[Vetteguy]

Hi there. I have been modding my 760 already. On the older turbos you can put a device between the intake and the wastegate that 'fools' the wastegate into staying shut longer. Most people call thes a G-Valve or more commonly a Dawes Device ( www.dawesdevices.com ).

My question is probably aimed at some of the dealer 'types' on here that are familiar with the engine. I have looked carefully at the 2.4T and figure I can probably use a DD on it. My only concern is that the ECU may adjust the fuel/timing curves as boost rises. Note that this device not only allows you to increase boost but (on older cars anyway) stops wastegate creep which is the tendancy for the wastegate to start to open before full boost.

My question is which of the two sensors on the intake pipe near the front of the engine is responsible for reporting to the ECU. If it is both of them, what do they both do in particular.

Any help would be appreciated.

Seems that when we are all talking $300 to $1000 dollars for ECU upgrades, this $35 (yes I know I need boost meter also) tweak is a no-brainer.

For the uninitiated, these devices are being used by tuners on new cars such as the WRX.

 

[Johann]

It's a nice trick but it is not the best way to treat your engine.
On newer models like the S60 T5 the pressure difference is compensated so you only gain a steeper boost curve.
The ECU can only compensate fuel to a certain amount and I think the ignition isn't totally compensating also.
All in all the risk is minimal because the Motronic 7 and 7.1 carry a lot of safety measures.
If boost runs over 1.5 bar the ECU reduces power for at least 60 seconds.
Reduced power mode means only 4000 rpm and 0.4 bar turbo pressure.
I've been told that the M7.1 has 3 or 4 different reduced power modes with the worst only allowing 1200 rpm or so.
The steeper boost curve gives the impression that the car runs faster but this is only minimal.
The 850's are more sensible to wastegate push rod mods.
The S60 rod is set at 30KPA also which makes it a tight fit already, it needs 6 or 7 mm to fit the wastegate lever.
The 850 is set at 15KPA which gives a few mm play on the rod.

 

[Johann]

Forgive me, I didn't read well
The thing you want to use isn't it an ordinary electronic boost controller?
Kai has fitted an Apexi AVC-R on his C70 and a guy at VVSPY fitted one on his V40 but it was a lot of work he said.
The S60 Motronic is really in control so I think it shuts down before the fun starts.

 

[Vetteguy]

Thanks Johann.

No, this is a simple pneumatic valve that holds the pressure signal until it reaches a certain bar and then lets the pressure through to the wastegate.

See www.dawesdevices.com

Steve

 

[T5 Dave]

quote:

Originally posted by Vetteguy:
Hi there. I have been modding my 760 already. On the older turbos you can put a device between the intake and the wastegate that 'fools' the wastegate into staying shut longer. Most people call thes a G-Valve or more commonly a Dawes Device ( www.dawesdevices.com ).

My question is probably aimed at some of the dealer 'types' on here that are familiar with the engine. I have looked carefully at the 2.4T and figure I can probably use a DD on it. My only concern is that the ECU may adjust the fuel/timing curves as boost rises. Note that this device not only allows you to increase boost but (on older cars anyway) stops wastegate creep which is the tendancy for the wastegate to start to open before full boost.

My question is which of the two sensors on the intake pipe near the front of the engine is responsible for reporting to the ECU. If it is both of them, what do they both do in particular.

Any help would be appreciated.

Seems that when we are all talking $300 to $1000 dollars for ECU upgrades, this $35 (yes I know I need boost meter also) tweak is a no-brainer.

For the uninitiated, these devices are being used by tuners on new cars such as the WRX.

Don't even think about it. The ME7 code in the ECU already runs the boost at hiher than usual levels. See the report on the IPD chip activity at the Swedespeed home page. They say:

quote:

It's important to note that ME7 operates differently than previous engine management systems used by Volvo. ME7 takes input from accessory loads, throttle position, rpm and speed to calculate how much torque is needed to meet the drivers request. One huge advantage of this system is that it lets the turbo stay in boost even when light knock is occurring. Ignition advance is used to control power instead of cutting boost as in previous systems. The ignition can respond and recover much quicker than the turbo can bleed boost and then rebuild it. This is how the new system is able to operate at boost levels that are 20-30% greater than previous upgrades.

So you can see wha't happening in the ECU is that the boost is already high but the ECU has backed off the ignition timing and fuel flow and runs over-lean. When power is needed, it just ramps up the spark timing and gas, which it can do instantly. This results in minimal, if any, turbo lag.

The Dawes device will screw this up!! DON'T put it in unless you're willing to buy yourself a new engine in case you ruin the first one. Let the professionals work out the details if you're not willing to spend the time, effort and $$$ to understand the ME7 code.

 

[Vetteguy]

Interesting. Thanks Dave. Looks like I'll stick to tweaking the 760 for cheap then!!