i know mivec (or Vtec or vvti) are cams that change timing, but does anyone know how they actually work with pics?
cheers

www.howstuffworks.com (beware of annoying popups) has an article on 'variable valve timing' which explains how VTEC (I think) works. From memory - the article makes reference to the fact that VTEC and VVTI are very similar in they way they work, it also briefly outlines how the more sophisticated variable valve timing system employed by ferrari works.

Don't know how VTEC, VVTI and the Ferrari method compare to MIVEC - but definetly an interesting read.

Here's the link (http://auto.howstuffworks.com/camshaft6.htm)

There is acutally a few differnent varients of MIVEC. The original MIVEC that was found on the FTO 2L and the cyborg 1.6L was variable valve lift and duration, where as the MIVEC finding its way in now (certainly the EVO IX) is not the same, and I think is only variable duration....I could stand corrected on this. The basic concept is a second cam profile that can come in to effect at a certain rev range, allowing valves to open further and for longer as power requires

VTEC ® - ©Honda
VVTI ® - ©Toyota
MIVEC ® - ©Mitsu

Mivec is Honda V-Tech system underlicence.

This one is good:

http://asia.vtec.net/spfeature/vtecimpl/vtec1.html

I can't find the animation on it though

Cheers

Marc

http://www.mitsubishi-motors.com/corporate/about_us/technology/performance/e/mivec.html
Pics included on link

someone mentioned the ferrari system...

The ferrari system works with a cam shaft that moves parallel to the crank and has 3 dimentional cams so the valve timing and duration changes slightly with a small movement of the shaft along the rail. It moves mechanically to suit the RPM and lengthens the powerband...so sweet

http://static.howstuffworks.com/gif/camshaft-ferrari.gif

I did a tour of the factory when we were in Marrinello and they showed how it all worked. Really smart.

I heard a rumour that nissan has someting like v-tec. is this true because I can't get a straight answer

I heard a rumour that nissan has someting like v-tec. is this true because I can't get a straight answer

Yeah they do, called NEO VVL, they had screamer 4 cylinder NA engines in the 90's.

There are five (5) VE motors:

SR16VE - 129kW@ 7800rpm / 161Nm torque @ 7200rpm 1.6L
SR16VE N1 - 147kW @ 7800rpm / 134Nm torque @ 7600rpm 1.6L
SR20VE - 140kW / 197Nm torque @ 6000rpm 97-2001 2.0L
SR20VE - 152kW@ 6200rpm 2001-Present 2.0L