Lexus is250 engine swap with gs300 engine (3GR-FSE)
04-28-22, 11:13 PM
#1
6th Gear
Thread Starter
Lexus is250 engine swap with gs300 engine (3GR-FSE)
How’s it going club Lexus! This is my first post. I have a 2008 is250. The main reason I bought the car is that I wanted the Lexus reliability and comfort, and it was a 6 speed manual. Not to mention I love the body style! I’ve read in another thread here about potential engine swaps that the gs300 engine is “externally identical” to the is250 engine.. Stock vs. stock The gs300 engine has an extra 48 horsepower/48 torque. And I’ve been seeing relatively low mileage engines around the area for ~$900. With the limited options for getting more power out of the is250 engine (besides paying $6,800 for the RR racing supercharger) I feel like this is an excellent option for some less expensive power. The gs300 (3GR-FSE) in the is250 body paired with my current intake set up, some ppe headers, full exhaust, and a tune I feel would make this car an amazing daily driver. the 3GR-FSE has slightly lower compression.. and RR racing has confirmed their supercharger will work on it. So if I ever did come into some extra money for a supercharger, I could get even more power out of the 3gr. but Again, right now I’m not looking for 400+ HP or anything like that. And no I’m not willing to just “sell and buy an is350.” My car has only 95k miles right now. so an engine swap would be later on down the road, but if anyone has done the swap successfully I would love to hear about it! I’m wondering if the is250 ECU will run the gs300 engine, if the plug-ins are all the same, if the bolt up to transmission is the same, etc. any info is greatly appreciated!
04-29-22, 06:05 AM
#2
Intermediate
I did the swap solo in my garage in roughly a 10x22' area with the car on 4 jackstands on their lowest setting, basic hand tools, and an old engine hoist (cherry picker). You need to depopulate the hood, radiator and it's support, and an absolutely asinine amount of plastic. You will re-use your wiring, electronics, and intake system, including the lower aluminum SCV plate, the 2.5L ECU has no problems whatsoever running a 3.0L engine. It's a straightforward remove and replace task with just the long block being what gets replaced. Since you've got a clutch pedal, I suggest going to a single mass flywheel, sprung disk (input shaft is 1.125", 21 spline, plenty of options), and swap the differential out for a Y38 out of a FR-S or BRZ, powering both tires completely changes the feel of the car in all of the best ways possible, and the extra power from the 3GR kinda makes it neccessary.
When going to stab the engine in, the easiest way would be to dress the engine completely sans the RHS exhaust manifold and plastic intake, land the engine on it's mounts, hook up the starter wiring stackup, torque the starter, torque the bellhousing bolts (2 sizes),torque the 6 pressure plate bolts, then install the RHS exhaust with everything in there. Flying the engine with both headers on creates a stupid situation where you can't clear anything enough to get the engine in. Replace the transmission mount while you do it, I bet yours is as soft as mine was. 3GR's are all automatic, so you'll need a input snout bearing, and you'll also want the throwout hub bearing from a V160 Mk4 supra.
If you get a JDM engine, it's wired differently, but all of the onboard electrical hardware is essentially the same and can be run by a USDM ECU/wiring. JDM engines usually have fewer options on them, like SCV position sensors, cold start injectors, etc.
Aside from unrelated things like brakes, bearings, bushings, braces, steering ECU, subframe cups, and swaybars, I think that's all I got, really.
When going to stab the engine in, the easiest way would be to dress the engine completely sans the RHS exhaust manifold and plastic intake, land the engine on it's mounts, hook up the starter wiring stackup, torque the starter, torque the bellhousing bolts (2 sizes),torque the 6 pressure plate bolts, then install the RHS exhaust with everything in there. Flying the engine with both headers on creates a stupid situation where you can't clear anything enough to get the engine in. Replace the transmission mount while you do it, I bet yours is as soft as mine was. 3GR's are all automatic, so you'll need a input snout bearing, and you'll also want the throwout hub bearing from a V160 Mk4 supra.
If you get a JDM engine, it's wired differently, but all of the onboard electrical hardware is essentially the same and can be run by a USDM ECU/wiring. JDM engines usually have fewer options on them, like SCV position sensors, cold start injectors, etc.
Aside from unrelated things like brakes, bearings, bushings, braces, steering ECU, subframe cups, and swaybars, I think that's all I got, really.
The following 3 users liked this post by Ultra4:
04-29-22, 11:57 AM
#3
I have done this swap some years ago and I also have a Rotrex supercharger kit which make the car reach 377WHP that means 431hp!I m very excited with the final result.I have the 250 ECU tuned of course with 350s injectors and AEM meth kit to help with fuel at higher RPMs because it’s not enough.
