RE: Supercharger bypass valve operation patprimmer (Publican) 22 Dec 08 05:55 Pat, which charging systems are you referring to? All systems use this bypass open at idle, if the SC is clutched. Where is your throttle placed? Do you use the electromagnetic clutch? What is the car used for? Using this method would result in a very noticeable moment when the gate changes position and would probably break something eventually. It was also fitted with a clutch.Īlternatively, applying full voltage to the actuator will hold it closed. The old MR2 SC just operated the valve when MAP determined. In reality the control is a mix of these two plus other factors. Closing the valve at very low MAP levels would offer the supercharger to work when it is needed, but the valve must then stay closed as the pressure rises. Using a linear coefficient over a certain rpm range and TPS signal would be the easiest. It would then be up to you how to control the valve. The TPS and MAF sensors can both offer an electronic signal that can be sampled and converted into a duty cycle by a simple chip and circuit, or you could use an already interfaced chip with PWM functionality. The bypass should normally be operated using a pulse width signal to give proportionality. J79guy RE: Supercharger bypass valve operation 70btdc (Automotive) 22 Dec 08 05:32 Yes, the newer cars' bypass valves tend to close "slower", but this is a function of several parameters that the VCM monitors to give the smoothest torque rise. A pure MAP controlled valve is stone simple, but you may have to slow the valve rate a bit by restricting the sensing line. The ultimate would be to use a pure microprocessor controlled bypass valve and the necessary programming to control it to give smooth operation, and yet reasonable throttle response, but in your particular application you don't indicate the end-use, so I can only relate what experience I've had with Eaton superchargers that have bypass valves. The Ford Thunderbird 3.8L supercharged cars had pure MAP actuated bypass valves, and yes, the boost rise was fast giving great throttle response, but you could quite perceptably feel the boost come on, and the cars were a bit "lumpy" to drive. In a racing application this may be acceptable, but for daily driving, it can get annoying. They are totally pointless on a turbo car, so I dont think I have any kicking around, but I'll go look.Back to the OP, mechanically operating the bypass valve, obviously is the most simple method, but can lead to some abrupt boost pressure changes, and thus effect driveability. Only way of testing that is by fitting a non-ecu controlled escape for the air, a dump valve. No idea if that was on or off throttle (though I never went about about 1/8 throttle, but with a stupid electronic throttle like Mercs have what you are pushing and how much the thottles actually open is often very different), as it MAY be the boost spiking as the throttle shuts as it now has nowhere to escape from, and unlike a turbo its a positive displacment unit so it cant just escape back out the inlet. The car idles just perfectly without it, totally normal, id almost go as far as to say it idled better.īUT! Could I test the car without it? Could I hell! The minute you even lightly tickle the throttle above 1500rpm, the blower pressure was enough to blow the (very tightly jubilee'd in) bung out like a ****** rocket. One things for sure, the common internet rumour (as clearly nobody has ever actually tried!) that the bypass is needed to make the car idle, as when the supercharger is de-clutched the supercharger is blocking the inlet air flow, is total and utter ********. Well, just removed the bypass throttle and plugged the hole. I made a tidy A-pillar mount for it that matches the rest of the Sport trim, but until I can find a place to run the pipe it's not much good to me! Well, hooking it up to the inlet system is incredibly easy, but finding a hole/grommet/anything in the bulkhead to run the pipe, well, it's beat me so far! I have just been hooking up the gauge for testing only and running the pipe thru the door, then removing it once im done, 2min job. Wouldnt be surprised if Mercedes electronic throttle mapping is preventing us from getting full throttle at all times despite what our foot is doing, but unfortunately SprintBooster don't affect that.īoost gauge install is a pain in the ****. It suits some people who rarely use full throttle as it gives more throttle without them pushing the pedal more, but if you use the full range of throttle, it does owt. Complete waste of money IMO, and I've used one in the past.Ī gimmick to make your car feel faster when its not any different by making the throttle feel more jumpy.
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