Answering your questions about By-Pass Valves.

What is a By-Pass Valve, what do they do, & do I need one?


The By-Pass Valve does just that, it allows air that is being forced down the throat of your motor to be by-passed back into the supercharger or into the atmosphere, depending on the application, and the requirements of the supercharger.

Why, you might ask, is there a need to add more air by bolting on a supercharger and then take it away. The answer to that common question is, when you are force feeding a motor with air, there are times through-out the rpm-range where the motor cannot handle more air. One example of this is, if an intake valve is closing on the cylinder heads, there is going to be a moment where it can not flow any air, but will immediately need air there after. Superchargers regulate the rate they flow air by the RPMs of the motor and not in those milliseconds through-out the RPM range that the motor can not handle the amount of air that the supercharger is forcing.

Even though some smaller supercharger systems don’t come standard with By-Pass Valves, we recommend the use of a By-Pass Valve anytime you are forcing air into your motor, even at low boost levels. If you are running at pressures in the proximity of 7psi or above, then it is definitely mandatory to run a By-Pass Valve or your chances of damaging head gaskets, rings, seals, or other important parts of your engine are extremely high, or just a matter of time.

Universal By-Pass [More Info]
 Most of your street-type on up to your medium-duty racing superchargers set-ups don’t require you to blow the air into the atmosphere, they use what is considered to be a standard type by-pass valve that is designed to re-circulate the air back into the supercharger, then the supercharger re-uses the air as it is needed. Due to the lower volume of air that these smaller type superchargers will be forcing, it is not necessary to have the air from the supercharger blow-off into the atmosphere. In general, it is recommended to use a standard by-pass valve on superchargers with 12psi or less.
Vortech’s Mondo Racing By-Pass [More Info]

As far as the larger type superchargers used for racing or other severe conditions, it is usually necessary to dispose of the excess air and not attempt to channel it back into the supercharger due to the larger volume of air that they are capable of producing. These type of applications use a blow-off type by-pass valve that normally mounts to the discharge tube before it enters the motor, and are higher in price due to their stronger construction and air-flow abilities. These type of by-pass valves are not needed or recommended for most low-boost standard street or street/race type applications, because they are over-kill and might even cause the motor to produce less power due to blowing off a portion of the air that the supercharger is producing. In general, it is recommended to use a race by-pass valve on superchargers with more than 12 psi. 

Note: A lot of the kits that we sell, already come complete with some type of By-Pass Valve Assembly. So if you are purchasing a supercharger kit here at SuperchargersOnline, make sure to check our Supercharger Inventory Charts (located under the description section of each supercharger) before purchasing a By-Pass Valve separately, in order to keep from purchasing an extra one that you don’t need. Or, if you already have a supercharger kit, and want to consider adding a By-Pass Valve to your already existing supercharger kit, then check with the manufacturer or the person who installed your kit to see if your kit already contains a By-Pass Valve Assembly.

Click here for more information & pricing for all By-Pass Valves

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