optimal RPM drop

Status
Not open for further replies.
Joined
Dec 18, 2014
Messages
52
Location
Ok, US
I have got some email tunes for my 2012 Ford Fusion v6 3.0(43k miles). While communicating with the tuner(James), he was not able to tell me how long would be optimal for the RPM to drop. At about 20% throttle, it takes about 0.35 s for stock tune, but James tunes give different results for different shift; some take about 0.25 s, while some others take more than 0.5 s.

My question is whether there is a range that is considered snappy enough but not too harsh.
Stock tune:
5.21.15%20stock.png

James tune:
5.21.15%20james1.png
 
The snappier the shift is the harder the shift [ higher shock load] is on the transmission.
 
I believe the RPM drop is a mechanical constant which cannot be tuned out.

To increase the drop rate, you must reduce flywheel mass. (or increase drag somehow)
 
Originally Posted By: CT8
The snappier the shift is the harder the shift [ higher shock load] is on the transmission.

Most people would say hard shift is better than soft one, but too hard is also not good. So, how hard is not too hard? Nobody tried to define an optimal time range it takes for RPM drop?
 
The rpm drop? No matter how hard or soft the shift is the rpm drop is caused by the gear ratios. Is rpm drop what you mean or the speed of the shift? If most people say a harder shift is better So what. The harder the shift the more shock load the trans sees. Transmissions aren't built to the highest standards.
 
Are you guys loosing your mind? Yes, the OP could have been clearer, but it is fairly obvious when he mentions 0.25 seconds, 0.35 seconds, and 0.50 seconds....that he is referring to the time it takes to shift from one gear to another.

From my experience, it depends on what you're looking for. If you are racing your car, and extra wear and tear are just inevitable (like you'll have to rebuild the tranny at some point), then a harsh shift is desirable. But if you're just looking for a slight improvement over stock for street driving....I'd say that a 0.25 seconds would be an improvement, would only be 30% quicker than stock, and probably be just fine.
 
If you know what the stock values are, stay close to those. Increase only ~10% at a time, and see how that feels.
Aren't the maps 3-dimensional, depending on engine speed and engine load? I expect that the calibration is made to give long shift times for smoothness at low speeds and loads, then to give short shift times for firmness at high speed and loads.
But since I don't really know anything about transmission calibration, I shall halt my flying fingers.
 
Originally Posted By: Phishin
Are you guys loosing your mind? Yes, the OP could have been clearer, but it is fairly obvious when he mentions 0.25 seconds, 0.35 seconds, and 0.50 seconds....that he is referring to the time it takes to shift from one gear to another.

From my experience, it depends on what you're looking for. If you are racing your car, and extra wear and tear are just inevitable (like you'll have to rebuild the tranny at some point), then a harsh shift is desirable. But if you're just looking for a slight improvement over stock for street driving....I'd say that a 0.25 seconds would be an improvement, would only be 30% quicker than stock, and probably be just fine.

Thanks. That is the answer I am looking for. Sorry I did not make it clear what I want to say, for I am not a native speaker.

The problem is that even James does not know why his tune changed the shift pattern. He just told me not to look at the time takes for RPM to drop, and said they should be different for different shift and cars. He said whether a shift is right should be felt by the drive with experience. However, I think whether a drive can felt the jerking of a shift also depends other settings such as pressure, not just how snappy the shift is.
 
Status
Not open for further replies.
Back
Top