Bypass valve modification

[BlueMax]

I will be fitting the GTT oversize crank pulley and CAI hybrid filter to my 04 MCS 210 JCW. Can anybody please advise what the bypass valve modification means - what is done and how is it done and what are the benefits performance wise? Are special tools, parts or machining work required?

[ScottyBoy]

Id be interested in this modification if anyone has any idea???

[pardonator]

It's not a modification more of a rectification of where the valve isn't aligned completely correct.
Hold on I'll find Rolands post ...

[pardonator]

Can't find the post I saw originally but here's a snippet of Rolands wisdom

"Hi Guys,From the factory every MCS weve ever worked on has a leaking bypass valve. Every car will benefit from having it adjusted properly. Not only will you gain more power,but better economy too. On full throttle any loss of boost is bad news.
The power increase is probably around 5-8 bhp for most cars."

Think of a hose pipe with a hole, going to lose pressure where you want it to come out.

Photos are not from roland but another thread, link at bottom





http://www.mini2.com/forum/engine-dr...libration.html

[Richard Crofts]

Basically remove the bypass valve...and shut the butterfly up a bit. Mine is almost completely shut when at rest...thus increasing boost pressure as the pressure finds it harder to escape. Some Ss have really open ones and some are much better. Mine was quite closed anyhow so was generating a fair bit of boost. There is a knack to it and its best to have it done on an exchange basis by rolnads IMO.

[BlueMax]

Thanks as always guys!

[ScottyBoy]

Pardonator, Richard..... Have you's done the BPV Mod and the VGS Vacuum Gain System any chance???

Id like abit of advice

[pardonator]

I haven't, going to give it a go at the weekend though.

[ScottyBoy]

Quote: Originally Posted by pardonator (original)

I haven't, going to give it a go at the weekend though.

Sorry to go off topic slightly but, do you understand how to do the VGS Mod

In the original thread about the VGS roland said you can do it with tapping in to the boost gauge vacuum line but i dont want to do that and do it wrong so would yous no if this is right



Does this look correct

[Richard Crofts]

I not touched the VGS

My bypass is done but it was by a MINI trained and also pretty experienced tech. Personally without that sort of mechanical (cooper S especially) experience I'd never touch anything as theres some other tricks to doing the bypass mod so the butterfly stays shut (however Roland is the man to talk to about getting one of his kits)

[PmP]

Wouldnt have a clue were to start myself without detailed instructions. Does Roland do this modification on it own? If so how much does he charge? Is this something that can be adjusted off the car or does it involve a trip to GTT?

edited
Ok other thread answered that, but where exactly do I get access to the valve? Wheres it situated?

I'm suffering from alot of yo yo effect in 1st , 2nd and even 3rd. So would be keen to look at this.

[minioneandrew]

The BPV is next to the throttle body i think. It has to be removed to get at the BPV??? And the VGS simply is re-routing some of the vaccum lines. I think to the FPR, but i dont even own an s yet, so i could be wrong.

[PmP]

Quote: Originally Posted by minioneandrew (original)

The BPV is next to the throttle body i think. It has to be removed to get at the BPV??? And the VGS simply is re-routing some of the vaccum lines. I think to the FPR, but i dont even own an s yet, so i could be wrong.

Hang on then, when the works air filter is fitted some vacuum lines are rerouted, so if ive a works air filter has this VGS already been done?

[minioneandrew]

With the JCW air filter, the vaccum is used to open the flap at 4000rpm, i think thats why you have an extra vaccum line.

[k-huevo]

When ever I can get the upload function to work I’ll show some photos of the bypass valve.

Over the years there have been three different builds of the bypass valve. The early version had slot head screws on the butterfly plate and the later builds have T10 Torx head staked screws; the latest version has different casting features than the earlier part number. First loosen the butterfly plate screws and center the plate, tighten just enough to hold the plate, adjust the stop limiter set screw with and allen wrench till the plate almost occludes all light passing through, don’t completely close or binding may occur later, and tighten the butterfly fasteners. Some set screws have a very strong thread lock bond and may require a hit with a small flame tip torch. I’ve split some screws while loosening with the allen wrench so I now file the set screw contact point to adjust. The diaphragm return spring can also be replaced with a stiffer wind or the stock spring can be extended to make a more positive return. I don’t recommend the spring modification although many prefer it; be prepared for poor gas mileage if you go that route.

Both the R&R and modification are a DIY, there’s no need to be intimidated by the prospect..