School me on bypass valves

DaveWertz · Sep 3, 2019

So I have been reading on bypass valves. As of now I have a aluminum bypass with 3 different springs. Not sure of the brand ect.... So what sets the high end bypass valves apart from ones like I have and something like the bosch plastic ones? I can't buy a $300+ one at the moment so I really am asking if this valve is good to use? What really sets them apart?

DSG2003Mach1 · Sep 3, 2019

This for a centri car?

If it has Springs you have a blowoff valve, with the correct spring it will behave like a bypass valve. A bypass valve stays open until you’re on the throttle, a blowof stays closed until reaching the pressure limit determined by the spring.

The main difference is probably flow. When you let off after WOT it needs to be able to vent the air quickly, if not it’ll stack up in the blower and can damage the internal seals etc... the amount of boost being run determines what you need. For example the valve that comes with most procharger kits is good to around 10 psi is all

Makobra · Sep 3, 2019

if its a turbo car the blow off/bypass and wastegates are integral to the operation of the system which works solely off pressure equalization.
it its a supercharged car they are less critical because created boost is limited to RPM because the engine directly drives the blower itself which creates more boost as rpm rises.

that said, if its a turbo car don't skimp here. go tial all the way. their lifetime warranty is the bomb.

if its SC and you aren't going for crazy power i don't see much sense in losing sleep over whatever you choose.
if you're making tons of boost with a blower than you're in the same situation as the turbo build.

DaveWertz · Sep 3, 2019

DSG2003Mach1 said:
This for a centri car?

If it has Springs you have a blowoff valve, with the correct spring it will behave like a bypass valve. A bypass valve stays open until you’re on the throttle, a blowof stays closed until reaching the pressure limit determined by the spring.

The main difference is probably flow. When you let off after WOT it needs to be able to vent the air quickly, if not it’ll stack up in the blower and can damage the internal seals etc... the amount of boost being run determines what you need. For example the valve that comes with most procharger kits is good to around 10 psi is all

It's going to be centri. To me the springs are all the same size, only diff I see is stiffness. It looks just like the stock bosch bypass valve just a aluminum housing with a screw off cap to be able to change springs.

DaveWertz · Sep 3, 2019

Makobra said:
if its a turbo car the blow off/bypass and wastegates are integral to the operation of the system which works solely off pressure equalization.
it its a supercharged car they are less critical because created boost is limited to RPM because the engine directly drives the blower itself which creates more boost as rpm rises.

that said, if its a turbo car don't skimp here. go tial all the way. their lifetime warranty is the bomb.

if its SC and you aren't going for crazy power i don't see much sense in losing sleep over whatever you choose.
if you're making tons of boost with a blower than you're in the same situation as the turbo build.

It is a SC car (or will be in the next couple months) and aiming for 450-500whp. The springs are all different tension so thats what has me believing they are for diff boost levels?? This stuff is new to me but as I stated above it looks just like the bosch valve it comes with from vortech just in a aluminum housing with screw off cap to change springs.

DSG2003Mach1 · Sep 3, 2019

DaveWertz said:
It's going to be centri. To me the springs are all the same size, only diff I see is stiffness. It looks just like the stock bosch bypass valve just a aluminum housing with a screw off cap to be able to change springs.

Ya the stiffness is what sets the boost level when used as a blow off valve. You need to contact whoever sold it or the manufacturer and verify which spring is correct for bypass operation. Usually they’re colored to help identify them

Makobra · Sep 3, 2019

why aren't you just using the SC pulley to determine your boost levels? you shouldn't need much for that power level. a BOV for a turbo is critical because it keeps the turbine from trying to spin backwards (it won't but its really bad for the turbo to suddenly be forced to shed speed because the throttle slammed shut.

when you shift with a SC and you slam the throttle shut your engine RPMS will drop and your boost will taper off in the same way. sure a BOV might help but i really see it as needless complexity for such a low power level.

DSG2003Mach1 · Sep 3, 2019

Makobra said:
why aren't you just using the SC pulley to determine your boost levels? you shouldn't need much for that power level. a BOV for a turbo is critical because it keeps the turbine from trying to spin backwards (it won't but its really bad for the turbo to suddenly be forced to shed speed because the throttle slammed shut.

when you shift with a SC and you slam the throttle shut your engine RPMS will drop and your boost will taper off in the same way. sure a BOV might help but i really see it as needless complexity for such a low power level.

sounds like he bought a kit where someone was running a BOV with the correct spring for it to behave like a bypass valve

DaveWertz · Sep 3, 2019

Let me see if I can post a pic of it. I will take one when I get home and link it here with the springs.

DaveWertz · Sep 3, 2019

wirelessguy2005 · Sep 3, 2019

i have the exact bypass you have listed above and use it with my KB 2.1, the springs are as follows:

Lightest spring is good for: 5-15 PSI

15-23 PSI (installed as delivered)

Heaviest spring is good for: 23-30 PSI

DaveWertz · Sep 3, 2019

wirelessguy2005 said:
i have the exact bypass you have listed above and use it with my KB 2.1, the springs are as follows:

Lightest spring is good for: 5-15 PSI

15-23 PSI (installed as delivered)

Heaviest spring is good for: 23-30 PSI

Perfect! Have you had any issues with it?

wirelessguy2005 · Sep 3, 2019

no problems, it has worked fine for me

DaveWertz said:
Perfect! Have you had any issues with it?

venom1997 · Sep 5, 2019

Just make sure you reference it to boost and vac because the vac keeps it open and as soon as you go into boost it forces it closed

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1996MysticSnake · Sep 10, 2019

If you're running that Vortech in a blow through setup no way that pos will flow enough air. Get a tial q with the supercharger spring and be done with it.

It will literally stall the motor out and/or destroy the blower if it can't vent the air fast enough.

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DaveWertz · Sep 11, 2019

1996MysticSnake said:
If you're running that Vortech in a blow through setup no way that pos will flow enough air. Get a tial q with the supercharger spring and be done with it.

It will literally stall the motor out and/or destroy the blower if it can't vent the air fast enough.

Sent from my Pixel 3 XL using Tapatalk

I'm running draw through. I will probably switch to blow through if I decide to go IC

School me on bypass valves

DaveWertz

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