IS250 to IS350 6MT Build

[Jeff Lange]

From Toyota, there's not a lot else available in a logitudinal setup. The RA62 with RA63 tail housing or an RA60 (possibly) would probably be the two contenders, but neither is rated for the torque the 2UR-GSE (in IS F or RC F/GS F spec) is rated for. A custom bellhousing/flywheel/clutch setup would also be required along with a custom front half of the driveshaft and different differential gearing.

Sounds expensive, but possible, maybe. IS F 6MT would be dope.

Jeff

 

[Canuckrz]

Such a much better read than on bookface.

 

[Jeff Lange]

Yeah, Bookface is lame for stuff like this. I've been going through a few headaches getting electronics sorted out, but have been driving the car for the past week (finally got ABS back 2 days ago). I'm going to be adding a couple of relays to control a couple of inputs to the ABS and Engine ECU's and then after some more reprogramming I will see about getting cruise control working before calling the car complete.

For what it's worth, driving it is even better than I had hoped for.

Jeff

 

[Jeff Lange]

I've spent the last month or so dealing with various electrical issues, some to deal with differences between the ECU and the car and so on. It was a bit more specific than I was expecting in some cases, but as of last night I finally figured everything out and hope to get the car completely functional in the next couple of weeks, just waiting for a few parts to arrive from Japan and the USA. Also need to send another ECU for reprogramming as the first one didn't work properly with the rest of the car.

That said, during my testing and troubleshooting I managed to put approximately 1,000km on the car. It's even more fun than I thought it would be. I've driven a few cars with the 2GR-FSE including the IS, GS and RC and mine is by far the most fun. Love the manual transmission and the extra rev-ability that the 2GR has over the 4GR almost (almost) makes you forget it's got a dual mass flywheel.

It's really fun to drive, really. Though I drove for the first couple of weeks without ABS, VSC or TRAC and then a few weeks without some other stuff including cruise, but it's all coming together now.

RIP: My tires.

Sorry it's so dirty!

Jeff

 

[Jeff Lange]

Finally got the last of the parts (aside from the ECU) today. Will need to add the wiring for these new sensors and I swapped out one of the MPX ECU's in the dash earlier this week. Not sure the best way to get the new wires into the engine ECU box, but probably de-looming the body harness. Not sure yet. :\

In some ways it is nice that the engine ECU is in the engine bay. It's accessible and so on, however you always need to be careful not to disturb the seal around the box so moisture can get in (the connectors inside are all non-waterproof type).

All that's left is wiring in these sensors, a single relay and then tidying everything up and installing the ECU once I get it!

This project ended up taking me a couple of months longer than I expected, which I guess in the world of cars is actually to be expected, so I shouldn't complain, haha. Some electronics in the car are more flexible while others seem to be very strict about what they want. Sometimes it's not always possible to know which way things will go.

Jeff

 

[Jeff Lange]

So the computer showed up last week and I got that installed, added a relay, and assembled a junction connector.

After a couple of hours of test driving the night I installed the ECU, I headed out for the weekend on a 2,500km (1,550 mile) trip through the mountains to properly test everything and give the car a good shakedown. Beyond a couple of minor issues (the IS350 traction control is much more sensitive to tire size variations than the IS250, and I'm not running stock tires), I declare the swap completed. I might make a couple of enhancements to a few things over the next few months, but nothing too major. I'm happy with the feel of the clutch and flywheel, but I may look into a custom flywheel at some point if I have any issues with the dual mass springs holding up to the increased torque.

Now I can finally present the world's first (to my knowledge), LHD IS350 6MT:

fin.

Jeff

 

[Jeff Lange]

Did the first oil change on the new engine this week and finally got the new tires on the car, they're Bridgestone Potenza RE-71R in 245/40R17 front and 245/45R17 rear. I would have preferred to keep the square tire setup, but the differences between the IS250 and IS350 VDIM parameters just weren't working for me. Thankfully it doesn't look too bad and the driveability is definitely much improved. Traction control does seem to come on a bit quicker than the IS250 (even when taking into account the higher power) but it seems to be a bit less intrusive than the IS250.

