www.Zetec-Cat.co.uk

Larger Fuel Tank

As I planned on fitting injection to my car, I had to order a specially made petrol tank from Tiger with internal baffling, a swirl pot and a fuel return line. This was made to the same dimensions as the standard petrol tank, notably 875 x 180 x 180mm, yielding a capacity of 28.35 litres.

During use, I found that when the tank was anywhere below about half full (or half empty depending upon your outlook on life) when going round left hand bends, air would get sucked into the fuel line. With carbs, this isn't particularly much of a problem as the carbs have float chambers which are full of petrol. With injection, the system is pressurised and any bubbles of air in the fuel lines cause the engine to misfire. Also, the fuel pumps tend not to like trying to pump air and can be damaged because of it.

The solution to this problem of sucking in air was to sort out either an external swirl pot, fed by a low pressure pump, or a better baffled tank with a sump style swirl pot. It was around this time, I saw "A Racing Car is Born" on the Discovery Home and Leisure channel. The TIG welded aluminium Westfield tank looked ideal for the job, featuring a sump style swirl pot on the nearside front corner. I got some dimensions from members of the Se7ens list and confirmed it would fit in the Cat. At this point, I obtained prices from Westfield which were £245.58 including VAT. It wouldn't have been so bad had it provided extra capacity, but it was only marginally bigger than the Tiger tank.

Whilst researching new fuel tanks, I was pointed in the direction of Chris Gibbons (AKA Plastic Tank Man). He makes custom made petrol tanks from plastic. Ben Marriott has one in his Stuart Taylor locost and it appeared to be a very nice piece of engineering. After an exchange of a few e-mails between myself and Chris, we decided that a plastic tank with a sump style swirl pot would be ideal.

On the Cat, there is a metal tag between the diff mounting plate and the rear of the parcel shelf. Making the tank fit round this protrusion would add significantly to the cost. I e-mailed Jim at Tiger to ensure removing this tag wouldn't cause any problems and he replied, quite fairly, stating that it shouldn't, but it would be at my risk if I did remove this. After talking it over with my Dad, we have decided to remove this tag and replace it with a small angled bracket just in case it performs some sort of bracing.

Rear Chassis Support
Rear Chassis Support

Our custom designed tank (click the link below for the diagram) has a theoretical capacity of 41.59 litres. This tank has been designed around both mine and my Dads car so we could order two identically specified tanks. The angled rear section is designed to be around 1" from the inner rear edge of the rear body tub. One of the main requirements we had in terms of tank dimensions was that we wanted to keep our aero style filler caps. This meant that although there is around 3" of space above the standard tank before the top of the rear body tub, we couldn't really extend the tank upwards. If you are willing to have a top mounted filler, you can add around another 15 litres to the capacity of the tank. Also, the cut-outs at the rear, effectively making it 'T' shaped when looking from above, are to fit round the rear drop bars from our roll bar.

The table below gives an indication of the distances which can be travelled with the original tank and the new custom made tank.

Consumption
(MPG)
Original Tank
(Miles)
Custom Tank
(Miles)
20 125 183
25 156 229
30 187 274
35 218 320

Please note that although the diagram is to scale and the measurements are accurate for our cars, they may not be for yours. If you are going to order a tank made to these specifications, please double-check the measurements as we cannot be held responsible for incorrectly specified dimensions.

Scale drawing of petrol tank - Visio Format

Scale drawing of petrol tank - JPEG Format

The tanks took quite a long time to arrive from Chris due to him changing jobs and setting himself up as a proper business building plastic tanks. Please see the pictures below. Due to the tanks being black, it is difficult to see where the corners are, but these have been built as to the specification above.

Tiger Petrol Tank
Tiger Petrol Tank

Plastic Petrol Tank
Plastic Petrol Tank

Plastic Petrol Tank Showing Swirl Pot
Plastic Petrol Tank Showing Swirl Pot

As well as replacing the fuel tank, I wanted to sort out the fuel filter arrangement. Initially, I had used an expensive (around £60) motorsport high flow filter before the pump and no post pump filter. This was mainly down to the need for a filter with an 8mm inlet and 12mm outlet to attach to the fuel tank and pump respectively. After buying this filter, I found that 8-12mm adaptors could be bought for around £2 each and I would therefore have saved myself a lot of money.

By specifying a tank with correct fittings, I could sort out the filter arrangement more to my liking. The filters were bought from Fuel Parts UK. The pre-pump filter is part code FF4012-12MM and has 12mm tails. The post-pump filter is part code FF4024 and has 8mm tails. The total cost, including VAT for the two filters was £9.02 and the ratings are more than enough to satisfy the flow and pressure requirements of the fuel system.


When I originally filled my tank, I had a couple of leaks. I returned the tank back to Chris and Neil picked it up for me the following week, supposedly repaired. I then tested this by filling it with water and found two more leaks, so called Chris. I then took it to him and waited while he repaired these two leaks. He then tested the tank with thinners and proved that there were no leaks. Chris suspected that the reason for the failures were probably caused by of his plastic welding tools malfunctioning and blowing hot then cold then hot etc. which consequently wasn't welding the joints correctly.

11 August 2003 - Plastic petrol tank has failed again :o(

I am saddened to have to report that my tank failed again. I had it filled with petrol for a while and had the engine running, but still hadn't not got the car back on the road.

This time, the failure happened whilst we were out at work. We got home to be greeted by a wonderful smell of petrol when opening the front door to the house. One of the seams along the rear angled section failed and caused the tank to deposit several litres of petrol onto my garage floor. Petrol was dripping from two separate places at a frequency of around one drip per ten seconds. As soon as I could, I drained the tank and removed it. To say I am annoyed and upset by this is an understatement!

I called Dad as he also suspected his tank was leaking (for the fourth time!). He investigated further and his suspicions were confirmed. He telephoned Chris and consequently has returned the tanks to Chris and received a full refund.


We spoke to a local steel fabrication company who have made us some tanks to the same dimensions as above from steel without the leaks! We requested the tanks in mild steel. However, the company have made them in stainless steel. These are slightly heavier than mild steel items would have been, but they do look very good quality. Another local company provided appropriate fittings for welding into the tank and consequent attachment to our rubber hoses.

Stainless Steel Petrol Tank
Stainless Steel Petrol Tank

Stainless Steel Petrol Tank Showing Swirl Pot and Fittings
Stainless Steel Petrol Tank Showing Swirl Pot and Fittings


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