It's not just the fuel pump that needs to be considered. The entire fuel delivery system found on most vehicles is not up to the task of feeding large cid engines making good power.
From what I've seen (with stock fuel systems), installing higher capacity mechanical pumps don't improve things much, if at all when we have fuel delivery issues in the first place.
Think of it this way, when you are under hard accelleration, and pinned against the seat, all the fuel in the tank is pinned up agaisnt the back of the tank. It becomes difficult for a mechanical pump to pull the fuel off the back of the tank through a stock sump, through 14 feet or more of stock fuel lines, then on to the carburetor. Keep in mind that 3/8" steel lines are only 5/16" inside diameter before you bend them.
In all cases, we recomend to test and evaluate the stock fuel system first, before making an upgrades. From what we've seen, the better the car hooks up, the worse the problems will be. It simply taxes the fuel delivery system harder with cars the hook up and leave hard.
Some folks have been able to cure fuel delivery issues by simply installing an electric pump back by the tank. Some also go in and modify the factory pick-up in the tank, by removing the "sock". Others have installed a larger supply line in the tank as well.
For our car, we ended up welding a sump on the tank, and installing a Comp 140 pump behind the tank, and 8AN lines/fittings everwhere. As we continued to work on the car to go faster, the stock set-up just simply could not keep up. At one point we ran an electric pump in front of the tank and stock lines, and couldn't run any quicker than about 12.60's. Our car currently runs 11.30's without any issues anyplace using the upgraded fuel system.......Cliff
