We put a lot of effort into designing this engine. We paid special attention to the following details:
- We managed to pack it in only 9 studs of length, while eliminating the crank end-to-end twisting and engine vibration.
- No V4 ever run so smooth on such low rpms, while at the same time offering 1500 rpms on only 4 bars of pressure.
- We managed to integrate a centrally positioned ballance shaft that also acts as a timing distribution gear. It prevents the crank and camshaft from twisting and enables a very precise operation even under great stress. No lego V4 crankshaft has ever been so stiff. The balance shaft is a rigid shaft that runs trough the sections, centraly positioned between the crankshaft and the camshaft with one pinion gear just before the front and rear block end-sections. The crankshaft end-shaft gear drives the camshaft end-shaft gear via the balance shaft pinion gear. In other words, the distribution gears are present from both ends of the engine. All Lego elements have a certain amount of elasticity and especialy the axles that connect each crank piece can easily twist. A balance shaft greatly reduces the torsion of the crankshaft, becuse it rigidly connects both ends of the crank/cam shafts. It is self explanatory how the 'balance' shaft greatly improves the torque output.
- We use only 2 valves in the engine, you might wonder why. It enables us a more balanced distribution of air to the paired cylinders and drastically reduces a lot of friction. Both are the key for such a smooth operation and for high rpms in a V4.
- A proper valvetrain geometry must pass the central point of the valve in as few degrees of the camshaft revolution as possible in order to offer the maximum air flow. During one camshaft revolution each valve spends only ~60° in its central dead point, on the other ~300° it offers full potential air flow to the cylinder.
- This engine is actually capable of a much greater speed than 1500 rpms, but we finetuned the timing for the smoothest operation on low rpms and the biggest torque output throughout the entire rev band.
Since we find it virtually impossible to obtain larger quantities of transparent cylinders for a reasonable price, we decided to go with yellow cylinders, which are slightly easier to obtain, but still come with a "nice" price tag.
The product ships fully assembled and without instructions!
|Number of cylinders:||4|
|Bore:||2 studs (big cylinders)|
|Crank throw:||1 stud|
|Crank type:||Cross-plane crank with crank pins 180° from each other|
|Valvetrain:||pushrod actuated rockers, one valve per cylinder pair|
|Conrod length:||6 studs|
|Max speed:||approximately 1700 rpms @ 7 bars (100 psi) of input pressure|
|Recommended operating pressure:||< 8 bars (116 psi)|
|Maximum pressure:||10 bars (145 psi)|
|Minimum pressure:||0,6 bars (10 psi)|
|Number of moving parts:||16|
Pushrod V4 engine