DSMLink V3 SD Elevation Change

[LucasEnglish]

So not sure if I am Dumb but I made this video driving form 100-5000ft or so showing how the tune does not change on SD and with no IAT. Temp at 100ft was about 40deg and it was around 26deg at the top of MT Hood.

I have gotten this question and thought if I did a little vid it would be easier to prove to people that our SD works just fine with Elevation Change.

The Reason it works is its based off of absolute pressure instead of "boost".

http://www.youtube.com/watch?v=yMWyf0_-6GY

 

[Rob10_99]

Isn't it quite obvious that SD works off of the MAP sensor?

You have MAP, temp, rpm, what else are people complaining about theoretical miss tuning from elevation change?

 

[DSM_munky_man]

Nice, that is good news cause I am converting here soon!!

oh and ps, you got a crack in your windshield!!

 

[mike96]

DSMLink V3 SD Elataton Change

and here with that goofy a$$ spelling i thought it was going to be something funny

 

[95gst16g]

Hey Lucas I want to convert to SD soon so once I get what I need I am going to come see you again! Whoo haha I'm pumped to make some more power you did an awesome job last time i got tuned. Thanks!

Sent from my DROIDX using Tapatalk

 

[LucasEnglish]

Spelling is my curse and the fact that I am to rushed some times.

 

[mike96]

Spelling is my curse and the fact that I am to rushed some times.

don’t feel bad if i didn’t have some kind of spell check i would be doomed as well.

 

[gofer]

I can back-up what Lucas said about elevation change not effecting a SD tune. I drive my car at sea level but the quarter-mile track I race is at 1100ft, my AFR's remain the same in open/closed loop driving. Elevation won't change your SD tune however, enough change in intake temps will without the use of an IAT sensor. By locking IAT temps running SD the ECU assumes 70* temperatures, unless of course you have an IAT sensor, so the ECU can account for intake temp. changes.
I tried looking at your video recording of the log but only at 0.43 seconds you can actually see the intake temperatures at 77* but it looks like its damn near snowing out? Is that an "actual" intake temperature reading and your just not using it for SD?

@ 100ft.
AFR- 11.3 ~ 11.6:1
Boost- 25.2psi @ 4400 rpm
Airflow- 38.7lbs a minute​

@ ???ft.
AFR- 11.3 ~ 11.6:1
Boost- 21.2psi @ ??? rpm (can't see that portion of the log)
Airflow- 33.6lbs a minute​

Ideal gas law is pV = nRT

p is absolute pressure of the gas (air in this case)
V is volume of the gas
n is amount of gas
R is gas constant
T is absolute temperature of the gas​

Knowing this, the change in the outside temperature might have been 14*, but what were the changes in under hood intake temps between the two pulls? A 60* temperature change going into the engine would be a the difference between a 10:1 AFR to an 11:1 AFR. I don't think your under hood temps changed that drastically during the WOT logs you recorded so the AFR's on the tune weren't changed much either.

Does this make sense or am I just talking? You know WAY more about tuning than I do, the point of what I posted wasn't to start an argument. I just want to hear your take on WHY the AFR's didn't change between pulls without the use of an IAT sensor.

Thanks for taking the time to do this Lucas!

 

[LucasEnglish]

Thanks for looking so close

I dont have a IAT on this car at all guess I am lazy on my car so its just stuck at the 77deg.

You know more of he math then me and the fact that a 60deg change is only 1 point of AF shows that it really does not matter. The coolest IC temp I have ever seen air to air is about 50deg and most of the time it avg about 10-20deg over the out side air temp (50s to 100deg) and really the only time I see a big swing is in the hot direction so no comp and getting richer is a good thing in my book. The worst I have ever seen is 12.0af in 3rd and a drop to about a 11.5 in the top of 4th.

Sorry on Vacation so I dont have logs here.

Guess my thought on Stock ECU based stuff is stock the MAF is just always in the hot engine bay and the temp stock is always about the same temp no matter what the air temp is unless you drop the maf in the fender or something.

I can back-up what Lucas said about elevation change not effecting a SD tune. I drive my car at sea level but the quarter-mile track I race is at 1100ft, my AFR's remain the same in open/closed loop driving. Elevation won't change your SD tune however, enough change in intake temps will without the use of an IAT sensor. By locking IAT temps running SD the ECU assumes 70* temperatures, unless of course you have an IAT sensor, so the ECU can account for intake temp. changes.
I tried looking at your video recording of the log but only at 0.43 seconds you can actually see the intake temperatures at 77* but it looks like its damn near snowing out? Is that an "actual" intake temperature reading and your just not using it for SD?

@ 100ft.
AFR- 11.3 ~ 11.6:1
Boost- 25.2psi @ 4400 rpm
Airflow- 38.7lbs a minute​

@ ???ft.
AFR- 11.3 ~ 11.6:1
Boost- 21.2psi @ ??? rpm (can't see that portion of the log)
Airflow- 33.6lbs a minute​

Ideal gas law is pV = nRT

p is absolute pressure of the gas (air in this case)
V is volume of the gas
n is amount of gas
R is gas constant
T is absolute temperature of the gas​

Knowing this, the change in the outside temperature might have been 14*, but what were the changes in under hood intake temps between the two pulls? A 60* temperature change going into the engine would be a the difference between a 10:1 AFR to an 11:1 AFR. I don't think your under hood temps changed that drastically during the WOT logs you recorded so the AFR's on the tune weren't changed much either.

Does this make sense or am I just talking? You know WAY more about tuning than I do, the point of what I posted wasn't to start an argument. I just want to hear your take on WHY the AFR's didn't change between pulls without the use of an IAT sensor.

Thanks for taking the time to do this Lucas!

 

[gofer]

As far as DD'ing my car, my actual IAT's remain fairly consistent (+/- 10*) whether its 40* outside or 70*, it doesn't matter. But I also live in SoCal where the climate is fairly mild all year round. If its a DD car, that never sees track duty, I could see where running an IAT sensor might not be necessary. Actual IAT's might differ enough on the street if you're stuck in traffic but even then, it wouldn't really matter since you wouldn't be mashing the gas getting out of closed loop. I DD my car but I also take it to the drag strip every chance I get. I've noticed my logged IAT's change drastically when I hit the staging lanes and it would effect the tune if I didn't have a IAT sensor. My cars IAT's usually hover around 84* but out there on the track I've seen 120*+ just from all the exhaust and heat reflecting off the black top.

Have a good vacation!

 

[LucasEnglish]

One thing that is cool about the Link is it does not do air temp correction till it hits high load so the heat soak problems that happen in traffic are not a porblem. AEM EMS Does not have that option that is why I only do cold temp correction so above 80deg its flat and below 80 deg it will correct.

The only time I have seen the temp correction to be needed for me was in our 1100hp Evo with a huge water to air IC so on a 100deg day if we packed it enough we could have mid 40deg temps at 1100hp,50psi in the top of 4th but if it was not packed well enough with ICE it could reach 140deg temps.