JBrady

Here is one of the better first gen NA SC400 power gains and this is WITHOUT headers.

https://www.clublexus.com/forums/sho...highlight=safc

211rwhp/231rwtq = 270hp/ 296tq

Now, new member jibbby had NA dyno numbers from TMEngineering of 220rwhp and that is 282hp.

Both of these had improved exhaust, inlet and ECU tuning.

JBrady

Not currently available but IMO the BEST possible NA mod for a street driven engine is the VVA system from http://www.pattakon.com/vvar/HelpRoll.htm

With such a system you can maximize the torque curve from very low to very high RPM. I am in discussion with Manolis regarding an application for the LSx engines. Due to the design of the xUZFE it will require at the very least a change in the cam design to allow the mechanism room between the cam and valves.

With VVA we could see near maximum torque from low rpm road driving to high rpm maximum power production. With optimized everything we are probably looking at a maximum of 350 pound feet of torque or 473Nm for our international friends.

Let's look at what 350tq can give us as we increase the engine operating speed. Remember with VVA you can maintain peak torque to very high rpm.

350tq @ 6000rpm = 400hp = 312rwhp

350tq @ 6500rpm = 433hp = 338rwhp

350tq @ 7000rpm = 467hp = 364rwhp

350tq @ 7500rpm = 500hp = 390rwhp

350tq @ 8000rpm = 533hp = 416rwhp

350tq @ 8500rpm = 566hp = 442rwhp

350tq @ 9000rpm = 600hp = 468rwhp

This is of course in theory but IMO very possible. It would take optimized intake and exhaust porting of the heads, ITB (actually with VVA you do not even need the throttles), and of course and extremely good flowing exhaust system.

I believe the block and crank would have no problem with this. You would want very good pistons and rods. Premium forged pistons and titanium rods would be my choice but good forged rods can handle these RPM.

Even with a completely stock short block the above numbers up to 8000rpm should be very realistic.

Dropping the torque to the GS400 numbers give us the following:

310tq @ 8000rpm = 472hp = 368rwhp

This I believe is probably the best case scenario for stock block non exotic xUZFE engine in stock street driven applications with stock like drivetrains.

jgscott

iTrader: (1)

John great info. I just posted in another thread that I felt 8000RPM's with engine changes could produce 500 + RWHP. The link is very interesting, I love links like that. I think that would work. Lets not foget a titanium and lightened Valve train that would live above 7500 RPM. Springs Valve etc.
I want to know what happens and if this develops I want to know. I have another engine. If you need actual parts specs or measurements let me know.

xirforever

Do all of these year engines have the same internals? Like does the 98+ in the SC400 (or any 1uz with VVT-I have weaker rods? Any other differences besides HP? yes i know thread says hp facts, but why not more...

JBrady

1995 LS400 1996 SC400, compression raised from 10-1 to 10.4-1, engines become interference with valves and pistons should timing belt fail, slightly longer duration exhaust cam timing, dual tube exhaust manifolds on the LS400s, minor mods to air cleaner system and exhaust system.

1998-2000 all, compression increased to 10.5-1, vvti cam timing with higher lift, different heads with different intake manifolds with straighter ports, weaker lighter rods, different MAF sensor type, variable runner lenght intake manifold with front mounted throttle body, no EGR plumbing (done with vvti) coil on plug ignition, throttle by wire.

xirforever

once again jbrady to the rescue! haha thanks for the great info as usual, one last question, on the 10.4:1 1uz's, is the short block the same as the 10:1 's? Like they didnt change the wall thickness at all between these two "tweeked" motors did they?

SCV8

I would tend to believe the 230hp also; my stock '92 SC4 was about as slow as you'd expect those numbers to provide.

SC400-V8

iTrader: (1)

Ive given this some thought... I have doubts that modding a lexus V8 to the point where it starts putting down some serious power might compromise the nice feel that it has. Like, it just wouldnt feel smooth and lexus-like any longer. Thats more important to me, but probably not to you.

xirforever

Thats all relative , but you realize that
some poeple like the nice feel of a very powerful motor all day and every day

SC400-V8

iTrader: (1)

Ive read this before and I realize what your saying, but if there was more than 10 hp difference for these cars and its actually about 30... then the 96-97 SC400s with 260 hp should be doing 0-60 faster than the quoted 6.8 seconds. The 92s do it in 6.9 seconds. All things equal, the 96s should be able to do it in 6.5 or so.

ISC400

Just for reference purposes I’d dyno'd my sc400 today at DSR in San Jose, the results where 202.0 HP and 220.7 TQ[U]. My SC has 195k miles I just gave it tune-up and switched the fully-synthetic 10w-30w oil 3 weeks ago. Only performance mod I have is BFI right now because I’ve spent allot of money on TT AGX's/TT eibach/ Yokohama tires/Strut bar. MY future plans are Full exhaust, SAFC, and daizen sways.

AME_VIP

iTrader: (2)

Nice !! What kind of dyno was that?

I forgot about this quality thread! Glad to see it back.

My latest mods/dyno #'s

92 SC400
Cut out intake box with K&N drop in
Walbro 255lph pump
SAFCII + dyno tuning
190 whp on dynodynamics

All of the above plus:
Nitrous Express wet kit, 150 hp jets
Zex bottle warmer, NX gauge, NX tps switch, B&M fuel pressure gauge
297 whp

ISC400

Thanks, it was a Dynojet 248H dynamometer. and by the way what kind of performance are you getting out of the Walbro fuel pump? Or is it just for your nitrous setup.

AME_VIP

iTrader: (2)

you are right sir. It doesn't add any horsepower gain. It is just for piece of mind with the nitrous.

Elliott17

Hey, do you know the vin on this car, i think i might own it now?