Quote:
Originally Posted by Wayno
The rev limit has 2 purposes:
1. Not blow up your engine i.e. to be safe. I don't mean the rev limit is to prevent damage, everyone knows this already, I mean the rev limit itself must not cause damage.
2. To retard the speed of the CAR. Notice I didn't say retard the engine speed. The engine is mechanically linked to the wheels, so it needs to be enough to retard the entire car enough to not over-rev the engine, in every gear, in all conditions. Slowing the engine rpm down on flat road in 4th gear isn't really good enough.
You're going to need to use the fuel cut as per stock, with a lower hysteresis (100-150-200 rpm).
Or use 3rd.
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Thanks. Yes both concerns of mine, as I see the FFS rev limiter causes FLKC (regarding your point 1). So I'm not even so sure if a hard limiter is such a good option in the first place?
Over revving the engine in 4th gear or higher (in gear while accelerating) is not that much of a concern though for 3 reasons.
1) The car doesn't have that much power to pull through at that speed.
2) Engine acceleration is quite slow in that high a gear.
3) At that speed, there will be few other distractions (no corners to negotiate etc). So the risk of over revving should be fairly low.
Of course, the rev limiter has to reliably stop the car (in gear) from accelerating beyond the rev limiter in lower gears where there is enough oompf to pull through and everything happens quite fast. With spinning wheels (drift) it's another matter though.
Shiv wrote the following in a VERY old thread:
Ways to 'soften' stock rev limiter?
Quote:
Originally Posted by Shiv@Openflash
The stock ECU tune has a big hysteresis value. Depending on the rev limiter that is active, it's either 200 or 350rpm. Which means that the rev limiter kills the engine at the higher RPM value and then doesn't enable it until it drops to the low rpm value. This causes a rather lazy rev limiter behavior.
To fix it, all you need to do is set the ON and OFF RPM very close to each othern (within 50RPM). Or even set them to the same value. This will make the rev limiter softer and more usable. I suspect the calibration team at Subaru decided to set up the stock rev limiter to be feel violent so that it wouldn't encourage drivers to stay up there 
FWIW, in our off-the-shelf Openflash maps we reduce hysteresis to 150RPM. Easy to change if you want something softer. |
I was wondering if anyone already experimented with different values?
Or if someone using Ecutek (as being used in both video examples in the first posts), can recognize what hysteresis has been used in the examples (as in if that maybe is a "standard accepted way" of fine tuning the rev limiter with Ecutek tunes)?
Also, your explanation makes me wonder if it could be speed/gear related which Rev Limit A and B is active? Hence, which one to change by how much.
As usual too many parameters!!
I think I will keep the soft rev limit for tomorrow to avoid any problems.