RobbMc Performance Products - Newsletter Volume 1 Issue 2

	RobbMc Performance Products News Volume 1, Issue 1 December 2007 Unsubscribe
FUEL SYSTEM MYTHS
Larger fuel lines hurt performance because the pump has to move a heavier column of fuel. This myth just never seems to go away. Probably because, at first glance, it seems to make sense. But it is absolutely false. The only time the fuel lines are too large is if they drag on the ground. The proof that larger lines are better can be shown using a bunch of physics and fluids equations but if the myth is ever going to be debunked, it is probably better to use a few examples that make sense intuitively. A pump does not push or pull against weight. Pumps must overcome pressure. If you take two fuel lines (both full of fuel) of different diameter (say one 5/16" and one 5/8" diameter) and the same length (say 10 feet long) and stand them up on end (to simulate a one "gee" launch), the pressure at the bottom of both lines is the same. Yes, the larger line will weigh more but the pumps connected to either line only "see" the pressure, which is the same. The only thing the added weight does in the larger line is put more strain on the clamps holding the line in place. So if the pressure the pumps must work against is identical, why is the larger line better? Because the pressure in the two lines is only the same when there is no movement of fuel. Once the fuel starts moving, line friction comes into play. The faster the fuel moves, the more line friction and the more pressure that develops in the line. The smaller line will have more resistance to flow (i.e. line friction) so the larger line creates less work for the pump. Many will still argue that the fuel in the larger line is heavier so it must be harder to pump. But remember, if both pumps are identical, the same amount of fuel per second is being pumped through both lines. So the total weight of fuel moved per second is the same. The pump connected to the larger line is not trying to move more weight per second. Plus, the pump connected to the larger line doesn't have to fight against as much line friction as the pump connected to the smaller line. A mechanical pump can't pump as much fuel as an electric pump. The problem with this myth is that it isn't always a myth. It depends on many variables. In some cases an electric pump can flow more than a mechanical. But if the system is built correctly, a mechanical pump can flow as much or more than an electric pump. An electric pump is powered by a small electric motor producing less than one horsepower. A mechanical pump is powered by the engine itself which may have several hundred horsepower. So the mechanical pump certainly has the advantage in power. The mechanical pump has one large disadvantage; It is located at the front of the car while the electric pump is located at the rear of the car. In the 1960's when electric pumps first started to gain popularity in high performance use, it was found that an electric pump mounted near the back of the car could pump more than a mechanical pump if the stock fuel lines were used. The electric pump puts the fuel under pressure because it pushes the fuel forward. The mechanical pump puts the fuel under a vacuum because it pulls the fuel forward. When you put fuel under a vacuum it is more likely to boil or vaporize (especially on a hot day). Once the fuel vaporizes, the volume of fuel pumped drops off sharply. When using the small stock fuel lines the mechanical pump can't compete because the line friction soon causes enough of a vacuum in the line to vaporize the fuel. A "cool can" (a container filled with ice the fuel line runs through) can be used to keep the fuel cool which reduces the chance of the fuel vaporizing. Racing fuel can help as it has more resistance to vaporizing under a vacuum. If the fuel tank were at the front of the car the mechanical pump would work even better than an electric pump at the rear of the car. But since most fuel tanks are at the rear of the car, the best way of improving mechanical pump performance is to reduce the line friction by making the line larger. Bigger fuel lines are better. Use the following as a rule of thumb for the minimum fuel line size for the line between the tank and the inlet on the pump: Up to 250 hp: 5/16" or –4AN Up to 450 hp: 3/8" or –6AN Up to 750 hp: 1/2" or –8AN Up to 1250 hp: 5/8" or –10AN World's Ugliest Car? Some say it's uglier than the beloved AMC Pacer. Called Aurora, the car was built in the mid-1950s by Father Alfred Juliano of New York, who went bankrupt seeing his prototype of the "ultimate safety vehicle" to fruition. It featured a roll cage, side-impact bars, a collapsible steering column, foam-filled bumpers and a padded instrument panel. After sitting in a field in the US for years, British mechanic, Andy Saunders has completely rebuilt it from the ground up.	Product Showcase RobbMc Fuel Pumps Valve body can be rotated to any angle — no disassembly required! Most pumps can be upgraded to include extra features, such as a vapor return line or boost reference (see website for more details). Applications: AMC 550HP 290-401 V8 Up To 560 HP AMC 1100HP 290-401 V8 Up To 1100 HP Buick 550HP 400/430/455 V8 Up To 550 HP Buick 1100HP 400/430/455 V8 Up To 1100 HP Cadillac 550HP 425/475/500 V8 Up To 550 HP Cadillac 1100HP 425/472/500 V8 Up To 1100 HP Chevy 550HP 262-400 V8 Up To 550 HP Chevy 1100HP 262-400 V8 Up To 1100 HP Ford 351C 550HP 351C/M/400 V8 Up To 550 HP Ford 351C 1100HP 351C/M/400 V8 Up To 1100 HP Ford FE 550HP 331–428 FE V8 Up To 550 HP Ford FE 1100HP 331–428 FE V8 Up To 1100 HP Olds 550HP 307-455 V8 Up To 550 HP Olds 1100HP 307-455 V8 Up To 1100 HP Pontiac 550HP 326-455 V8 Up To 550 HP Pontiac 1100HP 326-455 V8 Up To 1100 HP RobbMc fuel pumps are made in the USA, and are now available online. Buy direct through our secure Paypal shopping cart. "Even with a Carter 172gph NASCAR type mechanical pump the pressure would drop during acceleration. Switched to the big RobbMc pump and the pressure stays rock steady. Running -8AN line to tank with dual pickups." — Afret, Ford FE Forum We'd like to take this opportunity thank the following Forums for their support and encouragement in getting this business off the ground: Pontiac Performance Years Moparts Real Olds Power V8 Buick Ford FE 351 Cleveland Cowboy Seven Cadillac 460Ford AMCcars It's been a turbulent first year, but we honestly could not have done it without you! Thanks, Robb and Craig
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