Landracing Forum
El Mirage => El Mirage General Chat => Topic started by: Tudors Performance on October 20, 2010, 05:31:22 PM
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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 8-)
http://www.airdensityonline.com/trackresults.php?trackname=El%20Mirage%20Dry%20Lake
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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 8-)
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
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Fixed the link. Good catch John.
Jeff :cheers:
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Jeff,
Congrats on the great runs you guys did in Bonneville.. :cheers:
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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?
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Jeff,
Congrats on the great runs you guys did in Bonneville.. :cheers:
Thanks John. We put lots of time and effort into Pat Womacks turbo engine and dyno tuning, he did a great job riding too!
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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 8-)
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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
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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 :cheers:
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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! :cheers:
Jeff
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How do you deal with ram air?
Akk
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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
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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?
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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.
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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
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Keep in mind that density altitude was intended for use by aircraft to determine the lift capability at takeoff. It does not care if the change in density is due to humidity changes (which displace oxygen) or due to temperature changes.
Water vapor is lighter than air so increasing humidity reduces density (increases density altitude) and reduces the amount of oxygen in a volume of air by displacing some of it with water vapor. Two identical density altitudes one with very high humidity and one with very low humidity will require slightly different mixtures.
The high humidity mixture will have less oxygen per volume and the water vapor will change the specific heat of the air, so the combined effect will be for the mixture to be slightly richer and burn a bit cooler. An identical density altitude with very low humidity will be slightly leaner due to the increased oxygen content per volume and it will burn a bit hotter due to the low humidity.
I would watch the density altitude as a gross reference point but also track the humidity, and http://www.airdensityonline.com/ web site pay attention to the two values for
# air density(without water vapor) = 81.98
# air density (WITH water vapor) = 81.24
These are the reported values today here at Bandimere drag strip (5800 ft altitude) and :
# temperature = 50.0 deg f
# corrected barometer* = 29.81 Hg
# relative humidity = 68 %
Note that the high humidity effects the air density without water vapor vs with water vapor. As far as fuel air mixture you need to tune for the actual oxygen content per unit volume in the incoming air charge, but the humidity will effect how hot or cool a given AFR will burn, as humid air takes considerable more energy to increase its air temperature a given amount compared to dry air.
An easy way to see how humidity effects the heat capacity of air is to look at the dry lapse rate and saturated lapse rate values used in meterology.
Saturated air changes temperature at about 2.7 °F/1,000 ft change in altitude, where dry air changes temperature at a rate of approximately 5.5 deg F/1,000 ft change in elevation. As you can see the ratio is 5.5/2.7 = almost 2:1 difference in how much energy it takes to heat or cool a parcel of air depending if it is completely dry or fully saturated with water vapor. That means hot dry conditions are most likely to hurt the engine if it goes lean, compared to hot damp conditions and the same change in fuel air mixture.
Take a look at this web site, he does a good job of explaining how temperature, humidity and density effect engine power and how it compares to density altitude.
http://wahiduddin.net/calc/calc_hp_abs.htm
If you play with his calculators you can see that you can find two different conditions with identical density altitude but the relative power levels will be different.
For example if you input values of 50 deg F, absolute air pressure (station pressure = uncorrected barometer) of 24.3 in-hg, and relative humidity of 60% you get a density altitude of 6482 ft and a relative power level of 82.2.
If you put in a temperture of 51.42, Deg F, and the same barometric station pressure of 24.3 in-hg, and a humidity of 10% you get the same density altitude number but the relative power is now 82.8. The drop in humidity was worth an increase in power (due to increased oxygen to burn) of 82.8/82.2=1.00729
That does not sound like much but on a 400 hp engine it would be a change in power of 2.9 hp. That is assuming you nailed the tune for both conditions. If you hit one and missed the other, the difference could easily be 5-8 hp or more. The variation is much higher in hot temperatures because air can hold much more humidity in high temperatures.
If you use dry conditions 10% humidty, station pressure of 24.3 and temperature of 110 deg F your density altitude is 10093 and a relative power of 77%. If you drop the temperature to 75 degrees and 70% humidity and adjust the station pressure to 22.946 in-hg get to the same density altitude, you have relative power of 73.4%
Power has changed by 77/73.4=1.049 or about 5% between the two conditions even though the density altitude computed is the same.
