Hi, I’m Jay from Real Street Performance. Today we’re going to talk about what a surge tank is and how it’s used in your fuel system. For a long time high horsepower applications relied on an external fuel pump and an aftermarket sumped fuel cell. The external pumps were bigger and could supply the engine with more fuel. However, they didn’t like pulling fuel out of the factory fuel tank. So you had to sump the tank so the fuel pump would be fed by gravity because most fuel pumps are good at pumping fuel and not great at pulling the fuel to the pump. This is why we used aftermarket rear sump, fuel cells. There are a few reasons why people didn’t want aftermarket fuel cells in their street cars. Filling the fuel cell without the factory filler neck is a hassle. You have crash liability depending on where the aftermarket cell is placed. You have fuel smell in the cabin. And the accurate and available factory fuel gauge was no longer available with your aftermarket tank. This led the people modifying their factory fuel tanks to fit an aftermarket sump. So you would cut the bottom of your factory fuel tank out and weld an aftermarket sump on the bottom of it, leaving your gas gauge intact and your filler neck intact. It wasn’t a bad balance of things. If you had a plastic tank like on a Supra then you would just use a bulkhead fitting on the bottom. Wasn’t a great idea, but it worked ok for the times. But there were some people that didn’t want to do that. They didn’t want the aftermarket fuel cell and they didn’t want to modify their factory tank. This led to the use of the surge tank or multiple in tank fuel pumps. Since we know that the large external fuel pump does not like to pull fuel out of the factory tank, why not use the factory in-tank pump to feed it. Because the large external fuel pump moves more fuel than the factory in tank pump can supply instantaneously, the large external pump would cavitate and lead to the pump’s failure. Cavitation is when the fuel pump is moving air pockets through the pump instead of fuel. The pump will not last long like this. This is where the surge tank comes into play. It’s an external reservoir that fits between the in-tank fuel pump and the large external fuel pump to eliminate the cavitation. The combination of the low pressure high volume in tank pump filling the surge tank and the return line from the regulator filling the surge tank leaves the surge tank full with fuel faster than the external pump can empty it. This eliminates the possibility of the large external fuel pump sucking air and dying from cavitation. While this setup worked extremely well on race cars and track cars, it wasn’t a great option for a street car because people didn’t want to drive around with all the racket associated with a large external fuel pump. This led to people using multiple intake pumps instead of the large external fuel pump. They got the fuel supply they needed without all the noise associated with a large external pump. However, not all vehicles could easily facilitate multiple in tank pumps. Some vehicles have too small of a fuel hat to actually fit more than one pump into the tank. Some vehicles have a split fuel tank that relies on the relationship between the factory fuel pump and the balance tube to equalize the amount of fuel in the tank. Disrupting the relationship between these components can create cavitation and supply issues. Or maybe there are no multi pump hangers available for your application. These two approaches left a void in the market of people that one of the best of both worlds. Companies like Integrated Engineering and Radium Engineering now offer a surge tank that houses multiple in tank fuel pumps inside the surge tank, giving you the best of both worlds. An approach like this makes things easy because you’re only running the hoses and wires. You don’t have to worry about disturbing your factory fuel gauge. You don’t have to worry about getting multiple pumps in the tank or whether or not they’ll fit in the tank. You’re not dealing with an aftermarket fuel cell or a large external noisy pump. So if you’re into the easy way out, something like this works well for you. As vehicles become more advanced products like these will become more popular. Hopefully this video helps you determine whether or not a surge tank is right fit for you. If you have any questions you can post them below in the comments. Please like and follow and I’ll see you next week.