ff_

LOL, I didn't notice that. Post-n-run.

XeroK00L

But then DVVT-i > i-VTEC..
So the end result should be more or less the same.

AzNMpower

That is just Toyota's version of BMW's Valvetronic system, which has been out since 2002 with the 4.4 liter in the 745i.

Valvetronic also does not have the traditional throttle body. Many people confuse it with variable valve-timing (that's actually double-VANOS).

http://www.bmwusa.com/uniquelybmw/In...ce_Innovations

Bean

iTrader: (1)

As has been stated, the Toyota unit looks to be a lot more clean and less "clunky". It still also completely lacks a TB which the Valvetronic unit does...

in fact, go back and read the damn thread.

ff_

How can you tell? The image in the original post isn't detailed enough to generate any conclusions. And in the end, all the matters is how well the technology performs. How the assembly looks to a non-engineer is rather pointless, don't you think?

AzNMpower

Valvetronic doesn't have a TB (I'm assuming this means throttle body) either. And honestly, I really don't care how the engine looks from the inside; pictures do not show the full details of the engine, and honestly I wouldn't buy a car just cuz "under the hood" looks clean. As long as it works, it's alright in my book.

RocketGuy3

iTrader: (1)

I don't know if this has already been brought up, but from what I understand, BMW has struggled to combine this technology with GDi because of lack of room in the cylinder head. Has Lexus faired better? It would be nice if they could use both technologies to make improvements to engines like the 2GR-FSE.

Also, BMW's Valvetronic DOES have a throttle plate, but it just serves a very different purpose. It opens when the engine is running. I'm guessing Lexus will do something similar.

TRDFantasy

Based on what information?

Direct from Honda: http://world.honda.com/news/2006/4060925VTEC/

This news item is from 2006, so that means a production engine will be on the market by 2009.

There are always plenty of wild rumours out there on the 'net, but according to Honda themselves you won't see a production A-VTEC engine on the market until 2009, which means both Nissan and Toyota will have beat Honda to market with their systems by well over a year.

From the Honda press release:

Key word is highlighted. Honda doesn't know *exactly* what the benefit will be. This is simply their approximation. Toyota's approximation is that their system will give a 5 - 10% fuel economy benefit. Toyota also approximates power will increase by at least 10% for their system. We don't know how much of a power increase A-VTEC will give.

Either way it's silly to be comparing the two systems, neither of which have yet hit the market.

Valvetronic *does* have a TB. It typically stays in the full open position, and is there as a backup in case Valvetronic fails. It also adds weight and some efficiency is lost by having the TB still there.

Valvematic appears to entirely get rid of the TB, which means increased efficiency and less weight than compared to BMW's Valvetronic.

Correct. Valvetronic cannot be combined with direct injection because there isn't enough physical room in the cylinder head. Valvetronic also struggles to run above 6000 RPM. We will see if the systems from Toyota, Honda, and Nissan improve on this.

Bean

iTrader: (1)

It gives a good general outline of how it works. Less clunky = less crap to break. General drawings are used to explain a concept. And showing the valvematic controller on the back of the head like that is pretty easy to understand. It doesnt take an engineer to understand that concept; but it generally DOES take a person with half a brain. Don't you think?

MOST engineers strive for power in simplicity. Everything from automotive engineers to Computer/Electrical Engineers = me. I let my coding do my talking. (call me a non-engineer all you like, but I am a member of IEEE and have passed the FE exam -- I dont have the degree, but I DO have the title)

AzNMpower

The 6 liter V12 in the 760i has both Valvetronic and DI. All of the Valvetronic engines rev freely up to 6500 or 7000rpm. When was the last time you heard someone say a BMW petrol engine peters out past 6k? That's more of a Nissan trait.

