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I decided to start a build thread on my $900 1998 GS300. It's come a long way from a poor running, neglected, smog failing beater. I just completed phase 1 of my engine power gains. Still have an NA-T build to come. Thought I'd share what I've done and show some pics. The guidelines to my build are pretty simple. To make a street-able sleeper that is easy to daily drive, but fast enough to blow away today's modern muscle cars etc. I'm creating a daily driver that is substantially more powerful than stock and can easily be driven like normal with all the comforts in place.
After diagnosis, repair, and general maintenance, I started with the normal aspirations of a GS owner. Lowered on a nice set of wheels. Went with a set of Tein street basis z coilovers, and found a very nice set of used Piaa SuperRozza 19" rims. Put on a set of Power-Stop pads and rotors all around at the same time.
After that I wanted to enhance the look of the car. So I put on a rear window spoiler and window visors from HIC with a fresh window tint.
Once the looks were on point, I started getting the itch to increase the performance a bit. I started with the basics. Intake and Exhaust. Found a used Injen intake cheap and put a spare good condition K&N cone filter on I had from a previous car. I got a IS300 header, wrapped it, a Megan midpipe, and an ebay midpipe back exhaust.
I felt the need for a little better handling. Particularly the body role in the front. Installed a Megan 32mm front swaybar and a poly rack bushing to fix a blown out oem one. Car has felt outstanding with this and the coilovers.
Having started making modifications I knew a trans cooler would be a good idea. Got a cheap but effective little Hayden unit.
Now's where things start getting a little more advanced. I wanted to do a cam swap for both N/A power and for the further benefit once one goes forced induction. Being that I am restricted to mild cams for California emissions, I opted for a set of BC 264 cams. This is a very noticeable increase in power and I am really enjoying it. Even if I stay N/A it makes the car much more enjoyable. Did a great deal of maintenance while doing this job. All new seals and gaskets, ignition components, rewired the old wiring and replaced old broken connectors etc. Bypassed the coolant flow to the throttle to keep it cooler. Installed a Walbro 255lph fuel pump to support future growth.
Found a good deal on a Seibon carbon fiber trunk.
Car drives and handles great. Lighter weight in various areas, more power. Looking good, sounding good. More to come!
Last edited by TrueGS300; Apr 14, 2020 at 05:27 AM.
Not yet, I do plan to dyno at this stage though. I want to know the increase from these N/A mods. Then go NA-T. As of now, everythings running like normal, so it's not like a normal case where you have to hurry in for a dyno tune. The cams are plug and play. The higher flow fuel pump won't bother anything. So for now I'm just breaking it in and watching things to make sure the build went ok.
I like how your covering all the bases first. instead of just throwing the motor in and everything else being unmatched. do you plan on upgrading the trans next? a modified valve body from ipt in new jersey did wonders for my a650e when i was supercharged. my youtube videos show how well it shifts at wot with alot of power in front of it.
I like how your covering all the bases first. instead of just throwing the motor in and everything else being unmatched. do you plan on upgrading the trans next? a modified valve body from ipt in new jersey did wonders for my a650e when i was supercharged. my youtube videos show how well it shifts at wot with alot of power in front of it.
Thanks! I'll definitely look into it. I am considering a higher stall converter to hit at the new operating range of my cams. The trans is extremely sluggish in these cars and a valve body upgrade would be outstanding I'm sure. Thats a great suggestion
I haven't even began research on the trans side of things. I've never built a Toyota in general and don't know any companies/brands to look at. Open to suggestions. I've built many DSMs and LS powered Chevys. But this is all new to me. Same basics to make any car quick, just different places to research etc.
I do like that the GS300 has a 3.90 rear end. I would like to get a posi in there and get the trans quicker to respond.
Last edited by TrueGS300; Jun 1, 2019 at 05:32 PM.
if you want a posi unit, do what i did and source a supra rear diff. with the factory torsen posi unit built in. it comes with 3:76 ratio and is the best posi. ever made. and they bolt right in place of your factory diff. i paid 1000 a couple years ago but its worth it.
Not yet, I do plan to dyno at this stage though. I want to know the increase from these N/A mods. Then go NA-T. As of now, everythings running like normal, so it's not like a normal case where you have to hurry in for a dyno tune. The cams are plug and play. The higher flow fuel pump won't bother anything. So for now I'm just breaking it in and watching things to make sure the build went ok.
