VVEL control unlocked

Jordo!

I seem to recall an old chart from another forum that showed there was more lift possible...

I'll see if I can find the image and post it.

EDIT:

Here...

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Rusty

So that chart is saying max is about .500" lift. But it's only using up to .450" lift. HMMMMMM You know how much duration there is?

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Nissanboy

Where did you get that chart if you don't mind me asking?
Reason being is I've taken several Nissan courses (Currently a Nissan Tech) and they've always stated that the max lift is 11mm due to the eccentric cam only being to big. I'm not trying to say that I'm correct or anything, I'm just wondering why they wouldn't of mentioned it.

Another reason being is if there is more lift available, why did they not implement it into the power band? Only reason I could see why not is because our motors being interference motors it could cause a clash between the piston and the valves.

Jordo!

A site that shall remain nameless under pain of excommunication around here...

google VVEL and 370Z in images and it will pop up on the first page

EDIT: Whoops -- it just links back to another thread on here. I'll shoot you a PM.


I'm guessing because of the same factors that result in other tuning limits -- gas mileage and emissions. I find it hard to believe there's no wiggle room left.

Even with ignition timing, where there is not much room for advance, a couple of extra degrees can be safely dialed in, and that nets in reasonable power gains.

I find it hard to believe the valve timing is optimized for power and any other changes result in valves hitting the pistons or power loss. If the tolerances were THAT tight, it means that with just a little valve float at high revs, you'd see mushroomed valves occurring here and there, and I haven't heard of a single failure like that, even though most people bump up the rev limit by a few hundred RPM and plenty of people beat on the car.

Moreover, even if timing and overlap is optimized when stock, slap on a free flowing exhaust, different IM or set of headers and its (potentially) a different ball game.

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Nissanboy

I agree but one thing that people seem to misunderstand around here is just because something is used to provide better emissions and gas mileage doesn't mean it has been made only for that. Think about it; if the hydrocarbons in the air-fuel mixture is burned better or more complete, it will give us better gas mileage, emissions AND power. Just simply increasing the efficiency of the motor.

Jordo!

Yeah... in theory that is true (although with a few more mm of valve lift, that means a greater volume of air is sucked in!), but the reality is you can rarely obtain all three in practice without the risk of jeopardizing two other factors: Driveability and longevity.

For example, many OEM tunes run much richer than necessary under high load, and high engine (air, water, and or oil) temps and or dial back ignition advance, resulting in a less efficient burn and wasted power -- but it substantially reduces the likelihood of ping under extreme conditions.

Also, in general, peak torque tends to be made with a richer than stoichiometric mixture anyway... that might not be true with a good DI system on the same motor (or, I dunno, with water injection), but it's pretty tough to gain power AND use less fuel or produce fewer hydrocarbons in practice on a typical port injection engine.

As to valve lift and overlap on this particular motor -- it's all an empirical question. We simply need more data.

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Nissanboy

I agree with you, just stating that if fuel efficiency went up because of something, doesnt mean hp will go down. But that's factory OEM talk. Once more serious things get in the equation (like high boost or increasing displacement) there really isn't a way to save gas mileage.

Anyways back onto topic about VVEL unlocked. I want to see some more results!