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Thread: How to tell I have hit the stock rev limiter on a low port 1993 Sr20?

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2020-12-04 11:44:43
How to tell I have hit the stock rev limiter on a low port 1993 Sr20?
Can you please describe to me how rev limiting feels?
2020-12-05 09:22:00
The ECU stops feeding the engine fuel at 7,500 RPM. It's a little more complicated than that, but that is the general idea. It then waits until the engine speed has dropped all the way to 7,300 RPM (or there-abouts, we have a detailed thread about how this works, but these numbers are close) before it adds fuel again. So you will feel acceleration until 7,500 RPM but then it will feel like the engine has stopped working, and you will start to coast for a bit. It can feel pretty violent in 1st and 2nd gear. Eventually if you remain on the throttle, the power will return at around 7,300 RPM and the process will repeat once a second or so. It is supposed to feel very rough, so normal people will think something is very wrong, and stop accelerating.

Some of us with tunable ECUs like to change the hysteresis from ~200 RPM to 50 or even 25. This makes the rev limiter feel MUCH smoother and makes for a much better experience. However, it might actually be more prone to valve float than the stock rev limit even if it feels much less violent. The jury is still out.
Last edited by BenFenner on 2020-12-05 at 17-02-13.
2020-12-05 13:20:06
Wow Ben what a thorough answer this topic has been solved. Yes I let my leaded foot go because it felt violent. Now @ am aware.

It also is nice to learn that you view me as a normal person LOL

On a serious note, just tested free rev, it went that fast up that tacho needled bounced back before I could let go. Assuming it is not easy to replace tacho for just the part availabillity will try some more first gear and try to find out optimum it is my car and I repeat so that will happen, no hurries @ messing 27 year old car with 150k chain, maf is dead as it can be
Last edited by richardwbb on 2020-12-06 at 15-05-19.
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