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Discussion Starter #1
VVTL-i is equivalent to BMW's Double VANOS right? Looking at BMW's performance numbers, you can see how they benefit with the use Double VANOS in their cars. The Toyota Celica GTS uses VVTL-i right? Well I would have expected that VVTL-i be used in Lexus model cars. As far as the GS430 and LS430, was the engine displacement just bumped up or did they add VVTL-i in addition? You would expect that the LS430 being the technological wonder to have a double variable valve timing system...
Eric...
 

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i believe they do use vvti-l....i'm thinking that double vanos vvti-l and vtec are all basically the same thing, but i think one of my friends pointed out that vtec controls lift(to me i was just kind of like...okay that's great) but he made a big deal out of it so i don't really know
 

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...don't hold me to this I might be incorrect. There are no Lexus vehicles with VVTL-i, they all employ VVT-i. To my knowledge VVTL-I is only used on the Celica GT-S. I think that VVTL-i has something to due with producing high end horsepower, hence the stratospheric redline in the Celica GT-S. VVTL-i, VVT-i, VTEC, VANOS, and Double VANOS are all variable valve timing systems (there are others I think MB has one as well) but they function differently and have different levels of sophistication...VTEC being at the bottom of the hill, Double VANOS being at the top. Double VANOS not only functions on intake valves but exhaust valves as well.

[This message has been edited by Syndicate (edited September 08, 2000).]
 

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What Syndicate says is basically right.

There is no Lexus with VVTL-i right now.

It basically emphasizes high redline and high RPM power which may not suit Lexus. Part of the way Lexus keeps engine noise very low on their cars is by not having a very high redline.

============

The new BMW M3 has a very high redline and will probably be much more noisy than any Lexus.



[This message has been edited by TEG (edited September 07, 2000).]
 

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Discussion Starter #5
Ok TEG, that makes sense. So Lexus probably does not employ a VVTi-L because it will increase the redline, making the engine sound harsher. However, I'm sure Lexus will eventually control the valve timing of the exhaust valves. Possibly with their L-sport models ...
Eric....
 

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well i don't see anything wrong with using lift control as most lexus drivers won't visit that range of rpm anyways =) well...for a car like the IS< i don't see why they wouldn't use it, i mean yes its a luxury car but its also the "sporty" one :p he he
 

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Someone please correct me if I am wrong, but I believe the Double VANOS system from BMW only adjust the valve timing but not the lift of the valve. I think this is what they stated in the brochure.
 

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This is how I understand this...VVTL-i is not used on any model of Toyota/Lexus in the US except for the Celica GT-S. VVTL-i controls both valve timing and lift. The variable lift portion is on/off, just like VTEC. The VVT-i portion, which is used on most current Toyota/Lexus models, is just variable valve timing, but is continuously variable, not just on/off at one RPM. BMW's Double Vanos is only variable valve timing, not lift, but is employed on both intake and exhaust. VVT-i is used on the intake only, except in the Altezza (JDM) where it is called BEAMS Double VVT-i (BEAMS = Breakthrough Engine Advanced Management System, or something along those lines). Altezza (forum member) told me that Dual VVT-i is the same thing as VVTL-i, but I respectfully disagree. The Toyota Japan website says the Celica has VVTL-i and the Altezza has Dual VVT-i, so I don't think it is the same thing. Anyway, using Dual VVT-i, the JDM Altezza achieves 210 HP (manual) and 200 HP (auto) from a 2.0L engine. The US Celica gets 180 HP from 1.8L, and the JDM Celica gets 190 HP (I think). Of course there are other variables to the power output like exhaust piping, etc. Apparently both Dual VVT-i and VVTL-i are capable of producing 100+ HP per liter, so I don't know why one or the other is used. Both are employed on the intake and exhaust, but it might have to do with the power distribution. The Celica has a huge power surge when it hits the x-over, below that point not much goes on. Since the Altezza with Dual VVT-i is JDM I haven't read to much about it's power distribution, but I think the DUAL VVT-i has a slight edge on torque.
 

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VVT-i only control "when" the valve open. The earlier it opens, the earlier it closes. This will help some performance, but not a whole lot.

VTEC is the control of the crank shalf which will enable the valve to "prolong" the valve opening timing. The difference between this and VVT and the problem of this system is that it can only achieve 2-3 stage of timing. Which means it's not constantly varying.

VVTL-i (not VVTi-L, thank you) is the combination of both technologies. It not only adjusts the valve timing continuously, but also controls the lift. So if Lexus would ever use VVTL-i (I am very hope so!!!) on the IS, we can not only enjoy the smoothness of the low RPM, but enjoy the "sudden" boost at the high RPM.

ps. BMW's Double VANOS controls timing on both intake and exhaust. Even though it's better than VVT-i, it still has the same disadvantage as VVT-i. In my opinion, VVTL-i is a better design.

[From TEG: VTEC does not control the "Crank Shalf (SIC)". VTEC uses seperate _CAM_ shaft lobes that take over when oil pressure hits a certain point. ]

[This message has been edited by TEG (edited September 08, 2000).]
 

