Bill Sherwood's VVT Vs Vtec, page 2

Welcome, from sunny Australia!

More on the Honda V-TEC S2000 engine

I know that this page is intended to be a comparison between the Toyota VVT and the Honda V-TEC, but I've got a few more pictures of the Honda engine, so I'll write a bit more about it. ;) I only hope that my Toyota fans aren't too upset!

The engine is truly a product of Honda's Formula One experience.

(98kb pic) If you have a good look at the above picture, you can see a relatively conventional alloy block. There's a few plugs that bolt in to the side that I assume allow for the casting of the internal structure of the water passages, and also for some localised expansion. The interesting bit is the lower part that bolts onto the bottom of the block - It incorporates the main bearing caps, and so makes them extremely rigid. This is one of the factors that let the engine run to 9000rpm. You can also see that there are some nice, thick dowel pins to locate the lower casting, so that the main cap bolts are simply used for keeping the main caps on, and not to accurately locate the caps as well.

(197kb pic - big!)

In the above picture you can see a number of interesting details -
- Coil-over-plug ignition. Each sparkplug has it's own coil, thus letting each of those coils fully saturate (electrically & magnetically) before firing.
- The cams are driven by a 'morse hy-vo' chain. This takes slightly more power to drive than a belt drive, but it usually more accurate. (and slightly noisier)
- The cams are driven by a central idler gear, and so spin in opposite directions.
- The cam wheels are made from two pieces so that the rear piece can be turned a small amount to eliminate any back-lash.
- The oil pump is driven by a small chain, going down into the sump. Not sure why they've done this, as the more common 'pump sitting around the crank' type pump would seem to be more efficient and reliable.
- 4-2-1 extractors. Gives a better spread of power than the 4-1 type.
- The water pump is driven at crank speed. (the water pump pulley is the middle one of the right hand column of three.) A lot of engines have the water pump driven faster than engine speed when they don't need to, thus wasting power.
- Tiny little springs to keep the inner 'high power' cam followers working on the cam lobe when not engaged, and I guess to make the effective spring pressure and rate higher when V-TEC is working to allow very high revs.

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