How does supercharger bypass valve work

Conditions such as idle, during shifts, and backing off throttle during tire slip conditions are very important to have a bypass valve. A bypass valve utilizes a vacuum line port behind the throttle blade and vents when detecting an immediate change in pressure.

Bypass valves are different from a wastegate relief valve, which operates as a pressure relief valve and opens or vents excess pressure when a certain pressure is achieved. The correct answer is no. Our superchargers are designed to provide maximum boost and efficiency at the maximum engine rpm and by adding a wastegate relief valve to vent that boost is defeating the whole purpose of having an efficient ProCharger supercharger. Proper supercharger pulley size and knowing how much boost your engine can handle at its rated max rpm are the keys to success with a proper ProCharger setup.

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Have questions? We've got a team of ProCharger experts ready to help you. Skip to main content. Enter your keywords. Call Today If you are talking about a traditional air-to-air intercooler installed in front of the radiator or some other place equally remote from the engine, then having the entire intercooler system and all connecting pipes under intake vacuum might have some interesting consequences in the event of a leak, and all that "dead volume" behind the throttle might make throttle response a little interesting.

Depending on application, an air-to-water intercooler can be built directly into the intake manifold with relatively minimal volume. It all depends on the layout of the system in question. For what it's worth, the Ford Thunderbird bypass type supercharger systems have the throttle upstream of the unclutched supercharger.

I had a look at my logfiles and found out the following: the boost builds up over a much smaller TPS range than over which the valve is closing.

This makes engine operation feel jerky and somewhat uncomfortable because boost always build up at the same point, independent of RPM and driving conditions uphill-downhill. So, I'll have to extend the TPS range over which the valve closes or go for the other approach.

That will be to drive the valve so as to deliver a certain boost dependant of TPS. I'm tending to go for that second one, and in the mean time I'll foresee the necessary wiring for all the relevant parameters to be logged by one device and not by two separate like now, because that makes it awkward and unprecise to reconstitute te data.

We tried implementing electronic bypass control in the interests of pursuing part load fuel economy and improving response but the cost out-weighed the benefit and it never made it into production.

What is it you're actually trying to do? Enginead, What is so very useful in the experience that you shared here is that you mention the compensation from the two MAP sensors onto the ETC and torque model.

How it compensates engine parameters will be load dependent at first because these absolute pressures are load dependent. It is to note that in principle the ETC hardware is quite similar to the electromechanical bypass valve as used on the MB engine. The valve control that I described in my previous post and which is used now is load dependant too, albeit in a more crude way because the cable actuated throttle plays a role in it. Anyway it will be more load dependant than my first approach.

Winter was long and the opportunities to test on dry roads were very rare. The first -short- tests with this system look promising. The attached picture shows the path to a certain improvement. Boost buildup is more "the extension" of the manifold vacuum. Obviously, that was the setting yielding smoothest throttle response. What has to be refined? The slope of the positive pressure as function of the throttle position is still steeper than the vacuum as function of throttle.

I think drivability might benefit from stretching even more this part of the action. As to your question what I am trying to do I can answer you the following. This has nothing to do with my job. I'm working full time professionally, who knows even knowledgeably, doing something completely different.

Don't ask me why. Partially it was destiny That was quite a difference compared to my old twin-DCOE commuter. Since then I have walked different ways and meanwhile it became a project car. After being tired of playing with turbo's I mounted this charger that I had available. The challenge now is to optimise its control.

A first ECU remapping has been done last year and once I will have satisfactory results with this bypass, I plan to increase the boost. What will be next? Who knows, I have other hobbies too, and a lack of space and time. JCD06, I am interested in what you are doing as well. I am a hobbyist that likes to think "outside of the box". I am looking into using a Whipple 5. Like you I feel that there has to be a better way not necessarily cheap or easy.

More info on your progress would be greatly appreciated. Pokeytemplar, This project has been on hold for a while because of other priorities and I don't expect it to restart in next couple of weeks During summer I had the car for a series of laps on the track and I'm glad that it all held together For increasing the boost I am hesitating to make a larger crank pulley.

