Plenum chamber?

[Widge]

Hmmmm just been thinking about how I am going to make a plenum chamber for my planned ITB's and Andys S50 photo got me thinking. Does any one know where I could get an S50 plenum chamber, cheap ish? And does anyone know what diamiter the rubber tubes are at the middle jubilee clip on this photo? I'm sure if the hoses will match the bike throttles then I can match the AFM to the plenum, I just like the idea of using a BMW part. Also does any one know of an AFM with a larger cross section from another BM that i can use instead to get some more air flow?

I know I know I should use a MAF set up. But i just want to run it on all the motroonic stuff and save my mullah for a mega squirt system, when I'll be able to run TB's trumpets and sock filters
Cheers

[Demlotcrew]

I dont think what you are planning to do will work as all the M engines are pulse tunned from the start of the inlet trumpets to the cross pipe on the exaust. If you just stick anything on, it might make it worse.

A

[Widge]

That's a good point I hadn't though of, but I'm not going to use the trumpets just the plenum and those rubber tubes, I just think it will be neater than my welded aluminium tube idea. Are the trumpes attached inside the plenum?

[Demlotcrew]

I dont think they are, BMW used the rubber pipes to take the pressure off the TBS because of the added weight of the large plenum. I know some of the early M engines suffer this problem because of the buzzy nature of them.

A

[Widge]

I'm only *thinking* about using parts 13, 1, & 10. I was just trying to think of a way of connecting all the throttle bodies and the AFM and a part of a 6 cylinder seemed the most obvious option. I think it would work fine, it just depends on size of the apatures and the physical size and the space avalible.

[Demlotcrew]

With a M20 head plus your TBS i dont think you will be able to get it to fit as the plenum is rather large. It will be resting on the turret me thinks. But its worth a go!

A

[Widge]

Hmmmm thing is I have never actually seen one in the flesh so I have no idea how big it is. May have to fabricate one, and it'll be no where near as pretty

[Demlotcrew]

Actually it may not cause problems with turret, just the brake booster.



A

[Widge]

it may even clear the brake servo as i am not planning on having the long rummers like the S50 just clipping the rubber tubes on to the end of the TBs and having the TB's mounted as close to the head as possible. I'll have to modify the thermostat housing to do this but if it means the S50 plenum will fit I think it is worth it. Other wise I will have to get a smaller / dump the servo.

[Demlotcrew]

What about the alternator + dip stick? are those in the way on the M20?

A

[Widge]

Don't think the alternator will be too much trouble, and the dip stick will come up through the trottle bodies with a bit of modification. It's just an idea at the moment, need to get the 2.7 finished befor I start any of this stuff

[dazleeds]

keeping a close eye on your plans widge mate

[Widge]

Ahem...........not plans......more *ideas* yet to be proven to be workable let alone work! But in theory it is all sound. I think the plenum would probably end up costing more than the throttle bodies though

[dazleeds]

i prefer plans mate


got me interested anyway so hope you suss it all and get it workable would just look sound and go sool coool in a 3litre hinthint

[Demlotcrew]

Dude i think that you might be restricted with the design of the M20 head the inlet flows are not very TB friendly and it would be very interesting to see what gains you have in the real world. (ie not dyno graphs)

A

[Widge]

I'm not looking for big Hp gains, it just seems a pity to make a custom 2.7 engine then strangle it and hide it behind the standard inlet tract. Hopefully it would improve throttle response - and if that is all it did I would be happy. It's more for the challange than anything else