hey art,
I was basing my fuel system requirements on this article I found
http://www.centuryperformance.com/fueli ... g-140.htmldefines the need for a bypass regulator
let me know what you think
here is the part that piqued my interest:
Regulators and the Benefits of Return-Style Systems:
One of the biggest restrictions in most modern fuel systems is the "dead-head' regulator. Dead-head regulators are popular because you do not need to install a return line. However, they are not only more restrictive but also create several other problems that can be eliminated with a return-style regulator. Dead-head regulators also have a higher failure rate than return-style regulators.
Mallory, Weldon, and other fuel component manufacturers offer both dead-head and return-style regulators. You will base the regulator you use upon system demands and racing class requirements. Dead-head regulators regulate pressure by starting and stopping flow. Return regulators regulate pressure by sending excess fuel back to the tank in a continuous cycle. If you are confused about your regulator choice, think of this simple analogy of a dead-head regulator's operation:
Do you remember as a child, running around the house chasing a sibling or a friend? What happened when you chased them to a room and as they tried to close you out and they did not quite get the door closed? They are pushing, you are pushing, the door is only open a few inches, and then the person on the other side of the door lets go and moves out of the way. Remember stumbling across the floor trying to catch your balance and not destroy furniture or land on your face? A dead-head regulator is similarly doing the same thing, with the fuel being the object pushing, and the regulator holding the door and then periodically jumping out of the way.
Because a dead-head regulator starts and stops flow, fuel pressure between the pump at regulator is higher than the pressure between the regulator and the carb. This is different on injected applications, where the regulator is positioned after the fuel rail so that the injectors see maximum pressure and flow. However, if the pressure gets too high, it can and will damage the fuel pump. Therefore, the pressure coming out of the pump is limited in many pump designs by a device built into the pump called a bypass. Low pressure pumps are limited to less than 9 PSI and should not be used with dead-head regulators. High pressure pumps are limited to a pressure of between 10 and 25 PSI.
Not only can the fuel pumps being used with dead head regulators fail because of pressure issues, but pumps with dead head regulators also run hotter do not last as long as when connected to to a return-style system because it is the fuel that cools the pump. Pounding the fuel because it can not move creates more heat. Fuels pumps working against a dead head regulator will also be louder during operation.
The Mallory 70 and 110 pumps are low pressure pumps that can be used without a regulator for the street or with a dead head regulator for racing. Mallory 140 and 250 series pumps are high pressure and high volume, and must be used with a regulator (dead-head or return-style).
It is possible for the bypass in the pump can malfunction. This can cause the pressure to drop or increase so much that the pump motor fails. Even if the bypass in the pump is working correctly, it is still possible to have a pressure drop with a dead-head regulator, including use with a large pump. See the image below:
Let's say that at idle, gauge #1 will read 10 PSI and gauge #2 will read 8 PSI. At full throttle, the increase in fuel flow will create a pressure drop between the pump and the regulator. The amount of pressure drop depends on the restriction in the fuel line ... a 4 PSI drop is not uncommon. Gauge #1 will now read 6 PSI and because a dead-head regulator cannot raise the pressure, gauge #2 will also now read at 6 PSI. The result is a 2 PSI pressure drop at the carburetor or Nitrous solenoids even though a very large pump may be in use.
NOTE: When using a dead-head regulator, a second gauge should be installed just before the regulator. This will allow you to check that the pressure before the regulator stays higher than the set pressure.
Many race pumps have the bypass set very high (14-25 PSI) to avoid this problem. However, this creates another problem. The higher bypass pressure makes the pump work harder and draw more amperage. In fact, the pump works just as hard at idle as it does at full throttle down the track! This is one of the main causes of early pump failure. To counteract this problem of high amperage draw, some companies manufacture voltage reducers for street cars to slow the pump down and increase the life of the pump. The problem here is that reducing the voltage also has a negative affect on the pump motor.
I believe that banking institutions are more dangerous to our liberties than standing armies. If the American people ever allow private banks to control the issue of their currency, first by inflation, then by deflation, the banks and corporations that will grow up around [the banks] will deprive the people of all property until their children wake-up homeless on the continent their fathers conquered. The issuing power should be taken from the banks and restored to the people, to whom it properly belongs.
Thomas Jefferson, (Attributed)
3rd president of US (1743 - 1826)
I'm finding aftermarket fuel pump / regulators to be very expensive.
