Engine Australia released the ‘Y’ crown designed Nissan TD42Ti pistons over 12 months ago.
The design is based on a design Nissan released overseas in the TD42Ti and came into
Australia in the TD27Ti. Engine Australia adopted the design because years of observation of
the spray/combustion bowl (‘clover leaf’) on engines being reconditioned clearly showed they
did not work well – they did not successfully promote swirl! It is even more apparent on higher
horsepower modified engines. You would see the flame scorch mark from where it came out
of the pre-combustion chamber and flamed straight across the piston crown into the cylinder
wall on the opposite side. This phenomenon was also apparent on the Toyota 1HZ/1HZ-T
engines. The ‘Y’ crown just made good sense.
With hundreds of the Nissan TD42Ti ‘Y’ crown pistons now running in engines, we can report
they do make a difference. We decided to add them to the 1HZ-T pistons as well. These are
already a piston we have developed and modified significantly, with added oil gallery cooling,
lowered rings, increased crown thickness and shape, increased top ring land clearance etc.
Below are photos of the piston crowns from TD42Ti engines that have failed due to fuelling
and tuning related issues. The carbon patterns left on the crowns make it easy to see what
typically happens with the combusting fuel (‘plasma’) as it moves across the piston crown.
The swirl on the ‘Y’ crown is in marked contrast to the conventional ‘clover leaf’ crown.