On a 400 hp engine that change would be 20 hp difference if both tunes were ideal.
Larry
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Thanks all,
There's a lot of good info here that it would have taken me 20yrs to learn. I just started a fire in the wood stove and it's raining. Perfect opportunity to sit back and go through this with a fine toothed comb.
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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
Thanks Maj (Richard?),
So the ram air compensation is actually used to calculate miles per gallon :-o
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Greg :-D , Richard is the one with the funny accent :lol:
Yeah ... it would seem that table is for the mpg dash function , still lots more uncharted tables
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I Hope to keep this thread open a little.
OK we run a gas modified roadster......normally aspirated with Electromotive fuel and spark ...electronic fuel injection.
We burned up an expensive AA motor at speed week this year :cry:.....after setting the record. :wink:
We downloaded the recordings from race pack and ECU then sent it off to our Electromotive supplier for comment.
RO reported occasional bogging going down the long track. Race pack data show periods of about 1 second where the car slows down and the exhaust gas temps shoot up, then the car accelerates and the temps fall. This happened 18 seconds and 10 seconds before the motor disintegrated. The pulse width at these spots are reduced 25%.
The FI supplier says the ECU did exactly what we told it to do. You know ...the operation was a success unfortunately the patient died...! :roll:
We dynoed the heck out of the motor in Houston..as usual... the map table was tailored to compensate for barometric pressure changes and ram air....as usual. When dynoing I notice that the map sensor jumps all over the real time chart....these fuel injection systems are amazing but I think not capable of dealing with the radical cam shafts of a race motor. I feel that the lean spots are associated with standing waves and pressure pulsations within our intake manifold (TPI-style).
My question...Does any one out there have some wisdom about map sensors and pressure tap placement?
Akk
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Shane the ram air compensation adds fuel.
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Shane,
MPG is not the sole function of ram air compensation! Suzuki gave us ram air to burn more fuel and make more horsepower, so of course this will have an effect on mileage.
This is the simple version, not going to get into 3D mapping. The intake air pressure sensor reads vacuum/pressure. The sensor detects pressure then converts it into a voltage signal. Voltage output increases as the pressure rises. Fuel injection time/volume is increased when the ECM reads an increase in voltage from the IAP sensor. Also affecting ram air fuel is the engines rpm signal. At high speed the fuel injection time/volume is increased.
Jeff
8-)
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akk,
where do you have the map sensor plumbed now?
Maybe relivant or not, from a road race Miata with Haltech.
I had to move mine off the manifold when the cams became too big.
I moved mine to read the airbox pressure (ram effect) and bp, then changed load sensing to tps only.
I know the Electromotive is plenty good equipment, have the aps guys been any help?
John
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John,
I noticed the pressure bouncing around in the dyno room several years ago. Our tech guy said yea that happens...said he has moved the sensor around and the pressure spikes continued. We talked about moving the sensor from the back of the air box (where ours is now) to the front just behind the throttle body (ours is a homemade 6 inch through bore), to long tubes with restrictions and separate plenums....he said he had tried it all to no avail. What got me going on this thread is that I was considering going to mechanical fuel injection, this thread reminded me how handy but sloppy EFI is on a race motor. I am now considering a combination electronic and mechanical fuel injection...in effect a electronic barrel valve with barometric and ram map controlled main jet...sort of!!??!!??
I want to have a second map sensor, sensing the pressure in a tube pointing out the front of the car...it will measure barometric plus ram air. Either using a switch on the throttle or feed back from the electromotive ecu ....litetally switch from the manifold sensor to the remote map sensor. The old map sensor deals with partial throttle..idling...peddling thru soft spots etc....the new remote map sensor correcting for ram air and barometric conditions..providing a steady signal to the ecu so that I can tune the WOT line in the fuel map to precision. The only adjustment to make at Bonneville will be for relative humidity.
I think I will get a better tune in the dyno room and prevent lean spots at Bonneville.
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akk,
If I am understanding you correctly, you want to switch from map load sensing to map baro correction.
You would need two different maps to acheive this and seperate inputs.
Take a look at the setup/configuration for the system, you should be able to use tps as load sensing (simulates mechanical inj) and map baro trim mapping. The baro trim mapping would allow for a correction % that you can specify.
