Air Density/Density Altitude

[Tudors Performance]

I asked www.airdensityonline.com to add El Mirage Dry Lake to the list of race tracks they monitor for track conditions.
It is up and running on the website. This is a great tuning tool for racers that do not have a portable weather station
and want to know corrected altitude etc...

Enjoy,

Jeff Tudor  

http://www.airdensityonline.com/trackresults.php?trackname=El%20Mirage%20Dry%20Lake

[John Noonan]

I asked www.airdensityonline.com to add El Mirage Dry Lake to the list of race tracks they monitor for track conditions.
It is up and running on the website. This is a great tuning tool for racers that do not have a portable weather station
and want to know corrected altitude etc...

Enjoy,

Jeff Tudor 

http://www.airdensityonline.com/trackresults.php?trackname=El Mirage Dry Lake

Here is a better link Jeff..

http://www.airdensityonline.com/trackresults.php?trackname=El%20Mirage%20Dry%20Lake

[Tudors Performance]

Fixed the link. Good catch John.

Jeff 

[John Noonan]

Jeff,

Congrats on the great runs you guys did in Bonneville..

[V8Pinto]

There is a free air density calculator in there which brings me to a question.

I am trying to build up a map database for my bike at El Mirage but admittedly, I don't know what's important.

What I have been doing is making a pass and data logging the A/F and noting the density altitude, then saving that map relative to that density altitude.  I end up with a bunch of files that say "13.0 at 5,000 D/A" with the D/A being different. 

Say I make a pass and the A/F is 13.0 and that's where I want it and the density altitude is 5,000 feet.  next month, if I am getting ready to make a pass and I see the density altitude is going to be near 5,000 feet, I would select the map closest to that D/A.  However comma, isn't it possible to get a different density altitude with different combinations of humidity, pressure, and temperature?

This is too confusing...  what happened to light the fuse and get on it and ride?

I guess my main question is, what parameters are important to log for tuning.  If I had to pick three, what would they be?

[Tudors Performance]

Jeff,

Congrats on the great runs you guys did in Bonneville..

Thanks John. We put lots of time and effort into Pat Womacks turbo engine and dyno tuning, he did a great job riding too!

[Tudors Performance]

There is a free air density calculator in there which brings me to a question.

Shane, are you using a weather station or internet weather info for the data to make your calculations?

Jeff 

[fredvance]

Shane, your factory ecu compensates for a lot of changing conditions. We get my bike dialed in on the dyno. 1000 ft elevation, for Speedweek 90+ dg. I dont data log and this has worked pretty good so far. Of course I also feel like we are leaving a little bit on the table.

  Fred

[V8Pinto]

El Mirage is the biggest difficulty here - you get 1 or 2 runs and that's it.  I've had as much as 4 but if you average it over a year, I bet a nickel it's 1-2 runs per event.

So if I dyno and show up at El Mo, my first run out will (hopefully) be early in the morning with temps in the 50-60's and my tune is probably going to be off a bit (maybe 6% on the top end A/F ratio).  That 6% could be 1-2mph.  I apply the changes, then make another pass later in the afternoon where the temps are more likely to be 30-40 degrees hotter.  The tune is either off or on but the meet is over.

I would MUCH rather show up dyno'd, get the weather info before I run, load up a map from a previous race that was spot-on for that condition (in this case, I am thinking D/A), and not waste the run tuning.

So is D/A the correct metric that I should be using to decide which map to choose? 

I just want to learn from folks and improve what I am doing

Jeff - I have a weather station on the list of things the kids can get me for Father's day 

[Tudors Performance]

Shane. Density altitude is what you want to tune by.

If you are using the air density online.com calculator this is important when entering the values. If you are getting your barometer value from the local weather report, chances are it is the corrected value and needs to be adjusted, that means that you will need to provide the elevation of the location you will be at. If you are getting your barometer value from a barometer measuring device, it is most likely the uncorrected value and needs no adjustment. If this is the case, do not enter the elevation of your location when using the calculator.

Also, if you are tuning on the dyno to prepare for a race, you should get the Density Altitude number at the dyno shop so you know the target air/fuel number you are getting is baselined at that D/A. You can then make more accurate changes to your tuneup based on actual numbers as the D/A changes.

If you need dyno tuning you know where I'm at! 

Jeff

[akk]

How do you deal with ram air?

Akk

[Tudors Performance]

If you are fuel injected and your base map is good, the intake air pressure sensor will compensate/adjust the fuel curve based on the pressure it sees at the manifold.

Jeff

[V8Pinto]

Thanks Jeff,

I just read this, now I'm gonna read it again, then tomorrow I am gonna read it again and then I'll ask you a question

Regarding AKK's question, I have read that the stock ECU has gear based map compensation in it for ram air effect but I've often wondered what having a TRE on the bike does to that.  For example, if the 6th gear map has x% fuel compensated at a given RPM for ram air effect, with a TRE telling the bike it's in 5th gear all the time, are you shorting yourself some Suzuki Engineering horsepower?

Or...is it all accomplished with the intake pressure sensor?

[fredvance]

Shane if you run a tre you will get the ram air compensation for 5th gear. The ecu only has RA compensation in 5th and 6th gear. Have you thought about getting the flashing harness from Greg Smith? Get that and you can get rid of the tre, change the RA compensation, and a multitude  of other neat tricks.

[maj]

Shane and Fred, ram air calcs may not be quite what we have thought , RR is leading the field with the ecu re programming and his latest comments on this matter can be seen here http://www.gixxer.com/forums/showthread.php?t=207938&page=40

Have to admit i tune my bike at a very hot and dry 600ft in Australia and then run with very little change needed at Bonneville or El Mirage... i realy love this aspect of efi