Oil and fuel upgrades
I’ll never forget the time I was driving a Beetle-based kit car on the M62 when the dreaded rattle from the engine emerged from nowhere. Back home, the cylinder heads were removed and the pistons waggled to discover the big end bearings had failed.
As you can imagine, my current VW camper’s aircooled engine has quite a mass of metal, people and camping gear to move, so I’m determined to avoid another catastrophic engine failure. With only oil and air to lubricate and cool the motor, I wondered whether a larger quantity of oil would help. An extended sump can be fitted to the bottom of the existing sump by using longer studs for the original gauze filter plate. This helps to increase the volume of oil from the standard 2.5 litres, which isn’t much.
There are several sizes of extended oil sumps available, and I chose the largest of them all, which is made by EMPI and holds an additional 3.5 litres, meaning my engine now holds six litres of oil. It’s an easy conversion, which requires the old oil strainer (gauze) and base plate to be fitted onto the bottom of the new sump. Consequently, oil changes are completed in the same manner, but there’s more oil to collect.
When fitting the sump, I changed the sump plug for one with an oil temperature sensor, enabling me to fit a gauge to the dashboard. With more oil to warm up, I was warned that it would take longer for the gauge to spring to life and show a normal temperature reading. As an extra precaution I decided to fit a hot oil sensor from the US, which is a replacement dipstick that is wired to trigger the red oil pressure warning light on the dashboard if the engine oil gets too hot (around 105°C). And I also fitted an oil pressure gauge to ensure there was good circulation of oil.
Several teething problems arose with all of these precautionary measures. The oil did take a long time to warm up, but according to the gauge it struggled to exceed 70°C, yet the hot oil sensor occasionally triggered the oil pressure light on the dash. I checked the temperature
gauge by connecting it directly to the temperature sensor and immersing this in a jug of hot water, which I could doublecheck with a thermometer. It was accurate.
Then I realised what the problem might be. With the combined oil drain plug and temperature sensor being at the bottom of the engine, and the extended sump being in the firing line of additional airflow, maybe these components were being cooled more than the rest of the engine. Plus there could be something to do with convection, where hot liquids rise and cold liquids fall, although maybe not because the oil is being circulated.
I shopped around for a different oil temperature sensor and discovered I could have a dipstick type or one that’s fitted on the side of the crankcase. I opted for the latter and once the oil has warmed up, this seems to be providing a reading that’s more akin to normal. But the wiring was now getting messy, so I decided to remove the hot oil sensor dipstick and refit a standard one. Besides, I felt that an accurate temperature gauge was better than waiting for the oil light to illuminate via the dipstick sensor anyway.
A much bigger job that was undertaken around the same time was to discard the old and traditional distributor and carburettor in favour of a fuel injection conversion. I’ve lost count of the number of times I’ve checked the points gap, sprayed WD40 over HT leads and checked for a fuel supply when my VW’s air- cooled engine has spluttered to a halt. It’s fair to say I know how to deal with a breakdown and have only had to be towed home once, but I’m tempted by electronic reliability.
So I turned to Specialist Components, who have been making fuel injection conversion kits for BMC
A-series engines for several years. They offered to take my VW as a guinea pig and devise a new twin-point conversion kit. It uses a single throttle body mounted on the standard inlet manifold, which has two injectors and a Bosch MAP sensor attached to it. There’s a small Facet fuel pump and a large Weber swirl pot with its own pump to feed the petrol through to the injectors at around 3.5 bar. With a new toothed crankshaft pulley and a Magneti Marelli crank position sensor mounted above it, engine timing is monitored via a programmable ECU to control a Ford coil pack to deliver the sparks. And armed with freeto- download software, I can
“I know how to deal with a breakdown, but I’m tempted by electronic reliability ”
monitor and control the engine via a laptop.
SC completed the conversion over a few weeks and measured a moderate increase in performance of around 7- 8bhp, resulting in 65bhp at the flywheel. My first impressions were nothing short of amazing. The engine felt more responsive, there was more torque and it was so much smoother. It’s not quite the fit-and-forget system I’d expected because teething problems have arisen, mainly with component failure of the CPS and MAP sensor, but these are readily available from most motor factors. I’m still getting to grips with it, so I’ll report more in the near future.