Good luck!
Good luck!
The following users liked this post:
parkison25 (04-30-22)
04-30-22, 07:42 AM
#4
6th Gear
Thread Starter
Wow Thank you for the detailed explanation and the tips. I appreciate it and will update the thread once I get the project underway. I’ll try to take pictures and document things as I go… I swapped a 351w into my 67’ mustang about 10 years ago with my dad, but the idea of the ecu and all the sensors in newer cars always scared me away from ever trying anything like this. Glad to know others have done it successfully without any issues!
04-30-22, 12:41 PM
#5
Intermediate
Just to save you some time, I still haven't thrown some of the boxes away...
Input snout bearing I used is 90363-t0019
throwout hub bearing is 90903-63001
The transmission mount for manuals is the one with the 4 downward studs and an upward V-perch for the transmission side. Autos appear to be flat on the trans side. I know for a fact that the R154 IS300 mounts won't work, else we'd have aftermarket options.
More if I think of anything relevant...
Input snout bearing I used is 90363-t0019
throwout hub bearing is 90903-63001
The transmission mount for manuals is the one with the 4 downward studs and an upward V-perch for the transmission side. Autos appear to be flat on the trans side. I know for a fact that the R154 IS300 mounts won't work, else we'd have aftermarket options.
More if I think of anything relevant...
05-01-22, 01:35 PM
#6
6th Gear
Thread Starter
I did the swap solo in my garage in roughly a 10x22' area with the car on 4 jackstands on their lowest setting, basic hand tools, and an old engine hoist (cherry picker). You need to depopulate the hood, radiator and it's support, and an absolutely asinine amount of plastic. You will re-use your wiring, electronics, and intake system, including the lower aluminum SCV plate, the 2.5L ECU has no problems whatsoever running a 3.0L engine. It's a straightforward remove and replace task with just the long block being what gets replaced. Since you've got a clutch pedal, I suggest going to a single mass flywheel, sprung disk (input shaft is 1.125", 21 spline, plenty of options), and swap the differential out for a Y38 out of a FR-S or BRZ, powering both tires completely changes the feel of the car in all of the best ways possible, and the extra power from the 3GR kinda makes it neccessary.
When going to stab the engine in, the easiest way would be to dress the engine completely sans the RHS exhaust manifold and plastic intake, land the engine on it's mounts, hook up the starter wiring stackup, torque the starter, torque the bellhousing bolts (2 sizes),torque the 6 pressure plate bolts, then install the RHS exhaust with everything in there. Flying the engine with both headers on creates a stupid situation where you can't clear anything enough to get the engine in. Replace the transmission mount while you do it, I bet yours is as soft as mine was. 3GR's are all automatic, so you'll need a input snout bearing, and you'll also want the throwout hub bearing from a V160 Mk4 supra.
If you get a JDM engine, it's wired differently, but all of the onboard electrical hardware is essentially the same and can be run by a USDM ECU/wiring. JDM engines usually have fewer options on them, like SCV position sensors, cold start injectors, etc.
Aside from unrelated things like brakes, bearings, bushings, braces, steering ECU, subframe cups, and swaybars, I think that's all I got, really.
When going to stab the engine in, the easiest way would be to dress the engine completely sans the RHS exhaust manifold and plastic intake, land the engine on it's mounts, hook up the starter wiring stackup, torque the starter, torque the bellhousing bolts (2 sizes),torque the 6 pressure plate bolts, then install the RHS exhaust with everything in there. Flying the engine with both headers on creates a stupid situation where you can't clear anything enough to get the engine in. Replace the transmission mount while you do it, I bet yours is as soft as mine was. 3GR's are all automatic, so you'll need a input snout bearing, and you'll also want the throwout hub bearing from a V160 Mk4 supra.
If you get a JDM engine, it's wired differently, but all of the onboard electrical hardware is essentially the same and can be run by a USDM ECU/wiring. JDM engines usually have fewer options on them, like SCV position sensors, cold start injectors, etc.
Aside from unrelated things like brakes, bearings, bushings, braces, steering ECU, subframe cups, and swaybars, I think that's all I got, really.
05-01-22, 08:08 PM
#7
Intermediate
The 4.1 is roughly 10% higher than the factory 3.73-ish that 6MT -250s come with, so your speedo will show 10% faster than you're actually going. I bought a speedo-healer thinking that 10% was going to be noticeable, and the speedo-healer never made it on. With all the new additional feedback my mods have allowed the car to give, I don't end up looking at the gauges that often, anyway...needles are burnt out, so there's that, too.
