hey guys,
I was just wondering, what make the Gs400 engine make 300 horsepower, but the other 1UZ-FE's (98+) make only 290 horsepower ? Is it the intake,exhaust,etc. thanks.

 

Exhaust and some ECM programming. The same goes to the GS430 with bigger bore, but still has 300 hp and 15 more tourques than the GS400. I'm sure Lexus can tune those cars to be faster, but the emission level will be much higher.
To make the GS430 certified as an Ultra Low Emission Level(ULEV), they'd try really hard by take away the E-Shift and reprogrammed the ECM to meet the ULEV. Lexus is environmental friendly company and they rather make the car slower, but cleaner.

 

That cleared a lot of things up for me, thanks
one more thing, you may think I'm dumb for asking this but can the gs400 ecu be transplanted into a 98 sc400?
btw, love your car!

 

It is already done for you.
98-2000 SC400s and GS400s are using the same engine. I believe the difference in HPs is the exhaust system that is chocked more on SC.

 

This is correct. The SC and LS have the SAME engine and ECU programming as the GS. The difference is exhaust. The SC and LS neck down to a 50mm center resonator and then have silencers after the resonator. The GS has a 60mm center resonator and uses 2 more "glass pack" type straight through resonators prior to the final mufflers. The GS also has a much better splitter into duals than either the SC or LS.

As far as power goes, the 430 engined cars make their power at a lower peak RPM. They have MORE torque EVERYWHERE in the power band up to peak power and then are nearly identical to the 400 engined cars. This make them FASTER than the 400s up to peak power.