shiflet96

I recently bought a 1999 LS400 in really nice shape with the intention of building the engine, as I'm currently taking classes for my ASE certification and would like to get some practice outside of school.
So to get the biggest question out of the way, what kind of power can the stock block and transmission take? I would love to make around 400whp, but I'm not entirely sure if the engine can make that much. I have seen supercharger kits, but I'm also not entirely sure what supporting modifications need to be made. Keep in mind that this is my first build, so I'm not the most knowledgeable and I'm also just wanting straight line performance, regardless of the handling. I have eventual plans to swap the engine into a first gen Celica if I can ever find one in decent condition, to basically make a Japanese muscle car.

It wouldn't really feel right not to post pics, so here ya go
https://imgur.com/gallery/gQ9z8vI?nid=828027582

RA40

iTrader: (6)

Welcome to Club Lexus and congrats on the LS.

The stock engine management is the limiting factor with it being locked by Toyota. Aftermarket units are the choice and with your intended goal of swapping it into a first gen Celica your options are open. The guys down under in Australia and NZ have plenty of discussions on their forums regarding Celica mods. I haven't read through lately but it is accessible.

For the first gen there are suspension parts from this site:
https://technotoytuning.com/toyota/ta22

YODAONE

Since your LS400 is in really nice shape, then consider using an engine from a wrecked LS400 for your Celica project.

Extrude honing the intake manifold and, thermal management yield results.

Check on this forum using those keywords.

400fanboy

This guy supercharged his 1UZ


So it's possible. Beyond that I have no idea, so I wish you the best of luck.

peterls

That car is too nice to be torn apart like that... get a used engine from one of those japan oem importers and go crazy with that. I'd keep this beauty pampered, she deserves it.
Here is some food for thought:

1994 Ferrari 348 0-60mph ~ 6.0sec
1999 Lexus LS400 0-60mph ~ 6.5sec or thereabotut (depending on who you ask. Some claim as low as 6.3sec or even 6.2)

not bad for a luxury barge.

shiflet96

The Celica project is a good ways into the future, I'm looking to build the engine now though. I definitely could still go the route of pulling an engine from a wrecked ls400, but this will help me figure out what I can do to the engine. Just disregarding the Celica project, it seems like using an ECU piggyback and opening up the exhaust would be the first step toward making more power. Are there any specific suggestions for a piggyback and for the exhaust? At the very least, I'm going to the muffler shop tomorrow to get the back set of mufflers cut off. Note that I'm in USA, because a lot of the stuff I've seen is Australian.

YODAONE

You are dealing with a 4.0 liter 240 cubic inch engine...

You are already making over one H.P. per cubic inch.

Opening up the exhaust or cutting off mufflers will not add power and probably you will lose low end torque...so slower off the line, more vibration and noisier.

The neighbors will probably think your hormones are coming in.

Before cutting up original exhaust obtain the back exhaust from a donor vehicle and first experiment with that.

Extrude hone the intake;

See:

https://www.clublexus.com/forums/ls-...rude-hone.html

shiflet96

I've seen a lot of different posts in different places saying that removing the back two mufflers is a good mod for making at least a tiny bit more power. It's even listed in one of the stickies. I'm not removing both sets of mufflers, just the back ones so it won't be that much louder at all.

peterls

I am thinking that for such minimal increase in power you could just open up the air intake. Maybe take all that plastic off and leave the air filter exposed - or at least cut a big hole in the air filter housing. That should allow more air in, will probably increase fuel consumption somewhat, but should add a few HP, or maybe not. Don't remember exactly but I think that someone even tried that already...
Or you could just put a supercharger on it and be done with it - easy 600-700hp.

RA40

iTrader: (6)

There are other engine platforms that will yield easy gains for performance over the 1UZ in this Lexus. A 2JZ for instance where there are lots of parts and aftermarket support to tune it well. My suggestion would be to keep the LS400 as it is. A junk yard or already pulled 1UZ as suggested.

McPierson

iTrader: (3)

My understanding is the early (89-93ish) 1UZ have the strongest rods and support the most boost in stock form.

The auto trans will will die if you do manage to make power over I believe 350-400lb-ft.

The big big advantage of the 1UZ is you can buy a high mileage motor and go big boost without any internal work. If your not doing that then it’s probably an exercise.

Don't take my word though.

Bylan

This is one of the worst platforms to buy for modifying for power. Its already overengineered and pushed to near limits. Its going to get expensive fast. Buy a different platform

EthanS

Experimenting with power adders on a 1uz sounds awesome - I'm all for that!
Learning even more outside of school during your ASE training is also great and shows dedication - keep it up!
A blown 1uz swapped early Celica - wow, yes please. I want one too!

But after looking at the pictures of your 1999 - please please please just leave it alone! Meticulous maintenance with OE parts and a garage to live in is all that thing needs. Not only will the LS400 community thank you for that, but I'm positive that down the road you will be grateful that you left it alone too.

You can find a healthy earlier 1uz with the stronger connecting rods for less than $500 in junkyards or from online suppliers. Pick up one of those, put it on an engine stand, and go to town on that with your experiments. Hell, you can find a functioning ucf10 for under $500 without much trouble.

Just my two cents... good luck and keep us posted either way!