What gear box
What gear box
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lexusdaydreaming
16-04-2021, 02:42 AM #1Hey just wanting to know what gear box will fit is200 an upgraded box after I put stage 2 supercharger bits in I want peace of mind and quicker gear box that goes over 136 mph as am sure the standard box is limited to that.
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Unfortunately it won't help your top speed
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Read my thread here: The Evolution of my Turbo Lexus from NA-Supercharged-Twin Turbo-Massive Single
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Sparkystav
16-04-2021, 02:49 AM #2There isn't any uprated boxes. The standard box will more than handle it, both me and almost finished are running standard boxes.
Unfortunately it won't help your top speed
Read my thread here: The Evolution of my Turbo Lexus from NA-Supercharged-Twin Turbo-Massive Single
Please leave your comments.
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lexusdaydreaming
16-04-2021, 07:19 AM #3So there is nothing I can replace it with like a supra gear box?
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A quick screen shot from one of my spreadsheets might help here:
![[Image: w2npWHu.png]](http://i.imgur.com/w2npWHu.png)
6th gear in an IS200 is 0.869:1
Assuming you have lets say 24" wheel and tyre combo with the 4.1 sport diff and a rev limit of 6750, your theoretical top speed is going to be less than 1mph over 135mph. With the Supra V160's final gear of 0.793 and similar assumptions, you will be able to get to a theoretical maximum of 148mph; a gain of 13mph for what would be probably £3000 of modifications to an IS200.
The S15 6 speed is actually the same gearbox as an IS200 with a different gear set (or at least has the same designation from Aisin-Toyota) so that might be a cheaper alternative for a gearbox that wouldn't be any stronger than the IS200 box, but as Stav has said, it's more than sufficient. I believe his prop shaft broke rather than the gearbox, so that says enough about that.
If you are chasing top speeds, you will want to drop your diff ratio so something around 2.8-3.2 kind of range, and/or swap to one of the newer auto boxes. If, for example, you were using an IS250 box (0.582 final gear) with a 3.2 diff and the same assumptions as before, your theoretical maximum speed would be a nudge over 258mph, which your car will never reach anyway.
One further thing to note, the lower you make your gearing, the worse your acceleration will be. This is why we have moved on to 8 speed gearboxes, so we can have high top speed (and low revs at motorway speed) without sacrificing acceleration. If you look at 1st gear on the 8 speed IS-F box, it's 4.596:1, with a final 8th gear of 0.685:1 (not sure what the diff ratio is) but that allows it to accelerate very well through the lower gears and maintain low revs in the higher gears. Having more gears is also ideal for keeping your car in the optimum rev range.
As you're probably aware, one of the biggest problems with tuning the is200 up is the gearing, anyone doing 80 on the motorway with a turbo IS200 will be bleeding their fuel tank dry in no time because they will be nudging 4000rpm, probably at full boost, and be over the peak torque RPM for the engine. I don't know this first hand, but I'd also imagine 1st gear becomes a bit of a waste of time in a turbo IS200 as well.
Edit: there is also a TRD gear set available for the IS200 (altezza) but if I recall correctly that will make your top speed worse and your acceleration better.
el_bandido
16-04-2021, 08:33 AM #4A supra gearbox won't make your top speed higher by a large margin either, assuming you mean the 6 speed V160 or V161.
A quick screen shot from one of my spreadsheets might help here:
6th gear in an IS200 is 0.869:1
Assuming you have lets say 24" wheel and tyre combo with the 4.1 sport diff and a rev limit of 6750, your theoretical top speed is going to be less than 1mph over 135mph. With the Supra V160's final gear of 0.793 and similar assumptions, you will be able to get to a theoretical maximum of 148mph; a gain of 13mph for what would be probably £3000 of modifications to an IS200.
The S15 6 speed is actually the same gearbox as an IS200 with a different gear set (or at least has the same designation from Aisin-Toyota) so that might be a cheaper alternative for a gearbox that wouldn't be any stronger than the IS200 box, but as Stav has said, it's more than sufficient. I believe his prop shaft broke rather than the gearbox, so that says enough about that.
