Supercharger question

[e30_318i]

hey people! ive just bought another e30 318i (m40) and have been offered a supercharger from a bmw mini cheap! is there anyway i can fit this onto an m40 if so how?

[Turbo-Brown]

Not sure if anything in the M42 post might give some pointers.

Might be worth having a run through some of the equations in there to help you assess the suitability of the Mini Charger.

[chip-3door]

Would be an ideal choice i would have thought.

Only if you are looking more for midrange than top end though, that particular charger isnt capable of massive flow, so its not going to be still generating a bar of boost at 7000rpm, if you are after that then you would be better going for something like a rotrex sp 30-84 or even a larger eaton.

[Jhonno]

m40 only rev's to just over 6k tho so i think it would be fine..

[chip-3door]

m40 only rev's to just over 6k tho so i think it would be fine..

Surely thats very dependant on what management he uses and how he configures the limiter?

[Jhonno]

yes very true

i was making the assumption that this is on a budget so couldnt see much beyond supercharger and rising rate fpr being used

[chip-3door]

yes very true

i was making the assumption that this is on a budget so couldnt see much beyond supercharger and rising rate fpr being used

Yeah good point.

Although personally on a budget install i would use an ERL MF2 and a couple of extra injectors probably, as at least that way its mappable to a certain extent to get a decent AFR all over the place, rather than having to set a rising rate regulator up purely on how rich it is on full boost at the leanest point in the rev range and end up running too rich everywhere else!

[Jhonno]

yes definately - that is how i would look to go if i were doing this on a budget

but it depends i guess on how tight his budget will be

tbh if it starts costing more than Ԛ£500 you're better off with dropping a 2.5 m20 or m50 in, unless you dont have those facilities and or want to be a bit different

anyway back to the original topic

[chip-3door]

yes definately - that is how i would look to go if i were doing this on a budget

but it depends i guess on how tight his budget will be

tbh if it starts costing more than Ԛ£500 you're better off with dropping a 2.5 m20 or m50 in, unless you dont have those facilities and or want to be a bit different

anyway back to the original topic

True, although lots of people dont like engine swaps cause of the amount of space needed and having to have an engine crane etc, so it depends on the person in question as to wether thats an easy option or not.

[Jhonno]

exactly

a supercharged m40 would make a interesting proposition tho, lightweight and maybe somewhere around 323i power probably

plus the noise of course

diff would need uprating imo also

[chip-3door]

Use something like a rotrex its very easy to get big gains, like 50% on standard internals on most engines, but ive never seen a 318 specifically done, so wouldnt like to comment if its possible in that instance, but by running a relatively high amount of boost further up the rev range where the volumetric efficency is naturally lower due to the time available to fill the cylinder its normally possible to get big gains without getting det issues like you would if you tried the same in the midrange.

[Jhonno]

standard 318i is 115bhp

not many ppl have modified them tho so no idea what gains you can get with them either tbh

i think i would stick with cheap and cheerful on one tho..

if i were supercharging a 6pot then i would definately invest more in the supercharger as you say to run the higher boost in the higher rev range

[chip-3door]

standard 318i is 115bhp

not many ppl have modified them tho so no idea what gains you can get with them either tbh

i think i would stick with cheap and cheerful on one tho..

if i were supercharging a 6pot then i would definately invest more in the supercharger as you say to run the higher boost in the higher rev range

To get mega power of course is going to require a rebuild with lower CR, and at that point its foolish to put the 318 lump back in really, so i can see why no one takes them very far.

Interesting project, but not really any "point" to it!

[Jhonno]

i think thats why i keep seeing 6 pot lumps.. there would be more point in that

altho if i were him an offered it on the cheap i would give it a go, more out of curiosity than anything

[chip-3door]

i think thats why i keep seeing 6 pot lumps.. there would be more point in that

altho if i were him an offered it on the cheap i would give it a go, more out of curiosity than anything

Same stupid mentality that i have by the sounds of it

[Jhonno]

yeah i reckon

[e30_318i]

just in reply to your questions on the standardness of my engine it is far from standard having a major rebore wiv new internals! the engine is now a 2.3 wiv 92mm pistons. lightened everything. i know it sounds pointless doing it to a 318i but i wanted to be a bit different. budget isnt really a worry.
i dont mind taking the engine out etc but i wanted to keep the original m40 lump as not many people do much to them

many thanks to the input on the thread!

