up a custom bracket for the job? As i get the feeling this is what it entails.

Also i need to make some brackets to hold the bottom of the new radiator, which i can do. Then it's just finding a bit of pipe to extent the throttlebody pipe to the airbox/afm. And it should* work!

[Ant]

Contact David ( Apal) on the Racecar S/C thread M8

[Jhonno]

airbox's need to be a specfic volume to do the job properly Si.. Lots of r&d goes into it

[Simon13]

Well if it gives an M3 the extra ommph it needs then why wouldn't it help another engine? It's only the airbox changing as i've had to do some mods to get it to fit a 325i afm. All bmw did to help with the M3 was change the air box design

Well here is what i is trying to do



I'm going to have to mod this aircon bracket a bit more i think and make a plate up to mount it to the block and bracket to move it out in line with the other pulleys so the belt goes on straight. I can see the oil cooler pipes getting in the way possibly



Ant i'm sure i've looked through that thread in the past and not really found too much out

[ste]

Could you try a smaller alternator? e.g. M52 alternator is much smaller than the M20 one.

[DanThe]

Thats a good idea ste, if I were you Simon I would leave the rest of the M52 bolted to that alternator

[Dan318-is]

Simon you hero; ste is the man with the plan but surely they are light years in design guys?

Perhaps pop to alex's for a cup of tea si; nice too see some progress though!

[Simon13]

There shouldn't be a problem with fitting a smaller alternator would there? I mean they are doing the same job no?!

Dan your right but my M20 is going strong since it was revived from the dead!

[Dan318-is]

Just had a quick browse on real oem at a 1997 right hand drive 328i coupe and as far as i could see i couldn't even find a mounting bracket.

Maybe ste could provice a picture of his?

[DanThe]

Alternator mounting bracket is the oil filter housing on an M50, so you may have problems in that department

[DanThe]

Goes here

[ste]

I don't have any great pics, these are about the best ones showing the alternator and the way it attaches:









It does indeed fit quite differently to the M20 one. I'm fairly sure you could fabricate a mount though, If not M52, take a trip down the breakers and have a search about - all modern alternators have got smaller.

[Simon13]

true true but i'd need to change the pulley on the end so matches the others so i can get a belt on.


It's looking ok with the standard one so if i can get it work then it should be ok

[glenn]

Just wondering if anyone has done this, moved the alternator,

So has anyone made up a custom bracket for the job? As i get the feeling this is what it entails.

i've done this with a different vehicle si,
iirc, i split the front casing off the alternator and had to turn it so that the adjusting mount hole was in a different position and then made a different shape adjusting bracket.

[Simon13]

I see Glenn the way i have mocked that up in my picture of it on the stool is that the belt will have to be tensioned from underneath the car!

which is the same as the aircon compressor if it was still there

[glenn]

I see Glenn the way i have mocked that up in my picture of it on the stool is that the belt will have to be tensioned from underneath the car!

which is the same as the aircon compressor if it was still there

yes mate,
it's no big drama though to adjust it from underneath, if it gets you the airbox you want

[Simon13]

slight change! now this will defo work with alot less ball ache involved but it will involve no power steering for a bit until i sort an electic pump from a saxo (good chat with dips!)

So i've dropped the power steering pump out the way and pushed the alternator down there.

I just need to find a suitable belt to fit, any ideas?

[Dan318-is]

Go to halfords and find one easy peasy!

[tomtomiS]

am i right in thinking there's loads less feel when using an electric pas pump?

[d6dph]

Go to halfords and find one easy peasy!

Measure it with a bit of string/cable first.

[Karan]

am i right in thinking there's loads less feel when using an electric pas pump?

i was discussing this with demlot and the concensus is the kick mechanical pump ass in EVERY single way!!

gonna get one for my silvia i think.... engine response will also increase///

[Simon13]

less load on the engine i suppose aswell minus the pump, it just has to run the alternator

[Jhonno]

Stop wasting time with the turd and get the 'penis done!!

[Simon13]

too late the ball is rolling!

Dan you coming to the pistonheads meet? Charlies gonna let us do some dyno runs, so i'm gonna try and get 2 runs 1 with the M3 airbox and one standard

[ian332isport]

less load on the engine i suppose aswell minus the pump, it just has to run the alternator

Swings and rounabouts really. Although you don't have a pump to run directly off the engine, you need the alternator to run the electric PAS pump. This will in turn put extra load on the engine.

Ian.

[dips346]

less load on the engine i suppose aswell minus the pump, it just has to run the alternator

Swings and rounabouts really. Although you don't have a pump to run directly off the engine, you need the alternator to run the electric PAS pump. This will in turn put extra load on the engine.

Ian.

at least you can turn it on or off when you want

[Jhonno]

too late the ball is rolling!

Dan you coming to the pistonheads meet? Charlies gonna let us do some dyno runs, so i'm gonna try and get 2 runs 1 with the M3 airbox and one standard

i might be yeah.. I will out council everyone tho.. Turning up in my housemates e30 as i wont own a working car

[Demlotcrew]

less load on the engine i suppose aswell minus the pump, it just has to run the alternator

Swings and rounabouts really. Although you don't have a pump to run directly off the engine, you need the alternator to run the electric PAS pump. This will in turn put extra load on the engine.

Ian.

Not as much as you think, the higher the RPM's the less load on the engine as the alternator is producing more power. In a straight line there wont be a such a big power drain by the pump. And like Dibs has pointed out a very simple micro switch a WOT will turn it off

[Karan]

wont that be funny mid corner coming on/off throttle???

[Demlotcrew]

In terms of steering feel yes very. The steering goes heavy and gives much more feedback so getting assistance back when lifting off could be a right pain and confusing to say the least, which is why you would fit a delay of say a min after the engine comes off WOT the pump will get and if you are on a track the pump will stay off the time as you will be mostly on WOT the relay will be delaying the power all the time. And when driving in town cruising with the homies it will be on as you won't be in WOT unless you are Dave and you like to recide bach with the rev limiter

But in terms off engine power not really. It just comes on cam and revs harder if that makes sense?

[Simon13]

Just got back from surrey rolling road where i managed to do a run with a standard airbox and then 1 with the M3 box.

Now before you all laugh, the fuelling on my car is seriously out and this is losing me power big time.

So first run was 150bhp! and 151lbs

M3 box was 157bhp and 156lbs

I was well chuffed with that to say the least and proves that there is something in in possibly using one!
Not bad for just changing an airbox i'd say

[Theo]

Interesting that it made that much difference. Did you do just the 1 run with each airbox? There was a difference of about 2.5bhp and 2.5 ft/lbs when I dyno'd my car between the 1st and second run, bhp went up and torque went down.

Either way it definitely seems to be making a difference, quite suprising actually.

[Simon13]

he did 2 runs on each

second run was 151bhp on the standard air box

and the other run on the M3 airbox was 156bhp. I've got the graphs against each other and there is an improvement right the way throught rev range for bhp and torque. So the M3 box is helping give more power right from the off!

[oakey]

Thats pretty good going.
Are M3 airboxes easy to get hold of?

[Simon13]

like most M3 parts no!

It's a bit of work to get it on, but i think i'll defo do it to my touring now, just needs a 2.7 bottom end and standalone now!