Basically heres what Mivec does...

Think of it like choosing cam sets. People who want nice low end will stick with low duration cams. People who want high end will go with very high duration cams. With each increase in power at one part of the band, you sacrifice power in the other. Good low end will yield bad high end and vice verse.
Mivec adjusts the intake valve timing by retarding the cam to create a similar effect that longer duration cams would after I think 3500rpm. The Mivec Evos have noticable increased low end response due to this. You'll notice the peak numbers aren't much more from a non mivec, say, VIII engine, but the area under the power curve is more.

In a way its like s version of Vtec(shudders), except vtec switches to a different set of cam lobes. They both have the same effect though. Ultimately they adjust the valve timing to improve performance in both ranges.

Hope that helped

 

Got this from mitsubishi's site,

How does MIVEC work? At lower speeds (less than 3,500 rpm), the MIVEC engine intelligently adjusts itself to offer crisp throttle response to accelerate you through the intricacies of city driving. As engine speeds increase, MIVEC takes on its sportier side and spreads the power delivery throughout the rest of the RPM range by allowing more air into the combustion chambers.

 

You can feel Vtech better when it kicks in because its usually on a naturally aspirated engine. With the torque spike you get from spooling 20 pounds of boost, the mivec effect gets drowned out.

 

Got it now!! Thanks for the info!

 

your welcome, just go easy on me in that AMS forum, haha, made a fool of myself

 

wth it isn't pointless... and even if it was pointless why would you take it off if it's already on there...

 

mivec is the opposite of vtec to a point, vtec is for the higher end. when vtec owners go turbo that makes it pointless... b/c when by the time your spooled the vtec is ready to kick it. as stated above, mivec works the bottom end to give you some better foreplay before sex (or boost) ....

 

my car is at ams for a tune. i'm local so i stopped in to check out the progress. i was told that my base dyno run was around 290 hp with just exhaust from my evo viii that was sitting in my garage without a tune. i know the turbo is better than the viii but with the bolt on's with the viii and a tune i was probally right around there. i think the mivec had something to do with it. i could be wrong but i have some other parts going on with a flash so dyno charts will follow.

 

mivec continuously change cam timing on intake side, but you're still running the same cam with same lift and duration. vtec has two different cam lobs, it's like running two different cams with different lift and duration. that's why you fell the torque surge when the vtec engage. i-VTEC is a new intelligent vtec that incorporate the old dual lobs cams and adjustable cam gears similar to mivec. so you have two cam profile along with the ability to just the cam timing on the fly.

i've never seen a boosted vtec engine making less power than a non-vtec engine with the same setup. that includes top end power or under the curve. it's mainly due to the fact that vtec head flows better than non-vtec head. it's also very easy to disengage vtec but i don't see anyone with boosted vtec disengage it if it's pointless. in fact most will engage vtec sooner to help the turbo spool.

 

you really cant say either system is for a certain range. Because its mechanically impossible to design a cam that will excel in both upper and lower rpm ranges, they both incorporate one configuration for lower end and another for higher end. You would say that Mivec is less effective than Vtec since it only adjusts the same cam to be a little more suited for lower or higher rpm, but since its the same cam with the same lobe profile, you can't get the full effect of what its trying to do. Vtec on the other hand, like already mentioned, hydraulically(using oil pressure, like mivec) switches to a seperate cam lobe on the cam shaft. If you've ever seem these cams, you can see the different lobes on them. This way is more effective because it allows the valve to have a different timing as well as a differnet duration when it switches over. Mivec only allows for different timing, same duration, so Vtec is essentially more effective.

 

I don't know what the heck you talking about, going turbo on a vtec motor makes it pointless? Have you felt vtec and turbo together, that shyt is a rush. maybe on the low end vtec is caca with turbo because turbo spools so dam slow, but once vtec kicks in and turbo is at full boost that its crazy.