bpu

[Ewen]

Confusing info here. As I understand BPU on a J spec, you dont need a boost controller.

[hiten55]

Confusing info here. As I understand BPU on a J spec, you dont need a BC.

 

thats how i understood it too...

[bolarbag]

but am i right in thinking that export specs (i.e uk and us) need the boost controller, but the j-specs dont? or am i being thick?

 

No its just the j-spec needs the restrictor ring due to the fact they turbos cant handle boost spikes...ceramic blades, whereas the UK's can handle overboost within reason, they dont make anymore power it appears though so better off to try and tame them to 1.2bar

 

The boost controller is personal choice, as mentioned in Homers thread, you could use a bleed valve[a manual boost controller] or an electronic one, both cars need them to raise boost, the boost is raised via the wastegates staying closed until you have reached your specified boost, when it opens, in theory, the excess exhaust gas shouldnt reach the turbines of the turbos and your boost should rest at 1.2bar e.t.c

 

In reality it doesnt, the exhaust gas cant escape quick enough and you get a boost spike,

 

Fit a restrictor ring and Back pressure will build to keep the turbos at 1.2bar or thereabouts

 

Maybe a J=Spec will boost to 1.2bar without a restrictor ring, maybe 1.4bar, but that'll be because the wastegates are too lazy or too small, your going to want a restrictor ring in there to prevent spikes

Edited May 13, 2008 by bolarbag (see edit history)

[bolarbag]

I apologise, Read again, yes it seems that the j-spec has an inefficient wastegate meaning you will not need a boost controller to raise the boost but you will still need a restrictor ring,

 

If the design was not flawed as above, then you would need a boost controller and a restrictor ring they both do different jobs

 

So sorry if I have confused there,

j-spec = restrictor ring

UK-spec = boost controller

Edited May 13, 2008 by bolarbag (see edit history)

[bmx1lew]

its ok saves me a couple hundred quid

[SilverSoop]

I apologise, Read again, yes it seems that the j-spec has an inefficient wastegate meaning you will not need a boost controller to raise the boost but you will still need a restrictor ring,

 

If the design was not flawed as above, then you would need a boost controller and a restrictor ring they both do different jobs

 

So sorry if I have confused there,

j-spec = restrictor ring

UK-spec = boost controller

 

Ok well i have an EBC fitted to my Supe already. So do you think it would be wise to fit a 1.2bar restrictor ring, regardless to avoid overspeed??

Edited May 13, 2008 by SilverSoop (see edit history)

[bolarbag]

It may be slightly different on the VVTi, maybe one of the other guys can comment, but if its the same turbos then yes, if you are having full decat pipes fitted it would be recommended to fit a restrictor ring

 

 

I had actually never thought of this before, so does that mean that the ebc's fitted to j-specs are worthless, especially set at 1.2bar?

 

If the wastegate opens(at your predefined level) and theres not enough gas able to pass through then its pretty pointless having a ebc unless you want to open it at a ridiculously low boost setting