Replacement parts for BMW DASC kit

By · January 7, 2016 · 4 comments

If you have a BMW 3 series or Z3 with a Downing Atlanta supercharger kit fitted (DASC), at some point you are going to need to replace some parts. I have been researching what the replacement parts are.

Air filter

The filter that comes with kits for some models is a K&N filter that can be cleaned and re-oiled. Should you wish to replace it the model number is RU-0950.

Serpentine belt

This will vary depending on engine, but for the M44 engine the replacement serpentine belt is Gates K060863.

Top radiator hose

This will depend on model again, and some people have found different hoses that suit them better. In my case, with an M44 engine, the options are Gates 21673, Gates 21623 or Goodyear 61417.


I hope no one ever needs to replace the supercharger itself, but it may help to know that it is an Eaton M62.

Auxiliary Fuel Pressure Regulator (Rising Rate Fuel Pressure Regulator / RRFPR)

I don't know what brand of fuel pressure regulator is supplied with the kit, but I did find some instructions for adjusting the regulator on forums.

1) Install a fuel pressure gauge which goes to 100psi between the fuel rail and RRFPR.
2) Start car. Use some blunt pliers and crimp the line between the fuel pressure gauge and RRFPR. Check pressure reaches 100psi and then release. Don't hold it at that pressure long. This checks the fuel pump can reach the needed pressure.
3) The pressures we are looking for are about:
40 psi at idle, 18 inHg vacuum
50 psi at 0 psi boost
75-90 psi at 8 psi boost
Screw the top screw in to get the fuel pressure to increase. You can check the pressure at 0 psi by removing the small hose that goes to the top of the RRFPR. Leave the RRFPR open to atmosphere, and plug the end that goes to the manifold up.

Another person commented, "75-90 psi seems a bit high for 8 psi boost. I think it should be closer to 68 psi."


Some people have suggested fitting a "check valve" between the air shrouded injectors inlet pipe and the intake bellows. This is to prevent loss of boost through this pipe. Some of the valves mentioned for this job are NAPA 2-29000, CRB-2979, MPF-3879, AV-23 and Sorensen 779-2929.

As an option to the original crankcase ventilation valve, some people suggest fitting a PCV from a Chevrolet 348 PCV instead.

Do you know any other information about replacement parts for BMWs fitted with a DASC? Please let me know.
My 1998 318is

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Comments (4)

# Posted by Richard Emam-Zade G. · April 23, 2016

I'm looking for the two idle pullys which came with the DASC kit, any idea of a part # & brand?


Richard Emam-Zade G.
# Posted by Richard Emam-Zade G. · May 21, 2016

Check valve between intake and injectors air hose.


Richard Emam-Zade G.
# Posted by Robert · June 4, 2016

I have a DASC waiting to go into my e30 318i m42. Any advice on preventative maintenance to do beforehand? I was thinking new fuel lines and clean my injectors. I plan to retain the rrfpr.


# Posted by John Avis · June 5, 2016

I would suggest asking on or where there is quite a few DASC owners.

When you are installing the DASC you will have easy access to various vacuum hoses that might need replacing. Check for any error codes as if you need any sensors they might be easier to access at the same time. Is your cooling system okay (water pump, thermostat, radiator)?


John Avis
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About me
John Avis I am a bit of a 3 series fanatic, having owned a couple of E30s and a few E36s, plus a few parts cars. I like the combination of the compact size, good performance and handling, and that they are more sports sedan than an impractical and extrovert sports car. This blog is a place to share my experience and knowledge.

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