Modifiying Right The First Time!

[Darth Vader]

Har!

I'm in the Forge camp, as MSMS3 knows. I found my stock valve causing unreasonable flutter and soft throttle response in daily driving, with an intake installed. It DID NOT leak at high boost. The Forge holds boost to the same values at high pressure and bangs open and closed ALOT faster, which fits with the test results, to a point. The Forge V1 ain't subtle, with its noise and sharp driveline shock due to the heavy spring I use and the fast open/close but, I don't mind that, this is a total "me first" car, rather than an "after you". (drive2)

 

[MSMS3]

LMFAO to extreme!

Long drive for a beer, Darth, but if you find your way down this way or me up north of the border, I'd enjoy lifting a glass or two with you. We can fuss and snort back and forth about cars, most of which we'd probably agree on (boring). And there will be a few things we'd growl at each other (more lively) about while buying each other the next round and laughing our asses off!

We learn more by spirited debate than by sucking up to each other. But here, we keep it civil, not like on a certain other board where you have to put on Kevlar protective armor just to express an opinion!

 

[Jackis]

Every bpv will leak, if you apply way too much pressure from outside. It depends on its style - spring works faster, diaphragm holds huge boost better. It is clear for me, that "by design" ForgeV1 is much more "leak-able" than stock. That is what you see with 20psi and yellow spring. That is what I suppose was made in RR test. That is why it is so important to use proper spring setup.
PS: Forge FTW!

 

[Darth Vader]

Whatcha mean? All BPV have a spring and a diaphragm, that's essential to the concept of a BPV. Generally, spring loads don't change the held boost, assuming the same boost is poduced; 15 psi on Yellow is the same as 15 psi on Red. Spring loads change the RATE at which the valve bangs open and shut, yes, and allows you to RAISE the target boost. But, by and of themselves, any one of the springs provided with Forge V1 should hold stock or near stock boost levels.

What makes them leak is not the max applied pressure very often, as they are tested far above the psi most stock turbos can make. It's the pressure differential between the throttle side and the intercooler side, which can confuse them, as this value can change.

What most people interpret as a leak in the stock valve, is actually a built in safety feature. There is a tiny bypass hole in the base of the stock valve, allowing boosted air to bypass the valve. The intention here, in my opinion, is that if the valve failed and jammed shut, there wouldn't be a total backwash of compressor surge into the turbo. Also, this allows a softer spring to be run, making the car less jerky on shifting.

 

[anm6]

oK Shift a little, what does the spring do. I have HT and see boost around 20-21 Spike. I have the yellow with 2 shims ,Should I change it to the red?? Is yellow only good for 15PSI??

 

[Jackis]

Nevermind, Darth Vader, it is the lack of english words. I was speaking bulls***, when I read what I wrote. I was also misunderstanding a bit BPV concept - I thought it always has some pressure difference under it and in vacuum tube, but I was mistaken - vacuum tube is simply manifold extension, so it always has it's pressure. Now I see that even on 50psi boost, if motor supports it - spring would stay calm because this tube would have the same 50 psi. I was confused by its' name - "vacuum tube", now I investigated that and I see I was mistaken.
Thank you!

 

[Jackis]

anm6,
Darth said about springs - the more stiff is it (red vs yellow), the faster it will operate and produce faster closing after releasing air back to intake. On quick shifting (w/o flat foot shifting forsure) it will help recovering boost faster. But it will also produce more jerky behaviour, because air would be dumped faster. Right, Darth? Suis je bonne etudiant?

 

[Darth Vader]

Yes, yes, you can come back from the Principal's office now. Welcome back to class, lol.

I find the jerkiness is most pronounced when there's heavy manifold vacuum and boosted air on the front side of the throttle, like a brief stoplight rip and decel. I tend to drive the car the way we did before the world invented bypass valves. What I do is, I dip into the throttle on normal, closed throttle shifts a touch before the clutch engagement point. This helps balance the pressure slightly between the heavy vac engine side of the throttle and pressurised air ahead of it. Smooths things alot, improves boost recovery, on ANY force-inducted car.

 

[Jackis]

Yeah, Darth, when you said about you method of smoothing out the ride, I realized I was doing the same, but never thought about why I'm doing so

I got another quick question, but now about wastegate spring pressure. Some people recommend getting more stiff actuator spring. They say - we have 8 psi stock spring, and it's better getting 12-14 psi spring. As I understand, that will cause more strong boost spike on WOT because spring will simply operate faster, but yes, it will provide some sort of quicker acceleration. What are other pros/contras og getting more stiff WGA spring?

 

[Kyrosfactor]

I have a PG Turbo inlet and a Turbosmart BPV I am wanting to get rid of, Both are top of the line in quality. Hit me up if your interested!

 

[08cosmic3]

My car was a totally different car after installing the Forge BPV, My stocker must have been one that was leaking. I guess there are some stockers that don't leak. I'm running the AP and holding 19 lbs of boost with my Forge (blue+1)