On the contrary. A highly modified car would see the most benefit because any camshafts you put into it will not be ideal unless they are custom ground.

Cam gears can have a similar effect, but only at one RPM. Even if you only drive between 5-8K RPM, there will still be some measurable benefit behind being able to adjust your cam angles to different values at 5K versus 8K. More value still in that you can adjust the off-throttle angles for better transient turbo response, even at high RPM.

 

SaabTuner, you'd be right if trinababe hadn't already specified choosing the best cam setup for a given rpm, in this case top end power. The mivec, even if it were on both lobes, and even it if were infinitely variable (two things it is certainly not even close to) would not be able to improve upon a specifically chosen cam for a given rpm. Once you consider that the mivec adjustment is essentially static at i believe anything over 5000 rpms, it really is a moot point to making peak performance / 1/4 mile gains on a "race car".

Coincidentally evo's from the factory aren't quarter mile race cars. They're street cars, and the increased cylinder pressure = trq from the decrease in cam overlap at low rpms is useful in street/road race conditions. But if you think that mivec compares to v-tec or vanos or anything that alters both the lift and the duration of a cam lobe to create more power, you're way off. On an N/A mivec would not be nearly as effective. It is only once air is being forced into the cylinders do you really see an improvement in midrange power. An even then +12hp can be found with stock lift 264's as well.

 

You need more than RPM to choose a camshaft profile. Even the same camshaft at different manifold pressures will often like different lobe angles.

And, all those here who have had custom cams made which took into account any pulsetuning of the manifolds, any porting on the heads, the exact exhaust backpressure, the exact manifold pressure and the exact compression ratio (if upgraded pistons) ... please raise your hands now.

Aside from that, I was carefull to say that a custom ground camshaft would be equivalent at one RPM/load point. The problem is that generic 280 HKS camshafts don't exactly count as a "custom" camshaft.

According to BMW, single VANOS does not vary lift, just valve angle exactly like MIVEC: http://www.bmwworld.com/technology/vanos.htm

I have some BMW buddies who swear by VANOS. Give it a few years and I think people will be saying the same thing about MIVEC.

-Adrian

 

The Mivec is NOT static by any means. It is dynamic across the entire rpm and load range.

 

ur also Forced Induction.. no NA... i guess if you were looking for JUST a drag or Highway car... MiVEC isnt needed... but it still wouldnt hurt at all

 

This is evom guru worthy of a post

 

THAT'S what' i'm saying!! =P

 

I cant wait till they bring the mivec controller to the us! I say this because they have it for FTO's in aussie land

 

SaabTuner, now i think we're arguing the same point.

Obviously there are more variables to take into consideration in cam selection than just desired rpm for peak power. I didn't think i needed to state that those were held fixed in this discussion on peak horsepower which trinababe had brought up and i continued. Also i couldn't agree with you more that the off the shelf cams are an "80% solution" to maximizing a setup.

The fact still remains that vanos, v-tec, mivec, et al are considered fuel saving and driveability aids, not power aids. The exact same peak power numbers could be reached using the "max" cam profile or valve overlap from those systems.

PD, I have read in other threads that the mivec advance is essentially at maximum value around 5000rpms (essentially making it fixed at that advance point) at WOT, are you saying that mivec continues to vary timing through to redline? That is the first I have heard this, albeit I have not been studying and testing as long as you guys.

Rcebwl, i'm not surprised that bmw guys love vanos anyomre than honda guys love them some v-tec, toyo guys love their stuff, and domestic guys can't get enough of their single cams. Obviously each system has pros and cons. None of that changes the fact that mivec is a non-contributor to top-end power, and only a moderate contributor (when compared to the possible full cam profile/intake runner changes that other systems currenlty use) to the low and mid range power curve. [/book]

 

Except that he had 101 oct and MostWanted had strait 93. Do you know the difference in power between race gas and pump gas??

 

I do not believe the MiVEC continues to alter the timing after 5k. I was more under the impression that under a set group of variables it will lock it in a certain position... you could easily alter this position but would be extremely difficult to continue to allow it to alter on the fly all the way up the RPM range. I dont think it would be worth it either.

Yes I have degreed cams and no I dont see how that relates to this.

Yes, custom ground cams will benifit MiVec.. guess what.. it would without MiVec also.

And to sum it up, on a race car or any car that wants the most power at 5k and beyond, I do not believe MiVec will be able to help at all. Simple... MiVEC can help spool up, driveability, and everything else but I dont see it helping WOT, Full boost, past 5k. Even if it could, it will not reliably be able to produce anything over a 2% gain. Thats my best guess and I dont know much about it. I do know what it takes to make power and more time is spent ensuring everything else is tuned and working properly... worrying about the MiVEC stuff would just hinder people.

Trojan Man obviously understands what I am saying. It will help with mid range and spoolup, tip in, etc... it will not help peak power and anything over 5k at WOT. It will not help a "race car" and it will not help any of the people that currently want to make more power by adding cams, intake manifolds, etc... All those things hurt spoolup, hurt driveability and hurt low to mid range power.

MiVEC is great for a stock car and for people that drive thier car daily and want a snappy car. Most people reading to figure out if it makes power arent looking for snappy... they are looking for fast; Something MiVEC wont help them with.

 

why does it matter whether the IX engine or turbo is better than the VIII? once I upgrade to a GT ball bearing turbo then nothing else matters. it's all preference and who has the money to do what. once you start adding aftermarket parts then you're up to par with any car.

 

bc if it's MiVEC plays a big part.. then your "gt ball bearing turbo" could have alot more power with a MiVEC head

 

Spoken like a person who wishes they had mivec.

 

Non-degreed cams can be electronically degreed by MiVEC, which is why it relates to this. But, since MiVEC cannot adjust both camshafts, it's not as usefull.