View Full Version : Bleed Valves V's Chips
Can someone please tell me what the benefits of fitting a Bleed Valve are as opposed to a Chip upgrade?
I know that bleed vavles trick the engine into producing more boost, sounds good to me, are there any problems with fitting one to a Cupra ?
Back in the old days of RS Turbos and Renault 5's people used to fit bleed vavles with pretty impressive results if I remember rightly !
:confused:
chungster
20-01-2002, 12:35
In those days, they didn't use complex ECu's or whatever...they give it more boost, give it loads of juice, then there was a great big bang which gave the ooomph.
On a modern 21st Century car with a space age style of ECU programming courtesy of the VAG, fitting bleed valves on to a std car with original chip can only end in tears in my own personal view.
I'd take this mod with great care if I were you.
On a 2000quid RST maybe, but on a spanking new 20VT.....I wouldn't risk it on mine thats for sure.
Lee
Icecavern
21-01-2002, 14:42
Don't use a bleed valve. If you wind up the boost too much then you will end up underfueling which will kill the engine. You have been warned....
Pete
I was told that with the 3 bar FPR on the leon, it wouldnt underfuel till you get up past 230-240Bhp using a bleed valve? (and a chip as well, otherwise the boost cutout will work overtime!!)
A Bleed valve ups the boost... by bluffing the ECU...
so..... you'll blow the seals & it'll cost you a grand (if you're very lucky)
M
Would this also apply to diesel turbos ?
OK - someone try it....
Please
then blow your engine or turbo & post back here.
M
I believe Mosser already has one fitted !
Why, just by upping the boost would you blow the seals, when chipping ups the boost, doesn't make any sense ?
ibizacupra
22-01-2002, 22:19
If using a bleed valve, the ECU will still see the delivered manifold pressure.. and try to control it. Quite what it will make of this external leak (which is what it is) on its control loop I don't know. The boost control valve will be wound back to removed boost, as the base level has been increased by the bleed valve.
I know mosser has one (had one) on his LPG conversion, but that did'nt just have a bleed valve on it though. It had the LPG crap and control also.
Not sure it would be successful, even on a raising the boost question. You would need the fuel to go with this extra boost.
If it was a Renault 5 turbo... bleed away. They were so crude it was easy to boost them. don't add the fuel to go with it though and BANG - MELT.......... ya boo shucks.
Bill
I did have it fitted, it is in the boot at the moment, i will put it back on when Amethyst have sorted all my warranty work out, i intend running my turbo at 17psi with the bleed valve,
the Borg Warner KKK-03 turbo is tested to 20spi at the factory and rated for 15psi long term, so i dont see any problem with running 17psi, and when i was testing it immidiatly after all the LPG kit was taken off, i wound it up to 22 psi without any problems just to test it for a few days!! (although i would never leave it running that sort of boost long term!)
How did it feel at 22psi then??
ibizacupra
22-01-2002, 23:17
Originally posted by Mosser
I did have it fitted, it is in the boot at the moment, i will put it back on when Amethyst have sorted all my warranty work out, i intend running my turbo at 17psi with the bleed valve,
the Borg Warner KKK-03 turbo is tested to 20spi at the factory and rated for 15psi long term, so i dont see any problem with running 17psi, and when i was testing it immidiatly after all the LPG kit was taken off, i wound it up to 22 psi without any problems just to test it for a few days!! (although i would never leave it running that sort of boost long term!)
Which pipe did you connect the bleed valve to?
Got a picture?
cheers
Bill
At 22psi it is ridiculously fast for about 15 seconds, then it starts to tail off, (i presume due to heatsoak in the intercooler),
To combat this at 17psi i will be fitting water injection to the intercooler to keep the charge temperature down and will let you all know how it goes!,
I have got a picture on my other hard drive, but its not connected at the moment, i will connect it up tomorrow and post the picture in this thread Bill
bleed valves come in two kinds. two way or three way. two way bleeds fit in the actuator hose which goes to the ecu. three way bleeds like I have fitted to my punto GT replace the electronic boost controller ( may be different on other cars) . my normal boost is 15psi which tails off to 10psi at 6000rpm. with the bleed I can set it from 13psi to 20psi. it is currently set at 17psi which gives me 13psi at 6000rpm
Tazkenny
10-05-2002, 13:01
Can we fit zenner diodes to the boost pressure sensors to stop them reading past 9PSI. Thus the ECU never thinks there is an overboost situation. This is what MR2 owners do when they up the boost. (check the forums) All that is needed then is more feuling...perhaps by a rising rate fuel pressure regulator ?? Anybody got any opinions on that ?? Mosser ??
I can't accept that we need to pay BIG money to get 15PSI boost like the chip companies are telling us.
The GT overfuels anyway so upping boost slightly is fine. too much and your more than likely to break the turbo that melt a piston
ibizacupra
10-05-2002, 15:04
Originally posted by Tazkenny
Can we fit zenner diodes to the boost pressure sensors to stop them reading past 9PSI. Thus the ECU never thinks there is an overboost situation. This is what MR2 owners do when they up the boost. (check the forums) All that is needed then is more feuling...perhaps by a rising rate fuel pressure regulator ?? Anybody got any opinions on that ?? Mosser ??
I can't accept that we need to pay BIG money to get 15PSI boost like the chip companies are telling us.
You willing to try it on your motor?
more boost without the right fuel and ignition might work out to cost you a tad more than a rechip...
The 20VT ecu is one of the most advanced (read pinicky) ECU's on a road car.
Good luck though.
Let us know how you get on.
Bill
Tazkenny
10-05-2002, 15:50
Can anybody supply a set of schematics for the ECU external systems ? A long shot I know.
I have some extremely talented electronic engineers working beside me...If I think I can reliably supply the extra fuel without causing concern and fit the larger intercooler required then I'm well up for trying to trick the boost measurement systems and using a daws device or bleed valve.
I may well be underestimating the complexity (I know its way over the top) of the ECU, but surely if it does not believe it is running more than 9PSI then why should it be a problem. More than likely I'm wishfull thinking but its worth a look.
ibizacupra
10-05-2002, 21:00
Originally posted by Tazkenny
Can anybody supply a set of schematics for the ECU external systems ? A long shot I know.
I have some extremely talented electronic engineers working beside me...If I think I can reliably supply the extra fuel without causing concern and fit the larger intercooler required then I'm well up for trying to trick the boost measurement systems and using a daws device or bleed valve.
I may well be underestimating the complexity (I know its way over the top) of the ECU, but surely if it does not believe it is running more than 9PSI then why should it be a problem. More than likely I'm wishfull thinking but its worth a look.
I have a dawes device now but have not had time to try it.
After International perhaps I'll have time to look at it and try.
regards
Bill
well the basic belief of the modern ECU is that with a closed loop lambda sensor that the fueling will be corrected to get the optimum air/fuel ratio. however it depends on how your boost/map sensor works. if you increase boost you lean the mixture. your closed loop system should detect teh leaning off of the air/fuel ration and the ECU should inject more fuel. however what usually happens is that the ECU over compensates and so the car over fuels. howeer I don't have a clue how the VAG engine works????? :lol:
chriskaven
11-05-2002, 09:46
i think close loop lambda control is only used for idle conditions. For wide open throttle most modern engines use the predefined fuel/ignition/boost Map. This comes about due to the time delay between tip in and seeing rich mixture at the lambda sensor.
sportbilly
24-05-2002, 12:56
I see people are commenting on the extra fuel needed if using the Dawes Device but what if it was fitted and altered to give a little extra boost (no need to be greedy!!) surely its worth the little amount of cash to try ??