I might as well decide to go for a second belt and an intermediate shaft. About your plan. There was an article somewhere where was explained the differences between these vacuum based bypass valves and turbo bypass valves.

I'm talking here about bypass valves for the compressor side where as you're talking about wastegate which is for the turbine side. Perhaps you just confused names. Anyway, the main difference that I can remember of was the spring. So this might need some thinking and tweaking.

The advantage you could have with a vacuum operated valve over an electric actuator like in my setup will most probably be the response time, which I must admit is at the limit for track use. The inconvenient will be the need for a vacuum tank but these can be cannibalised from stock cars where they are often used for various actuators, for example variable inlet runner length.

What solenoid valve will you be using for this PWM? Those used in turbo boost controllers usually work with a frequency in the Hz range but all specs are top secret. Response time of such devices is in the ms range.

Good luck and keep us informed about your project. The bypass valve has 2 potentiometers, one to feedback the position of the actuator and the othr to feedback the actual position of the valve. I just have to decide which parameters to use to control the bypass valve position. I look forward to seeing your progress.

Mark, Making this work with a Megasquirt is a nice project. It seems to have very useful features like PWM outputs as you mentioned. I don't know what is the power capability of these outputs. In my setup the valve actuator motor has a resistance of 2ohm and it needs about 2A to open completely. We might just have the same bypass valve but what you're telling about the potmeters confuses me.

Before mounting it, I have opened the actuator housing and as far as I can remember both potmeters were on the same shaft, one having a longer stroke than the other, probably for some kind of a fail-safe system.

Unfortunately I did not take a picture of the internals, I'll make sure to do so whenever the charger has to come off the engine. You can see a couple of graphs in an earlier post.

As my approach is completely analog it would drive me too far to define an algorithm but I think the graphs speak for themselves.

I still have some reserve about this approach. When accelerating, for the short time that the bypass is partially closed, the valve is regulating pressure and I am not sure about the practical inconvenience this might bring. For that very short period, the engine charge is air that has been bypassed around the compressor and so far I did not pay too much attention at its absolute temperature. A temperature peak high enough might as well start a pinging in the engine.

I want to use a faster logger and check for unwanted temperature rise during this transition. With a faster logger it will also be possible to monitor the valve reaction time and perhaps try to find a way to speed it up. For normal driving its response is fast enough but for track work it is a noticeable -although not insurmountable- lapse but for a moment I thought I had reinvented turbo lag It's not at all sure that this is caused by the valve response, it might as well be the volume of the intercooler and ducts being taking time to get pressurized or just a combination of both.

Is there a place where I can follow the progress of your project? Mine has the same electrical characteristics that you quoted. I was mis-informed about the potentiometers - I took mine a part, as you can see, there are 4 brushes for the pots connected in pairs, shorting the brush for track 1 to the brush for track 2 and likewise for tracks 3 and 4. They are wired so that when one pot gives a max voltage, the ather gives a min, I dont know why. I plotted a graph of the 2 pot values for the complete range of movement of the valve.

I am having difficulty accurately controlling the valve. I have built a 2A PWM test circuit, but the positioning is very vague. I will try a different frequency as the 12KHz I have at the moment is probably too high, although DC seemed vague too. The Megasquirt has a built in fucntion for control of a turbo charger valve which would achieve the same result.

The position of the valve can be defined by RPM and Throttle position and you can set a max boost pressure. I have contacted Bosch in England for some info on the valve and the guy there has in turn applied for info from Germany as he didnt have the data due to it being a part number.

I will pass on the info when I get it. Hi Mark, Thanks for the pictures, indeed the chargers are similar. As for the potmeters, R1 and R2 are ? The reason why there are two pots is most probably for redundancy. I'll draw a sketch of the circuits used.

I'll do this when I'm back home end of April. The first one I built was TPS based and in fact nothing more than just a servo drive. Using an external pot to simulate TPS gives a circuit that allows to check the working of the valve on the bench. Throttle flap follows the pot angle. One wonders why Japanese car builders have problems achieving this. I can't see why 12kHz would prevent accurate positioning.