Measure, change, measure... sorry, just something beaten in to me. : )
Originally Posted by badblackgs
if you want a posi unit, do what i did and source a supra rear diff. with the factory torsen posi unit built in. it comes with 3:76 ratio and is the best posi. ever made. and they bolt right in place of your factory diff. i paid 1000 a couple years ago but its worth it.
Believe we have a stock Torsen in our '94 Miata R... definitely can't complain. Then again, that car has 1/4 the torque? : )
if you want a posi unit, do what i did and source a supra rear diff. with the factory torsen posi unit built in. it comes with 3:76 ratio and is the best posi. ever made. and they bolt right in place of your factory diff. i paid 1000 a couple years ago but its worth it.
I may want to keep the 3:90 gears and do the project of building my own diff. For well under a grand I can install an LSD and not lose a ratio geared more toward acceleration. I think it would be cool to be different and keep the 3.90s. But not sure what I'll do yet. That diff is a substantial upgrade to your GS430 and it's lower oem rear end ratio, but its a loss to a GS300 (minus the torsion posi). But I can get the results from an LSD.
Last edited by TrueGS300; Jun 3, 2019 at 06:55 AM.
I may want to keep the 3:90 gears and do the project of building my own diff. For well under a grand I can install an LSD and not lose a ratio geared more toward acceleration. I think it would be cool to be different and keep the 3.90s. But not sure what I'll do yet.
This is a great start to a build. I will definitely be following along as I'm going this route as well.
It's a bummer these diff pumpkins are a different from the IS300 ones. I would've recommended a diff from the BRZ/FRS (4.1 LSD) which is plug and play on those IS chassis. I have one in my IS which I picked up from the junkyard (for like $210), and it was a very noticeable gain in acceleration. Maybe swap out the guts, for cheap and quick fun? 😉
Sometimes a little more work is required to get the right results. It's always nice when things are plug and play. But if they are not, it's not something that stops me from doing the work. Swapping pumpkins is always a sweet easy way to get results, but if I have to get into the diff because one that swaps in isn't my desired specs, it doesn't bother me. The top three things I dedicate time to match well in any build are the camshaft(s), torque converter, and rear end ratio. So once I have a good idea of what I want, I'll decide exactly what I want to do. This car is desperate for it's gear ratio. I'm pretty sure I'm not going to want to lose any of it. It's become obvious, especially after my N/A build, that the drive-train is the biggest area in need of work to make this car perform in any way. I knew it would need some attention, but after the cam swap, the need for a higher stall converter is so understated its sad. I'm loving the power increase, but it dogs so bad from a take off and almost worse now that the oem stall is too far under the rpm range of the new cams.
That's why I suggested the 4.1 diff. It'll give you that acceleration from the shorter gearing needed to get within powerband of where the cams are most effective. However, once you throw the turbo on, that'll go out the window since you'll probably want taller gears. I'll agree with the TC though, that's one drivetrain mod I believe every AT needs when adding more power.
Deviating from oem gear ratio can cause issues in many cars without tuning for it. I think it will be best to stay with the 3.90s. Its a good ratio and I wont get any odd issues from changes. When the time comes for the 3200 stall I'm thinking about, I definitely will be turning up the line pressure. Thats an easy one. Maybe do the accumulator shimming too. My power level, even going NA-T, is still only going to be around 300whp. I don't worry that the trans can't handle my modest power goals. But what I want is some decent shifting performance. The converter is going to be the biggest factor in performance. And I want to do an LSD at the same time because thats when launching will make it necessary. As of now the car still isn't powerful enough to really need LSD. But I have no doubt it will after a 3200 stall TC.
If you want an LSD in the factory 3.92 ratio buy a locking center section and build it. The only ones out there in that ratio are ones that other people have had made
If you want an LSD in the factory 3.92 ratio buy a locking center section and build it. The only ones out there in that ratio are ones that other people have had made
Yes the diff will need disassembled and the spider gear carrier ditched for an LSD. It's pretty simple really. LSD bolts to the ring gear and shim it correctly. I'll probably just buy a used GS300 diff since they are so cheap and undesired. 100-150 bucks. Build it and refresh all internals at my leisure. Then install the whole unit when I have a free day.
If you're already taking the diff apart I would recommend that you buy a clutch type LSD center section. If you can find a used torsen its going to be $1500+ but they're getting really scarce. Kaaz, Tomei, and OS Giken all make clutch type diffs
TrueGS300's build
