corradoMR2

***CORRECTION: As confirmed from Lexus, the below engine enhancements are false. The 2IS 2.5L V6 is 100% carryover to the 3IS. Transmission however has the enhancements as stated***

Found this interesting post on my.IS which I didn't find in this forum. It describes the carryover engines and transmissions have actually had some improvements and therefore not technically a 100% carryover over the 2IS. Similar changes to the engine are described for the 3.5L V6.

"There are, however, a number of IS 250 powertrain tweaks and improvements. The engine receives spark plugs repositioned nearly to the center of the combustion chamber (to enhance anti-knocking and optimize combustion); enlarged-diameter intake and exhaust valves; the use of an aluminum die-cast cylinder block (as a weight reduction measure), revised low temperature target idle speed in D range (to enhance fuel economy) and, most notably, a roller rocker arm is adopted for the valve mechanism, which reduces friction losses and enhances fuel economy. In addition, IS 250 F Sport models feature an intake sound generator that employs a resin damper in the air cleaner hose to amplify the sound pressure level of certain frequencies during mid-to-high RPM acceleration."

"...the A960E 6-speed automatic transmission incorporates numerous technologies including faster shift speeds, earlier torque converter lock-up and downshift throttle blips, upgrades that were previously applied to the A960E's other major application in the Scion FR-S / Toyota GT 86 / Subaru BRZ sports coupes. Also, the 2nd-gen IS 250 automatic's switchable ECT Power, Normal and Snow driving modes have morphed into a 4th-gen Lexus GS-like rotary Drive Mode Select switch with ECO, Normal and Sport modes (a separate Snow button remains). ECO reduces throttle response and modifies air conditioning operation to reduce engine loads, all in the name of increased fuel economy, while Sport mode increases throttle response and firms up the Electric Power Steering."

Interesting to point out the "revised" 6-speed in the IS250 is the same transmission in the sporty and renowned FR-S / BRZ /FT-86

AndyL

CorradoMR2,


That is a good find.

When I did the test drive with the IS250 AWD regular version, I did notice the transmission is better than the 2nd gen. Besides, in my test drive with Scion FR-S (aka FT-86) last year, i found the 6-speed was very quick to shift. In fact, my friend who also did the test drive commented how impressed he was with the auto transmission. He also had the test drive with the manual version of the FR-S right afterwards. So it was a candid comment about the 6-speed auto.

natnut

Nice find!

Are there similar enhancements to the 350 engine/drivetrain as well? Could you share the link where you found all these technical information?

Jeff Lange

iTrader: (1)

The 6-speed tranny shifting is definitely nicer. I am not sure on all those other changes though, but cannot confirm on my phone.

Jeff

UpSideDown

The tranny shifts much smoother. Despite the other changes on the engine, the new 250 has a little bit higher fuel consumtion and Co2 compares to the latest 2IS 250.

2IS 250:
8,4L/100Km
Co2 194 g/Km

3IS 250:
8,6/100Km F-sport: 9,2L/100Km
Co2 199 g/Km F-sport: 213 g/Km

corradoMR2

Here you go:

http://my.is/forums/f41/3rd-gen-lexu...trains-459322/

AndyL

Thanks for the link. Somehow I could find it on my.is and now I know why. It was back in April. There are just so many aspects of a brand new car.

Learned something new today. I wasn't aware the 8-speed in 3IS is actually different than the one in IS-F as I saw identical values from 1st to 8th gear. Forgot the G-AI feature in 3IS.

Used to read & participate in posts as often as in here. Somehow their 3gen discussion forum has been quiet.

SecPole14

Do these changes apply to the GS's 3.5L and 6-speed auto?

Jeff Lange

iTrader: (1)

I just had a chance to double check and can confirm that there are zero changes to the IS250's engine from the 2IS. It is exactly the same in every way. Literally zero changes internally. Externally there are a few changes like the intake pipe and the plastic cover.

I don't know who wrote that article or where the information came from, but it is not true.

Jeff

mrraider

Start scrubbing the deposits.

corradoMR2

I found another article describing similar internal engine improvements as posted in my.is:

http://www.autoweek.com/article/2013...iews/130329882

"The powertrain is largely carryover with improvements throughout. Engine castings are lighter, valve size has increased slightly and spark plugs have been moved to the center of the combustion chamber. Specific fuel consumption improves, though output remains the same: 204 horsepower, 185 lb-ft for 2.5-liter V6 in the IS 250; 306 hp, 277 lb-ft in the 3.5-liter IS 350."

Hoovey689

iTrader: (16)

The transmission improvements I reported months ago, that we knew. As for the 250 engine, if they were smart they'd have added port injection and help against the carbon build up issue. As it stands and so they say, Toyota didn't want to go through emission regulations with the engine again. Makes sense though since the 250s days are numbered anyway

Jeff Lange

iTrader: (1)

It's probably something someone misheard and has been repeating in various articles.

The part numbers for everything (including the entire engine assembly) have stayed the same from 2IS to 3IS. No casting changes, no valve size changes, no spark plug movement. Nothing changed.

Jeff

jdmSW20

iTrader: (12)

i wouldve thought the same thing with them adding port injection to fight the build up issue but i also heard the same thing, that the 4GR days were numbered

RXSF

hmm, and yet EPA numbers for 2013 vs 2014 didnt change