# Speed limiter?



## markherrin (Aug 28, 2005)

Hey is there any kind of speed limiter on a 92 Nissan 
240SX? and what is the top speed for a S13


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## yangs13 (Oct 15, 2005)

i think the top speed is 130. i got my auto s13 to 122


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## markherrin (Aug 28, 2005)

but what about a speed limiter


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## Harris (Nov 11, 2002)

markherrin said:


> but what about a speed limiter




Read that post again.


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## hslabbert (Oct 25, 2005)

markherrin said:


> but what about a speed limiter


The speed governor on the s13's cuts of the fuel at about 115 mph (185 kph), which is a real pain in the ass because that's only about 5,000 rpm in fifth. There are several pieces of advice floating around on how to bypass the governor.

Method 1 (the only one I've tried so far)

1. Remove the kick panel on the passenger side to locate the ECU.
2. Unclip the little clear plastic cover that keeps the wires in place.
3. Cut the 8th wire from the top on the left side as your looking at it. It is a yellow wire with a green stripe.

This wire sends the vehicle speed to the ECU after it travels through the instruments. In other words, you're keeping the computer from knowing how fast you're travelling without disabling your speedometer and odometer. This does work, but after doing this I had idle problems similar to a dirty or faulty IAA valve (i.e. engine speed drops drastically with clutch engaged before stabilizing; engine sometimes even stalls as a result). I've considered just inserting a rocker switch to disconnect the send if I need to pass 185 kph.

However, even if you can keep the ECU from reading the vehicle speed, it still seems that there are rev-limits in place for 4th and 5th gear that prevent you from passing much over 115 mph. The fuel cut-off is usually fairly smooth and knocks you down a few mph, but after following the above-mentioned steps, a rough, abrupt cut-off occured just past 115. The following is a description of how you can supposedly get around that.

***WARNING***
I have not yet tried this following bit of advice, and I have heard really mixed reviews of it's effectiveness. In particular, someone claimed their car would not raise engine speed above idle in 4th and 5th after doing this. I plan on trying this in the next few days and will keep you posted. For your own safety, make sure you check in a safe place that everything is in order.

1. Lift the front of the car (lift, jack, ramps, whatever) and secure on something safe life jackstands.
2. Locate the transmission from under the car.
3. There should be four (4) sensors on the transmission. I have not looked for this myself, but apparently the 4th one is more difficult to find...regardless...
4. You must disconnect the middle two sensors (this is why it would be helpful to know where the 4th one is, so you can figure out which two are in the middle). This is trial and error if you can't find the 4th sensor, although some 240 owners have lifted the rear onto jackstands as well in order to get the tranny into 4th and 5th and see if they're still limited.
The connections should be snap-lock, and so should not have to be cut. Just be sure to follow step #5:
5. Tape up the connections so that you don't get any moisture into the lines.

This _should_ keep the ECU from knowing your engine speed in 4th and 5th gear. As a result, your ECU should know neither your vehicle speed or engine speed, and it can't very well impose a limit on a speed that it can't read.

Some disclaimer-type things: For more information on this, head to http://www.240sx.org/faq/index.html and find the topic "Rev Limiter/Speed Governor". Thanks goes to Mike Lee and Steve Kovacs; the stuff mentioned above is just a paraphrase of their ideas. If you plan on exceeding the governed speed on an s13:

1. Make sure your tires can handle it (speed rating and such)
2. Do it on the track: 120+ mph isn't legal on any public roads I know of in North America, and it's hella fast to be driving on public roads.

That being said, I hope that has been of some help. Cheers.


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## sunnydet90 (Sep 10, 2004)

hslabbert said:


> The speed governor on the s13's cuts of the fuel at about 115 mph (185 kph), which is a real pain in the ass because that's only about 5,000 rpm in fifth. There are several pieces of advice floating around on how to bypass the governor.
> 
> Method 1 (the only one I've tried so far)
> 
> ...


 or you could just buy an s13 auto ecu and then you have no rev limiter and no speed limiter.


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## apex1717 (Sep 16, 2005)

sunnydet90 said:


> or you could just buy an s13 auto ecu and then you have no rev limiter and no speed limiter.


yep! safer on your car and a hell of a lot easier.


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## BoostedSE (Jun 26, 2005)

not having a rev-limmter is deffinitly not "safer" In fact i think its asking for trouble.


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## Terran200sx (Dec 30, 2004)

Rev limiters are improtant, believe me, i've done some racing before and the last thing you want to be thinking about is where you are inthe rev range. That and 120 isn't THAT fast. I went 110 in my 200sx, and i've ridden in a volvo doing 130mph.


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## 240sxstud (Sep 20, 2005)

Terran200sx said:


> Rev limiters are improtant, believe me, i've done some racing before and the last thing you want to be thinking about is where you are inthe rev range. That and 120 isn't THAT fast. I went 110 in my 200sx, and i've ridden in a volvo doing 130mph.


