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Hey guys,

Im not up with the new IS250-350 and I have a customer tossing up the idea of fitting the 350 motor into his 250.

The info I was after is are the box patterns the same and are the 250 ECU's like the IS200/300 and run the motor and body?

Would I need to run both the 250 ecu and 350 or could I swap it for the 350 and run the car functions of that, as all air bags and dash function would be the same I am assuming?

Any other things you can think of and any input is appreciated.
Thanks
 

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Hey guys,

Im not up with the new IS250-350 and I have a customer tossing up the idea of fitting the 350 motor into his 250.

The info I was after is are the box patterns the same and are the 250 ECU's like the IS200/300 and run the motor and body?

Would I need to run both the 250 ecu and 350 or could I swap it for the 350 and run the car functions of that, as all air bags and dash function would be the same I am assuming?

Any other things you can think of and any input is appreciated.
Thanks
Tell him to trade the 250 in for a 350. It'll be a -lot- cheaper and easier.

Apart from the fact the motor (assuming he's buying a new one) costs more than the trade-in difference you have the following problems-

They don't use the same transmission

The 250 transmission isn't rated to hold the power of the 350 engine.

They don't use the same ECU

You can't reprogram the ECU at all.

The 350 ECU will run the 350 engine, but not the transmission. It will be expecting a 350 transmission.

You could transplant both the engine -and- transmission and be a lot more likely to get the 350 ECU to work... but then have the problem of the 350 having VDIM and the 250 doesn't... so there'll still be sensors and wiring it's expecting to be there that isn't.

For a 2009 this'll be a little easier as both models will have VDIM, so you might could swap a completely powertrain and ECU from a 350 into a 250 then... still at a much higher cost than just trading the 250 in for a 350.

(the 250/350 have very complex electronics BTW, the body has its own ECU, steering has its own ECU, etc... among other things, you'd have to check if those ECUs are also the same part between models but I'd imagine they are as the optioning in those areas is similar between the models )
 

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Also dont forget about the direct injector on the 250, and the direct AND port injector on the 350. You would need the fuel injector harnesses as well.

I agree, tell him to trade it in. If he does swap, he will pay loads of money in parts and labor trying to get it to work, as well as loosing his factory warranty. If he trades, He will be in a vehicle that is made for the power, as well as a factory warranty on a car thats not all hacked up.

Definitely more trouble and money than its work in my opinion. I cant imagine how much those engines are going for.
 

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exactly, hes better off swapping the 250 engine for a twin turbo supra engine, same trouble but much faster lol.
 

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If he's considering a 350 engine, he's better off trading in his car for a 350 instead. Doing a swap and not considering anything else, doesn't seem like a realistic idea, since he still needs to think about other things such as the tranny most importantly. Knightshade pretty much nailed all the points.
 

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Just get the complete swap with wiring harness and ecu. If no ecu, then just run a standalone. You'll be set.
Except no standalones exist that can run the IS350 and all its attendent ecus and systems.

And a complete swap will be useless since you'll still have the problem of the transmission...unless you get a 350 transmission too... at which point you're paying like 3-4 times more than just trading the car in for a 350...and you'll still have the VDIM problem.
 

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Probably easier to have a machinist bore out the is250 engine. From what i can tell it's the same engine with a liter missing and only direct injection.
 

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+1 for just trading in the car and getting an IS350.
 

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Probably easier to have a machinist bore out the is250 engine. From what i can tell it's the same engine with a liter missing and only direct injection.
How is that easier than just getting a 350 that is -designed- for that displacement?

Adding a liter, besides being a huge overbore, would mean much of the remaining engine design (cams, valves, heads, tuning) could need changing as well, and as you note there's a whole set of injectors missing in comparison.
 

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How is that easier than just getting a 350 that is -designed- for that displacement?

Adding a liter, besides being a huge overbore, would mean much of the remaining engine design (cams, valves, heads, tuning) could need changing as well, and as you note there's a whole set of injectors missing in comparison.
true that..
i think the thought of force induction will be the only way for now..
unless a toyota aurion/ 3,5L camry (US spec) might be another option wat do u guys think about that?
 

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true that..
i think the thought of force induction will be the only way for now..
unless a toyota aurion/ 3,5L camry (US spec) might be another option wat do u guys think about that?
I doubt it would communicate properly with the other lexus ECUs in the vehicle among other issues.

No engine swap can be done properly in an IS250 for less than the cost of just trading it for an IS350.

For that matter, no forced induction can be either.
 

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Whoa, what is everyone so scared about? This kind of attitude is what keeps us with no modifications for our car or improvements if you don't let anyone explore. To the comment that it would be even more difficult to mate the 350 to the 250's manual then it's automatic? I completely disagree? Why would it be more difficult for the computer to work with a transmission that requires no computer to work (manual operation) then with an auto it isn't designed for? Here's another question for you guys. Do you really think that in the factory lexus has a different body for the 250, 350, is-f, or that they are determined during production as to what they will be fitted with? This platform is very interchangeable and as I research I learn this more and more. It seems car companies are getting smarter with interchangeable parts to lower costs which in turn gives us more options. Here would be a good start, IS350 complete engine out of a wreck (motor, harness, fuel injection system, computer, everything). Transplanting that, and assuming it bolts up to the IS250 manual transmission (which it should considering it has the same bell housing). You should be able to get engine to run even if it thinks the transmission is missing. From that point you would have the joy of getting someone to crack the computer and disable the various features your car won't have. Have fun, if you don't try it, someone else will; shoot i'd love to the first to swap it. Watch out IS-F for the 350 manuals!
 

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interesting insight :)

anyone have any idea what the going rate would be for an IS350 engine/tranny

including harness/ecu etc

probably be looking to sell mine soon
 
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