m20 engine with a turbo

[the_mighty_one]

ok, this may seem like a silly question, but what with me being new to bimmers (only had an old 316 before) im gonna go ahead and ask it.

ive been looking around on the net, and according to one website, you can turbo a m20 engine as fitted to the 525i without changes to the management system at all.

is this possible? i presume if it was possible you have to put the air flow meter on the intake side of the turbo rather than in the pressure side?

is it best to upgrade injectors?

it seems to be that the general consensus is 7psi max boost for a standard engine?

i hope you guys can help!

[WillG]

it depends where in the rev range you got 7 psi tbh, its possible with a RRFPR but I wouldnt advise it, you are best off investing in megasquirt which will look after your engine alot better and you can move it over onto any setup you decide to do in future

[infusion]

just on his point with the AFM.....

Mine is on the air let side of the turbo.... but i have seen many on the intake side in front of the inlet manifold

which is better ? mine seems to work fine...... but it would make sense in front of the inlet man !

[Turbo-Brown]

Wanna be careful that the AFM you're using, wherever you put it, is giving a meaningful reading all the way throughout the rev/load range.

If you get to half throttle and the flap's pinned wide open already you're gonna run into big problems!

As will said, I'd go for something mappable so that you can apply accurate sparking and ignition for all conditions.

[infusion]

but which side should it go? on turbo air inlet?

on turbo outlet side ??

or manifold inlet side ?

[e30_Turbo]

but which side should it go? on turbo air inlet?

on turbo outlet side ??

or manifold inlet side ?

It should go.... in the bin.....

You really need a MAP sensor for any boosted engine, AFM's and boost aren't ideal, as Alex said the min you hit boost the AFM flap is pegged and the ECU gets the same signal, it needs to see the increase in pressure to raise fueling etc.

IMO using the stock ECU isn't a good idea, you have no control at all and an incorrect set of mapped values for boost, the stock ECU can NOT see boost so you need to compensate with a higher fuel pressure and thats a sure way to ensure most of your engines time will be spent either pegged rich or flat lean. RRFPR are not mappable, just adjustable.

HTH, Mark.

[Mops]

well... all thought i'd say it is best to get megasquirt (= $$$), up to about 6-7 psi of boost can be achieved wit motronic, but it does require some mucking around:

you would need m30 afm and wideband lambda sensor = $$$ (or some dyno time = $$$) and then you will need probably put some bigger injectors = $$$... possibly 24 lbs ones and RRFPR = $$$

it it's the matter of adding up... basically unless you know how to tune AFM and have access to free (borrow for a week or 2) wide band sensor you might be able to do it cheaper then getting Megasquirt... otherwise just get a megasquirt... it will be cheaper in the long run....