325 throttle body on 323i manifold

[skidz 197]

Has anybody done this? Did you just grind out the manifold at the throttle body end?

Or should I try to get the 325 manifold?

Would I use the 323i injectors? or the 325?

And the 325 air flow meter?

So many questions...

[my_e36 43]

This is quite a common mod. Most refer this as OBD1 conversion or M50 manifold for M52 engine. I am looking at this mod as well myself, just need to save up for it now.

[Gus 5]

he means the m20, am i right?

i dont think it would make too much difference to be honest (maybe a little, but prob not)

just my 2c

[m325i 709]

I haven't swapped, but from what i can tell the price is pretty high for the gain you get.

[Surge 1]

With a larger throttle body, you'd need larger piping, going to a larger AFM... But the restriction on these motors is (apparently) the intake ports - Wouldn't a port and polish be a better option to improve airflow?

No offence sic*, but unlike Japanese engines from the exhaust and intake side of things these are quite good from the factory - meaning the money you spend on them doesn't offer big gains.

Btw - 323i injectors should be more than ample should you go with a larger throttlebody + all of the above stated.

[bumpstop325 0]

on paper i think this is a good idea.

even the 325e has a smaller t/b than the 325i

it will be easy with a 325i afm to install. I have a spare one at the moment if you want one.

you could prob have the entier 325i intake system on the 323i head.

afm, intake boot, manifold, and t/b.

Problems arise if you 323 is L-jet and the 325i is motronic.

as you will have problems with the idle.

AN afm swap would be idle. You will have to swap the brain of the afm from the 323 and put it in the 325i afm. This is not as hard as you think i have already done a swap on mine.

Edited May 28, 2005 by bumpstop325

[skidz 197]

Thanks for the replies, guys.

Yes, it is the M20 motor I am talking about.

The motor is 2.7, and already has the head job (bigger ports, valves, cam etc) and headers, but the inlet side is all standard 323. So I am picking it will run lean at higher revs. (But I haven't had it running, yet)

So, from the sounds of things, I can use the 325i airflow meter, throttle body and inlet manifold, but I need to change the circuit board in the AFM back the the 323 one to make it all compatible?

[BMW POWER 2]

325e

And what does the E mean.. i know I is Injection, is E carby'd?

[CaM 0]

With a larger throttle body, you'd need larger piping, going to a larger AFM... But the restriction on these motors is (apparently) the intake ports - Wouldn't a port and polish be a better option to improve airflow?

No offence sic*, but unlike Japanese engines from the exhaust and intake side of things these are quite good from the factory - meaning the money you spend on them doesn't offer big gains.

Btw - 323i injectors should be more than ample should you go with a larger throttlebody + all of the above stated.

moving Vane AFM would be the biggest problem

changing the AFM for a 535i one or something will only work if you use the adjuster to set the mixture right, as Tim said - the idle goes lumpy as a mofo-heard his the other day in town... shouldn't need to change the guts of it though, just adjust it - also have to di this afte head mods and crap

I rekon theres alot of gain to be had from intake & exhaust mods-the ports seem fairly restrictive, and BMW exhaust manifolds are terrible looking, new exhaust system makes a difference. -

[petone 0]

Tim's right, probably will need to change the guts of the afm because of the different managment systems. Is this the baur that you bought? I agree with Cam about the Vane AFM being the biggest restriction, MAF setup would be awesome.

emma- e is eta, or economy. actually a 2.7 but less revs, smaller intake/exhaust etc

[CaM 0]

Tim's right, probably will need to change the guts of the afm because of the different managment systems. Is this the baur that you bought? I agree with Cam about the Vane AFM being the biggest restriction, MAF setup would be awesome.

emma- e is eta, or economy. actually a 2.7 but less revs, smaller intake/exhaust etc

theres MAF setups available from the states, however it's more expensive just for the parts than to buy a brand new Link ECU... go figure....

honestly, I'd never bother changing the AFM for a slightly bigger unit, especially if you have to change the guts. - bigger cross sectional area moving vane AFM will open less than a smaller one at the same air velocit/volume, when the insides of a smaller unit are put in to rectify the different ECU type, then it will end up running lean = :gay:

[bumpstop325 0]

the guts i was talking about is just pulling the circuit board out and swaping that with each unit.

Each of these boards have different numbers which mean at certain flap postions it will be reading a certain electrial resistance. Now, it is important to keep this because it is telling the computer that there is this amount of air going into the engine and the computer will supply the right amount of fuel to complete the combustion. If this changes then you will lean out or over fuel your engine.

My my setup i have the added help of a rising rate fuel pressure regulator. Hence with the more air i can get in, i can increase the supply of fuel i can supply the engine.

Personally, in my opinion a 2.7 build with the 325i/323i head, using the standard injectors is not a good idea. As you willbe running the risk of leaning out. Because you have increased displacement without compensation with the changes to the engine. This is what i need to look into aswell.

[BMW POWER 2]

emma- e is eta, or economy. actually a 2.7 but less revs, smaller intake/exhaust etc

Thanks