[lentec]

just in reply to your questions on the standardness of my engine it is far from standard having a major rebore wiv new internals! the engine is now a 2.3 wiv 92mm pistons. lightened everything. i know it sounds pointless doing it to a 318i but i wanted to be a bit different. budget isnt really a worry.
i dont mind taking the engine out etc but i wanted to keep the original m40 lump as not many people do much to them

many thanks to the input on the thread!

When i was looking into my supercharger conversion
i was advised (by an x-indycar engineer) not to lighten my crank! as the forces that be will do verry bad things!
Dont know if this stands same for your engine tho.

Anyway isnt a 2.3 m40 differant enough!!

[chu346]

just in reply to your questions on the standardness of my engine it is far from standard having a major rebore wiv new internals! the engine is now a 2.3 wiv 92mm pistons. lightened everything. i know it sounds pointless doing it to a 318i but i wanted to be a bit different. budget isnt really a worry.
i dont mind taking the engine out etc but i wanted to keep the original m40 lump as not many people do much to them

many thanks to the input on the thread!

When i was looking into my supercharger conversion
i was advised (by an x-indycar engineer) not to lighten my crank! as the forces that be will do verry bad things!
Dont know if this stands same for your engine tho.

Anyway isnt a 2.3 m40 differant enough!!

What you talking about?

Do it mate!!!!!!!!!!!!

[chip-3door]

If you have 2.3 pistons, you probably also have much higher CR dont you?

Might not be ideal for a charger unless you get a management change, and even then you may be pushing it!

[e30_318i]

yeah just waiting for my megasquirt! its faster enough as it is but im a bit of a speed freak when it comes to cars having own a 155mph rover metro and mk.2 fiesta turbo and a s1 rs turbo have always liked getting the maximum power out of the engines! thanks for your input on this topic guys it has been a real help in my head weather i shud sc it or not! think i mite just play around wiv the engine a bit more to try and find the most power possible! gonna get the cam redone to a 288 or maybe a bit more? only running a 276 at the mo so shud be fun!

[chip-3door]

Cam numbers dont mean anything without knowing how they are measured, as piper and kent do it at a different number of thou, so a kent is always as hot as a piper with a number thats half a dozen (ish) degrees more.
But either way i should think there was too much lift on overlap for a supercharger, so you would need to go back to standard cams probably.
Especially for a displacement type charger thtas going to be all about midrange.
Same goes for CR, you might get away with it on a centrifugal charger, but not on a mini displacement one.

I think you've pretty much picked the N/A route now by the sounds of it mate, so you may as well stick with that.

Personally, i would nitrous it, only way you are easily going to see a big and still reliable hike in power.

[e30_318i]

already got nitrous on it mate! soz for the late replies as computer has been a c**t this last week but all sorted now!

i have decided to leave the engine as it is for now and go for the light weight option! so far the rear seats and all the carpets are out. new light weight seats, boot emptied, looking at taking the heating out soon but really dont want to as its coming up to winter!

[Jhonno]

2.3?!! where did you get the pistons from? had it rolling roaded? any pics of the engine as a short block?

seems like a massive jump from a 1.8.. must have huuuuuge cylinder walls..

[stevetigger]

2.3?!! where did you get the pistons from? had it rolling roaded? any pics of the engine as a short block?

seems like a massive jump from a 1.8.. must have huuuuuge cylinder walls..

I agree words mean nothing without photo's

[chip-3door]

Well looks like my late reply is even later than the previous one LOL


NO WAY you are going to bore a 1.8 to be 2.3 on any engine.

Generally most manfucaturers use a bore wall about 5mm thick at most, so you would be into the water jacket a long time before you got an increase of that order.
Also you would end up joining the cylinders together before you got that far as well!

Possible to get that sort of CC increase potentially on some engines if massively stroked i guess, but i wouldnt fancy the rod angles very much!!!!