Boost Controllers

Steve940estate · Apr 9th, 2013, 13:18

I decided to have a play with my car again and give myself an excuse to make a few things on my lathe !

I did have a bleed valve fitted on my car a while ago but after the boost going high after removing the cat I decided to take it off.

I had to put the cat back for the MOT and it's been there since so I thought it might be worth having a play again.

Before trying various things before I read loads about what others had done. Bleed valves that allow a certain amount of pressurised air to escape were the most popular method. People have then started favouring adjustable ball valves. It's this type most commonly made from pneumatic/plumbing fittings seen for sale on ebay.

This is one of them for example.

While this type seems to work very well they need to have some sort of vent to allow the wastegate actuator to return quickly after it opens. Most I have seen don't have this and rely on leaks from the adjustment screw to work properly. I tried drilling a very small hole in one of the fittings which seemed to work. When I tested it on the car the boost semed very on or off which is fine if all you want is instant power but not very nice to drive around town.

Steve940estate · Apr 9th, 2013, 13:30

I ended up fitting a bleed valve and used the valve shown below.

I fitted a T piece into the line from the turbo to wastegate actuator running into the car to the valve. The outlet from the valve then runs to the air intake pipe after the air mass meter. I found this didn't work as the amount of air needed to be bled away was too much. More reading suggested fitting a restrictor in the line between the turbo and T piece. I experimented with a few size holes in a mig welding tip until I found a 1.4mm hole gave a good amount of adjustability. This has now been replaced, along with the T piece, by this which incorperates both.

With this current setup the boost rises very quickly but still allows the total boost to be set from standard up to at least the 14psi I wanted.

I'm now trying to think of ways to limit the boost in first gear and for it to be set back to standard if needed.

Diesel-do-nicely · Apr 9th, 2013, 17:51

You are thinking along very similar lines to me, i was going to investigate the turbo + fitting on my sports ed with the thought that a solenoid operated boost device could be jockeyed onto the full throttle micro swich.
My idea is to have a bleed valve (the turbo + device) for all part throttle running, with a ball valve coming on stream at only full throttle, which you rarely use in 1st and 2nd.
I have messed about with a valve spring under the accelarator pedal to stop full throttle being to easy, without much success.

I am suspicious that the ball valve may not flow enough air through its tiny apetures to deal with the volume of gas discharged to the wastegate suddenly in lower gears, hence the shutdown problems in 1st and second but the engine is ok in 4th.
I will be fitting one of these :

Honeywell Pressure Reducing Valve with Gauge 15mm
from screwfix.
Product Code: 69396

to test its flow capacity at the weekend. It is a pressure stabiliser , not just a reducer for sceptics, with 15-8mm reducers soldered up the pipes can run into the drivers cab, and with a turn you can adjust it and see the pressure as you go.

popuptoaster · Apr 9th, 2013, 18:23

I have a ball valve one and it is annoying in the lower gears, it gives wheel spin in first and second as the it hits about 4psi then suddenly starts pulling like a train, i guess a LSD may stop the spin but its not curing the problem which is a sudden power step.

Steve940estate · Apr 9th, 2013, 18:56

The only way I can see to doing this manually is to have a switch on the gear lever mechanism which will operate a solenoid.
I dont really have a problem with excessive power and wheelspin it's just that 1st gear runs out so quickly I don't drive it that hard. The other concern is that the clutch and gearbox will suffer.
I actually enjoy the benifits of the extra power more when driving at reasonable speed so perhaps just having the extra boost on 3rd and 4th might be a better plan.

I'm getting silly ideas of big red buttons on the steering wheel ! It would be a bit like having KERS system.

barkster1971 · Apr 9th, 2013, 19:15

Having a small lag free turbo is part of the reason of low down instant boost. As soon as you press the pedal it builds boost quickly. Even a 15g gives low gear near instant boost. I am prefering my 19T to a 15g as it's much more progressive in power delivery. The 13c is more of a low down low boost turbo to sort of " get you going" with the torquey T cam.
Once you start putting a bar of boost in there it's more tricky to keep it there than 5-8 psi .
Having said that , a V cam and a 15g at 14psi certainly was fun miles.

popuptoaster · Apr 9th, 2013, 19:37

Ooh i like the idea that a bigger turbo will smooth it out a bit, brilliant excuse to fit one, I shall wait until the missus is applying makeup and give it some welly, when she complains I'll tell her I can fix it with a new turbo.

foggyjames · Apr 14th, 2013, 18:04

Boost control is a bit of a can of worms. If the boost controller isn't behaving itself, or if too much pre-load is put on the actuator, you'll risk spiking, and if the port is too small you'll get creep (i.e. the boost will run away above a certain RPM point).

