Around 2009 I installed my home self-built unforged L28 stroker into my Datsun 240Z. Since installing the motor it has been in continual development and featured in my YouTube channel. I have made an overview video if watching something more your thing!
The basis of a stroker motor is the use of a crankshaft to increase the stroke of the piston. Historically stroking a Datsun L6 was done using an LD28 ‘V07’ crankshaft from Nissan diesel motor. In 2007 my LD28 V07 crank cost $150NZD and twice that to ship to Australia. Nowadays (and in the future!) it is likely to be more cost effective to modify an RB30E crank or purchase a billet kit.
My L28 stroker
When I set out to build this motor myself it had to satisfy the universal car law of you can only pick two from power, cheap and reliability. I chose cheap and reliability. With that in mind I spent endless hours searching catalogues for suitable off the shelf items, some from different engines. The fruits of my labour are listed below.
The base engine used was a barn find – literally! The donor engine was from a late 80s Nissan patrol and was swapped out for V8 in the 90s being stored at the back of a hay shed. Apart from a little long term surface corrosion the engine was a very good example of factory motor. The pistons I select is what I am most proud of. They are cheap, sufficiently strong and readily available. The bottom has all the fast rotating components so I had the rotating assembly balanced for 10,000 rpm. Overkill? Not really when it cost no more at the machinist!
Engine head setups make and break performance. The head I used was to factory spec and in good condition that came with the F54 block. At the time my own porting skills were limited so I kept head work to the basics. I kept to the basic match porting and unshroud the valves for a bir extra low lift flow. My head specifications are below:
I assembled my L28 stroker in much the same fashion and to the specs as a factory L28. I clearance everything that the stroker crank affected. In the end some slight grinding of the inside of the block for conrod clearance was really all I was required to do.
One thing I did do was dummy assembly and blueprint the engine, really verifying the piston to valve clearance to confirm my ‘design’. This was done with a lump of soft air drying clay coated in a bit of engine oil (to stop sticking) on top of the piston. Cylinder 1 from crank to cam was assembled and rotated a number of times. Using a standard thickness head gasket the clearances measured 3.5mm to the Exhaust and 3.3mm to Intake valves to give a guide. I was comfortable with this clearance.
Next the last caps over the valves need my attention. Using various combinations of copper shiming plate I was able to determine the required lash cap thickness. If I can recommend one place to purchase shims, it is Precision Shims in Australia http://www.precisionshims.com.au/
As a result of many years of ownership and development there are a number recommendations I feel that I am qualified to make on an L28 stroker long engine: