Can You Adjust A Bleed Valve?

[aido]

Bit of a stupid question potentially but is it possible to adjust a bleed valve?

I've had a search on the forums and see mention of adjusting them, but not actually how to adjust them.

I have two nuts from memory on mine, is it just a case of putting them as close as they'll go together which will lower the boost and then in summer open them up again to raise it or is it the other way around? Not sure so this is why I haven't changed it yet! Guessing that if I turn it down fully it will mean the car is running pretty much back at stock levels?

Just wanting to try adjusting it to see if it will increase mpg and driveability of the Aristo now it's getting crap outside!

Thanks in advance

[Adie]

I wouldn't touch it mate unless you put the car on a dyno or something too. To check the fueling is still ok and for detenation. You don't want to just up the boost incase you damage something. You've also got no way of knowing what boost you'll be running and of controlling it properly. Best get a proper boost controller fitted.

[aido]

To be honest pal I'm purely looking to lower boost at this moment in time so not looking to up at all.

What I thought was measure the setting at the moment, the car currently boosts at around 1.1 - 1.2 bar, that's the max recommended on the Jspec turbos, and then adjust to lower the boost, push comes to shove I'll use the boost gauge to monitor for now, she's hitting 0.8 bar on the first turbo, so I really want to lower that quite a lot to be honest to make it more drivable in the current conditions, I'm driivng to work at 6am and the last two days have been a nightmare as the temps are so low!

I've had a read about and it seems on the Jspec it's best to get the cats gutted and then install one of the Chris Wilson restrictor rings which limits the car to 1.2bar max, and he personally prefers the bleed valves over the boost controller on the jspec, or at least he did in the old posts I read :)

It's pretty cool having the Defi's as well as I can get it to tell me what the peak boost level is that I've hit in a run at WOT, gives me a nice idea I guess of what difference any adjustments will make!

Just need to make the car slower for now :o

[Bazza]

be wary of adjusting the valve

be wary of a cheap leaky valve

the easiest method would be to take the valve out, the valve can only increase boost

the most you can adjust it down to would be the same as if there wasnt one there

far better to start with a low boost level and let an electronic valve controller control increase in boost when you want it, from the comfort of your seat !

[goodoldgrandad]

Easier to keep your foot off the accelerator pedel !!

[aido]

Easier to keep your foot off the accelerator pedel !!

Was waiting for someone to say that :P

The method behind my thinking is that if the bleed valve is shut as tight as it'll go, the car won't spool up as quick at any level of throttle, which in theory means less petrol as the car won't be using quite as much petrol all the time!

[goodoldgrandad]

I'm not sure such a mechanical pre-restriction is advisable - what happens if one day you're out driving and need to put your foot down in an emergancy to get out of the way of something. It would be sad if the car behaved like a bag of spuds because of a bleeding valve you've tweeked.

You save more petrol by anticipation and getting your foot off the accelerator early so you brake less than you do on the few occassions the road is clear and you can kick your foot down.

[skeet94]

If you know how to - remove the bleed valve and you should be back at stock wastegate boost. If anything just as Gramps said, take it easy with the accelerator...where you won't hit full boost :). Just cos you have increased boost it doesn't necessarily mean that everytime you get on the throttle you'll see full boost ... increasing boost only increases the maximum threshold acheivable at WOT. I'd just keep it as it is and learn the car ;) .

[Kazi]

do you mean a manual boost controller looks like a t peice with a bolt in it to controll the presure release befor the wastegate?

if so DO NOT FULLY TIGHTEN it you will probably blow your engin. if you don't want to inmprove the boost over stock then remove it like Bazza said or just unscrew it as far as possible without the nut falling out.

all the above coments are if its the same as the valve I used to have on my old car, yours may be different so please check it.

[aido]

OK guys thinking I'll remove this for now as it can be refitted next year if needs be - so what do I replace with?

Is it something that is going to be easy to replace, ie something that holds the two pipes together, or will the whole pipe need replacing?

Am I not right in thinking that the car spools up faster with a bleed valve fitted?

To be honest I've not really gone above 3000rpm for weeks apart from when it's safe to do so, so wouldn't have thought you can get much lighter with the pedal than that?!

[Bazza]

OK guys thinking I'll remove this for now as it can be refitted next year if needs be - so what do I replace with?

Is it something that is going to be easy to replace, ie something that holds the two pipes together, or will the whole pipe need replacing?

Am I not right in thinking that the car spools up faster with a bleed valve fitted?

To be honest I've not really gone above 3000rpm for weeks apart from when it's safe to do so, so wouldn't have thought you can get much lighter with the pedal than that?!

not sure on the length or route of the pipework, but if possible replace the whole pipe, most motor factors will sell it

if not possible use a hose connector and clamp up nice and tight, as any leaks will increase boost !!

spool up will not change, the bleed valve simply bleeds off pressure which in turn allows the actuator to stay closed longer which in turn increases boost level,

if you want to improve mpg and driveability you need to buy a gs300

[Ahhhh__Aristo]

Why not stick the turbos into parallel mode with a little mod. Will help with the fuel consumption more than turning the boost down to stock

[dangerous brain]

if you want to improve mpg and driveability you need to buy a gs300

Well if the NA version of the supra is anything to go by you actually get better fuel economy from the TT version than the NA version if you are driving light footed. After all turbo's were actually invented for fuel economy.

[aido]

Brian, that was my train of thought from reading the MKIV forums, got Dave's SMIC on the way so going to give that a go over Xmas to see how that fares, only really got sparks and O2 sensors to try changing then!

Noticed you've bought another Supe, what's she like pal?

[dangerous brain]

Brian, that was my train of thought from reading the MKIV forums, got Dave's SMIC on the way so going to give that a go over Xmas to see how that fares, only really got sparks and O2 sensors to try changing then!

Noticed you've bought another Supe, what's she like pal?

Old news mate the other supes gone. I am heading back to the aristo club now, the one in the thread that dissapeared overnight????

Thinking about it actually you could limit the boost over the winter by fitting a smaller restrictor ring in the exhaust?

[aido]

That's bizarre mate

Seems quite a few threads are going missing lately without explanation!

@ Admins - have we got database problems or something as I don't remember anything wrong with that thread????

Think I'd posted the above before I'd seen you'd got the Supe, saw that you'd been to Michael Lane and just assumed it was a Supe!

Not sure what to do, I was only thinking about reducing boost as I assumed it would spool quicker due to the bleed valve, if it doensn't actually spool any quicker then I'll leave as is I reckon as I'm not boosting in this weather anyway!

[dangerous brain]

A 1 bar restrictor ring will bring your boost back down to close to stock. Turbo's will spool a bit slower though.