Depending on what kind of racing your wanting to do as well...115 in a 1/4 mile is pretty impressive, either way, removing your rev limiters can easily lead to abused/blown engines


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## Terran200sx (Dec 30, 2004)

Actually my friend has a honda (gasp) without a rev limiter, and i've seen him accidentally overrev it on a few occasions, it's not a pretty sight.


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## Nismo14-180 (Mar 31, 2004)

BoostedSE said:


> not having a rev-limmter is deffinitly not "safer" In fact i think its asking for trouble.


I know this from driving daily.....I REALLY need to send in my spare ECU to JWT....


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## OPIUM (Aug 18, 2002)

I don't want to see the stretch of road an NA ka motor needs to make it past 130mph...


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## Nismo14-180 (Mar 31, 2004)

Highway 840, Franklin,TN- Lebanon, TN. 50-ish miles. No cops, no brains, and one hellofa lead foot......


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## sunnydet90 (Sep 10, 2004)

Nismo14-180 said:


> Highway 840, Franklin,TN- Lebanon, TN. 50-ish miles. No cops, no brains, and one hellofa lead foot......


 god i love that road nice and open


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## hslabbert (Oct 25, 2005)

BoostedSE said:


> not having a rev-limmter is deffinitly not "safer" In fact i think its asking for trouble.


The "rev-limiter" I mentioned in my previous is not a rev-limiter in a traditional sense that prevents you from over-revving say, on a downshift. It is a secondary speed governing method. The two sensors are for engine rpm in 4th and 5th gears and the rpm limits are set to the engine speeds at which the 240's will reach the governed limit of approx. 115 mph in those gears. Your regular rev-limiter remains in place in other gears at least, although I'm not positive if it does for 4th and 5th. Regardless, you'd have to be pushing more than 115 anyway in order to break the redline in 4th.


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## BoostedSE (Jun 26, 2005)

redline or over-revving in fourth isnt much past 115. My s14 is limmitted @118 and i didnt hit the speed cut when i was doing dyno pulls in fourth.


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## hslabbert (Oct 25, 2005)

BoostedSE said:


> redline or over-revving in fourth isnt much past 115. My s14 is limmitted @118 and i didnt hit the speed cut when i was doing dyno pulls in fourth.


Fair enough. Let me elaborate here. If you have the speed governor disabled or removed in an s13, you still would not be able to drive much faster than the governed speed limit, which I believe to be around 115 (I'm from Canada and work in kph, and I believe the governor kicks in on the s13's at around 185 kph).

Now, in any given gear, the speed you are travelling at corresponds to the engine speed. For example, you can just about reach 100 kph (62 mph) at the top of 2nd. This proportion of engine speed to vehicle speed depends on the gear ratios, final drive ratio, and finally also the tire diameter. This is a ridiculous example, but if your engine were spinning at 1,000 revolutions per minute with a gear ratio of 1:1, a final drive ratio of 1:1 (told you it's a ridiculous example), and your tire's outer diameter were 1 metre. Since your engine is spinning at 1,000 rpm and with 1:1 gear and drive ratios, your wheels would spin at the same number of revolutions per minute, i.e. 1,000 rpm, and you would therefore travel 1,000 metres in a minute, i.e. 1 km/minute, i.e. 60 kph.

So, as another speed governing system for the s13's, Nissan determined the engine speeds for fourth and fifth gear at which your corresponding vehicle speed would be just a bit higher than the speed governor's set speed of approx. 185 kph. So, if you have the speed governor disabled/removed and you were to shift into 5th just about as you reach 190 or so, your engine speed would be approx. 5,200 rpm. If the so-called "rpm-monitoring speed governor" were not bypassed, you would be limited from reaching higher speeds since that would require that your engine speed be higher than the imposed engine speed limit for the 5th gear.

You don't have to believe me on this, but I hit it several times the other night after disabling the speed governor. There is a distinct difference between the regular speed limiter and the "rpm-monitoring speed governor". As you may know, if you hit the regular speed governor, your fuel is cut off and you experience a loss of power and a corresponding loss in speed that is actually fairly smooth and gradual. The "rpm limiter", however, is a rough, abrupt, and short cut-off. With the regular speed governor, even if you keep your foot on the gas, you still get squat. With the "rpm limiter", after a half-second cut-off, power returns so that if you keep your foot on the gas you hit the limiter again, and again, and again...

Getting rid of the sensors from the transmission is not meant to let you break the _red-line_ in 4th and 5th. It is just coincidental that the limit is reached just about at red-line in 4th. The rpm limit is not set for the red-line in 5th, but removing the sensors allows you to break this second, lower-set limit that was determined by vehicle speed, rather than by the engine speed.


