Fuel Pump:

With a  "Sequential Double Fire" Fuel Injection system it is possible, under boost, that this system could end up with all the injectors on 100% of the time. This would require the fuel pump to match the flow of 4 injectors at once at max fuel rail pressure. If the pump does not keep up, the engine will lean out.

You can find the high output pumps on the German cars in the wrecking yard. This includes the Volvo's, BMW's, Audi's, Mercedes, and VW's. Most of these ran some version of the Bosch fuel injection. The electronic versions didn't run quite as high output of pump as the mechanical versions did. Why, I don't know. I do know if you find a VW Rabbit with a mechanical version fuel injection, it will have a high output pump!

Test the Fuel Pump: The only real way to know what you have is to do a flow test @ 45 PSI. This test includes everything from losses due to restrictive fittings to the voltage. Unless you do this test, everything else, charts, graphs, etc., everything these people tell you is 100% Pure Bogus! I can't stress this point enough. (Probably because with fuel injection, you have to be able to generate a fuel surge, where with a carb, you pulled it out of a reservoir of fuel).

To test a pump for a turbo 2276 VW using four 45 Lb/hr (16.5 Ounces/min), Take the fuel pump and connect it to a regulator with a pressure gauge, set the regulator to my max rail pressure (static is usually 30 PSI and Boost compensation is 15 PSI max boost) which is 45 PSI. Next measure the amount of fuel that returns to the tank in one minute. The amount of fuel that returns to the tank is what the capacity of the pump is at 45 PSI. The pump either keeps up, or it doesn't. If it doesn't pass this test, you need another pump. Don't expect the "Little Girlie" pumps, the ones that are the size of a roll of quarters, to pass this test. The only ones that we have found to work best are the Bosch. There are some other options here, but none cheap.

Gas Tank Mod: The intake of the fuel pump is 12mm, or about 7/16. We have gotten away with using 3/8 ID hose if it is real short. The pump needs to be mounted under, or as close as possible to the tank. They are a roller vane style pump. They cannot suck very well, but they sure can push the fuel.

The output of the pump can be either 5/16 or 3/8, whatever is convenient. The input and output of the Bosch fuel pressure regulators is 5/16.

Most round aluminum gas tank have to be modified. First, the 1/4 pipe thread fitting, inside the fitting where the fuel comes out of the tank, if you look, it only has a 1/8 hole punched into the tank. This will have to be drilled out as big as possible without cutting into the threads on the fitting. Next, a second port will have to be added for the fuel return.

Note Some have added a 3/8 pipe port and use this as the intake to the pump and then use the 1/4 pipe port for the fuel return line.

Don't let the guys at the welding shop song and dance you to how dangerous this will be by adding the second port. Any competent shop knows that if the tank is filled with an inert gas, such as CO2 when welding, it cannot explode. You have to have fuel and oxygen to have an explosion. No oxygen, no problem. Some boat shops and truck stops do this all the time.

They can be bought from Summit Racing for about $61 (#MSD-2222) That unit is the Bosch regulator shown above but MSD has repackaged it with their own pressure sensing port in the adjustment screw. To save a few bucks pick one up at the junkyard for $5, or buy a new one ($40) and add your own pressure port.

To make a Turbo Fuel Pressure Regulator: Start with an adjustable fuel pressure regulator Bosch #0 280 160 001. It was used after 1968 on the Bosch D-Jetronic cars: VW Type III 68-73, Porsche 914 70-76 1.7L or 2L, Saab 69-74, Volvo, Renault 72-74.

The screw below is the modified adjustment screw.

You need to drill a hole across the bottom of the screw, then drill a hole down the length to meet that hole. The lengthwise hole is difficult to drill by hand so you will probably need a machinist to do it on a lathe. Once you get the hole drilled, solder a piece of tubing into the hole. The local hardware store should have a small piece of brass tubing.

To solder to steel, it has to be freshly ground, not wire wheeled, or sanded. You can use regular electrical solder, 60 / 40, rosin core. If the top of the bolt has just been kissed on a grinding wheel, solder will stick to it just like copper!

Octane is a rating of how fast fuels burn under compression. The higher the compression, the faster fuel burns. The higher the octane, the slower fuel burns. Remember, it is a rating. It is impossible to have over 100% of something, so don't be confused by a rating of 110 octane! (Read the Gasoline FAQ)

There are lots of different fuels out there that claim all kinds of things. It is a matter of personal choice. On a turbo motor, you will have to use a good fuel, but just how good is another story. Is a good fuel measured by it's "Octane" equivalent number, or by price? Different fuels use anything from paraffin to ?? for octane boosters. I have tried just about every fuel known in the free world, all with different results. What I like about the Av-Gas is it is controlled by the FAA. Nobody wants to go to jail for messing with the quality. Peoples lives depend on it! It is designed to have low vapor pressure, doesn't sour, and not a whole lot of "Brother In-Law" additives. The price for the Bang-For-The-Buck is a lot cheaper than the "Other" premium fuels. (Note that a lot of the "Others" use Av-Gas as the base stock for their fuels. They just add their snake oil and mark the price up 300%. Then there are legitimate vendors. Just be aware).