The Mega/Microsquirt Mega Thread, There's enough of us, time to share info Options

[GregAmy]

Have we decided on which is our official Mega/MicroSquirt thread yet? If so then merge this into it.

I recently took the Microsquirt 914 on a 5-hour each way journey from Connecticut to New Jersey Motorsports Park. I was a bit hesitant to substitute my comfy radio-A/C-and-DSG-equipped GTI for a 45-yr-old ride through the wilds (and traffic) of NYC, but the weather was forecast to be a nice Fall day so I went for it.

Loved it. Car ran flawlessly and the engine was a smooooooooooth as I've ever experienced it. No stumbles, no faults, ran cool on CHT and oil, just an absolute pleasure. 27.5 mpg average on 89 pump gas.

But of course, with no radio (by choice) I had a lot of time to think about my tuning as I was tootling down the parkways and interstates, watching the Android tablet display of engine parameters...it runs good, and it sounds good, and it feels good, but...is it actually good?

One of the biggest issues I faced/am facing with tuning is not the mechanics of the process; I quickly figured out how to use TunerStudio and Megalog, and I'm logging to either laptop or an Android tablet (ShadowTuner) via Bluetooth. And the VE Analyze function of Megalog makes it quite easy to review the AFR outputs in the logs and make changes to meet my AFR goals.

No, that's the easy part. The hard part is knowing where our engines want to be, for example in terms of AFR and ignition timing.

"Take it to the dyno!" you'll say. And you'd absolutely be right. But there's two problems with that.

First, dyno time ain't cheap if you want to do it right. It's not just a matter of showing up and tuning the VE tables to meet the AFR goals (and I can do that on the street). No, to do it right you need to spend an afternoon, or even a day, with a skilled tuner who can run the engine through a series of tests and tickle the edges safely to discover things.

The second factor relates directly to the first: finding a skilled tuner that not only understands the concepts of dyno tuning but also understands the needs and desires of a 75-year-old air-cooled engine design. Sure, the basics are the same as other engines, but I suggest the edges are much much fuzzier.

If I had someone with that talent in my area I'd absolutely leverage them. But I don't. I have some local guys that are good with their dynos but they're Honda guys, or Chevy guys; When I bring my 914 to them (and I have) they're glad to take my couple hours' money but other than tuning to my settings they're not really qualified to tickle (and if they're smart, they're not comfortable trying to tickle the unknown edges on a customer's car).

So any dyno work I've done was to my AFR and ignition settings. And I really don't know what I'm doing either.

I don't know what air-cooled dyno tuning experience there may be on this board, but I'd love to begin sharing some info on where we're going with these Micro/Mega installations. Where do these engines want to be? How much can (or should) we push them? What symptom(s) are we looking for to decide if we need more or less of anything? What's the sweet - and safe - spots?

I'm atttaching my AFR target and ignition tables, let me know what you think. Am I in the ballpark?

I'm not asking you for any secrets. I'm just looking for some feedback to understand if I'm setting myself up for problems in the future. This is not my race car, I'm not looking for that nth hp advance; this is my street car, one that gets driven only 3000 miles a year (if I'm lucky, especially lately). I want to enjoy it and not worry about it. And maybe I'll learn something in the process.

And...discuss! - GA

[JamesM]

SOOOO much to comment on here, both general information and specific cases that have been posted.

I expect its going to take me a couple hours to address everything though so will be looping back on this when I have a little more time.

[BeatNavy]

SOOOO much to comment on here, both general information and specific cases that have been posted.

I expect its going to take me a couple hours to address everything though so will be looping back on this when I have a little more time.

Uh-oh. I feel like I'm 10 years old sitting outside the Principal's Office waiting for him to call me inside... (IMG:style_emoticons/default/blink.gif)

[JamesM]

SOOOO much to comment on here, both general information and specific cases that have been posted.

I expect its going to take me a couple hours to address everything though so will be looping back on this when I have a little more time.

Uh-oh. I feel like I'm 10 years old sitting outside the Principal's Office waiting for him to call me inside... (IMG:style_emoticons/default/blink.gif)

LOL

Hey, If your car is running well no one can knock that.

But, if we are going to talk about what we can do to really dial in our tunes, as with everything else Megasquirt that becomes a a pretty big discussion.

Honestly the timing and AFR tables you posted are pretty inline with where I usually start out save for a couple minor points so I would imagine its running pretty well. Of course the reason I start with those numbers is that they closely mimic what the factory parts do. Where it starts to get interesting is that we can do a lot more with Megasquirt than the factory d-jet and mechanical distributor could but at that point we are entering undocumented territory so who is to say what is right and wrong? (IMG:style_emoticons/default/confused24.gif) I mean at least until your heads melt or you crack a piston, then its usually safe to say someone may have been wrong.


When I look at the maps @GregAmy posted my initial thought is "WOW, thats a ALOT of ignition advance" BUT then noticing that the WOT areas are more conservative I cant say for certain one way or another if it would be a problem or not as the increased advance is all taking place under part load and overrun where it is a little safer to do such things. Then however we have the other important question of is it gaining(or hurting) anything to run that much advance? Because of the nature of the mechanical/vacuum distributor the factory couldn't do things like this even if it was advantageous to so i suspect there are gains to be had but because optimal timing is a function of the mixture figuring that out for anything other that WOT without additional instrumentation is going to be tough.

While its not ideal I usually fall back on head temps and drivability to work out the rest (non WOT areas) of the map, but my MS car is currently only used for autocross so I haven't cared to much about optimizing anything but the part of the map that makes POWER, other than to keep it from melting down on my way to/from autocrosses. But on that point of melting down, I am "blessed" to live in one of the worst parts of the country for air cooled cars from a survivability standpoint so special attention needs to be paid to keeping a tune from melting heads around here. These motors can run on a surprisingly wide range of timing and AFRs however what runs fine on flat ground at sea level on a cool fall day might not work so well in the summer over one of the passes around salt lake with ~20% less cooling air density, 100+ degree temps and 5000ft elevation changes.

and I see a couple things that may be of concern if you were to run at the extremes.

anyways... this wasn't the post I was planning on responding to so... more to come when I have the time.

times a bit limited for me at the moment, recovering from knee surgery so basic stuff is taking a lot longer than normal.