jurutera

Just to share a myth/fact that ive heard ever since i drove a car.

Is it true that wenever u choose to WOT, u have to switch off the a.c first to avoid the compressor from being damaged. With my older cars, wenever i switch the a.c after i drive, the compressor screeches. But never had this experience with the Lex. I do know for a fact that it robs HP wenever u switch on the a.c but then again i dont know wat advances are made regarding a.c in cars.

Anyone can enlighten me over this coz the price of one compressor is unbelievable for the IS.

Bichon

The A/C compressor in the IS is a variable displacement design. It uses some clever engineering that increases or decreases the piston's stroke on-the-fly. By changing the displacement, it is able to vary both cooling capacity and engine load from full capacity to near zero. Under heavy engine load such as WOT, the computer simply reduces the displacement of the compressor to reduce parasitic load on the engine -- no need to switch it off.

Incidentally, the variable displacement design is why you don't hear the compressor cycle on and off, and why leaving it on has a minimal effect on fuel mileage during mild weather.

Koz

Great info, Thanks.

Koz

CRB

When one of the car magazine (R&T?) tested the IS350 on a scorching S. CA day they noted that the A.C. doesn't make very much cold air at WOT. Which jibes with what Bichon said. And all that wonderful technology undoubtedly makes the compressor more expensive.

Brian231

I remember my buddy telling me that his 1994 Supra has a OEM feature that shuts off the compressor while you are nailing it or Wide Open Throttle. It then engages back when the computer senses a lower RMP. Not sure if the gen 1 IS has this for the OP. I never noticed it on the gen 1 in my 4 years of ownership, but then again, it was not the turbo (2JZGTE) but rather (2JZGE).

jurutera

Ahhh the wonders of engineering. Great info now i dont have to worry about switching it off again. At least the price is now justified and i dont have to worry wenever i floor it. I guess the sweat from the hot afternoons really didnt improve my mileage LOL.

Thanx for the info.

Bichon

The original poster has a 2IS. The IS300 is a current model in his country (Brunei): http://www.lexus.com.bn/lexus_cars/i...s300/index.asp

Brian231

Wow, I had no idea they offered the 2gen in the 300. I could not locate that via the website? I wonder why Lexus released it that way? I only knew of the 220d, 250 and 350. See, you learn something new every day. Kind of a dissapointment in HP though for a larger displacement. Thanks for the post.

Type 3.0 liter V6 Four Cam 24-Valve (3GR-FE)
Piston Displacement 2995
Maximum Output (kW/rpm) 170(228bhp)/6400
Bore x Stroke (mm) 86x86
Maximum Torque (Nm/rpm) 300Nm/4800rpm
Fuel System Electroninc Fuel Injection

Bichon

The reason the power bump is unimpressive relative to the IS250 available here is because the engine in the 2nd gen IS300 has port fuel injection instead of direct injection. (At least the folks in Brunei won't be complaining about the loud ticking at idle. ) That same engine, equipped with direct injection, put out 245 horsepower when it was offered in the '06 GS300.

As for why they released it that way, I believe it's because the fuel quality in China, Brunei, the Middle East and other markets where the car is sold is inadequate for direct injection.

jurutera

Yup we have the 300. The reason given was exactly that. Kind of a blessing and a curse. Blessing because it is a TINY bit more powerful(and yes, no loud ticking) than the 250 and a curse because i dont believe anyone wud want to develop performance parts for the 300. But still a good car and faster than any 1.6 liter engine(stock anyways) hehehe

GSteg

iTrader: (15)

My GS400 does this too. It A/C shuts off when you're at WOT. I dont really feel any power lag anyways.

Koz

The 250 should not tick loud because it doesn't have direct injection.

Koz

Brian231

Yes, it does make perfect sense with fuel standards in other countries and the necessity to develop engines and fuel systems that are compatible. I did share the link with some good friends who are car buffs and they thought it was interesting to have the 2gen IS300.

Bichon

You are mistaken. The IS250 does have direct injection. It has a 4GR-FSE engine, where the "SE" suffix means direct injection. (And a forum search for "ticking noise" will turn up dozens of posts from IS250 owners concerned about the sound of their injectors)

suorum

Nice info here!!!! Thanks to everybody