If you are chasing top speeds, you will want to drop your diff ratio so something around 2.8-3.2 kind of range, and/or swap to one of the newer auto boxes. If, for example, you were using an IS250 box (0.582 final gear) with a 3.2 diff and the same assumptions as before, your theoretical maximum speed would be a nudge over 258mph, which your car will never reach anyway.
One further thing to note, the lower you make your gearing, the worse your acceleration will be. This is why we have moved on to 8 speed gearboxes, so we can have high top speed (and low revs at motorway speed) without sacrificing acceleration. If you look at 1st gear on the 8 speed IS-F box, it's 4.596:1, with a final 8th gear of 0.685:1 (not sure what the diff ratio is) but that allows it to accelerate very well through the lower gears and maintain low revs in the higher gears. Having more gears is also ideal for keeping your car in the optimum rev range.
As you're probably aware, one of the biggest problems with tuning the is200 up is the gearing, anyone doing 80 on the motorway with a turbo IS200 will be bleeding their fuel tank dry in no time because they will be nudging 4000rpm, probably at full boost, and be over the peak torque RPM for the engine. I don't know this first hand, but I'd also imagine 1st gear becomes a bit of a waste of time in a turbo IS200 as well.
Edit: there is also a TRD gear set available for the IS200 (altezza) but if I recall correctly that will make your top speed worse and your acceleration better.
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lexusdaydreaming
16-04-2021, 09:17 AM #5That's a lot of info thank you. My friend has an integra and he hits 140 easy And keeps going with no mods. I was hoping to get over 150 with having more power. I know I will get there faster but then nothing after 136 I can live with it but seems such a Shame to be limited and early if I may say so. So are supra limited to around the same speed?
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el_bandido
16-04-2021, 09:22 AM #6Depends on the diff that the supra is running. I think a 2.8 is available for the Supra, which would put the top speed over 200 with a V160 depending on wheels and rev limit. You could always get your engine balanced and get it revving to 8000rpm, then you'd top out at 160. Not cheap though.
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lexusdaydreaming
16-04-2021, 09:31 AM #7You say engine balance so I don't need to touch gear box?
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top speed is ultimately determined by engine rpm; the higher your engine rpm, the higher the maximum wheel rpm. The ratio between engine and wheel rpm is governed by the diff and gearbox. So in short, you have some options: raise the engine RPM limit, lower the gearing or put ridiculously big wheels on your car.
el_bandido
16-04-2021, 09:38 AM #8Well, I'm saying in theory you could up your engine RPM and keep your standard gearbox/diff etc and hit 160mph, but the money you would have to sink into an IS200 to achieve that (and you'd be bouncing off the 8000rpm red line in 6th) would be ridiculous. You might see the car to 200 horse power in the process as a bonus, but at higher RPM but you'd probably need to balance everything, upgrade valves, bearings and god knows what else to cope with it. Plus obviously the higher the RPM, the more fuel you'll use.
top speed is ultimately determined by engine rpm; the higher your engine rpm, the higher the maximum wheel rpm. The ratio between engine and wheel rpm is governed by the diff and gearbox. So in short, you have some options: raise the engine RPM limit, lower the gearing or put ridiculously big wheels on your car.
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lexusdaydreaming
16-04-2021, 11:57 AM #9So to raise the engine rpm that will be costly?
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The long and short of this conversation is that there is no cheap way to tune an IS200, there certainly isn't a cheap way to up your top speed. The cheapest method might be getting someone to make you a custom ring/pinion gear to drop your diff ratio, but I don't actually know how much that would be or if it's even practical on an IS200. I know there are companies out there like drexler that will make you a diff to your own specifications, but you can be **** sure it won't be cheap.
el_bandido
16-04-2021, 01:02 PM #10unless you want to blow up your engine, yes. NA tuning is notoriously expensive.
The long and short of this conversation is that there is no cheap way to tune an IS200, there certainly isn't a cheap way to up your top speed. The cheapest method might be getting someone to make you a custom ring/pinion gear to drop your diff ratio, but I don't actually know how much that would be or if it's even practical on an IS200. I know there are companies out there like drexler that will make you a diff to your own specifications, but you can be **** sure it won't be cheap.
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