V-8 Engine Model ------------------------------------- This is a MOC designed by barman (http://www.brickshelf.com/cgi-bin/gallery.cgi?f=276743) which is a working model of a V-8 engine. It does not actually produce power, rather it is powered by a single electric motor which turns the engine. A 9V train speed regulator serves as a throttle control to adjust speed. I built the MPD file from scratch using the photographic instructions produced by Barman. The following are functional or aesthetic features of the model. Parenthetical items refer to image file names in this directory. - Crank Shaft (crankshaft.jpg): This is a crossplane crank shaft (4 crank pins at 90 degrees orientation). The crank pins are arranged in the order of a "standard" American V-8 engine. Keen eyed observers may note that the front and rear pins in the picture are actually reversed, but this was later corrected. There are 5 main bearings (axle supports). Technic cams are used for the crank shaft connections, and their shape mimics the balancing weights which would actually be on such a crank. There's a harmonic balancer on the front of the crank shaft which is connected via chain to the electric motor which drives the engine. - Pistons (reciprocating_parts.jpg): The 8 pistons are each made from a pair of Model Team wheels. - Cam Shafts (cams.jpg): This engine has 4 overheads cams, 2 in each head. Each pair of valves (intake and exhaust) open at the same time and are 180 degrees out of phase. Note that the image does not properly reflect the relative timing between adjacent cams. I've added rollers to Barman's design to simulate roller rockers (even though they are on the cam shaft in this case). This also serves to increase the lift on the valves. The cams are chain driven off of the crank shaft (chains.jpg). The crankshaft has a 12 tooth double bevel gear driving a pair of 16 tooth gears. Each of these, through the chain, drives the 24 tooth gear on each cam. This results in a gear ratio of 2:1 (cam rotating at half the speed of the crank) which is correct for an Otto (4- cycle) engine. - Valves (valves.jpg): There are 32 valves. The upper valves (nearer the valley) are intake and the lower valves (nearer the motor mounts) are exhaust valves. - Rockers (rockers.jpg): The 16 rocker arms are spring loaded via blue elastic bands (not pictured) to close the valves. Contact with the cam shaft roller drives them down and opens the valves. - Distributor (dist.jpg): The distributor uses a Technic fiber optics element to simulate the firing of the coil. The power for the fiber optic light comes from a separate 9V battery pack so that it does not change intensity as a funciton of motor speed. A chain (fan belt) driven by the harmonic balancer rotates the fiber optic element. Pneumatic tubes represent the spark plug wires and run to each cylinder through a series of looms. The spark plugs enter through the top of the head suggesting that this V-8 is a hemi. - Heads (head_bottom.jpg, head_top.jpg): These images show the heads with the cams, rockers, and valves installed. - Block (engine_block.jpg, front_short_block.jpg): The engine block is constructed almost entirely from studless beams and angle connectors. The water jacket looks a bit leaky. - Intake Manifolds (intake.jpg): There are two intake manifolds which each contain 4 individual single barrel carbeurators. - Exhaust Manifolds (exhaust.jpg): The exhaust manifolds are equal length headers which are made up of 2x2 round plates placed over a flexible axle. Kevin Clague's LSynth 3 made modeling this possible. - Fan (fan.jpg): There's a 6 blade fan with a significant pitch constructed from a pair of 3 blade rotors. It is driven by the same shaft which drives the distributor. - Flywheel (flywheel.jpg): The back of the block holds a bell housing containing a flywheel represented by a motorcycle wheel. It could be argued that this is actually a torque converter, but I can't tell without seeing the transmission. So how big is this thing? Take a look at (size.jpg) and you will see that it is huge; as big as the 8275 bulldozer. I've included a parts list in case anyone would like to procure the parts to reproduce one of these like I am doing. (1-render.jpg) (2-render.jpg) (3-render.jpg) (4-render.jpg) (5-render.jpg) I've made 5 renders of the engine at various stages as I progressed through construction of the MPD file. The first four all use radiosity (Type 3) with a plain white sky sphere and a transparent background in addition to the 3 default light sources. In 2-4 I changed the default light sources to be slightly yellow in color. The final render (#5) use radiosity Type 5 (final) and uses High Dynamic Range (HDR) lighting with the light probe of the Uffizi Gallery (from debevec.org) rotated upside down. In this case there is also a black floor which is slightly reflective. I also used a single overhead conical spotlight. The final render uses recursion anti-aliasing with a depth of 3. (6-render.jpg) (7-render.jpg) These renders now include all of the synthesized spark plug wires (pneumatic tubes) and fiber optic elements. -Blakbird 2009