What changes did Lexus make to the 98-00 GS engine to come up with 4.3L in the GS/LS/SC430? Also, what changes were made to the trans to deal with the extra torque? Thanks

 

u get a little useless torque for the cost of the Tip-tronic tranny in return for that 0.3L of displacement.

Does that sum it up?

 

Actually, it was gain of 15 pounds of torque along with ULEV status...no tiptronic cuz of the ULEV...but that's ok cuz you can gateshift. It doesn't take a rocket scientist to gateshift...

Which engine would I have if I had a choice? Please, I'll take the 4.3L 3UZ-FE.

 

The LS430's 3UZ-FE engine is the evolution of the 1UZ-FE light alloy, quad-camshaft, 32-valve V8, with a bore increase from 87.5 to 91 mm (3.44 to 3.58 in) to obtain 4.292 L. The engine adopts the VVT-i continuously variable timing system on the intake camshaft for a 45° variance in intake valve operation (vs. 50° in the 1UZ-FE). Compression ratio is unchanged at 10.5:1. The engine designers' aim was increased low- and mid-speed torque, which is about 10% greater in the usable up-to-4000-rpm range. The 3UZ-FE is rated at 206 kW (280 hp) at 5600 rpm, in deference to the Japanese industry's voluntary constraint of maximum advertised power, and peak torque is 430 N*m (317 lb*ft) at 3400 rpm. The U.S. LS430 is not governed by this restraint, so a truer 216 kW (290 hp) at the same engine speed is quoted.


Light alloy components figure prominently in the Celsior's front suspension design.
The Celsior is one of two cars that qualify for Japan's stringent SULEV standards (the other car is the Nissan Bluebird Sylphy, whose 1.8-L inline four-cylinder engine is an adaptation of the U.S. SULEV Sentra unit). The Lexus LS430 meets the U.S. ULEV and European Stage 4 rules. The exhaust cleansing system employs two-stage catalytic converters. The manifold converter for each bank of cylinders is Toyota's new ceramic monolith type with 140 cells/cm2 (900 cells/in2) - one of the densest substrates in automotive application. The monolith's wall thickness is only 0.05 mm (0.002 in). Each manifold converter has a 0.87-L (53-in3) volume, its monolith coated with platinum, rhodium, and palladium active substances. A 1.01-L (62-in3) platinum/rhodium underfloor catalyst is combined in the system.

An interesting departure from the first- and second-generation Japanese Celsior powerplant practice is seen in the cooling system. Toyota's designers adopted a hydraulic motor to drive the single cooling fan whose switching action was accompanied with hardly a swish of fluid. However, for the LS400 a conventional twin-electric fan system was used. For the new Celsior/LS430, they adopted the twin-electric fan system across the board now that the whole power unit is housed within a well-insulated compartment.


The LS430 in a 64-km/h 40% offset crash.
The transmission is the latest refinement of Toyota's rear-drive A650E 5 Super ECT (five speeds, electronically controlled transmission). The artificial intelligence control extends the grade logic to downshift from 4th to 3rd on steep downhills as well as adapting gear ratios to frequent changes of direction as on a twisty mountain road. The engine and transmission are now centrally managed by two 32-bit ECUs vs. the LS400's two 16-bit system.

 

When I commented on the transmission in my 01 shifting up to soon and down to late compared to my 98, the head tech at my dealer said the software was changed to give the same epa figures as for the 400. And that is why the e-shift is gone.

 

Japanimal, good data, where did you find this, I would like to review it further.

 

Anyone know if Lexus changed the transmissions in the GS from 98 to 03? I recently had my tranny replaced any there was a different model number written on the repair order. Just wondering if they had changed something slight on the design.

 

n/t