GS400 Vs. GS430

[Lextreme II]

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[JBrady]

Thanks to you I have studied this and like documents previously.
Notice in addition to the changes listed that the 1UZ piston has more material in the piston deck, edges and around the pin boss. I am surprised that the ring pack is tighter on the 1UZ vs. the 3UZ as that area looks beefier on the 1UZ. Also the piston pin hole location looks to be farther from the deck on the 1 vs the 3 assuming these are correct scale engineering drawings.

Another interesting observation is the change in camshaft VVTi timing between the 1 and 3. Earliest opening and closing of the intake valve is 5 degrees less in the 3. All else would indicate identical camshafts. Cam lift would be nice to have factory documented. Reports from the field indicate just over .300” lift on the pre VVTi engines and .350” on the 1998 and later VVTi engines.

All else equal a bigger bore creates higher compression and since the 3UZ has the same compression ratio as the 1UZ but the 3 has a smaller combustion chamber the net dish volume in the 3 must have enlarged although not apparent in the pictures. Certainly some of this would have come from the elimination of the thrust squish/qwench areas.

A clear error on the drawings can be seen in the dyno chart. It shows the 3 with more low end torque than the 1 but at the same time showing the 1 with more low end power than the 3. This is obviously impossible as is showing the 3 with more peak power even though they are both rated at 300hp. The torque curves look accurate but the power curves are skewed. This of course draws to question the rest of the image accuracy.

 

[JBrady]

A clear error on the drawings can be seen in the dyno chart. It shows the 3 with more low end torque than the 1 but at the same time showing the 1 with more low end power than the 3. This is obviously impossible as is showing the 3 with more peak power even though they are both rated at 300hp. The torque curves look accurate but the power curves are skewed. This of course draws to question the rest of the image accuracy.

Looking closely I think what has happened is Lexus moved the 1UZ power curve to the left and down to hide the fact that the 1UZ makes more power above 5800rpm than the 3UZ. If you slide the power line to the right and up to line up the peak power of 300 with 6000rpm you will have a better idea of the engines comparative power outputs. The bigger 3 has better low and mid power but the 1 has better high end power. I credit this to the return of the single tube exhaust manifolds. Solution: headers!

 

[Lextreme II]

Major Differences

The major differences between the 3UZ-FE on the ’01 GS430 and the 1UZ-FE engine on the ’00 GS400
are the following:

Engine Proper
• The water passage of the cylinder head has been changed to improve
the flow of the water around the valve seats, thus reducing
the temperature of the combustion chamber.
• The cylinder bore has been increased in size, and the thickness of
the liner has been reduced.
• The shape of the cylinder head gasket has been changed in conjunction
with the increase in the size of the cylinder bore.
• The material of the cylinder head bolts have been changed to increase
their axial tension. As a result, the head gasket’s tightening
has been improved.
• The piston diameter has been increased in size, and its shape has
been optimized to achieve weight reduction.
• The material of the inner surface of the bushing in the small end
of the connecting rod has been changed from lead bronze alloy to
phosphor bronze alloy.
• The material of the sliding surface of the crankshaft bearing has
been changed from kelmet to aluminum alloy.

Cooling System
The shape of the water inlet housing has been optimized to increase
the water flow and to achieve weight reduction.

Intake and Exhaust System
• A resonator and a tuning hole have been provided in the air cleaner
inlet to reduce the amount of intake air noise.
• The air cleaner case has been increased in size to reduce the
amount of intake air sound, and the construction of the air cleaner
element has been optimized to achieve weight reduction.
• A plug-in type air flow meter with a plastic housing has been
adopted for weight reduction.
• A stainless steel exhaust manifold with a single-pipe construction
has been adopted. As a result, the warm-up performance of the
TWC (Three-way Catalytic Converter) has been improved.
• Two TWCs (Three-way Catalytic Converters) have been provided
in the front, and one in the center.
• Ultra thin-wall, high-cell ceramic type TWCs have

Ignition System
The construction of the ignition coil has been
compact and lightweight configuration.

Engine Control System
• Torque activated power train control has been newly adopted for
the control of ETCS-i. Also, the fail-safe control has been reconsidered
with the adoption of the link-less type throttle body.
• A fuel cut control is adopted to stop the fuel pump when SRS driver’s
and front passenger’s airbags are deployed.

 

[EyesofThunder]

Any chance these original pictures are still around?

Here is something interesting. Check it out....