The Y58 (4.3:1) wasn't available when I purchased my diff, otherwise I probably would have, since it gives you a lower gear to accelerate with. The 4.1 actually improved our highway mileage by a point or two, but I think the 4.3 might be the point of diminishing returns in that regard. The 4.3 will be ~15% faster through each gear than factory, all other things equal.
The dynamic change in how you use the first three gears in every driving scenario is the big selling point. It's nice not to make a spectacle of myself at cars and coffee because Lexus pooped the bed with gearing and clutching this platform. There's a tight hairpin that goes through about 20' elevation change near my house that used to be absolutely impossible to negotiate in either 1st or 2nd gear that now we'll occasionally muse, "hey, remember when we wanted to light this turd on fire because it couldn't do this road?" after driving through it with zero drama/clutch slip/tire slip/trac control stopping us dead in the road. The differential swap alone fixed that. The sway bars and IS-F steering ECU made that apex fun. All of the stiffening and power adding I've done has made it driftable, if you pedal dance beforehand.
The Y58 (4.3:1) wasn't available when I purchased my diff, otherwise I probably would have, since it gives you a lower gear to accelerate with. The 4.1 actually improved our highway mileage by a point or two, but I think the 4.3 might be the point of diminishing returns in that regard. The 4.3 will be ~15% faster through each gear than factory, all other things equal.
The dynamic change in how you use the first three gears in every driving scenario is the big selling point. It's nice not to make a spectacle of myself at cars and coffee because Lexus pooped the bed with gearing and clutching this platform. There's a tight hairpin that goes through about 20' elevation change near my house that used to be absolutely impossible to negotiate in either 1st or 2nd gear that now we'll occasionally muse, "hey, remember when we wanted to light this turd on fire because it couldn't do this road?" after driving through it with zero drama/clutch slip/tire slip/trac control stopping us dead in the road. The differential swap alone fixed that. The sway bars and IS-F steering ECU made that apex fun. All of the stiffening and power adding I've done has made it driftable, if you pedal dance beforehand.
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05-03-22, 02:32 AM
#8
6th Gear
Thread Starter
I checked my cars VIN today, it starts with a “J”. So does that mean a JDM engine will just be “plug-and-play “ as far as the wiring/electronics is concerned? I’m trying to make this as simple as possible for myself 😅
05-03-22, 05:36 AM
#9
Intermediate
Yes, the hard parts of a JDM engine can be run with no issue by the wiring and electronics of a US market vehicle. Like I mentioned before, the Swirl Control Valve plate will need to be swapped between the two engines, since JDM engines don't seem to come with the SCV position sensor, just the actuator.
If you have the ability to remove the engine from the vehicle, the hardest task by an overwhelming margin is getting all the plastics back where they need to be. I tagged, bagged, and labelled everything that came off and still second-guessed myself a couple dozen times and had to work backward to make forward progress. Matter of fact, my test drive with the new engine was done with the bumper almost falling off because the underpan nonesense had to come off a third time, and it was almost a month from when I bolted in the engine. Only way I can think to avoid that would be to video everything coming off, as well as bagging and tagging.
If you have the ability to remove the engine from the vehicle, the hardest task by an overwhelming margin is getting all the plastics back where they need to be. I tagged, bagged, and labelled everything that came off and still second-guessed myself a couple dozen times and had to work backward to make forward progress. Matter of fact, my test drive with the new engine was done with the bumper almost falling off because the underpan nonesense had to come off a third time, and it was almost a month from when I bolted in the engine. Only way I can think to avoid that would be to video everything coming off, as well as bagging and tagging.
05-04-22, 09:14 AM
#11
The 4.1 is roughly 10% higher than the factory 3.73-ish that 6MT -250s come with, so your speedo will show 10% faster than you're actually going. I bought a speedo-healer thinking that 10% was going to be noticeable, and the speedo-healer never made it on. With all the new additional feedback my mods have allowed the car to give, I don't end up looking at the gauges that often, anyway...needles are burnt out, so there's that, too.
The Y58 (4.3:1) wasn't available when I purchased my diff, otherwise I probably would have, since it gives you a lower gear to accelerate with. The 4.1 actually improved our highway mileage by a point or two, but I think the 4.3 might be the point of diminishing returns in that regard. The 4.3 will be ~15% faster through each gear than factory, all other things equal.