Admittedly, there is a slight downside to Valvetronic and that is the throttle response from what I remember isn't as sharp as the non-Valvetronic engines. The X5 4.6is I drove definately felt crisper than the 4.8is, although response is good anyways. However, there is a reason that the M cars don't use Valvetronic, since response isn't as sharp as a system with an individual throttle for each cylinder.

kit cat

iTrader: (6)

The E46 316ti was the first. And can someone tell me what the difference is between Valvetronic and this new Toyota thing? No answers for the past 3 pages.

Koma

iTrader: (3)

From Wikipedia:
The Valvetronic system is the first variable valve timing system to offer continuously variable timing (on both intake and exhaust camshafts) along with continuously variable intake valve lift, from ~0 to 10 mm, on the intake camshaft only. Valvetronic-equipped engines are unique in that they rely on the amount of valve lift to throttle the engine rather than a butterfly valve in the intake tract. In other words, in normal driving, the "gas pedal" controls the Valvetronic hardware rather than the throttle plate.

First introduced by BMW on the 316ti compact in 2001, Valvetronic has since been added to many of BMW's engines. The Valvetronic system is coupled with BMW's proven double-VANOS, to further enhance both power and efficiency across the engine speed range. Valvetronic will not be coupled to BMW's N53, "High Precision Injection" (gasoline direct injection) technology due to lack of room in the cylinder head, or the N54B30 bi-turbo engine. Cylinder heads with Valvetronic use an extra set of rocker arms, called intermediate arms (lift scaler), positioned between the valve stem and the camshaft. These intermediate arms are able to pivot on a central point, by means of an extra, electronically actuated camshaft. This movement alone, without any movement of the intake camshaft, can open or close the intake valves.

Because the intake valves now have the ability to move from fully closed to fully open positions, and everywhere in between, the primary means of engine load control is transferred from the throttle plate to the intake valvetrain. By eliminating the throttle plate's "bottleneck" in the intake track, pumping losses are reduced, fuel economy and responsiveness are improved.

It is important to note however, that the throttle plate is not removed, but rather defaults to a fully open position once the engine is running. The throttle will partially close when the engine is first started, to create the initial vacuum needed for certain engine functions, such as emissions control. Once the engine reaches operating speed, a vacuum pump run off the passenger side exhaust camshaft (on the N62 V8 only) provides a vacuum source, much as a diesel engine would, and the throttle plate once again goes to the fully open position.

The throttle plate also doubles as an emergency backup, should the Valvetronic system fail. In this case, the engine would enter a "limp home" program, and engine speed would once again be controlled by the throttle plate.

Valvetronic has so far been limited to BMW's mass-market engines, with no high-performance M-series car using the technology. The Valvetronic hardware adds a great deal of mass to the valvetrain, limiting maximum engine speeds (~7,000 rpm peak rpm in N52) engines and making it unsuitable for the high-revving M engines.

I don't know too much about the valvematic system though. Only from what the original article said.

TRDFantasy

You're right, the 6.0L BMW V12 does have both. It works in that engine because there is enough room in the cylinder head, since the V12 is a physically large engine. You don't see Valvetronic and direct injection in other BMW engines though. The V12 looks to be an exception within BMW's engine range.

Again, the Valvetronic system has trouble running above 6000 RPM. I didn't say it has problems, just struggles above that. You definitely do not see Valvetronic running above 7000 RPM.

Why have we never seen an M engine with Valvetronic? Simple, because the system cannot run at high revs above 7000 RPM.

TRDFantasy

Re-read the whole thread. Although info on the Toyota system is a bit limited at this time, so far it looks like the Toyota system gets rid of the throttle body entirely, while the BMW system still keeps the throttle body. The BMW system also has several limitations already mentioned in the thread, and it uses additional rocker arms inside the engine to work. The Toyota system based on Toyota's diagram does not appear to use additional rocker arms. The BMW system also adds a lot of weight to the engine. That does not appear to be the case with Toyota's system.

In summary, the Toyota system seems to be less clunky, smaller and simpler, and ultimately should be more efficient and more reliable.

kit cat

iTrader: (6)

thanks
I guess "I can't read good".