Blow off valve

[Bill Sarkozy]

At 01:02 PM 2/26/96, you wrote:
>
>
>>If the blowoff valve were controlled by the engine management unit,
>>the blowoff valve could be opened _fully_ when going off throttle.
>>(The EFI unit already have the data to detect this condition.)
>>Then the turbo should have less resistance and keep the speeed.
>>Right or wrong?
>
>That makes sense to me, but I have also been wondering about the turbine 
>side. Wouldn't the turbine be trying to pull a vacuum through the engine 
>during throttle-lift and cause the turbo to spin down? If so, the same 
>concept could be applied to the exhaust side by using an electronicly 
>actuated wastegate. What do you think?
>
>I have been thinking about this because I was considering implementing some 
>sort of electronic wastegate to allow the boost limit to adjust from 12-15 
>pounds at low rpm to 7-10 pounds at red-line. Why? Well the way I see it 
>there are all sorts of restrictions to power at the top end (air-flow, 
>exhaust-flow, fuel-flow) that disappear at say half red-line why not take 
>advantage of them? Any comments?
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Jeff Hansen
>Anaheim, California, USA
>JHansen777 at gnn.com
>http://members.gnn.com/JHansen777/car/index.htm
>Seven pounds of boost is a 'Good-Thing'
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
If you had some sort of RPM-activated switch, the solution is
easy......bleed off some of your boost via a solenoid valve to "fool" the
wastegate at low RPM.  When you hit your arbitrary limit, close the bleed
solenoid and the wastegate will see full boost and react normally.  Most
T-Bird Turbo-Coupe owners know of this trick, but simply use a manual bleed
valve to keep the boost high all the time........hang on!!!!!!