Hi guys,
I dont post much here but I wander if anyone isnt using their M62's "bypass" valve.
You may or may not know, but this isnt being used on a cobalt. I would have used the one that came with it but it leaked and was causing me to loose boost.

Anyhow, my question is, I know that without a bypass or blowoff valve on a turbo vehicle the compressor can see "surge" witch can prematurely wear out the turbo.

Will there be any side effects of not using one on my supercharged neon besides a slight mpg drop under "cruseing" conditions?

 

so what happens here is your blower is still compressing air and forcing it into your intake manifold when you let off the gas, the stock ecu is desgined so that the PSI is blown off so using my logic (which may not be entirely true) you might be boosting when your computer doesnt think so and when it checks its charts for AFR it will inject a leaner AFR then you actually want

 

You need to have that bypass valve operating. The Eaton is a positive displacement pump, and will always move a given amount of air per revolution. This will always cause (more or less) a higher volume of air being pumped into the manifold than the engine can take in. You do not want this during low throttle and steady state cruising. It will cause your milage to suffer and will have ill effects on your engine. The valve open at steady syate cruising to allow the boosted air to reirculate back into the unboosted side of the blower - thereby equalizing the pressure and allowong the blower to freewheel and (more importantly) the engine to operate in a "naturally aspirated" mode. Also, your throttle body and (mostly) closed throttle plate may not like having themselves "majorly sucked on" by a supercharger 100% of the time. This could also do damage to the EVAP and PCV systems.

It would be easier to send the blower to a shop to have it looked at / rebuilt. During the rebuild, the shop should check the bypass operation and fix boost leaks as well as calibrate the system.

Hope that helps!

-P

 

^ how does a blower freewheel when its directly attached to the crank via the belt? The blower wouldnt need worked on its the actual vacum activated valve that pulls the butterfly open thats shot, not the internal valve in the blower. Its not like the blowers always making boost. At idle iam at vacume usually 10-13. Hadent thought of throttle body or pcv damage tho


^ No, Remember this isnt on a cobalt. I have a full stand alone engine managment, fuel and spark change by map and rpm.

 

"Freewheel" meaning that it still spins, but because the intake and output sides of the blower are equalized, the blower is not stacking air, and the parasitic drag is reduced significantly - even though it is still spinning perportional to the engine RPM. You could probably get a replacement vaccuum actuator for the blower, and you should be golden.

 

^ I prob will do that here by spring. Shes in winter hibernation for now.

 

I just read through your project thread. It looks like you have something pretty cool/different going on there. The only thing is that that doesn't look like an M62. What did you get the blower off of?

 

Its def a m62. rebuilt unit from a bonneville.