I don't know how much difference the motor is from the IS350 compared to the IS250, but what can be done to run an aftermarket supercharger that won't affect the higher compression in the IS250 engine?

 

With the money spent, might as well buy an IS350.

 

I have to agree as well, there's really no point in doing anything significant to the IS 250, the money invested to make any reasonable gains will easily surpass the price difference between the 250 and the 350.

 

LMS Supercharger... stock internals. stock injectors. stock ecu... 5psi..

nothing big. but hey.. its a difference. and it still allows for some fun.

you could just get a 350.. but IMO you'll just be another RARE 250.. cuz not everyone has a S/C 250



im gonna be deisgning something similar... the LMS kit uses a LMS S/C bracket and a Procharger .. you can just buy the bracket from them or get someone to make one for you and buy a procharger and do it at a slightly cheaper cost.. or slightly higher if u wana go more boost.. u'll need to work on the fuel system and u'll need someone to make an engine management system (unfortunately hasnt been done for us yet)

http://www.luxurymotorworks.com/prod...tegory_key=210

 

You all should read this regarding boosting...

https://www.clublexus.com/forums/sho...3&postcount=12

 

If you FI the 250 first you'll still probably be slower than a 350 and you'll loose your warranty and it'll probably be much less reliable. Why do it? Trade that sucker in for a 350 and you'll pay less in the short AND long term while having your warranty.

 

also, the fact that our intake manifolds are plastic...doesnt help much either

but w/e boost is boost.. if we can safely boost it at 5psi...with an LMS supercharger... (and can afford it).. then why not?

 

I agree, for the money the 350 would be the way to go...
but wait , how much to add AWD to your 350 ?

If you can afford it go for it. It will be a very cool 250.

Other then the internals, bore and stroke, what would be the difference with the 250 engine and the 350?

Couldn't you drop in a 350. And if that's the case, find a wrecked 350, do the motor up, the drop it in... Now you have an AWD beast, (AKA GTR )

 

hell yeah! I like your thinking.. not only that. the 350 is fast. from factory..

but it lacks an available 6 speed manual transmission , and an available AWD drivetrain..

now if u slap a supercharger / even the smallest amount of boost in either a AWD 250....

or a RWD 6 speed 250

..or even an Automatic RWD 250

its gonna be a fun car hands down.

 

Does anyone have info on the outside DI of the 350 vs. 250 engine?
I can't see them actually making 2 castings ? You would need to do some ECU work but thats going to need to happen no matter what you do.
I saw 06'350 that was totalled when I first joined the site, but I havn't seen it since then.

 

you assume the 6 spd manual and differentials of the AWD system can handle a significant power gain, those will have to be built up too. It is still far easier to trade in the car for a 350 and you will get bigger brakes also

 

I agree , it would be much much easier to just get a 350.
But I'm not sure that's what everyone is looking to do. This would be a huge accomplishment putting a project like this together. You will feel great when it all works out and you can say it was done the way you wanted to do it...
You would deffently need to change a few things...Like your driving style.
I don't think you would want to do hole shots with 500hp on a stock awd system, but I think it would handle say...350-375 HP.maybe even 400.
As for the brakes, the 250 stops fine. Bigger brakes are more rotational mass,
I would look to lighten up the drive train to take some of the stress off the components. This is how Acura went about the RSX, and that turned out to be a very nice track car.
But don't kid yourself...this would be a huge undertaking with lots of trial and error to find the right balance.

 

Interesting comments *****,

What specific cars have you seen that use the AWD IS250 transmission with 400 hp? With 350 hp? Links please?

What is the weight of the IS250 brakes (calipers and rotors)? What is the weight of the IS350 brakes (calipers and rotors)? I wonder why Lexus even bothered putting bigger brakes on the IS350 if the IS250 brakes work fine?

Would just like some of the answers to further clarify your comments for other members who may be reading this thread.

 

And I want to say I totally agree with your comment on building something unique and the sense of accomplishment. I could have bought an M5 (or two) instead of building my GS.

I'm just concerned that off the cuff commentary becomes 'fact'. As you say there is a lot of trial and error but I'd more strongly caution folks that you are venturing into the unknown rather than throw out numbers.

 

I couldn't tell you what other autos would be using a lexus AWD transmision with 350 or 400hp...my guess is there are none. Would you really ecpect to use a stock drivetrain after you did all that work on an engine?
( I think I mentioned Balance...)
I can't tell you why Lexus would use bigger brakes on the 350 vs. 250...
( Maybe the idea of less rotational mass on the 250 drivetrain has something to do with it...)
Has anyone noticed issues with stopping that I'm unaware of ?
My answer to this would be stop driving like an A**.

Not sure what your trying to clarify...?
Just because no one has done it does mean it can't be done.

Like I said, don't kid yourself into thinking this would not be a huge undertaking with lots of trial and error.
Can it be done? I have to believe that somewhere, someone is throwing a wrench across the garage as we type...