Redspencer's Track-Tuned IS350 w/ OS Giken LSD Build Thread
02-01-19, 08:59 AM
#527
Unfortunately, I don't. I didn't start my adventures in datalogging until April of last year when we were trying to figure out why my RWHP dyno readings were lower than expected (which was very likely due to the exhaust flow being bottlenecked by using the OEM midpipes). The MAF g/s data I had recorded then was 234 g/s ( https://www.clublexus.com/forums/bui...l#post10172177 ).
Comparing similar IAT (high 70s/low 80s) and now having the Megan Midpipes to complete the exhaust setup, the datalog MAF g/s readings are typically in the 245-246 g/s range.
Comparing similar IAT (high 70s/low 80s) and now having the Megan Midpipes to complete the exhaust setup, the datalog MAF g/s readings are typically in the 245-246 g/s range.
02-10-19, 04:12 AM
#528
Power wise, our cars are probably within 5-10hp of each other, and we are running with the same rear tires. I can't go wot on a warm day under 30 without breaking traction, and I believe you might have the same problem. I'm really considering following you and getting a proper lsd in the rear. My question for you is, if you could do it all over again, would you think it's worth it to swap out the final drive to the 3.7x:1? I have been thinking about this recently and am strongly considering trying that out. A spare carrier from a GS350 isn't much. If it's not too hard to swap them out I'll try comparing acceleration between the two.
02-10-19, 05:45 AM
#529
Power wise, our cars are probably within 5-10hp of each other, and we are running with the same rear tires. I can't go wot on a warm day under 30 without breaking traction, and I believe you might have the same problem. I'm really considering following you and getting a proper lsd in the rear. My question for you is, if you could do it all over again, would you think it's worth it to swap out the final drive to the 3.7x:1? I have been thinking about this recently and am strongly considering trying that out. A spare carrier from a GS350 isn't much. If it's not too hard to swap them out I'll try comparing acceleration between the two.
If I had to do the differential swap again, I personally would not swap out the 4.08 final drive for a 3.7 version from a GS350. IMO, the 4.08 final drive on the 2IS350 is a crucial component into making the 2nd Gen IS350 a certified sleeper as its slowly being learned from car enthusiasts (especially on YouTube as I'm seeing more frequently).
If you do decide to go the route of getting an LSD, I would instead recommend upgrading the bushings on the differential which will help prevent wheel hop. With the constant tinkering and lab work that you put into squeezing every potential naturally-aspirated horsepower out of the 2GR-FSE, installing an LSD will further enhance traction for your IS350 (especially with good tires and warmer weather).
With my IS350, as long as the asphalt is warm, I'm still able to get decent traction most of the times when I decide to go WOT at under 20 mph and the transmission kicks down to first gear. It's usually when I try to floor it from a dig where I'll have 50/50 traction.
02-11-19, 11:15 AM
#530
I forgot you didn't use the IS350 FD on your LSD! Yeah, you're definitely missing out a tad bit on acceleration in the lower gears, which is where our cars shine!
Don't forget about the ATS carbon 1.5way LSD at only $1300!: https://www.nengun.com/ats/lsd-carbon & http://www.ppi-ats.com/LSD/LSD_%20ap...2010_Lexus.pdf
Don't forget about the ATS carbon 1.5way LSD at only $1300!: https://www.nengun.com/ats/lsd-carbon & http://www.ppi-ats.com/LSD/LSD_%20ap...2010_Lexus.pdf
02-11-19, 01:02 PM
#531
Mine has the 4.08 FD and is definitely one of the best features of the 2IS350! 
I've theorized that the 2nd Gen IS350 received an aggressive 4.08 final drive ratio due to the fact that the Lexus IS Chief Engineer, Suguya Fukusato, was a part-time rally car driver!
https://autoweek.com/article/car-new...-new-direction
Chief engineer, part-time rally driver helped to take next-gen Lexus IS in new direction
July 24, 2005
Suguya Fukusato may have spent most of his Toyota career as chief engineer of Toyota front-drive econoboxes, but he knows a thing or two about fast cars. He's a rally driver in his native Japan.
Fukusato also has had two Porsche 911 coupes in his stable, currently a 1980 911SC, as well as a 1989 911 Turbo he was compelled to unload because of Japan's claustrophobic traffic.
Finally, Fukusato got his chance to work on a real rear-wheel-drive sports sedan. As chief engineer of the new IS 250 and IS 350 sedans, Fukusato saw the opportunity to take Lexus in a new direction.
At the July media launch in Los Angeles, Fukusato spoke with Automotive News Staff Reporter Mark Rechtin about his latest project.
You said Lexus left out some 'must haves' from the previous IS 300. What do you mean by that?
We made a list. There were nearly 1,000 things that were missed. Most of the list is confidential. But there were some luxury touches that were not Lexus. The damping speed on the doors on the interior fixtures. The exterior paint quality, deviations in the paint and the surface flatness. The LED license plate lamp wasn't right. On the mechanical side, the ride comfort and handling performance were not up to Lexus standards. Neither was the body control and stability.
What was the benchmark for the new IS sedans?
The marketing side, not the development side, looked at the BMW 3 Series, Cadillac CTS, Acura TL, Audi A4 and Mercedes C-Class. But my personal benchmark was in my own feeling of what was right for the car.
In that sense, I decided for myself what to do. But in final comparison, we wanted performance like the BMW 330i M edition and the Mercedes-Benz AMG C32.
The original IS 300 was known for its inline-six engine. Was there ever a hope that such an engine would carry over? Or was it always known that it would be a V6?
There were several advantages to a V6. An inline-six is longer, so that moves the center of gravity point farther forward in the car, which affects handling. The inline-six also is heavier than the new V-6, and the V6 fits in a more compact space.
