Corsair
Veteran Member
I have seen some activity recently where people are seeking table or graph displays of engine RPM and vehicle speed for a given gear.
I started doing this many years ago. For this first post, I'm showing information for a stock A4 Jetta TDI 5-speed (such as 2002).
The images come from a circuit design software named Genesys, originally made by a software company based in Atlanta, GA named Eagleware. (I used to work there). In 2005 Eagleware was bought by Agilent Technologies (If you don't know Agilent, think Hewlett Packard).
What the software does is to analyze the response of an electronic circuit across a range of RF frequencies. That is really the same thing as entering the gear ratios and tires size, then sweeping the tachometer through a range of RPMs and looking at the result of some simple linear equations.
How to decipher the graph image below- It's pretty easy, really. Just ignore the MHz label, and treat it as RPM. In the upper left area is where the differential ratio and gear ratios are entered. The tire circumference is entered in inches. On the graph, engine RPM is swept across the horizontal axis, and resulting speed is shown on the vertical axis. The successive lines are the resulting vehicle speed in each gear. The lowest line (brown) is 1st gear, working upwards through the gears. I have placed markers at certain chosen (by me) engine RPMs, and those markers show text on the right side which gives the speed in each gear, for each marker.
So tonight I make this first post after figuring out how to upload pics to the forum. First car I chose to do is the one I happen to own. I plan to make a seperate thread for each different set of trans ratios, and keep track of how I title them so I can make them consistent names and thus easily searchable. I plan to put them all in this 101 forum, unless the mods tell me to do otherwise.
Once set up, it's fairly easy to do different variants. It's also easy to do 6-speed, or add a 6th or 7th trace etc. to show, for instance, the results of changing 5th gear to a couple different ratios (in addition to the existing stock 5th). Also I am aware that some of the 6-speeds use two different internal differential ratios depending on what gear is selected; I can deal with that easily, too.
The image showing the table is same info as shown in the graph, just given in table form. I set up the RPM sweep in 100 RPM increments.
I will make new threads with different combinations of transmission scenarios, each with a graph and table, in the future. If someone has a particular set of tire circumference + differential + gear ratios they want done this way, please PM me with the pertinent info (and what it's for so I can make a title). Be patient, I'll try to get to them promptly and create a new thread. My intent is to build a group of threads with similar names which are easily searched.
Hope this is of interest. This is my first time including photos in a post, forgive me if it doesn't come out quite right and I have to fool around a bit to fix....
[EDIT]- I completed this thread and viewed it online, I realize the resolution & size of the pics is a bit small- I'll have to figure out how to improve this before making more threads.
I started doing this many years ago. For this first post, I'm showing information for a stock A4 Jetta TDI 5-speed (such as 2002).
The images come from a circuit design software named Genesys, originally made by a software company based in Atlanta, GA named Eagleware. (I used to work there). In 2005 Eagleware was bought by Agilent Technologies (If you don't know Agilent, think Hewlett Packard).
What the software does is to analyze the response of an electronic circuit across a range of RF frequencies. That is really the same thing as entering the gear ratios and tires size, then sweeping the tachometer through a range of RPMs and looking at the result of some simple linear equations.
How to decipher the graph image below- It's pretty easy, really. Just ignore the MHz label, and treat it as RPM. In the upper left area is where the differential ratio and gear ratios are entered. The tire circumference is entered in inches. On the graph, engine RPM is swept across the horizontal axis, and resulting speed is shown on the vertical axis. The successive lines are the resulting vehicle speed in each gear. The lowest line (brown) is 1st gear, working upwards through the gears. I have placed markers at certain chosen (by me) engine RPMs, and those markers show text on the right side which gives the speed in each gear, for each marker.
So tonight I make this first post after figuring out how to upload pics to the forum. First car I chose to do is the one I happen to own. I plan to make a seperate thread for each different set of trans ratios, and keep track of how I title them so I can make them consistent names and thus easily searchable. I plan to put them all in this 101 forum, unless the mods tell me to do otherwise.
Once set up, it's fairly easy to do different variants. It's also easy to do 6-speed, or add a 6th or 7th trace etc. to show, for instance, the results of changing 5th gear to a couple different ratios (in addition to the existing stock 5th). Also I am aware that some of the 6-speeds use two different internal differential ratios depending on what gear is selected; I can deal with that easily, too.
The image showing the table is same info as shown in the graph, just given in table form. I set up the RPM sweep in 100 RPM increments.
I will make new threads with different combinations of transmission scenarios, each with a graph and table, in the future. If someone has a particular set of tire circumference + differential + gear ratios they want done this way, please PM me with the pertinent info (and what it's for so I can make a title). Be patient, I'll try to get to them promptly and create a new thread. My intent is to build a group of threads with similar names which are easily searched.
Hope this is of interest. This is my first time including photos in a post, forgive me if it doesn't come out quite right and I have to fool around a bit to fix....
[EDIT]- I completed this thread and viewed it online, I realize the resolution & size of the pics is a bit small- I'll have to figure out how to improve this before making more threads.
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