Fuel system with Swirlpot

It was not long ago I uprated my fuel pump and since then I only used my car once. But I never felt satisfied with the new system. I feared the fuel surge while cornering problem would be even worse than before, so I decided to do it properly with a swirl pot and a low pressure pump.

Pumps

The fuel demands for a 280 hp NA engine is according to the book Four-stroke performance tuning: power * k = 280 * 6 = 1680 cc/min = 100.8 liters/hr including 30% oversupply.

The pumps and filter is located under the trunk.
A pity to hide those expensive AN-fittings?

According to Cosworth their 280 hp crate engine should have fuel in excess of 1.4 l/min = 84 liters/hr.

I want to be able to run E85 in the future if I decide. That is another 30% = 131.0 l/hr. And as before, I don't want the pistons to melt if the alternator fails and the supply voltage drops a volt or two.

The low pressure pump doesn't need quite as much flow as the high pressure pump as it always have the swirl pot as a buffer. The Facet Posi-flow pump can deliver 32 gal/hr = 121 l/hr which will be enough. It turned out that the Facet fuel pump is extremely noisy! I don't think I can stand it and I probably need to find a more quiet one.

Generally it is not a good idea to just fit the biggest pump you can find because all that fuel flowing back and forth will increase the fuel temperature. High temperature could mean detonation problems or less power. As the stock CSR fuel system is a non-return type with the regulator in the back, that might not be a big problem as the fuel never goes that far. Also, the fuel tank is cooled by the wind. But anyway.

A one litre swirl pot in the trunk compartment. 

The classic Bosch 044 pump is too much with >250 l/hr @4 bar and 13.8V. It also uses a lot of power and is very expensive, at least the originals.

Biltema 52-203 pump flows a bit less with about 156-174 l/hr @4 bar and 13.2V (source). It is also very cheap and quiet!

Hoses and fittings

Rubber hoses tend to leak a few fuel molecules now and then. Teflon hoses doesn't. Instead they have the problem with build up of static electricity and small sparks can jump through the hose to the mantel and cause small holes in the hose and even cause a fire. To solve that problem some manufacturers have added a bit of carbon to the hose, allowing the electricity to flow and avoid this problem. The cheaper hoses (including Torques' hoses) doesn't have any carbon in them. Some say that the fuel flow in a car's fuel line is too small to cause any problems. I don't have enough knowledge to trust that statement, so I went the safe path and bought more ordinary nylon braided rubber hoses. If someone would like to calculate on this, I found a good source of information including formulas and samples.

I bought all AN6 hoses and fittings from Torques.

One challenge was to connect the system to the already mounted hard fuel line that goes through the car all the way to the engine. The fuel line's thread is 16x1.5mm. I couldn't find an AN-6 adapter that fit, so I used the existing fuel filter adapter and a Saginaw AN-6 adapter from Earls part number 9894DBJ.

The end result.

Doing the plumbing was much harder than I thought it would be. It was like a puzzle to get the pieces to fit in a small space without occupying the whole trunk. The braided hoses are very rigid and did not make it easier. I also realized I should have ordered more 90-deg fittings and less straight ones, but too late for that now. Also, holding things in place with zip ties is probably not considered the best engineering but will do for now.


Allright, I haven't tested this properly yet, but at least there is fuel flowing to the engine :-)