M54 manifold conversion.

[Devon Z]

Well the parts are coming together, manifold arrived today and I test fitted the thottle body adaptor and there was minimal porting required in the end, just a small lip to take off with a file and some wet n dry.

How many of you have one of these on your manifold?

Going to seal this port up with some resin I think? Just got to get a new manifold gasket and I should be good to go?

 

[the Nefyn cat]

Had a rubber cap on mine looking exactly like that, didn't cost a lot from Sopers for a new one. Amazing what you find when you go poking about in unfamiliar places.

 

[Jack Ratt]

I was wondering about doing this mod while my Zed is in bits. I'm watching with interest

 

[Devon Z]

My M54 DISA arrived today so all the bits are here, I will try and make a start at the weekend

 

[Devon Z]

Due to other commitments this weekend I'm only halfway through this job but looking at the size of the M54 DISA over the M52 there's far more air volume within the M54 manifold. Looks promising?

Work comensing tomorrow, hope to get it finished and see the results.

 

[MRH1966]

That little cap is a £1 from BMW. Just changed it on my uncles Z3M. Was running like a bag of sh&t , put new cap on and wow!! like brand new......

 

[Bazza]

Watching this with interest? keep it going

 

[Devon Z]

Well it's been a late night in the garage but it's all back together! Must say it went back together easier than it came apart!

Well that's it out! How I didn't break something I will never know with all those plastic pipes with funny clips. I did drop one of the manifold nuts but thought I'll find it when the manifold is off? Could I f***!! disappeared into the abbis!!

As has been mentioned the ports are bigger 46 aposed to 42mm across and D shaped to match the ports in the cylinder head, the tubes appear the same size but main area where the DISA fits is much larger internally.
I did have to bend the thottle cable bracket to give the cable the correct angle to compensate for the adaptor plate, also the wiring loome bracket dosant fit round the thottle body correctly for the same reason but I'll address that another day.
So how does she go now? Well it was only a short drive of about 8 mile but it has transformed the character of the engine, the thottle response is better, revs rise and drop quicker, low and midrange pull is soo much better and as the revs rise the engine note deepens and she keeps on pulling! She just seems more eager than she did before?
So far I'm well impressed! And all for a £100! I'm at work for 4 days now so I'll take her for a longer test drive when I'm off next. Can't wait!

 

[Bazza]

Great write up thanks, just one question could the original manifold be modified / machined bigger to take the larger DISA valve.

 

[Devon Z]

Great write up thanks, just one question could the original manifold be modified / machined bigger to take the larger DISA valve.

I'd say not, the flap fits into slots molded into the inside of the manifold. But the reason the DISA is bigger is because the manifold is bigger and that is where the benefits come from.

 

[Devon Z]

Been out for a long drive today over some of my favourite roads and for me its a revelation! The best £100 I've spent on the car, it's a different car, more responsive off the line and through the gears because she revs better the changes are smoother, even the 1st to 2nd has lost that irritating bog I used to get. Mid range is much improved, pulls up hills better all the stuff that makes a car fun to drive can't wait to get out there again tomorrow.
One happy bunny

 

[Devon Z]

A final point, I had to remove the DISA today to modify the wiring bracket around the throttle body, as a precaution I had replaced the O ring on it with an "ungraded" one from eBay, I noticed at the time that it's not a removable one like the M52 but I had to cut and scrap it out of the groove.
Well on removal the "upgraded" one had pinched and separated, I tried the M52 one and it's too thick so for now I've had to put it back. So I've ordered one from a vender in the US who seems to of done his homework on this to source one the right size as there is no replacement available from BMW.
https://www.ebay.co.uk/itm/162575535469

I'll let you know how I get on when it gets here.

 

[Devon Z]

P.S I'd like to thank Murray for all his work on this conversion and bringing it our attention

 

[mrscalex]

I have hopefully identified the correct M54 DISA o-ring if you want a quick delivery from U.K.

 

[Devon Z]

I have hopefully identified the correct M54 DISA o-ring if you want a quick delivery from U.K.

Thanks for the offer unfortunately I've already ordered one, if it gets lost over the Atlantic I'll give you a shout.

 

[mrscalex]

For info I believe it's this part. Size BS139. That's the one I ordered but I am yet to try it.

http://www.ebay.co.uk/itm/IMPERIAL-...CROSS-SECTION-SIZES-BS126-BS150-/371555611426

I say 'believe' as if you google it there's some minor variations (BS139-BS142) that people think are the correct size. There is no spare part from BMW as it's integral to the DISA. So unlike most o-rings you can't measure the original part. So it comes down to what people think is a good fit.

There was only one person I was willing to believe and that's possibly the same guy you are referring to. German Auto Solutions who do the M54 DISA repair kit. During the development of the repair kit he was posting regularly to a BMW forum and volunteered BS139 as the correct size and the size that he stocks.

When you refit the DISA the o-ring is meant to be a tight fit that gets drawn in gradually as you tighten the bolts.

If you'd like me to send you one of mine PM me. I'm happy to send it FOC for you to try as I'm keen to make sure it's the right part. And I'm not going to get around to using mine any time soon as I didn't need to remove the DISA just yet.