Speed Density or Alpha N

larryc · Post by **larryc** » Sun Sep 02, 2007 7:22 am

Just received my Microsquirt a few days ago. Reading is pretty intense at this point as there are a lot of bases to cover to even get started.

I just read a very interesting success story thread for a BMW motorcycle installation. Ultimately, after all was said and done, the owner ended up using Alpha N after having initially starting out using Speed Density.

My application is motorcycle installation, Inline 4 cylinder, Air cooled. I'm interested in what successfull installers / tuners have to say regarding Alpha N vs Speed Density.

Have others started out with one and switched at some point?

Am I better off staring out with Alpha N?

Best Regards,
Larry C

newtyres1 · Post by **newtyres1** » Mon Sep 03, 2007 12:34 am

Motorcycle, IL4, four throttle bodies? just go straight alpha-n, (unless you have a turbo), you can always try speed density down the track if you feel the need...just my opinion. With alpha-n, the TPS spacings on the VE table need to be very close together at low throttle openings to give good fuel control, unlike speed density.

That was Mark Bohn's BMW? He was very thorough in his research/tuning, I miss his posts.

Ian.

larryc · Post by **larryc** » Mon Sep 03, 2007 5:31 am

newtyres1 wrote:Motorcycle, IL4, four throttle bodies? just go straight alpha-n, (unless you have a turbo), you can always try speed density down the track if you feel the need...just my opinion. With alpha-n, the TPS spacings on the VE table need to be very close together at low throttle openings to give good fuel control, unlike speed density.

That was Mark Bohn's BMW? He was very thorough in his research/tuning, I miss his posts.

Ian.

Thank you Ian....and yes, Mark's post was excellent. I wish I could have a good long conversation with him.

I found another post in my search that leads me to believe you can blend a combo of a-n and s-d. As I understand it [correct me if I'm wrong] for low rpm, small throttle openings, s-d yields the best drivability. As you progress up in RPM and past 1/2th throttle openingm a-n provides a more precise fuel curve. My cam selection and timing values will be such that overlap will be as minimal as possible to yield a broad powerband.

So somewhere in Megatune, there are options to taylor the system in such a manor????

I must confess, I'm getting confused by the documentation for the Microsquirt. I don't which to [bash / bad mouth] the documentation efforts. I just wish I could find docs that would walk me through setting up the Megatune for the latest version I downloaded from a Microsquirt reseller.

I'm not certain where the configurator leaves off and megatune begins for some of the settings.

So, for example, if I'm going to start out with a-n and not attempt to blend in s-d until I have the bike running and driveable, it's unclear if I need to tweak a file using the configurator or not?

Would you have any input / help on that?

Thanks again,
Larry

Bernard Fife · Post by **Bernard Fife** » Mon Sep 03, 2007 7:42 am

I just wish I could find docs that would walk me through setting up the Megatune for the latest version

larryc,

Try here: http://www.megamanual.com/mt28.htm

This is not completely finished, but will be soon.

Lance.

larryc · Post by **larryc** » Mon Sep 03, 2007 1:01 pm

Lance wrote:
I just wish I could find docs that would walk me through setting up the Megatune for the latest version
larryc,

Try here: http://www.megamanual.com/mt28.htm

This is not completely finished, but will be soon.

Lance.

Thank You Lance! I REALLY appreciate that. Hopefully you can answer a couple of newbee questions that are holding me back from getting anywhere.......

I have the tweaked version of Megatune from DIY Autotune. I emailed them about not being able to follow along with the instructions to activate a file. To my understanding, activating a file is not required with their tweaked version. I was told to select MS2-Microsquirt BG 2.872 from the drop down list when Megatune first opens. I do that but notice that in the lower portion of the screen, where to my understanding it's supposed to tell you what file you have open, the screen says "no file loaded".

NOTE - My microsquirt is not hooked up to the computer. I'm trying to just have a look at the Megatune software and get the initial settings input into Megatune Version 2.25P1 Build on March 19, 2006.

I did find the common.ini and set the interwrite delay from 1 to 5.

PLEASE Help me to understand this process correctly so I can get to first base. Do I need the microsquirt hooked up to setup the base settings in Megatune 2.25P1? Can I simply enter in the required baseline data and then burn it to the Micro later? I don't honestly know what to input for some of the values and I'm going to have to hunt down some more info.

Why doesn't the tweaked Megatune 2.25p1 recognize any file as being loaded? I thought because DIY Autotune took care of the activation process in their tweaked version that I now have a default "megasquirt-II.ini" file at it would load when I run Megatune 2.25p1?? See why I'm confused now?? I have no car1 folder or anything like that either...

Also [and this will sound stupid to the experienced users but it's a valid question in my mind] When you tweak a file in the configurator from one choice to another, I see the "set" and "unset", but both have # in front of them. Doe's that # need to be removed ? Is it a comment indicator or what?

From the Manual----

"Pick the one where N.N matches the version of embedded code you are running, highlight the .ini file version that you wish to use and execute File -> Activate. This will rename it to be "megasquirt-II.ini" (deleting the existing megasquirt-II.ini file first). It will then be used by MegaTune when it starts up. "

End From Manual Paste

Larry C

Bill Shurvinton · Post by **Bill Shurvinton** » Mon Sep 03, 2007 2:11 pm

IRTB setups can be a bit funny. Way way way back I helped fit the first MS install onto a bike engine. It ran great, but tip in just off idle was a major pain. That was when Alpha-n support was added to MS. Later on mapdot AE and hybrid alpha-N were introduced, all addressing the same problem,which is that MAP is very high at idle (80+KPA), then as you pull away it plummets.

IIRC the OEMs get around this by time sampling MAP.

So I would agree that Alpha-N is probably best to get you running, but I would investige SD down the line.

wildwestsydney · Post by **wildwestsydney** » Tue Sep 04, 2007 7:25 am

I have done an aircooled dr 350 single cylinder motorcycle with a standard MS. I am using Alpha-N with good results at some point I plan on trying speed density and I plan to purchase a Micro squirt when I get some extra cash.

larryc · Post by **larryc** » Tue Sep 04, 2007 12:03 pm

Thanks guys for the feedback on the Alpha-N vs Speed Density. I appreciate your input.

A big thank you and thumbs up to DIY Autotune. Matt was a pleasure to speak to on the telephone. Using their tweaked version of the installer and allowing it to do the default location install cured my software problem.