The valve control was very good in my case but this was probably because I was using other parameters than you. As you can see in my previous posts, positioning the valve as function of the throttle position did not result in smooth engine operation. What works well is boost as function of the throttle position.

Here absolute valve position is not important but on the other hand in this case the amplification of the differentiator is more important. If it has a wrong value, the reaction to the throttle will be vague under reacting and not completely closing the bypass, or oscillating overreacting.

Unfortunately I can not give you a value for this amplification factor. I seem to remember aftermarket stand-alone boost controllers drive their solenoid with a rather low frequency. I don't think it would be a problem to drive this bypass valve with a low frequency. I hope for you that the Megasquirt is flexible and transparent enough. Train dogs, Teach people. Hi Mark, I attached the schematics in pdf format. Although the positioning was very clear and reproducable, this was not the good way to go in terms of drivability.

I must admit that I have been a bit sloppy with taking notes so it might be possible that you'll have to swap the connections 2 and 3 of the valve pot. P1 is set at It controls pressure as function of TPS. I connected the voltage from one of the valve pots to a LM LED dot display driver so at least I have a visual indication of the valve movement.

Let me know if you have questions. I just realised how long this project has been going on and I hope to be able to do some further testing before summer because after August there won't be much time for this kind of fun. From the calculations I have done sometime ago I could conclude to have reached the limits of this charger. Keep us updated.

Regards, Jean Train dogs, Teach people. HI just came across this excellent site and this very useful post I have a audi tvs charger that also uses an electronic bypass that i was going to try to convert to vac control the tps feedback looks to be magnetic not a swiper , so is a bit different Now i have found this i just require some one to translate as i have not a clue when it comes to electronic's I have a DTA S60 ecu but i dont think the low current 'simple' PWM output will power this?

Hi Bob, I'm not sure I understand your question and the reason why you want to modify. Do you want to convert the valve actuator to a diaphragm one or do you want to modify the electronic drive so it takes into account the MAP signal and not only the TPS? Hi Jean I would want to use the electronic bypass if I can and after showing your diagrams with the DRV to an electronic friend , we have decided to use the dta ecu via turbo control but with an external drv to boost the pwm and with flyback protection hopefully this will work bob.

In that case it might even be possible to incorporate a RPM component in the process. Personally I don't plan to go that far. I am satisfied with the fact that I found a way to actuate the bypass valve in a more delicate way than the vacuum actuators where only the spring pretention can be adjusted. I also realise that the latter have the advantage of simplicity and reliability. Good luck and keep us updated.

Jean Train dogs, Teach people. Bypass valves should always be connected to the intake side of a supercharger. The vacuum side of a bypass valve should never be connected to a vacuum line that will see boost pressure! Low vacuum cams or lengthy valve overlap : Low vacuum cams can cause loss of bypass function. Cams with lengthy valve overlap can cause low boost numbers and hot exhaust temperatures. Incorrect internal supercharger parts : Use of incorrect replacement components can lead to early component failure or engine damage.

Bearings and seals must be rated for the correct RPM, heat, load, and component materials. Failure to comply will result in supercharger damage and even possibly engine damage. Belt slip can be a common problem with a supercharger. Twin screw or roots style models are more prone to belt slip due to the higher rotational weight inside these units. Adding more belt tension to an already tight belt puts more stress on the bearings within the drive snout or supercharger.

It can lead to early failure of the supporting bearing. If belt slip is occurring, always check belt wear first. Gates has a free tool that they can send you for checking belt wear. Always use a belt tension tool to check tension. Using the internet method of grab and twist half turn is a sure way to damage the input shaft bearings.

Poorly made supercharger pulley : Aftermarket supercharger pulleys with incorrect v-groove channels will accelerate belt wear and increase belt slip. Check shaft and keyway size for fitment issues as well. Incorrect installation of pulleys: Never use an impact wrench to remove a pulley bolt or hub.

It will knock the timing off of the rotors on twin screw and roots style superchargers.