Undercar pictures of LS400 exhaust

[JBrady]

The LS400 exhaust system was very similar in all years.

Restrictive exhaust manifolds.

Good to very good catalysts bolted to the manifolds.

1.97"/50mm duals into 2.36"/60mm single Y pipe with very effective design.

Most models have a resonator in the single middle pipe that is slightly smaller internally than the 60mm pipe feeding it.

Some cars (California emmissions 1990-1994) had a center side in side out catalyst instead of a resonator for a total of 3 catalysts.

60mm to dual 45mm Y pipe feeding strange side CASE inlet center outlet mid body mufflers. These mufflers are more than enough by themselves to reduce noise to the level of many other stock vehicles.

45mm pipe leading to dual large canister reverse flow mufflers.

Here is the original 1990 system with chrome for looks.

 

[JBrady]

Here is the California model exhaust Y pipe with a center catalyst in addition to the dual manifold mounted catalysts.

You can also see the formed metal turns from the catalyst outlet to the round tube 50mm pipe leading to the center cat. This is also the same on systems using a center resonator.

 

[JBrady]

On the 95-00 models some minor changes were made to the basic design. After the cat flanges instead of 2 bolt flanges Lexus changed to a band clamp design.

The system received more heat shielding on the primary pipes but the size remained 50mm.

While appearing complicated and restrictive this system flows pretty well and supported the 290hp/300tq rating of the 98-00 models.

Instead of the formed metal cat outlet turns the 95-00 system uses very strange "slash" cut sections that use 60mm pipe from the cat flange/slash/60mm that then necks down to 50mm where the oxy sensor is located. Also on this section are harmonic dampeners to reduce noise and vibration. Not sure if the slash cut caused the noise that the dampeners surpress or if they are simply more refinement.

Here is a complete 1995-2000 system.

 

[JBrady]

98-00 models also got the better metal substrate catalysts. These appear more round than the previous flat ceramic core design.

You can see the core design and the light passing through.

These cats are VERY high flow. Higher than most aftermarket HI flow offerings. They will not restict peak power and removing them will definitely reduce low end power.

 

[JBrady]

Look carefully at this center pipe to resonator section. The main pipe is 60mm = 2.36". Just before and just after the resonator the pipe squeezes down to about 55mm. This reduces noise and is part of the 10hp less that the LS400 is rated vs the GS400. The GS400 maintains the 60mm pipe right through its smaller length resonator.

FYI even though the SC400 is rated the same 290hp I believe it is more like 280hp since it has even more problems notabley the very poor manifolds.

 

[spf_lexus]

good reference material. any literature/specs on the LS460 exhaust? its supposed to support 380 or so right?

 

[JBrady]

good reference material. any literature/specs on the LS460 exhaust? its supposed to support 380 or so right?

It is very different. Dual 60mm or so it looks with dual 2nd cats. Has a termination type H pipe and very long resonators.

Here is a pic. The final mufflers shown are aftermarket and smaller than the stockers as can be seen by the available area of the heat sheilds.

 

[JBrady]

moved question from richonenz to its own thread titled modified LS400 exhaust drone