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Hibboyscott,

Yes, I admit that I once thought the VVTL-i and Dual VVT-i were the same thing. But that was just when the Celica came out and I didn't have the chance to research it thoroughly. You have a good memory Hibboyscott

Its Dual VVT-i, by the way. (Gotcha!
)

As of now, Dual VVT-i is only used on the Altezza 4CYL. I wonder why. VVT-Li is now on the Celica and the JDM Corolla Wagon (Corolla Fielder). They use the same engine BTW.

Toyota usually put new technologies on higher end models and gradually standardize to their rest of their cars. (When they can make them more cheaper.) I guess in the next 5-10 years, all Toyota engines will have VVT-Li unless there's some problem with cost. (Or the introduction of the Fuel Cell car.)
 

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Discussion Starter #14
Originally posted by yamaot:
VVT-i only control "when" the valve open. The earlier it opens, the earlier it closes. This will help some performance, but not a whole lot.
Yamaot you say that VVT-i will help a little with performance but not a whole lot. Well the 4.0 liter engine inside the GS400 makes 300hp. That same 4.0 liter engine was used in the LS400 and in 1997 (WITHOUT VVT-i) made 260 hp. So with the use of VVT-i the horsepower jumped 40 horses and I think that VVT-i helped a lot in this case.
Eric....
 

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Hey Altezza, I only wrote "Double VVT-i" once (I think)! Hehehe. I think I went back and changed the others to "Dual VVT-i" although I wrote one as "DUAL VVT-i" and I have no idea why I capitalized all of dual. But you know what, it's "VVTL-i" not "VVT-Li" so gotcha back!
Hehehe.
 

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VVT-i and BEAMS are generally used to make the torque curve more flat. Rather than switching to radically timed cams that emphasize high RPM, Toyota has chosen to make the engine more flexible with good acceleration available even at low engine RPMs.

If you want to learn more about variable valve timing systems, go here: http://www.fortunecity.com/silverstone/lancia/58/technical_school/engine/vvt_1.htm

Note that the Celica 2ZZ-GE engine was co-developped with Yamaha engineering. Toyota probably cannot apply VVTL-i to any of their (other) engines unless they work out an arrangement with Yamaha.

2ZZ-GE info: http://www.corollaperformance.com/TechInfo/2ZZGE.html http://www.hinterland.com.au/November99/celicakit.htm#17

"High Lift, Long Duration: Toyota's variable valve lift system operates on the inlet and
exhaust valves. The Toyota 2ZZ-GE engine switches to the high-lift camshaft settings
at 6000rpm. The high-lift cam lobes increase intake lift by 54 percent to 11.2 mm and
exhaust lift by 38 percent to 10.0mm.

The high-lift cam profiles have the effect of increasing valve-opening duration, and
therefore the range of inlet timing variation.

Valve overlap can vary between 4 degrees (full-retard inlet setting and low-speed lift
settings) and 94 degrees (full advance inlet and high- speed lift settings).

A valve overlap of 94 degrees would normally be associated with full race engines.

For comparison, superseded Celica's 5S-FE engine had six degrees of valve overlap
and the sports two-litre 3S-GE engine in the first front-drive Celica model had 14
degrees of overlap.

Inlet camshaft timing is varied according to engine revolutions, throttle position, inlet
camshaft angle, engine coolant temperature and intake air volume.

Variable Timing Activation:

Toyota Celica's VVTi is a computer controlled and oil-pressure activated push-push
type system, using the engine oil.

The engine ECU can command the system to advance or retard the inlet camshaft
timing, thereby providing for faster response.

The hardware is a camshaft timing oil control valve (mounted adjacent to the inlet
camshaft gear wheel) and a VVTi controller mechanism built onto the inlet camshaft
timing gear.

The camshaft timing oil control valve is a spool valve, controlled via a coil and plunger
by the engine ECU.

It can signal advance, hold or retard.

The VVTi controller consists of a housing on the front of the timing wheel, driven from
the timing chain, and a four-bladed vane coupled with the intake camshaft.

When the engine ECU requires a change in inlet timing, it signals the oil control valve
to provide oil pressure to either the advance or retard side of the four vane chambers.

Inlet cam timing is set to the maximum retard position for engine start-up, operation at
low engine temperature, idle and engine shut-down.

A locking pin in the controller locks the camshaft timing in the maximum retard
position for engine start-up and immediately after start-up (until oil pressure is
established) to prevent any knocking noise.

Celica's VVTi system can vary inlet camshaft timing over a range of 43 degrees relative
to crankshaft angle.

However, the variable lift system has the effect of increasing valve opening duration, so
the full range of inlet timing variation is 68 degrees.

(Taken from the maximum retard intake valve opening in the low-medium engine speed
range at minus 10 degrees BTDC to the maximum advance intake valve opening in
high engine speed range at 58 degrees BTDC.)

Variable Lift Activation:

Toyota's intelligent variable valve lift system uses a cam change-over mechanism to
increase the
 

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Eric,

when I say VVT-i (valve timing) doesn't boost engine that much, I was comparing it to VTEC (cam lifting). But both has disadvantages. and it doesn't matter at this point. Since the best of both system has come together as VVTL-i, we should hope Toyota would put this technology into the IS300.
 
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