Not sure if this should be in this section or under engine management. I put it here since it's more of a general view on the topic.

I have done some research (was bored at work) and I found some information scattered here and there that implies that the MIVEC technologies used in the Evo IX is actually limited. Limited in the sense that it only controllers variable timing and not flow. In other words, with the MIVEC in the Evo IX, the pulse of the valves opening and closing is variable, but NOT how much it opens and closes. This seems different than the common MIVEC ability used in other Sirius engines. What is the reasoning behind this? (assuming this is true of course) My limited understanding of engines tells me not to care too much, and that performance will not be sacrificed, rather fuel economy at lower RPMs will. Again, that is only my understanding of it.

 

where have you been????

 

werd, aint no vtec

 

I think that's right. The Evo's mivec is variable timing / not variable lift. I believe when the MIVEC is advanced the valves have some overlap and flow IS increased.

 

Yeah thanks for the info.

 

so, did we conclude that evo is better with or without MIVEC?

 

All about timing, and during time,how long and when it's stays open more or less.MIVEC for better low -midrange power.but for the higher end power, you need cams for the IX too.If you change cams both mivec and no mivec engine ,the mivec will be better .Reason is: more low and midrange power.the no mivec engine with cams will have the same whp ,but under let say 5000 rpm the mivec will perform better.so on the tract /road corse and street/ it will be quicker. also i saw in this site, mivec vs 8 turbo kit tests. The mivec responded much better for the same turbo kit. Also its more enviroment friendly./suppos to be/

this is what i figure it out about MIVEC. I can be wrong ,but thats my understanding is.
i hope i will learn more about this here.

 

Mivec only advances the intake cam. I believe the maximum advance is 6 or 7 degrees. I can't remember exactly right now. You keep the same duration and lift but you change the time the lift begins. In my opinion mivec is great because you have more control of your engine. The ultimate solution would be a camless engine with solenoid actuated valves. Each cam is designed for a sweet spot in the rpm range. The same cam designed for power up top will sacrifice low end mainly because the velocity of the air is different. With solenoid actuated vales you could maximize power/response throughout the range and even make adjustments from cylinder to cylinder.

 

errr. i need to do some more research.

 

There has been some dyno testing and a modified mivec map on a stock car made 26 or 27 hp over a stock IX with no other modifications on the car. The IX's consistantly outperform VIII's with the same mods. Mivec is at least partly responsible for those gains, the IX's turbo is also a factor. Also it seems like IX's boost earlier than VIII's which is also partly a function of the mivec.

 

This will happen. I believe Honda has already announced their R&D on this late last year saying it will be available for 08 Acuras and higher model Accords. Haven't heard about it since, but I think ti's supposed to be the new VTEC type called Advanced VTEC or A-VTEC for short and is said to be superior to all previous VTEC types include DOHC I-VTEC. The setup is probably going to be similar to BMW's Valvetronic system, by varying the lift and duration of the valves throughout the powerband... so no more sudden 'VTEC climax' for all the Honda junkies. Which I'm pseudo guilty of being myself... and yes .. if that works out well, I will definitely be trying to drop one of those engines in my 98 Accord.