spi and mpi cars
Turbo Mini Forums

as there injection wheres the fuel swirl pot?

not every car has to have one!

there isnt :)

alex

AlexF

i thought all injection cars had them as theres no float chamber to stop starvation

Don't think you need one if the petrol tank is sufficiently baffled.

Andy

is there any difference in the pumps?

minipares list different part numbers for the mpi and spi?

Wouldn't have thought there'd be that much difference, they both need to pump higher pressure than a N/A carb system.

MPi pump has a slightly higher pressure than the SPi pump - they look visually identical. Not easy to tell them apart!

You dont need a swirl pot as the fuel rail will hold sufficient

The fuel delivery pressure is much higher on injected engines, so theres always more fuel in the rail than the injectors can possibly flow.

alex

AlexF

A swirl pot wont help with fuel rail pulsing....

alex

AlexF

I thought the point of a swirl pot was to de-airate fuel returning from the fuel rail to the tank?? I thought the problem comes from fuel spurting back into the tank in an uncontrolled manner leading to airated fuel, and when this gets pumped through to the engine the air causes leaning out/misfire??

I believe the mini doen't have a baffle because of the shape of the tank - it's more vertically oriented than a conventional tank - so if the pickup is near the bottom, only if it's very close to empty will fuel starvation be an issue.

This could be summit to do with it as I remember me mates mk1 fiesta with a pace turbo kit had a swirlpot fitted,but they use a flat tank..

Metro turbo weekend driver,Mini turbo in the making again!

The idea of a swirlpot in a fuel system is to make sure that the fuel rail NEVER runs dry.
A basic system would have a closed 1 litre container (as a guide) with an outlet at the bottom, one 7/8 way up, and two at the top.

The primary pump would drag fuel out of the main tank, and fill the swirl pot from the top. The second (main) pump drags the fuel out of the bottom of the pot, into the fuel rail, and back into either the main tank, or the top of the swirl pot. The outlet 7/8 way up the pot then returns the excess from the swirl pot to the main tank.
There are a few ways to do this - depending on pump specs, desired pot location, etc, but they all do the same thing.
So, the basic idea is that even under heavy cornering conditions, when the primary pump is sucking air momentarilly, there is always fuel in the swirl pot to feed the fuel rail with the secondary pump.

You'll often find OE tanks have a 'mechanical' swirl pot - resembling a simple frying pan - the idea being that under cornering, there will be enough fuel in the 'pot' to prevent starvation. Too much of a risk for turbo motors used in anger on the track mind. Best to stick with the stock tank, or make a tank with a little height to it, or to have a 'well' in the bottom and drag ther fuel out of that.

Edited by turbodave16v on 22nd Feb, 2005.