If you only want to run a static boost pressure, the most "reliable" way is to change the actuator. If you want to change it, I'd add a good quality MBC with a solenoid-controlled bypass. In other words with the solenoid open, the bypass is active, and you get actuator pressure. Close the solenoid, and the MBC comes into play. Whether you control that with the WOT pin (good idea...) or a switch (for 2-stage boost) is your call...

The problem with MBCs seems to relate to the design of an individual unit. We've one crappy one, one which mostly behaved itself (but did some odd things), and one which worked perfectly.

Big turbos are a beautiful thing. We've never regretting going bigger (without going wild). A T3/T4 hybrid spools in the 2500-3000 range, and is good for 400bhp with the right bits attached. The T5 crowd have finally realised this, and large GT28s and GT30s are now the norm for higher power builds. Next stop, Holsets!

cheers

James

Steve940estate · Apr 17th, 2013, 20:56

I found this info on another site. It gives a few reasons why people favour ball and spring controllers over bleed valves .
http://www.sr20-forum.com/informatio...-up-boost.html

Diesel-do-nicely · Apr 18th, 2013, 22:40

partial success using the pressure reducing valve, it allowed a maximum or continous 5psi to the wastegate,depending how you drove it, which helped the surging in 1st and second as the wastegate "creep" kept a sudden hike from arriving to quickly, but is almost at its lower limit of adjustment, hmm.
But it pre ignited like hell , and the cluch slipped in 3rd on full chat.

Apr 9th, 2013, 13:18	#1
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	Boost Controllers I decided to have a play with my car again and give myself an excuse to make a few things on my lathe ! I did have a bleed valve fitted on my car a while ago but after the boost going high after removing the cat I decided to take it off. I had to put the cat back for the MOT and it's been there since so I thought it might be worth having a play again. Before trying various things before I read loads about what others had done. Bleed valves that allow a certain amount of pressurised air to escape were the most popular method. People have then started favouring adjustable ball valves. It's this type most commonly made from pneumatic/plumbing fittings seen for sale on ebay. This is one of them for example. While this type seems to work very well they need to have some sort of vent to allow the wastegate actuator to return quickly after it opens. Most I have seen don't have this and rely on leaks from the adjustment screw to work properly. I tried drilling a very small hole in one of the fittings which seemed to work. When I tested it on the car the boost semed very on or off which is fine if all you want is instant power but not very nice to drive around town.

Apr 9th, 2013, 17:51	#3
Diesel-do-nicely Master Member Last Online: May 16th, 2014 08:31 Join Date: Mar 2010 Location: edinburgh	limit You are thinking along very similar lines to me, i was going to investigate the turbo + fitting on my sports ed with the thought that a solenoid operated boost device could be jockeyed onto the full throttle micro swich. My idea is to have a bleed valve (the turbo + device) for all part throttle running, with a ball valve coming on stream at only full throttle, which you rarely use in 1st and 2nd. I have messed about with a valve spring under the accelarator pedal to stop full throttle being to easy, without much success. I am suspicious that the ball valve may not flow enough air through its tiny apetures to deal with the volume of gas discharged to the wastegate suddenly in lower gears, hence the shutdown problems in 1st and second but the engine is ok in 4th. I will be fitting one of these : Honeywell Pressure Reducing Valve with Gauge 15mm from screwfix. Product Code: 69396 to test its flow capacity at the weekend. It is a pressure stabiliser , not just a reducer for sceptics, with 15-8mm reducers soldered up the pipes can run into the drivers cab, and with a turn you can adjust it and see the pressure as you go.

Apr 9th, 2013, 18:23	#4
popuptoaster Master Member Last Online: Aug 2nd, 2018 19:03 Join Date: May 2011 Location: Essex	I have a ball valve one and it is annoying in the lower gears, it gives wheel spin in first and second as the it hits about 4psi then suddenly starts pulling like a train, i guess a LSD may stop the spin but its not curing the problem which is a sudden power step. __________________ 2.3 Turbo "Celebration"

Apr 9th, 2013, 19:15	#6
barkster1971 VOC Member Last Online: Apr 23rd, 2024 16:56 Join Date: Jun 2009 Location: Swineshead/Salford	turbo Having a small lag free turbo is part of the reason of low down instant boost. As soon as you press the pedal it builds boost quickly. Even a 15g gives low gear near instant boost. I am prefering my 19T to a 15g as it's much more progressive in power delivery. The 13c is more of a low down low boost turbo to sort of " get you going" with the torquey T cam. Once you start putting a bar of boost in there it's more tricky to keep it there than 5-8 psi . Having said that , a V cam and a 15g at 14psi certainly was fun miles. __________________ new engine! new car!

