Forge BPV and yellow spring

[Trevinator]

so, tonight I installed my forge BPV that i bought from BNR on my sonic. I first tried it with the green spring and it was ok, but felt like the boost dropped off earlier than with the stock BPV. so I tried the yellow spring. wow, what a difference that made! now my car is finally holding boost the way it should! with the stock BPV, boost would peak at 21 psi right around 3200-3400 rpms, then quickly drop to about 16 psi by 4100 rpms.

now, it will build to 21 psi around 3000k and hold it. at the minimum, the boost fell to 18 psi while above 4500 rpms. it actually has good pull throughout the rev range now and it will also build and hold boost much better in the lower rpms.

i have two things that worry me now though. how much flutter is too much(will a little hurt the turbocharger), and will trifecta need to alter the timing and fueling for it building boost better than before?

i plan on doing a log tomorrow to send in and see what they say.

i notice just a touch more flutter with the yellow spring than when using the stock BPV, but the car just seems to run so much better with the yellow spring that i don't want to take it out!

it only has the flutter sound if i slowly lift off the throttle. if i completely lift off the throttle quickly, there is no flutter sound and it dumps the boost properly. should i be concerned about the little bit of flutter?

also, since there are no instructions as to which way to have the opening in the valve facing, i just put it in facing up. im not sure if its supposed to go in a different way or not.


anyone else here have trouble holding boost, then try the yellow spring and have it work better? the yellow spring seems to have solved my boost holding issue that has been plaguing me for over a year now! :banana:

sorry about the long post, im just excited that my car will hold boost in the higher rpms now!

 

[Natesriv]

I've a forge with the green spring (no tune)...so I was told the yellow is for tuned or higher boosts...so I think you're in the right ballpark...

I'm not sure of the position though...I don't recall that being an issue.

cool post though!
Good luck!

 

[RMinNJ]

That sounds really cool.. I noticed with my tune that the boost does not always hold up.
I assumed it was the programming but now I wonder if the stock BOV is just letting it out?

 

[Trevinator]

I think maybe the computer is still dumbing down the hp even with the tune. I did a couple short pulls tonight on the way home, and it fell to 15.xx in 3rd in the higher revs, but at least now its holding the hp and not falling on its face like before.

I didn't have a long enough straight to get into the higher revs in 4th to see how its holding there now, but last night it was keeping a nice 18 psi in 4th.

I tried to do a datalog tonight, but I cant seem to get the computer to connect to the car. :blankface:

 

[totino's]

Have you done the bypass mod? I'm wondering if there are benefits of running both of these mods together.

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[Trevinator]

I've had the bypass bypassed for the last, i don't even know now, maybe year, year and a half? i wouldn't switch it back for anything.

 

[totino's]

Ok cool. I was just wondering if the spring rate would negate any effects the solenoid would have on the forge spring. So, you are seeing benefits of the forge on top of already having the bypass. Good too know!

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