John
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Got it. Thanks folks.
Time to read through this some more - thanks!
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John, The electromotive system has many sensors... crank, cam, water temp, throttle position, exhaust oxygen, air inlet temp, battery voltage, MAP (manifold absolute pressure) and many optional triggers. The ECU has tables for pulse width vs. RPM, spark vs. RPM and more... it is even possible to adjust spark timing, fuel pulse width and more for each individual cylinder! There is a whole screen for setting primary and secondary rev limiters (normally for burn out but we use it as an interrupt for our air shifter).
It all sounds very impressive but the truth of the matter......At WOT (wide open throttle) the only sensors that really matter are the crank, cam and MAP. All that fancy tuning and number of other sensors primarily deal with partial throttle, cruse, cold starting, knock control, idle air motors, "accelerator pump simulation".....it goes on and on.
At WOT if the MAP senses a standing pressure wave or gets confused by pressure pulses in the intake manifold....the ECU gets garbage in, reads the pulse width vs. RPM chart and very precisely pulses the injector for the wrong duration! BOOM the motor melts down or "goes duck hunting". Currently our MAP sensor pressure tap is at the back of a custom "TPI" type manifold.
I see two solutions: 1 Tune the upper rows of the pulse width table all the same in the dyno room and tune with air density/density altitude like mechanical FI(this lets the ECU deal with patrial throttle and all the rest) or 2. Switch to another MAP sensor sensing local air pressure and ram air at WOT.
What do you think?
Akk
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John, The electromotive system has many sensors... crank, cam, water temp, throttle position, exhaust oxygen, air inlet temp, battery voltage, MAP (manifold absolute pressure) and many optional triggers. The ECU has tables for pulse width vs. RPM, spark vs. RPM and more... it is even possible to adjust spark timing, fuel pulse width and more for each individual cylinder! There is a whole screen for setting primary and secondary rev limiters (normally for burn out but we use it as an interrupt for our air shifter).
It all sounds very impressive but the truth of the matter......At WOT (wide open throttle) the only sensors that really matter are the crank, cam and MAP. All that fancy tuning and number of other sensors primarily deal with partial throttle, cruse, cold starting, knock control, idle air motors, "accelerator pump simulation".....it goes on and on.
At WOT if the MAP senses a standing pressure wave or gets confused by pressure pulses in the intake manifold....the ECU gets garbage in, reads the pulse width vs. RPM chart and very precisely pulses the injector for the wrong duration! BOOM the motor melts down or "goes duck hunting". Currently our MAP sensor pressure tap is at the back of a custom "TPI" type manifold.
I see two solutions: 1 Tune the upper rows of the pulse width table all the same in the dyno room and tune with air density/density altitude like mechanical FI(this lets the ECU deal with patrial throttle and all the rest) or 2. Switch to another MAP sensor sensing local air pressure and ram air at WOT.
What do you think?
Akk
Neil, not that you guys need any help but you have your answer in #2.
If intake pressure is near zero why does the map need to be in the intake? Not the first time that's been done........ :-)
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Akk,
what I have said is to take the map sensor off the manifold, and set up the unit to use throttle position as the load sensing for the mapping.
this gives you a 2 dimensional map, tps and rpm, very simple and effective when cams and ram air are fluctuating.
Then use a map sensor to read baro correction with ram air and just trim the mapping with small increments ~10% or so. simular to temp trim.
What SW are you using? I will see if it has the capability.
I think Dynoroom is following, maybe he has more input, I would like see from his experience.
John
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Thanks dynoroom it helps to have confirmation.
John what is SW?
Akk
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Soft Ware and version
best bet would to be talk to application engineer about configuration (electromotive)
John
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John,
We have TEC3r upgraded a few years ago...I am told that a new version is on the way soon. I am told it will not fix my problem..ie. set up for two MAP sensors...My electromotive support suggests using a GPO to control a relay to switch the map. This sounds elegant but I feel it will not be reliable...5 volt relay, lots of wires...salt,salt,salt......a switch on the throttle is simple..RO rarely lets off the hammer....outa work! 8-)
Akk
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Akk,
I would be interested in seeing your configuration/suggested config.
My inclination is like yours, less is better when reliability is key.
Let us know how this works, maybe Nov?
John