DulceSeek

Is250 3grfse swap. Are fuelmaps needed?any more reliability mods required?

2013FSport

iTrader: (2)

I received you PM and honestly I don't have an answer for your questions regarding the interaction swapping various combinations. You might ping @PAVGR as he did a swap of some kind...

Ultra4

I'm of the understanding that the 4GR-FSE's fuel/air maps were originally intended for the 3GR-FSE, and the 4GR's higher compression ratio is how the air demands were kept within the fuel/spark margin of error the ECU provides.

I have zero doubt a 4GR-FSE vehicle network (all the different modules/controllers) can drive the 3GR-FSE hardware and operate as if it just had the strongest-pulling 4GR-FSE on the planet. The more pressing/interesting question to me is if I'll be able to run the 4GR-FSE's heads and intake on a 2GR-FSE's bottom end without falling off the air/fuel island provided by the OEM 4GR-FSE ECU.

2013FSport

iTrader: (2)

^^ that seems like a stretch. Looks like 3 and 4GR share the same injectors (23209-39057-A0) while the 350 has different ones.

350 injectors:
DI = 949 cc/min - 23209-39155-x0 (A0, B0, C0, D0) <why so many and different colors?
PI = 298 cc/min - 23209-31070

Jeff Lange

iTrader: (1)

This has been done a few times and it seems the 4GR-FSE’s ECU has no trouble adjusting its parameters in closed loop to run the 3GR without modification.

It’s a good swap option for IS250’s, particularly do for 6MT’s.

Jeff

PAVGR

iTrader: (2)

I did the swap and I believe it's a perfect swap if you want to gain decent power.Mine is supercharged and all I can say is that the 4GR had power after 5000 RPM to 7000 and now the 3GR has at 3000 to 7000RPM.The ECU has no promblem handling the extra power(not in my case).It needs more gas for sure!

Ultra4

Yep, but I'll be running the 3/4GR injectors that come with the 6-injector heads. The 2GR-FSE DI squirters have two slits in a V pattern in order to more completely fuel the inboard portions (relative to the engine, so the short turn/intake valve side) of the combustion chamber at higher port velocities, because the port injectors are shooting fuel-laden air toward the lower/outboard (exhaust port side) of the combustion chamber. The 3/4GR injectors have a single flat spray that is stratified purely by the turbulence of the incoming air, so it isn't hard for me to imagine that the 94mm bore (+11 from a 4GR, +6.5 up on the 3GR) of a 2GR block will stretch that charge like crazy, hopefully increasing quench (still gotta play the head gasket game, seems factory is a smidge too thick) and consequently producing a higher peak torque number lower in the RPM range than the 2GR can. Supposing the 4GR topend and electronics can run the 3.5L bottom end through the RPM range, I will likely learn something new and exciting as I approach the rev limit. Probably low fuel rail pressure, needing a code fix or a bit shaved of the high-pressure fuel pump lobe of the cam. As far as my ECU is concerned, I'm just putting an almost perfectly efficient positive displacement blower on the 2.5L bottom.

DulceSeek

Thank you all for replies. I wont be supercharging it it was just about longterm reliability.
Thanks again for support

Samad5169

Would it be possible to complete the 3gr-fse swap in my 2009 is250 awd? I sourced a 3gr from a 2006 awd Gs300, and the mechanic was supposed to start the swap today but told me he called the junkyard and they said the engine won’t bolt up to the transmission. Is this true? If so what would need to be done to complete the swap?

2013FSport

iTrader: (2)

By the book, it does not. These folks are breaking the rules and it works...

Your issue here it now one of warranties as the seller and the installer have *proof, this isn't supposed to drop in as a viable swap but it does. You have a difficult case if something goes wrong. What are the warranty details of the seller? The installer? It may still be worth it if the warranty is 100 miles 10 days (crap warranty).

Samad5169

So basically, it should bolt up, it just won’t be warrantied because that’s not the engine Lexus wants you to put in there?

Jeff Lange

iTrader: (1)

If you put the engines side by side, they are identical. It will bolt up fine.

All differences are internal.

Jeff

Samad5169

See that’s what I was assuming after reading all the forums, I really appreciate the confirmation and all the quick replies! Is there anything I can tell/show my mechanic to ease his concern? Something other then “just take the engine out and see how they’re identical god dammit” I wanna say the latter but also don’t wanna get him mad😂😂

GrizzlyMan

lets see that supercharged engine bay, any videos?

Ultra4

I have a 3GR on an engine stand standing by for me to be done playing with our 4GR. If you get a JDM engine, your mechanic will need to swap wire harnesses and the plastic intake at the least; a USDM GS300 intake will need you to fab a new intake tube to the MAF or use your 4GR intake setup. If you want me to take pics, I can, but ebay LKQ junkyard photos would probably be higher quality and show your wrench spinner what he wants to see.