spdrcr771

iTrader: (21)

my question is does the 98+ GS400 have maybe different cams. cause tell me how that my buddy Rock-a-Lex is getting this. This is what he has & this was part of our conversation.

2000 Lexus GS400-RMM grille-TTE front lip & trunk lip-Lsportline sides & rear-debadged-TMs-K&N FIPK-S&S Headers-Apexi Neo-Borla-PI TC-3.76 LSD-B&M SuperCooler-Supra TT shafts-Bilstein PSS-19" Ace Forged AMF030-Bridgestone RE0760 sports-X/S rotors-Akebono ProACT ceramics-Clear side markers w/PIAA Extremes-'01+ headlights w/Koito 6400-'01+ tails-Rockford-Kenwood
Dyno: 2/2/08 - 267.1whp / 291wtq
Dyno: 4/11/09 - 281.8whp / 306wtq

The latest dyno of ~282whp and ~306wtq was with the addition of my headers and a re-tune of my Apexi Neo A/F controller. Keep in mind my car wasn't running right at that time and I went to a shop that has never dealt with tuning a Lexus V8. So, this is why I am going to get one last re-tune come Spring time at another dyno place not too far from me that has more experience with our cars.

I understand the NEO & the S&S headers but look @ the #'s b4 that.

Salil022

iTrader: (1)

235 is the horsepower at the rear wheels not at the crank...250 hp on a GS300 is at the crak

DaveGS4

iTrader: (2)

GS400 has the same cams and engine internals as 98+SC, but the intake and exhaust are different and was rated for 10hp more if I recall correctly. Most GS400's dyno stock between 230 and 250 rwhp.

Rock's GS is also a 'factory freak' one that has always dynod high, but his mods contribute with intake, headers and tuning.

spdrcr771

iTrader: (21)

Are you saying that even though the intake manifolds look the same that the internals in the intake are "bigger" or better flowing. Cause i just did the starter on my car and i got a good chance to check out the intake and i didnt relize that there are 8 small throttle bodies mounted on the roof of the intake that transfers the air to the cylinders.

what im sayin is that ,we both pretty much have the samething except for the headers & neo & TM plugs, which my plugs are proly **** but,i was expecting to be more around 245hp & 255tq, compaired to what i knew his #'s were @ w/what he has & what i have.

ScottURnot

iTrader: (33)

Got a picture of that? 8 small throttle bodies? I have never seen that on the older ones but I have never been in a 98+

spdrcr771

iTrader: (21)

sorry scott i didnt take a picture of it but yes there are 8 small throttle bodies in a single row that have a butterfly that is open and im not sure if it opens and closes for like bottom & top end like an exhaust valve. I just thought it went into a big chamber and then just made its way into the intake runners. if i get a chance it, ill put the throttle body of "real easy" and see if i can get a pic of it.

scfou

iTrader: (3)

I wouldn't be surprised to see 245-250rwhp if you tune it with a s-afc, especially after installing headers.

DaveGS4

iTrader: (2)

Yes The intake design and flow is different. I'm also not sure your SC has the little 'snorkle' that takes cold air in from the front of the car as part of the intake like the GS does

Need to also take into account that you dynod on a Mustang dyno which reads significantly lower than a dynojet in most cases. My old GS read about 20% lower on a Mustang vs Dynojet with the same mods.

spdrcr771

iTrader: (21)

no i dont have any snorkle, all stock intake gone. & i didnt know that about mustang dyno's ive only been on a dyno twice, once with my old 92 & now the first was a dynojet, so maybe that makes me feel better about my #'s

JBrady

OK, lets get this into the proper perspective.

Intake means two different things depending on the subject. There is the intake tract including the air filter and housing to the throttle body and there is the ACTUAL intake which is the cast aluminum structure that the throttle body bolts to and that directs the air to each of the 8 intake ports.

Most times when someone states "intake" they speak to the variety of air filter to TB options. NOBODY that I am aware of offers a bolt in intake that replaces the factory aluminum throttle body to intake port INTAKE manifold.

The factory intake manifold is the SAME for all 1998-00 engines and looks to be identical on 2001+ engines. This intake is VERY good. It has long runners for low speed torque and has the mentioned internal throttle bodies that open and effectively shorten the runners at (IIRC) 4400+rpm.

The BIG difference in the SC400 are the the exhaust manifolds. On the GS and LS there are tri -Y manifolds that flow better than previous designs. The SC uses the previous single log manifold. IMO for model years 1998-00 the GS400 is accurately rated at 300hp, the LS400 has a VERY similar exhaust manifolds but a more restrictive exhaust after that and is accurate at its 290hp rating, the SC400 has the very restrictive exhaust manifolds and the more restrictive exhaust after that for a more probable 280hp even though rated at 290hp.

So, the GS400 starts with a 20hp advantage IMO.

Tuning which leans the fuel mixture is a big advantage.

Headers are a big advantage on the GS but a bigger advantage on the SC.

There is definitely a variance between dynos of the SAME design and a bigger variance between dynos of a different design.

My advice is get some solid actual performance numbers from a GTech, I-phone ap or track test. Make sure to record the air temp AND the air pressure (barometric pressure). If you can run low 14s or better it doesn't matter what any given dyno records...

spdrcr771

iTrader: (21)

Thanks very much for your response, you tought me a few things, makin me feel even better about my SC#'s

wonder if the GS exhaust manifolds are swappable if you wanted to go a cheeper route to the S&S tri Y headers, not that i would but someone else might.