Compressor Bypass Valve

Steve940estate · Sep 15th, 2009, 11:03

I have been trying to find an alernative to the standard Volvo part for my 940. I understand 850's and a few others use the same valve.
Whats the general opinion regarding increased boost verses bypass valve life ?
The on on my car is ok at the moment but genuine Volvo ones cost about £130 and no aftermarket direct replacement is avaiable. I have spotted some for sale in Japan for a slightly better price.
Trouble is even a new one might have limited life when running higher boost.
The other alternative is to fit a Saab type bypass valve (re-circulation type) and fit a blanking plate.

Can anyone help ?

Alan M · Sep 15th, 2009, 21:01

With a little alteration to some pipework you can fit a DV30 Bailey recirc valve that is rated upto 60psi IIRC. You would fit a blanking plate then fit the valve taking the pressure forom the throttle body (as near as possible for best results) then dumping it back post Maf but pre Turbo.

Steve940estate · Sep 15th, 2009, 21:27

Thanks for the reply. I'm thinking that might be the best way at the moment. I know Forge do the blanking plates and LMA do various valves and bits of pipework. All it would need is a pipe fitted into the steel one from the intercooler. It's just the return that might be difficult to do well.
I have found that IPD in America can supply diaphrams but I don't know exactly what they are yet.
It surprises me that nobody keeps them in this country. Plenty of companies supply recon turbos, I wonder what they fit ?

Steve940estate · Sep 15th, 2009, 21:53

I have just been looking oon turbo vricks site and found a bit of info on CBV's.
I'm wondering if the part I was told about by Volvo is the right one. Are there different types of Mitsubishi bypass valve ?
The price did seem over the top for a diaphram and spring and the picture on Vadis looks more like a thermostat for want of a better discription.
The part number I have is 271640. This part is also listed for the V70.

if there are different ones then the choices are more limited than I though.

Alan M · Sep 16th, 2009, 08:10

You can step off the CBV internally with a spacer behind the spring to increase the spring closing pressure so that it will work with higher pressures. The refurb kits on ebay from a few sellers are actually genuine Mitsubishi parts direct from Japan.

Steve940estate · Sep 16th, 2009, 09:14

I've got a shim under the spring seat which has helped I think. Trouble is the diaphram is the original and it's being asked to do a bit more than it was designed for. Saying that the turbo plus lit on the 940 gave about 10psi and there must be a reasonable safety margin built in.

Sep 15th, 2009, 11:03	#1
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	Compressor Bypass Valve I have been trying to find an alernative to the standard Volvo part for my 940. I understand 850's and a few others use the same valve. Whats the general opinion regarding increased boost verses bypass valve life ? The on on my car is ok at the moment but genuine Volvo ones cost about £130 and no aftermarket direct replacement is avaiable. I have spotted some for sale in Japan for a slightly better price. Trouble is even a new one might have limited life when running higher boost. The other alternative is to fit a Saab type bypass valve (re-circulation type) and fit a blanking plate. Can anyone help ?

Sep 15th, 2009, 21:01	#2
Alan M Senior Member Last Online: Jan 24th, 2023 07:05 Join Date: Dec 2007 Location: Cannock/Solihull	With a little alteration to some pipework you can fit a DV30 Bailey recirc valve that is rated upto 60psi IIRC. You would fit a blanking plate then fit the valve taking the pressure forom the throttle body (as near as possible for best results) then dumping it back post Maf but pre Turbo.

Sep 15th, 2009, 21:27	#3
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	Thanks for the reply. I'm thinking that might be the best way at the moment. I know Forge do the blanking plates and LMA do various valves and bits of pipework. All it would need is a pipe fitted into the steel one from the intercooler. It's just the return that might be difficult to do well. I have found that IPD in America can supply diaphrams but I don't know exactly what they are yet. It surprises me that nobody keeps them in this country. Plenty of companies supply recon turbos, I wonder what they fit ?

Sep 15th, 2009, 21:53	#4
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I have just been looking oon turbo vricks site and found a bit of info on CBV's. I'm wondering if the part I was told about by Volvo is the right one. Are there different types of Mitsubishi bypass valve ? The price did seem over the top for a diaphram and spring and the picture on Vadis looks more like a thermostat for want of a better discription. The part number I have is 271640. This part is also listed for the V70. if there are different ones then the choices are more limited than I though.

Sep 16th, 2009, 08:10	#5
Alan M Senior Member Last Online: Jan 24th, 2023 07:05 Join Date: Dec 2007 Location: Cannock/Solihull	You can step off the CBV internally with a spacer behind the spring to increase the spring closing pressure so that it will work with higher pressures. The refurb kits on ebay from a few sellers are actually genuine Mitsubishi parts direct from Japan.

Sep 16th, 2009, 09:14	#6
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I've got a shim under the spring seat which has helped I think. Trouble is the diaphram is the original and it's being asked to do a bit more than it was designed for. Saying that the turbo plus lit on the 940 gave about 10psi and there must be a reasonable safety margin built in.

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