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]

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?

In some cases it may be a bit subjective, I guess we should start by asking...

What is your measure of "actually good"?

Power? Fuel Economy? Not Blowing Up? Emissions? Something else?

I mean it sounds like you are at least fairly happy with it. I guess the blessing (and maybe the curse) of something like this is that there is almost always room for additional refinement and tweaking though.

Its hard to say without riding in/driving the car or at least looking at some datalogs if something is obviously out of whack, but if you are happy with it and it isnt blowing up, that seems pretty good.

Just glancing at your AFR targets and timing map though I would guess you have both a little power and fuel economy still on the table, but optimizing it is going to be a lot of trial and error, and fully optimizing it will probably need additional instrumentation.

[GregAmy]

In some cases it may be a bit subjective, I guess we should start by asking...What is your measure of "actually good"?

Drivability. Reasonable power (it is, after all, a 75-yr-old engine design). Certainly some reasonable level of fuel economy.

My tuning standard is that I want my Honda-driving brother-in-law to be able to jump into the car, fire it up foot-off, and after figuring out where first gear is drive away slowly (I'd coach him being easy on it the first couple miles) and not complain how it drives. Smooth, no choking, no burps. You know, like his Honda.

I want him to be able to come back with the car, complain about first gear (they all do), and go "yeah, it drives OK, whatever."

It took a bit but I *think* I'm close right now. I still need to work on my sub-60-degrees ambient cold tuning, but I'm pretty solid in 70s-plus.

Power? Fuel Economy? Not Blowing Up? Emissions? Something else?

I'm not going for outright power, that's not the car's mission; I have the race car for that. But I want the option to be able to take it to a Track Night in America and enjoy an afternoon of 20-minute lapping sessions without worrying about blowin 'er up. I AM NOT convinced I've got that, as I haven't really played out there.

Fuel economy and efficiency is certainly a plus, but given the low miles it's being driven anually a 1-2 mpg difference will have neglible financial value. Given I averaged 27-28 highway on this last trip I can't think I could be greedy and ask for more, but I certainly wouldn't reject it, as long as it doesn't compromise driveability.

Emissions is not really a consideration, for the same reasons as fuel economy. But I'd not kick it out of the bed.

I am reasonably happy with it within the range of driving that I have been doing. But, as Rob, illustrated above, that's a narrow range and nowhere near pushing the edge where I could potentially cause damage (and/or have poor driveability.) So I'd like to have a better concept of where I should be at these extremes to where I can feel safe to tune out there, either at a dyno or during a track lapping day.

But within the current driving ranges, I'd be hard-pressed to justify any significant changes.

Here to learn... - GA