The only unfortunate thing about having the taller rear tires is the effective gearing difference. I was considering going to a shorter final drive before, but now that I have the taller rear tires I think it's pretty much certain that I will. It's not bad, but it is noticeable.

I also took a video of the car starting up inside:

https://www.youtube.com/watch?v=hpEeVr1PLq4

Jeff

 

[Jeff Lange]

So I've driven the car about 20,000 km over the last year and in that time I have decided that while the clutch setup isn't terrible, it could use improving. The throttle response from the 2GR-FSE is better than the 4GR was and as such having the dual mass flywheel with the dampened clutch disc, while smooth, can actually be a bit annoying in certain situations.

After spending some time thinking about options and designing a new flywheel, I found what I've put together what I was looking for. My new flywheel is chromoly steel and weighs about 2/3 of what the factory dual-mass flywheel weighs. While it is lighter, it still has some weight to it.

I am using an Aisin NVR 250mm clutch disc with a larger inner and outer diameter and a much larger sprung hub. I've used the NVR clutch discs in a few of my other cars and always been very happy with the way they drive. I will be keeping my existing pressure plate for now, but with the larger clutch disc, it should hold about 20-25 ft-lbs more torque while maintaining the same pedal effort.

I hope to get it installed shortly, depending on how the weather looks. I've still got the Potenza RE-71R's on the car and they don't care much for the snow, haha.

Jeff

 

[4U2QUIK]

Beautiful flywheel!

 

[Jeff Lange]

It's been a bit of a crazy year, meant to post some updates earlier, but didn't get a chance to.

I did get the flywheel installed along with the new clutch disc. It feels fantastic, though I may still adjust it a bit, not sure yet. Much lighter makes for a more rev-happy experience, but it's not crazy light and so does still drive very smooth, as a Lexus should. Additionally I did replace the 3.91:1 Torsen T2 differential setup with a low mileage 4.10:1 T2 to give me a bit more gearing advantage and did a few other items here and there as well.

Original Dual-Mass Flywheel (120,000 km, 20k of which was with the 2GR-FSE), still in spec, but heavy:

New Aisin NVR clutch disc beside previous TSB-updated clutch disc. More torque capacity:

GRMN clutch line/hose setup with no accumulator to replace my previous pieced-together setup:

4.10:1 Torsen T2 Limited Slip Differential:

In an effort to freshen-up but also increase a bit of the tight feeling of the car, I went ahead and replaced a few of the bushings/mounts on the car. I carefully considered which engine mounts to go with and almost went with the Megan ones, but I just couldn't get enough confirmation about their characteristics to make the leap.

2GR/6MT engine mounts / GRMN transmission mount (stiffer than 4GR):

Replacement shifter bushings:

TRD differential mounts/stoppers (front upper/lower and rear solid rubber instead of liquid-filled):

IS-F rear subframe mounts (stiffer than ISx50 stuff):

Overall, the car feels fantastic at this point, I am still considering other ways to improve its performance, however now that I am back in school things will likely progress a bit slower.

Jeff

 

[Piratetip]

Great stuff Jeff.

I love getting boxes of new Toyota / Lexus parts in the mail.

UPS / FedEx and USPS know me too well....

 

[Jeff Lange]

Great stuff Jeff.

I love getting boxes of new Toyota / Lexus parts in the mail.

UPS / FedEx and USPS know me too well....

Yeah... haha. I actually may like having the parts more than I like using them... sometimes anyway. It's always a bit sad to use a part. Maybe that's just me, lol.

Jeff

 

[Piratetip]

Agreed.

When you think about what it took to make it and what it would take to duplicate it again.
Yes it is sad to use it sometimes.

Even more so in the MKIV world, where TRD parts are going for thousands of dollars.
Its nuts.