The dynamic change in how you use the first three gears in every driving scenario is the big selling point. It's nice not to make a spectacle of myself at cars and coffee because Lexus pooped the bed with gearing and clutching this platform. There's a tight hairpin that goes through about 20' elevation change near my house that used to be absolutely impossible to negotiate in either 1st or 2nd gear that now we'll occasionally muse, "hey, remember when we wanted to light this turd on fire because it couldn't do this road?" after driving through it with zero drama/clutch slip/tire slip/trac control stopping us dead in the road. The differential swap alone fixed that. The sway bars and IS-F steering ECU made that apex fun. All of the stiffening and power adding I've done has made it driftable, if you pedal dance beforehand.
The Y58 (4.3:1) wasn't available when I purchased my diff, otherwise I probably would have, since it gives you a lower gear to accelerate with. The 4.1 actually improved our highway mileage by a point or two, but I think the 4.3 might be the point of diminishing returns in that regard. The 4.3 will be ~15% faster through each gear than factory, all other things equal.
The dynamic change in how you use the first three gears in every driving scenario is the big selling point. It's nice not to make a spectacle of myself at cars and coffee because Lexus pooped the bed with gearing and clutching this platform. There's a tight hairpin that goes through about 20' elevation change near my house that used to be absolutely impossible to negotiate in either 1st or 2nd gear that now we'll occasionally muse, "hey, remember when we wanted to light this turd on fire because it couldn't do this road?" after driving through it with zero drama/clutch slip/tire slip/trac control stopping us dead in the road. The differential swap alone fixed that. The sway bars and IS-F steering ECU made that apex fun. All of the stiffening and power adding I've done has made it driftable, if you pedal dance beforehand.
05-04-22, 10:29 AM
#12
Ultra4, what's this all about? You left the pressure plate loose to ease the stab, then tightened it once stabbed?
I guess the only downside is the time it takes to rotate the engine through 5X to access the bolts, and not being able to use a torque wrench? JM2C but I'd use a clutch alignment tool and do that on the ground taking into account these items.
One tip is to leave the plugs out, have the parking brake set with the trans in 4th gear. When its about stab, turn the crank to align the splines. Talking solo install here. If solo trans stab, one does the opposite. Plugs in, trans in 1st or reverse and spin the tail shaft.
"When going to stab the engine in, the easiest way would be to dress the engine completely sans the RHS exhaust manifold and plastic intake, land the engine on it's mounts, hook up the starter wiring stackup, torque the starter, torque the bellhousing bolts (2 sizes), torque the 6 pressure plate bolts, then install the RHS exhaust with everything in there."
I guess the only downside is the time it takes to rotate the engine through 5X to access the bolts, and not being able to use a torque wrench? JM2C but I'd use a clutch alignment tool and do that on the ground taking into account these items.
One tip is to leave the plugs out, have the parking brake set with the trans in 4th gear. When its about stab, turn the crank to align the splines. Talking solo install here. If solo trans stab, one does the opposite. Plugs in, trans in 1st or reverse and spin the tail shaft.
"When going to stab the engine in, the easiest way would be to dress the engine completely sans the RHS exhaust manifold and plastic intake, land the engine on it's mounts, hook up the starter wiring stackup, torque the starter, torque the bellhousing bolts (2 sizes), torque the 6 pressure plate bolts, then install the RHS exhaust with everything in there."
05-05-22, 06:49 AM
#13
Intermediate
Now about the clutch: the disk and pressure plate were hooked up to the transmission in the car, then I brought the engine to it. If you mated the clutch stackup to the engine outside the car, then you'd need a clutch alignment tool (which comes with every disk I've bought). Barring the engine over to torque each of the 6 PP bolts isn't that hard, and I think I left the plugs in, too. With all 4 tires in the air, I was also able to use my toes to spin the rear wheels to help line everything up.
And PAVGR: the 4.3 will be ~5% faster through the gears than the 4.1, which is ~10% faster than factory itself. If you're currently on the factory pegleg--given the increased torque output of your engine--I'd say the 4.1 is a better choice for you than the 4.3, since I'm betting 1st gear is already pretty short for you. The 4.3 Y58 is a better choice for someone planning on staying naturally aspirated on stock displacement. In my opinion, anyway...different drivers like different things from their cars.
05-05-22, 01:10 PM
#14
Thank you for the reply Ultra4.I currently use the OEM IS250 manual diff and first gear is useless with my supercharger set up.Second gear is spinning until red light and only when I shift to third gear the car is able to handle the power down the road.That’s the reason my 0-100 is 6.5sec which is bad for the BHP the car made.
05-06-22, 05:44 AM
#15
Intermediate
Yeah, in your case, I think either Y38 or Y58, but with a different ring and pinion on it might be the best answer. I'm not sure if there's a factory ring numerically lower than the 3.7 you have, though...maybe in the IS300 autos...either way, the torsen's worth the effort.