Maxflow Race Bypass Valve fluttering

[Nodster]

Hey.

I had to do some data logging yesterday for Wengerd and I noticed when I let off the gas in 3rd gear at 5k rpm the car made fluttering sounds as it decelerated. No whoosh.

I've read online that this is compressor surge causing the sound and could be that the the bypass valve needs loosening via the adjustment screw. But the kit instructions said it was set and shouldn't need to be adjusted. Am I just unlucky?

This is the valve - Bypass Valve

This is my first forced induction setup. Can anyone advise? I'm still having the car tuned but I don't think that would impact any potential adjustments to the bypass valve? Has anyone else had to do their adjustment?

Thanks.

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[Nodster]

Oh. So Ive just read the guide again and it is already backed out from factory.

In general, the spring adjuster should be left fully backed
off as supplied. The valve opening point can be adjusted
from 3" Hg (spring adjuster all the way out)...

Well if that is the case, why did I hear fluttering?

 

[Nodster]

This chap Dan seems to have had better luck swapping to the race valve.

In the video you can hear the flutter from the bypass model.



I'm going to rev mine at lunch and see if I get similar flutter when in park.

Thanks.

 

[Cory S]

Fluttering means the valve is too small for the volume of air needing to be discharged.

 

[Nodster]

Fluttering means the valve is too small for the volume of air needing to be discharged.

Thanks. So sounds like the race valve might be required here? Odd they ship it with the "kit" if it isn't fit for purpose.

 

[Cory S]

Thanks. So sounds like the race valve might be required here? Odd they ship it with the "kit" if it isn't fit for purpose.

I mean it still works yes, but if the fluttering is annoying (which usually is) a larger discharge is the only way solution.

 

[Nodster]

I mean it still works yes, but if the fluttering is annoying (which usually is) a larger discharge is the only way solution.

Cool thanks. I've reached out to beefcake as well to get their take on it. I'm guessing I need to get it fixed as the surge will be damaging the blower? Or is that a bit of nonsensical panic that is currently running through my head.

 

[Cory S]

Cool thanks. I've reached out to beefcake as well to get their take on it. I'm guessing I need to get it fixed as the surge will be damaging the blower? Or is that a bit of nonsensical panic that is currently running through my head.

It's a small surge pulse, nothing damaging. If you ever plan to add much more boost though, it could get worse.

 

[Nodster]

It's a small surge pulse, nothing damaging. If you ever plan to add much more boost though, it could get worse.

Thanks that's a relief and good to know. I should really ask wengerd how much boost I'm running. I have no idea.

 

[Cory S]

Thanks that's a relief and good to know. I should really ask wengerd how much boost I'm running. I have no idea.

Probably 8-9 psi if it's entry level sized pulley. Was it ever on a dyno?

 

[Nodster]

Probably 8-9 psi if it's entry level sized pulley. Was it ever on a dyno?

Thanks. Not yet, it is still being tuned. Had it together just since Sunday.

 

[HKusp]

I don't know about this specific situation, and Cory is VERY knowledgeable. That being said, having a decent amount of experience in the Superduty diesel world, surge is a bad thing. It is rapid pulses in compressor speed. Think slamming on the brakes, then speeding up, then slamming on the brakes, over and over again, very rapidly, which can absolutely be damaging to the compressor bearings over time.

 

[Nodster]

Oh man, thanks @HKusp (and @Cory S). I've asked beefcake for a price on the race valve just to get that avenue of enquiry going. But I've been out and done a rev at idle whilst in Park, and unlike the YouTube video, I have no flutter. So I will take the car out later and see if I am definitely hearing it under load.

Here is what I recorded earlier (which seems fine to me).

 

[Cory S]

Oh man, thanks @HKusp (and @Cory S). I have no flutter. So I will take the car out later and see if I am definitely hearing it under load.

You shouldn't hear anything under load. You will have pressure and the spring holding the valve closed allows manifold pressure to build.

 

[Nodster]

You shouldn't hear anything under load. You will have pressure and the spring holding the valve closed will build manifold pressure.

Yeah sorry I know what you mean, I wasn't clear, my bad. I meant when I take the car out and accelerate / decelerate I'll see if I can hear any fluttering (instead of just rev'ing on the driveway).

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