BPV Leakage

[Flattop]

I've been reading for years how the stock bypass valve leaks badly under boost, but without any convincing data beyond marketing videos on youtube. Since I was chasing a low boost issue anyway, decided this was the perfect time to do a test of sorts. Turns out PVC pipe caps fit perfectly in the intake hoses at the turbo outlet (1.25" cap) and at the throttle body (2" cap). Screwed a 14mm spark plug defouler in the small cap, hooked up the leakdown tester, and we're in business. Pressurized the intake between those two points and heard a definite leak, then felt a pretty good breeze coming out of the bypass hose. Numbers are on the graph below if it attaches correctly. Did the same with a Turbosmart BPV, and heard/felt a much smaller leak, numbers also on the graph.
I wouldn't get too hung up on the specific numbers, as the turbo is pumping a lot of air into the intake and can make up for some loss, and the leakdown tester is designed for much smaller leaks from a much smaller volume. But there is clearly less air volume and pressure lost with the Turbosmart valve than with the stock valve. For what it's worth. I left the Turbosmart valve installed.

Sponsored

 

[Buldawg76]

I wonder what leakage if any there would be with the Go Fast Bits DV+ setup.

https://www.gfbuk.com/product.details.cfm?vehicleid=5438&productid=1034

I have it on my eco and have had no issue with it and do not believe it has any leakage. I have not tested for leakage though so no proof available.

My eco with the FP tune will max out at 24 psi boost at WOT.

BD

 

[Flattop]

I didn't expect the TS valve to leak either, but there was a little. I expect the GFB might be similar, but didn't have one to test.

 

[Buldawg76]

Does the TS valve piston have a rubber seal on the face where it sits against the charge pipe seat or is it plastic like the stock BPV. The GFB piston has a rubber seal on the face that sits against the charge pipe seat. Not sure it would make a difference though but with just spring pressure on piston if the TS is plastic like the stock one that could be an issue.

I know with the engine running I think the PCM does bleed some boost off at steady speeds and throttle positions at highway speed.

BD

 

[Flattop]

TS valve does have a seal there. I believe you're correct about the PCM bleeding air at cruise, I wanted the test to emulate what happens under boost.

 

[Buldawg76]

I am not sure in the TS valve, but the GFB has two springs that apply pressure on the piston to keep it forced against the charge pipe seat, one spring can be removed to alter the resistance/speed/pressure differential that is needed to allow boost to be bled off to fine tune so to speak to personal preference.

I have both spring in mine so it will hold boost as long as possible till the PCM electronically energizes the solenoid to release boost.

It is an interesting test you have done.

BD

Sponsored