1UR-FSE into 2009 iS250 swap

The 1UZFE EGR Delete Kit is available for sale here.


New Member
Greetings everyone, been a long time lurker and definitely learned a lot from this forum. I'm finally planning to get a Lexus (most likely IS250) as a project car. My initial plan is to either turbo or supercharge the 4GR-FSE, but a new opportunity arises. A friend who works in a salvage yard recently received a totaled LS460 with extensive rear damage (heard the owner spun and hit a tree but thankfully no serious injuries). The front end however is mostly intact, I have an opportunity to buy the entire front end including the engine 1UR-FSE, 8 speed AA80E transmission, all the auxiliary (alternator, AC compressor etc), the ECU and all the harness.

I'm really tempted by this opportunity to build a poor man's IS-F.
Following are some of my thoughts and doubts :
- IS-F has a 2UR and 8 speed trans, I'd assume the engine bay and trans tunnel should have enough space to fit 1UR and its trans?
- modifications needed for engine and trans mount?
- need any modifications to the subframe? or maybe steering rack?
- IS250 rear diff probably can't survive the torque long term?
- IS350 rear diff is the easiest swap? noticed its a popular mod for LS460 guys
- do IS350 and LS460 share the same driveshaft flange?
- fueling system upgrade? high flow in-tank pump?

My biggest question
- does any of the LS460 harness works / compatible with IS250?
- for example the gear shifter? the instrument cluster? A/C systems?
- I'd try to avoid splicing and messing with the original harness (either of the car or the engine side) unless absolutely necessary.

I noticed 1UR isn't nearly as popular swap for IS250 as UZ swaps, mostly because of the electronics and the 1UR being a lot more sophisticated. So do you guys think its a possible swap? Would the complete harness and electronics from the donor car help? Or should I just stick to the 4GR? Thanks in advance, cheers!
Hi Joe,

Anything is possible if you have enough money, but unless someone here has done the swap before, its unlikely you'll find any answers here. Lextreme is mainly focused on the UZ engine. Have you tried the IS forums?

Even though the 2UR was available in Gen2 IS, there is every chance that everything (you've asked about) is different in the LS460 and nothing is a direct swap. Getting everything to fit and work properly can get expensive - even if you can do all your own fabrication and wiring.

Their kit costs about $7K makes about 350hp at the wheels... the same as a stock IS-F.