planetommy

What are the main Engine differences between 2002 and 2003 LX 470. The Super chargers have different list numbers? Is it fuel? Exhaust?

aedgington

i believe engines are the same, but the transmission went from 4 to 5.

toyotafan2

Steering ratio changed a bit too. Fuel ratings were unchanged, though car was more aerodynamic now with variable gear-ratio power assisted rack and pinion steering now standard. VVT-i was not implemented until the 2006 model, increasing overall fuel ratings 3%, allowing to switch to 4-cylinder mode while coasting on highway. Also increased power and torque ratings from 235 to 275 horsepower and 320 to 332 pound-feet of torque.

Jayson

I still cannot understand why Lexus waited until 2006 to introduce VVT-i in the LX, yet put it in the 2005 GX.

toyotafan2

GX is thousands of dollars less than LX. Plus, it was much easier to do that since GX is built off of 4Runner. 4Runner had VVT-i in the 4.7 Liter V8 Engine implemented into it in 2004, much easier for transition to Lexus model. Land Cruiser did not have the engine till 2006, would have made no sense for LX to get it first. Production, transition, and maintenance costs would have made sticker price higher than what marketing agents wanted. Had to wait till 5-speed auto tranny was in before they played around with electronic components within the engine. 4-speed auto would not have handled the newly added power and torque so well, 5-speed first, then the engine fine-tuning and upgrade.

lexusls430

The LX doesnt have cylinder deactivation.

toyotafan2

Uh hello, what do you think VVT-i stands for??? Variable valve timing, with intelegence, aka Displacement on Demand as GM calls it. Swtiches to 4 cylinders at highway speeds, learn the parts of the engine before saying what you don't know.

BobsGX

Not for nothing bud, but you are the one who is wrong. Toyota/Lexus has no such thing as cylinder deactivation on their V8, V6 or 4 cylinder engines. In the future, they will probably adopt this feature.

Gohawks63

WRONG. and you got belligerant about it too. You need some education.


VVT-I and V-TEC (Honda) adjust valve timing, not cylinder deactivation or displacement on demand.

The cames have two sets of lobes, one set more fuel efficent for low-rpm driving. The other lobes have a more aggressive profile for higher-rpm speeds. When you accelerate past a certain rpm, an actuator engages the more aggressive cam profile which causes the valves to open wider producing more power.

The fuel efficiency is only because you don't have to trade-off having an aggressive cam. You have the best of both worlds. Fuel efficient timing for sedate driving, and a more aggressive personality when you mash the accelerator.

Gohawks63

Unfortunately the Toyota site didn't have an explanation. This is what I found on the Lexus site.

VVT-i continually optimizes intake valve timing over a broad range of engine speeds. It increases torque at lower speeds and horsepower at higher speeds to improve engine performance and fuel economy, as well as help reduce emissions.

I also found this on How Stuff Works

http://auto.howstuffworks.com/camshaft.htm

Here is an excerpt....

Variable Valve Timing
There are a couple of novel ways by which carmakers vary the valve timing. One system used on some Honda engines is called VTEC.

VTEC (Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system in some Honda engines that allows the engine to have multiple camshafts. VTEC engines have an extra intake cam with its own rocker, which follows this cam. The profile on this cam keeps the intake valve open longer than the other cam profile. At low engine speeds, this rocker is not connected to any valves. At high engine speeds, a piston locks the extra rocker to the two rockers that control the two intake valves.

Some cars use a device that can advance the valve timing. This does not keep the valves open longer; instead, it opens them later and closes them later. This is done by rotating the camshaft ahead a few degrees. If the intake valves normally open at 10 degrees before top dead center (TDC) and close at 190 degrees after TDC, the total duration is 200 degrees. The opening and closing times can be shifted using a mechanism that rotates the cam ahead a little as it spins. So the valve might open at 10 degrees after TDC and close at 210 degrees after TDC. Closing the valve 20 degrees later is good, but it would be better to be able to increase the duration that the intake valve is open.

Ferrari has a really neat way of doing this. The camshafts on some Ferrari engines are cut with a three-dimensional profile that varies along the length of the cam lobe. At one end of the cam lobe is the least aggressive cam profile, and at the other end is the most aggressive. The shape of the cam smoothly blends these two profiles together. A mechanism can slide the whole camshaft laterally so that the valve engages different parts of the cam. The shaft still spins just like a regular camshaft -- but by gradually sliding the camshaft laterally as the engine speed and load increase, the valve timing can be optimized.

Several engine manufacturers are experimenting with systems that would allow infinite variability in valve timing. For example, imagine that each valve had a solenoid on it that could open and close the valve using computer control rather than relying on a camshaft. With this type of system, you would get maximum engine performance at every RPM. Something to look forward to in the future...

lexusls430

Thanks for the back up guys. Toyotafan VVT-i doesnt have anything to do with cylinders. It just controls the valves.

V8_Fan

The 2UZ V8 does not shut down cylinders, as other responders have mentioned. In 03, engine output was increased by 10hp, I think (JDM LC magazine says "engine response" increased). Probably all from a new engine chip associated w/ the 5 spd auto. That's probably why there are two different S/C part numbers for the V8.