So why couldn't you just borrow the new 3.5-liter V6 from the Toyota Avalon? Why did you need to invent a different engine family?
The IS is the first vehicle with this new V6. It's mounted north-south, while the Avalon is mounted transverse. We couldn't borrow the Avalon engine because of that.
July 24, 2005
Suguya Fukusato may have spent most of his Toyota career as chief engineer of Toyota front-drive econoboxes, but he knows a thing or two about fast cars. He's a rally driver in his native Japan.
Fukusato also has had two Porsche 911 coupes in his stable, currently a 1980 911SC, as well as a 1989 911 Turbo he was compelled to unload because of Japan's claustrophobic traffic.
Finally, Fukusato got his chance to work on a real rear-wheel-drive sports sedan. As chief engineer of the new IS 250 and IS 350 sedans, Fukusato saw the opportunity to take Lexus in a new direction.
At the July media launch in Los Angeles, Fukusato spoke with Automotive News Staff Reporter Mark Rechtin about his latest project.
You said Lexus left out some 'must haves' from the previous IS 300. What do you mean by that?
We made a list. There were nearly 1,000 things that were missed. Most of the list is confidential. But there were some luxury touches that were not Lexus. The damping speed on the doors on the interior fixtures. The exterior paint quality, deviations in the paint and the surface flatness. The LED license plate lamp wasn't right. On the mechanical side, the ride comfort and handling performance were not up to Lexus standards. Neither was the body control and stability.
What was the benchmark for the new IS sedans?
The marketing side, not the development side, looked at the BMW 3 Series, Cadillac CTS, Acura TL, Audi A4 and Mercedes C-Class. But my personal benchmark was in my own feeling of what was right for the car.
In that sense, I decided for myself what to do. But in final comparison, we wanted performance like the BMW 330i M edition and the Mercedes-Benz AMG C32.
The original IS 300 was known for its inline-six engine. Was there ever a hope that such an engine would carry over? Or was it always known that it would be a V6?
There were several advantages to a V6. An inline-six is longer, so that moves the center of gravity point farther forward in the car, which affects handling. The inline-six also is heavier than the new V-6, and the V6 fits in a more compact space.
So why couldn't you just borrow the new 3.5-liter V6 from the Toyota Avalon? Why did you need to invent a different engine family?
The IS is the first vehicle with this new V6. It's mounted north-south, while the Avalon is mounted transverse. We couldn't borrow the Avalon engine because of that.
02-11-19, 05:43 PM
#532
Driver School Candidate
Yes, the 4.08 is one of the cars great features. It would be better yet with a 4.22 or 4.56, but the diff shop I used to install my OS Giken LSD said no lower gears were available. Who would go higher? The car already has three gears that you can't pull to redline on most tracks.
02-11-19, 11:57 PM
#533
I need to figure out how hard it is to swap out the rear carrier. I remember the debates between 3.73 vs 4.10 gears with my mustang and there really wasn't any conclusive advantage for 4.10s unless you had the traction to take advantage of the steeper gearing. Even then there wasn't much of a difference. Right now I don't have the traction, so I am thinking I might be better off with a little less gear. If I do decide to swap my diff, I will want to set it up in a spare carrier, and the rear end from the GS really isn't much. If it's not too hard I'm thinking I'll do back to back testing and put the lsd whichever I'm happiest with. I might just take one for the team on this.
02-12-19, 01:52 PM
#534
Yes, the 4.08 is one of the cars great features. It would be better yet with a 4.22 or 4.56, but the diff shop I used to install my OS Giken LSD said no lower gears were available. Who would go higher? The car already has three gears that you can't pull to redline on most tracks.
I need to figure out how hard it is to swap out the rear carrier. I remember the debates between 3.73 vs 4.10 gears with my mustang and there really wasn't any conclusive advantage for 4.10s unless you had the traction to take advantage of the steeper gearing. Even then there wasn't much of a difference. Right now I don't have the traction, so I am thinking I might be better off with a little less gear. If I do decide to swap my diff, I will want to set it up in a spare carrier, and the rear end from the GS really isn't much. If it's not too hard I'm thinking I'll do back to back testing and put the lsd whichever I'm happiest with. I might just take one for the team on this.
02-12-19, 04:15 PM
#535
Driver School Candidate
The OS Giken is one of the best mods if you are doing trackdays. It is fantastic how well the car comes off the turns. You can definitely feel it lock as you get back on the throttle mid corner.
02-14-19, 03:40 AM
#536
I'm looking at options. There is an os giken lsd on eBay now, but I'm also seeing a few Cusco options online. Which lsd should I go with 1, 1.5, or 2 way? Reading online it looks like probably not 2 way.
02-14-19, 05:01 AM
#537
As a daily driver, you'll want to go for a 1.5-way for street and track use. The 2-way is more appropriate for drifting and to my knowledge, the 1-way tends to favor a FWD platform more.
- 1 way locks only on acceleration
- 1.5 way locks on acceleration and partially on deceleration
- 2 way locks fully on both acceleration and deceleration
- 1 way locks only on acceleration
- 1.5 way locks on acceleration and partially on deceleration
- 2 way locks fully on both acceleration and deceleration
Last edited by redspencer; 02-14-19 at 05:18 AM.
02-14-19, 10:31 AM
#538
Driver School Candidate
I can't remember which mine is. I just ordered it by the part number sold for the IS350. It came direct from O S Giken USA. Figured they knew what worked for our cars.
02-14-19, 11:51 AM
#540
However, if you manage to acquire a used unit from Japan, you may later discover that it is a special built 2-way LSD that was used by a professional Formula Drift team. I'm not going to name who that person was but I may be quoting that exact person down below *cough cough*
:https://www.clublexus.com/forums/per...pic-heavy.html
