Italian engineering

The Slabang is a Swedish design intended to derive the maximum speed from a twinshaft engine. Very much like an enlarged Russian schools car, it incorporates a quite delicate front suspension controlled by nothing more than a single piece of piano wire. In the hands of Swedish drivers with much modified Olivers, or their own, home built versions these cars can regularly exceed 100mph. John Goodall described his own car that he used to break the 100mph mark, the only British person to achieve this. Now, Gianmauro Castagnetti has updated the concept by fitting fully damped, rear suspension, described and illustrated below. This design could equally well be adapted for any twinshaft car that has a suitable pan shape.

I started construction with a casting purchased in Sweden, I built the engine completely with the possibility of rotation and mounted a rear shock absorber. The body is made of fiberglass and higher to allow the engine to be sprung. I will take it to Buckminster in June for use.

We met Gianmauro at Gt Carlton in 2019 where he had a bag full of original and historically important cars from Italy, France and the UK, as well as examples of his superbly engineered replica cars and engines. Communication was not easy but we are delighted at last to be able to feature a few of the engines he has built, mostly Oliver inspired.


Replica Oliver Tiger MkI RVB	Replica Oliver Tiger MkII	Replica Oliver integral gear motor


Parts count for the MkII	MkII crankcase	MkII on test rig


Replica ETI twinshaft	Exploded view of the ETI	Engraved logo rather than cast in

Oliver Twin Recreated. Gianmauro Castagnetti

When the MCA was set up, there was considerable disquiet about 'professionals' competing, primarily manufacturers such as the Olivers, father and son. By way of a protest, JO set to and built a 5cc twin based on two MKII Tiger units. The car was formed from hand beaten aluminium with the centre section removable for access to the motors and tank.

initially two separate fuel systems were used to get the tanks in the correct position, but by reversing one venturi, a single tank and cut off could be used.

The engine, in a later MI special survived and has now been built into a replica by John Goodall, that he ran on several occasions in 2023.

Photo right shows JO with the original car

Gianmauro has built this superb replica that included machining the entire motor from scratch.


Replica of the one-off 5cc twin built and raced by John Oliver


Superb reconstruction of the Oliver twin in a period style, cast pan, with a one piece GRP top

All photos supplied by Gianmauro.


Raw castings	Finished car with suspension	Rear, fully damped suspension


Superbly engineered, home built twinshaft	Trunnions on the cylinder fins	2.5cc diesel twinshaft


Trunnion blocks	Rocker arm for damper	Adjustable damper in position