Apr 9th, 2013, 19:37	#7
popuptoaster Master Member Last Online: Aug 2nd, 2018 19:03 Join Date: May 2011 Location: Essex	Ooh i like the idea that a bigger turbo will smooth it out a bit, brilliant excuse to fit one, I shall wait until the missus is applying makeup and give it some welly, when she complains I'll tell her I can fix it with a new turbo. __________________ 2.3 Turbo "Celebration"

Apr 9th, 2013, 13:30	#2
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I ended up fitting a bleed valve and used the valve shown below. I fitted a T piece into the line from the turbo to wastegate actuator running into the car to the valve. The outlet from the valve then runs to the air intake pipe after the air mass meter. I found this didn't work as the amount of air needed to be bled away was too much. More reading suggested fitting a restrictor in the line between the turbo and T piece. I experimented with a few size holes in a mig welding tip until I found a 1.4mm hole gave a good amount of adjustability. This has now been replaced, along with the T piece, by this which incorperates both. With this current setup the boost rises very quickly but still allows the total boost to be set from standard up to at least the 14psi I wanted. I'm now trying to think of ways to limit the boost in first gear and for it to be set back to standard if needed.

Apr 9th, 2013, 18:56	#5
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	The only way I can see to doing this manually is to have a switch on the gear lever mechanism which will operate a solenoid. I dont really have a problem with excessive power and wheelspin it's just that 1st gear runs out so quickly I don't drive it that hard. The other concern is that the clutch and gearbox will suffer. I actually enjoy the benifits of the extra power more when driving at reasonable speed so perhaps just having the extra boost on 3rd and 4th might be a better plan. I'm getting silly ideas of big red buttons on the steering wheel ! It would be a bit like having KERS system.

Apr 14th, 2013, 18:04	#8
foggyjames 300 Register Keeper Last Online: Apr 24th, 2024 09:13 Join Date: Dec 2001 Location: Nottingham	Boost control is a bit of a can of worms. If the boost controller isn't behaving itself, or if too much pre-load is put on the actuator, you'll risk spiking, and if the port is too small you'll get creep (i.e. the boost will run away above a certain RPM point). If you only want to run a static boost pressure, the most "reliable" way is to change the actuator. If you want to change it, I'd add a good quality MBC with a solenoid-controlled bypass. In other words with the solenoid open, the bypass is active, and you get actuator pressure. Close the solenoid, and the MBC comes into play. Whether you control that with the WOT pin (good idea...) or a switch (for 2-stage boost) is your call... The problem with MBCs seems to relate to the design of an individual unit. We've one crappy one, one which mostly behaved itself (but did some odd things), and one which worked perfectly. Big turbos are a beautiful thing. We've never regretting going bigger (without going wild). A T3/T4 hybrid spools in the 2500-3000 range, and is good for 400bhp with the right bits attached. The T5 crowd have finally realised this, and large GT28s and GT30s are now the norm for higher power builds. Next stop, Holsets! cheers James __________________ VOC 300-series Register Keeper '13 V70 D4 SE Lux '89 740 Turbo Intercooler '88 360 Turbo Intercooler '84 360 GLT '81 343 GLS R-Sport '79 343 DL '70 164

Apr 17th, 2013, 20:56	#9
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I found this info on another site. It gives a few reasons why people favour ball and spring controllers over bleed valves . http://www.sr20-forum.com/informatio...-up-boost.html

Apr 18th, 2013, 22:40	#10
Diesel-do-nicely Master Member Last Online: May 16th, 2014 08:31 Join Date: Mar 2010 Location: edinburgh	partial success using the pressure reducing valve, it allowed a maximum or continous 5psi to the wastegate,depending how you drove it, which helped the surging in 1st and second as the wastegate "creep" kept a sudden hike from arriving to quickly, but is almost at its lower limit of adjustment, hmm. But it pre ignited like hell , and the cluch slipped in 3rd on full chat.

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