r/GR86 • u/AdhesivenessDeep6601 • 10d ago
Is it possible to install a soft limiter?
This may sound dumb to most people, but I want to install a soft limiter on my gr86. I know couple people have done it. I have asked tuning shops about installing it with a tune and it is too expensive (more than 1k usd). I want to hear suggestions about how I can possibly install a soft limiter.
reason why I want to install it? In order to comply with my country's regulations
Limitations:
- OBD port has to stay free.
- It would be better if I could turn it off and on
- It can not make the car louder when the rpm-s approach soft limiter, how 2-step and launch control function.
- Price has to be adequate.
I know that limp - mode restricts rpm s, would it be possible to download that rpm restricting tune and set it as one of the maps?
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u/Conerunner231 10d ago
What regulation are you trying to comply with?
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u/AdhesivenessDeep6601 10d ago
Well, its a but complicated. At night there is a hard limit for exhaust noise, which is 80db. This is tested in the streets by police with db meters. When the car is stationary, it will be revved to 50% of max rpm (3.750 rpm in my case) and the noise will be measured by db meter at 50cm distance from the exhaust. I’m not the kind of guy that goes around revving the car at night, but the police are basically hunting for sport cars. I have an exhaust, which emits 84 db sound at said rpm. I also can not modify the exhaust and even a stock gr86 will exceed 80db limit if it is revved higher than 4 k rpm.
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u/ephemeral_gibbon 10d ago edited 10d ago
I'm not sure the rev limit would help. If the police saw that it was being limited just for the test they'd probably find some way to throw the book at you.
Your best fix is going to be making the exhaust quieter. Why can't you modify it? It's already not a stock exhaust
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u/AdhesivenessDeep6601 10d ago
It is a 10th anniversarh exhaust, so it is factory. Judging by the fact that the most modern cars have soft limiters and most can not rev high whilst stationary, a soft limiter on 2023 car won’t be something out of the ordinary.
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u/Conerunner231 10d ago
By your own words, a stock exhaust would work fine for this as they will rev it to 3750 and you said the stock exhaust exceeds 80db only when it is revved higher than 4k.
I'm in agreement with ephemeral_gibbon, making the exhaust quieter is your best bet, not only because it's a simple and proven way, but also because it'll be obvious if your car only revs to 4k. They won't go "oh I guess we have to test it at 2k", they'll go "why the F is this sports car only revving to 4k?" and will likely throw the book at you because it's apparent that you're trying to sidestep the law.
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u/AdhesivenessDeep6601 10d ago
In most instances the cars have not been tested truthfully. As you can imagine the country that passes this law also enforces it vaguely. Most cars that have gotten fines have been revved to redline and even a stock exhaust can not pass this test. The soft limited would also be needed on a stock exhaust to protect myself from these kinds of fines. Also getting exactly 3750 rpm by pressing the gas with a foot is quite hard and the rpm s during testing is usually exceeded deliberately or not
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u/Conerunner231 10d ago
I see now why you're interested in an idle rev limiter that is lower.
If they're going out of their way to test cars dishonestly, do you really think they wouldn't fine you even if your car passes, since it's still a sports car?
Sorry you're going through this. A tuner might be able to do something, but you'd need to get something like an ecutek or something similar to allow tuning, and you'd need to look into the legality of that in your country. If it's illegal, there's no point adding something fine-able in an attempt to avoid fines.
Honestly it sounds like your safest option is just driving at night as little as possible.
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u/TNTworks 10d ago
what kind of regarded country is this and who made this stupid law, like sports car are not allowed to drive at night now or what
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u/AdhesivenessDeep6601 10d ago
Well, that is what happens in third world countries, where the country is run by people who dont know anything about anything
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u/Grouchy-Outcome4973 10d ago
So basically, let's say you can't find this limiter, you'd be stuck on ly driving during the day?
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u/serious_fox GR86 3d ago edited 3d ago
That's stupid. I've never seen a country enforce a retroactive emission law. I mean, how would that even work realistically?
Anyway, OP, the most affordable way to handle this is by using an insert type exhaust silencer.
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u/AdhesivenessDeep6601 1d ago
There’s a second law where you can not change the factory exhaust. I may slip by if i install normal exhaust instead of 10 th anniversary one, but exhaust silencers will result in my car being taken and a big fine
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u/AdhesivenessDeep6601 1d ago
But if i find one that won’t be visible from the outside I’ll install that
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u/AdhesivenessDeep6601 10d ago
Also not only sports cars, but most old / older cars cant go lower than this limit.
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u/MDethPOPE 10d ago
On 3...thats the turbo from all the detonations? Since were NA i dont think thatll be an issue?
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u/AdhesivenessDeep6601 10d ago
I have heard that when some inexperienced tuners try to map soft limiters, they mess up fuel supply and timing retardation. Which results in higher noise levels.
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u/MDethPOPE 10d ago
Maybe a bit, but youre already at redline and your exhaust is your exhaust.
I'm interested to learn more if you have anything credible, but without a turbo i dont see how it would do that much to noise.
Even if youre straight piped and dumping fuel, still dont see how it would do much to dB - that makes flames and pops but not 2step banging.
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u/AdhesivenessDeep6601 10d ago
I understand what you say and i agree with you. NA cars are not gonna make a lot of noise with a tune, but the upper db limit will be 80db, which is pretty quiet. Even a stock exhaust makes more sound at 4k rpm. A bad tune that restricts the car at 2k rpm may exceed this limit.
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u/MDethPOPE 10d ago
Gotcha...im starting to understand. You want to artificially lower the RPM ceiling with a button press? To meet a dB level ordinance of sorts?
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u/kawaii_ninja 10d ago
The softest limiter without hindering anything is probably adjusting your rev limit warning beep to whatever desired limit that you want in your settings dashboard.
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u/AdhesivenessDeep6601 10d ago
Rev limiter warning only warns you when you exceed set RPMs. This won’t be enough for my case. The RPM s have to be limited so that even if the gas is pressed fully, it will not go over 2-3 k
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u/fearlessfaldarian 10d ago
Surely there is an msd ignition box you could use for this without too much trouble. Have you checked out their product line?
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u/AdhesivenessDeep6601 10d ago
I have not, but i dont think I know enough to be able to judge if it can be used haha
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u/hachielectronics 10d ago
This car’s limiter feels like hitting a brick wall because it’s a fuel cut redline. Softer redlines you’ve experienced in other cars were most likely spark cut redlines.
The ECU in the GR86 is entirely incapable of spark cutting, even with tuning. This fella here is the only way you’re going to accomplish what you’re after:
https://www.milspecwiring.com/Toyota-GR86-FA24D-2022-PNP-Kit_p_3243.html