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

[Montreal914]

Nowhere near your level of expertise/experience but would data logging exhaust gas temp be a good guide too?
I would weld a female 3/8” NPT half nipple on the heat exchanger near head output and use a through hole brass 3/8npt to 1/16” Swagelok and a 1/16” SS k-type thermocouple poking in to measure the hot gas.
Would this info help on the tuning? (IMG:style_emoticons/default/confused24.gif)
Implementation is simple.

[GregAmy]

(IMG:style_emoticons/default/beerchug.gif)

...You have a lot more advance than I do...Your AFR table is a bit richer than mine.

Those go hand-in-hand. I'm running fatter more as a safety measure, but I'm comfy with more timing mostly because it's a street car and I don't tend to run it hard. Any hard running I do will be momentary, rather than extended such as if I were doing lapping days.

Don't we normally set our stock D-Jet cars up at around 29 degrees total advance? With good gas and better fuel management I suspect they'll tolerate more timing.

Plus, I normally run it on 91 pump gas which should be more than enough for this 9:1 FAT 2056 engine, and a conservative cam. I ran it on 89 for my NJ trip because I knew I'd just be highway cruising all day in the middle of the tables...plus have you seen the price of 91 lately...??

I'd like to get a better idea if, for example, I were to do a track day of 15 minute sessions, am I setting myself up for trouble?

...would data logging exhaust gas temp be a good guide too?

Sure. But as with AFR, timing, and CHT (all of which I'm logging now), what's the bogey numbers for EGT? My prob is that I have all this data, which sounds great, but I don't know what to do with it...thus my thread. (IMG:style_emoticons/default/wink.gif)

We have a large historical dataset of what we don't want CHT to exceed on these engines, but the other stuff seems to be mostly wizardry and guesswork.

I've given thought to using either CHT or EGT to swap to alternate tables - for example if CHT or EGT exceeeds xxx then go fatter and pull timing - but again I'm not even sure what I'd do with that. - GA