Most liked posts in thread: Bypass valve DELETE!!

Mike, I run the race car without it. Just make a plate to block it off. I'll make ya one if you want. I don't think I'd want to use epoxie as it softens with heat.

 

you might want to data log it so everyone can see what really is going on........ you might be surprised

 

This is going back a bit...

but Ryan did this with a wire tie called the Ryephix-I in chasing down early engine yo-yo. What you will find is no codes, a bit of a drop in gas mileage, and a bit snappier throttle response. Since it was just a wire tie closing of the BPV, I don't know how the smoother surface affectes peak airflow....

Matt

 

Look forward to seeing the results Thumper

 

people for quite a few years have been locking them closed to see if it they have an issue...I think some folks have used Zip-Ties on a temp basis...I know my mechanic has done it for folks on track days if the valve suddenly fails to "salvage " the day for them if he is around...
I seem to recall hearing the drawbacks were big enough that it was only a temporary test/fix, and not suitable for most cars for the medium or longer-term.
I would love to see a DINO comparison, and a general around town comparison though!!

 

LOL time warp!

Make sure you keep track of the results. I'm sure all prior ones have been lost.

 

Now then...

Tuls, now that you can recognize these thread-warps-to-the-past, next thing you know you'll have some grey hair! Ack!



Matt

 

FWIW

A well set up valve has very little leakage, but there will be a smoother flow with a closed-up and smooth SC horn. So you might see something on a dyno...

The downside is only in gas mileage.

Matt

 

Way back when...

early on in US New Mini times, a lot of the ECU versions from MINI had an instabillity called yo-yo. This is what got all the attention to the bypass valve. Ryan here was instrumental in doing the RyPhix-I (wire tie) and RyePhix-II (what became the DT-BPV). This was in 2002, I think.... That's why the references to the time warp.

Also, BP valves used to have much worse stop settings from the factory, so taking it off to set the stop screw could up peak boost by as much as 1 psi. Pretty good for just some time and effort.

I'm still running a modified BPV. I didn't like the effect of the stiffer spring, so when I was putting my diaphram back together, I stretched the stock spring a little bit. This moved the vacuum required open the valve a bit, and effectively shuts the valve at a slightly lower RPM range without the binary slam on/slam off nature of the much stiffer spring....

End of Mini Modding History Lesson for the day...

Matt

 

the yo yo was never the bypass valve, it was a band aid for the poor mapping of the ecu by BMW......... the timing and fueling maps were the problem. There were people even saying it was the intake manifold, all were incorrect in their assumptions.

 

Depends on how you drive....

so you'll know soon enough! I never did the test myself. Those that did reported 1-2 MPG, but you never know, most of the reports were right after the change, and peoples driving hadn't adjusted to the new behaviour yet....

Matt

 

Be nice to know the effects on the IATs....

 

It's small...

the only real time that there's a difference is at no load or low RPM. Really, at high RPM and load, the sucker should be closed anyway!

the reason that there's a BPV at all is to reduce load from the SC that is just wasted work. The SC gets to basically free-wheel because the pressure on both sides of the unit is about the same. If there were no quest for efficiency and max MPG then there would be no by-pass valves to begin with. Light load would just be done with the TB closing more, and there would be more vacuum on the TB side of the motor, the SC would pump what it could to bring the manifold to what pressure was needed for the RPM and load demanded of the system.

Mercedes does it a bit differently. They use a BPV, but also a clutched SC pulley. They actually stop the SC from running. Saves even more energy. But it's not about IATs. It's about fuel economy.

Matt

 

You'll see more than that: count on a 10% loss, all other things being equal.