Mivec Vs Vtec, ?? Options

[Guest_bullet_bike_syke69_*]

no a aggressive cam profile handles just as well as a eco cam profile at low-mid ranges. yes the eco does slightly handle better as in running your engine at lower rpms. but for power it doesn't do much. once you slam on that pedal even at a low RPM the aggressive cam will produce better HP than a eco. why do you think that with a aggressive cam profile when someone surges the gas pedal to rev up to keep running the engine revs quicker than a economic set cam profile, better power!!!

does that answer your question?

[pwee05]

But at the low & mid range, doesn't a normal camshaft perform slightly better than an agressive one, which is designed to opperate best at high rpm? Excuse me if i'm wrong, but the way i see it, since a normal cam has smaller duration (or so i believe, please correct me if i'm wrong), it best fits the low range, where there's enough time for mixture intake, and should perform just slightly better power.
[right][snapback]164090[/snapback][/right]

vasiour your assumptions are correct. the "normal" cam will give you better driveability at low RPM, but less high RPM power. The performance cam will give you better high RPM power, but will sacrifice low end torque and driveability.

when speaking in terms of a DOHC engine:

"normal" cam lobes are typically shorter in duration and have less lift.
Lift is measured in inches and duration is measured in degrees.

A camshaft with this profile will be better for a turbo because you have some "overlap." Overlap created with an intake cam that has a higher lift and longer duration than the exhaust cam. This helps to create higher exhaust pressures when leaving the cylinder to spool a turbo quicker.

A camshaft with this profile(let's pretend it is the stock cam for informational purposes, it is actually very much NOT stock in reality) will create your most economical driving conditions. smooth idle, good low RPM torque, reduced emissions and overall good driveability,, but will sacrifice some top end power because it doesn't open the valves high enough or for a long enough period of time compared to a performance cam.

A camshaft with this profile (let's pretend it is a performance cam, wait, it is) will provide for the most top end power, a lumpy idle, less than good driveability at low RPM, and a loss of low RPM torque.

now, lets say that you put both of those cams together and install them on one engine. When oil pressure and rpm are low the stock cam will be the one controlling the valves. But when oil pressure and RPM are high the performance cam will be controlling the valves. This is the basic premise of v-tech, mivec, etc

[ochi]

vtec: praaaaaaaaaaaaaaaaaaaaaaaaang!

mivec: brooooooooooooooooooooooooom!

other than their sound and what rpm they engage in, both are pretty much the same...

here's a link in youtube comparing mivec, vtec, and vvt... but it's all in japanese... but you'd at least get the idea of how each system works from the pictures and diagrams used in the video...

http://www.youtube.com/watch?v=mgDdbrMh6bo...feature=related

[Lancer Boy]

respec fa d vid ochi