97-00 SC400 Exhaust Manifolds

[LexStarr]

Does anyone know if the exhaust manifolds on the 97-00 SC400 are bigger than the 92-96 manifolds? I was underneath a 97 SC400 that had its cats pulled off the other day and noticed that the manifolds look a lot bigger and more open than the ones on my 93. It could just be my imagination but I figured I'd ask.

 

[stevechumo]

I'd guess it should be bigger, because of the VVTI heads that are bigger than non-VVTI heads. Also, the newer year models have more power, so the exhaust should be bigger. If you can post the picture of your exhaust, then I can probably tell if they're bigger or not.

 

[JBrady]

Actually I believe they are nearly the same with the exception of the flange being larger to mate to the newer catalyst flange size and the absence of an EGR port flange.

They are shorter than the GS4xx manifolds which are shorter than the LS400 VVTi manifolds.

This is IMO one of the reasons the VVTi SC400s do not seem to out perform the VVTi LS400s even though both have the same power rating, 290hp/300tq, and the SC weighing less. The LS400 and GS400 have the better try-Y style manifold with the SC retaining the log style. All 2001+ xUZ-FE engines went back to the log style for faster catalyst lightoff.

Below are some pics of the GS400 manifolds vs the early SC400 design

 

[spf_lexus]

The stock GS and LS tri-y design could be heaps better if the second runner did not merge at a 90 degree angle. worlds better than the sc's sorry excuse for a header though.