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## BoostedSE (Jun 26, 2005)

I know the differences between rev-limmiters and speed governers. I was saying that you DONT have to be going faster than 115 in fourth to hit your rev-limmitter (in s14s anyway). I know this because on the dyno i would hit my REV limmter not the governer. I dont support pulling the 4th and 5th tranny sensors either, the governer should be cut through a ECU re-tune.


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## trmn8r (Apr 16, 2005)

ive gotten my sr20det to about 120 in 4th gear. but thats with an auto ecu. i havnt droped the 5th gear yet but i know possitive i can get past 135 easily.


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## hslabbert (Oct 25, 2005)

BoostedSE said:


> I know the differences between rev-limmiters and speed governers. I was saying that you DONT have to be going faster than 115 in fourth to hit your rev-limmitter (in s14s anyway). I know this because on the dyno i would hit my REV limmter not the governer. I dont support pulling the 4th and 5th tranny sensors either, the governer should be cut through a ECU re-tune.


My mistake; I think some of our misunderstanding here might also be coming from s13/s14 differences. I agree, it would be best to get JWT just to retune the ECU; I simply don't have the cash for that at this point, and this is my interim solution.


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## streetracer (Nov 4, 2005)

apex1717 said:


> yep! safer on your car and a hell of a lot easier.


I have done the unpluging of the sensor and it was cheaper than buying a auto ECU.
The unplugging the sesor has made my 240 have no speed govenor or rev limiter but what i have notice is that the car still tops out about 5500 rpms and give no more so i am going to say it goes to about 140 or 145 mph not sure on how fast the car will go since my speed odemintor says it tops out at 110 so i could be total wrong about the speed that it tops out at know.
Just my .02 cents.


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## hslabbert (Oct 25, 2005)

streetracer said:


> I have done the unpluging of the sensor and it was cheaper than buying a auto ECU.
> The unplugging the sesor has made my 240 have no speed govenor or rev limiter but what i have notice is that the car still tops out about 5500 rpms and give no more so i am going to say it goes to about 140 or 145 mph not sure on how fast the car will go since my speed odemintor says it tops out at 110 so i could be total wrong about the speed that it tops out at know.
> Just my .02 cents.


After getting rid of or disconnecting all the speed governing systems, I was able to push it up to about 5950 rpm in 5th before having to slow down approaching other cars. Obviously the needle is past useful at this point as it gets stuck on the bottom edge of the dash by the trip, but using a conversion of about 19 kph gained in 5th for every 500 rpm (approximate found by checking change in vehicle speed versus change in rpm at various points in 5th gear), that works out to about 225 kph (140 mph). Conservatively, allowing for miscalculation and other variables, I would peg it at at least 215 kph (133 mph) or so, with about 1,000 rpm to go. Now, I'm not even sure if a stock NA KA would be able to even gain that last 1,000 rpm (or how freakin' long it would take), but it seems that an S13 with some added juice has quite a bit of speed potential with the stock tranny.


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## ITA Champ (Dec 30, 2004)

*My real life experience*



hslabbert said:


> After getting rid of or disconnecting all the speed governing systems, I was able to push it up to about 5950 rpm in 5th before having to slow down approaching other cars. Obviously the needle is past useful at this point as it gets stuck on the bottom edge of the dash by the trip, but using a conversion of about 19 kph gained in 5th for every 500 rpm (approximate found by checking change in vehicle speed versus change in rpm at various points in 5th gear), that works out to about 225 kph (140 mph). Conservatively, allowing for miscalculation and other variables, I would peg it at at least 215 kph (133 mph) or so, with about 1,000 rpm to go. Now, I'm not even sure if a stock NA KA would be able to even gain that last 1,000 rpm (or how freakin' long it would take), but it seems that an S13 with some added juice has quite a bit of speed potential with the stock tranny.


When I started racing my single cam S13, the scariest thing that happened to me was the speed limiter. This has to be the most dangerous form of speed limiting. Imagine how the rapid deceleration at 115 mph can upset the balance of a car. Going down a long straight and the engine would just quit at 115 mph for 3 seconds as you instantly became a moving chicane to all of your competitors. I've seen other speed limiters that won't quit, but just won't give anymore. Much safer. I tried removing the speed sensor and disconnecting the 4th & 5th gear sensors to no avail. The car would shut down at different RPM's. The only thing that worked for me was sending the ECU to JWT for a new chip. It wasn't cheap, but it kept me alive. At Daytona, I was able to reach 7,000 rpm in 5th gear which, by my calculator, is approx. 160 mph.


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## zellx2004 (Sep 30, 2004)

Why not just cut the speed sensor wire, and replace it with a switch? I've read about this on thirdgen f-body camaros and firebirds, but I never tried it.


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