I have managed to get reasonable boost control by adjusting the size of the little brass restrictors that sit in the pipe from the intercooler hosing to the T-piece and then the wastegaste actuator. But I would really like to source a restrictor that could sit in the pipe as well as or instead of a restrictor, but don't want or need a bleed valve. I have tried 1.3 and 1.4mm drill bits, and the optimum clearly lies somewhere in the middle - the only 1.35mm drill bit I could get was tungsten carbide and broke instantly! 1.3mm overboosts, 1.4mm never really peaks and ambles up to 16PSI. I have filed the end of this slightly to narrow it and it works for now, but if it got very cold a nice 1/4 turn of an adjustable valve would be very useful! Hopefully there is a valve type thingie I can put in the pipe and say adjust a grub screw 1/4 turn at a time to make fine reliable adjustments.

Any ideas welcome, and no I don't want HKS EVC 4! (£)

 

I have never tried this its just an idea so be warned

Get the 1.4 restrictor and fill the hole with solder let it go off and then run your 1.35 drill through the soft solder thus giving the desired result.

 

john u have mail
richie

 

very good idea, but is it possible ?

i think alot of people will benefit from such a device


sam

 

John,

Also take a look at

 

I will let you know if it does - Richard (above) works in pneumatics and may be able to advise us further.... I know bleed valves in this pipe run at just a crack open -with restrictor still in place- and are difficult to control from Lee's site, but I am trying to *reduce* the overboost peak and may use this instead of a restrictor.

 

John,

Isn't this what a Boost Controller does? I know they cost more money but do a good job?

Just a thought....

Matt

 

have a look at

 

Fantastic looking product Richard. What size? - the internal diameter of the hose is about 4mm based on the size of the restrictor which fits in OK, but would you need a fitting slightly bigger to give a nice fit? Presumably the choice of valve lies between 1/8" 2mm or 1/4"? The flow goes A to B in the direction of the arrow -O>- ? What is the cracking pressure (max) of 7.5PSI?

I am looking at the flow graphs and thinking that a 1/4" valve with a 4mm orifice may only be opened about one turn from shut off whereas the 1/8" 2mm orifice would need about 6 turns for the same flow rate allowing better control? Is this flawed logic?

Matt "no I don't want HKS EVC 4! (£)" unless you want to flog me one cheap? £500+ IIRC?

[This message has been edited by john banks (edited 27 September 2001).]

 

Thanks Gavin - had seen that already. They have a kit specifically for MY01, but my concern with a relief valve is that when they reach target pressure they can suddenly dump pressure onto the wastegate actuator and lead to undershoot. Might try it if the flow restrictor doesn't work though.

 

John,
You have mail.

Derek..

 

John,

The Dawes valve works on earlier cars as well - I have a 94 WRX.

I can see your point about potentially overshooting - I have one fitted between the wastegate and turbo "nipple" - i.e. the Link ECU doesn't control the boost.

With this setup, atmospheric conditions can vary the boost level by a maximum of 0.5psi (on my car at least) but the more tubing used, the more likely it will overboost.

It makes a very dramatic difference to the boost curve of a TD05 though...

Changing the subject slightly, I don't know if you've seen this article on Autospeed about using pneumatic valves to create a boost control system but may be of interest:

 

John,
Not sure about variable jetting but the best bet is to buy some Weber DCNF jets for about £1.5 these start from .1mm and increase by .01 in size.
GRant

 

john
yep the 2 mm oriface would be best i think
i'll send u some fittings with it
as for cracking pressure i'll find out what that is when i'm back in work on wednesday
only condition is that when i an up in scotland next year(mother in law has a farm at granton on spey) you take me for a blast in your beastie
richie

 

I have now found out that the cracking pressure is the pressure required to open the valve. So 7.5 PSI is OK as that sort of pressure would not do anything to the wastegate actuator anyway I don't think.

Certainly I'll take you on a blast.

 

Has anyone bought the Dawes devices kit?

They have quite a good Lambda thingy as well, anyone had one of these as well?

F

PS Richie, how's the pipe?