Getting Started -- Timing map for ACN's Squish Pistons

[thedrew]

Hey Folks -- So I'm just diving into this Megasquirt thing and I'm seeing if any one else has a timing map they'd share when using ACN's super squish pistons.

According to John it should "Start with around 6-8 BTDC at idle, and 24 total timing. The curve needs to come in slowly or it will ping."

I have a 2276 with a Fk8 cam, 10:1 CR.

Thanks!

[Chip Birks]

Just setup the timing similar to how a stock curve was built, then take 5-7 degrees off in the upper ranges. I run more than 6-8 at idle, more like 13-15. Mine is boosted, but had similar compression at 9.4:1. I have had a bunch of different timing maps in mine, to suit bigger and bigger cams over the years. The latest setup which would put up a pretty good fight with an 86c needed fast ramping timing to get the car out of its own way at low rpm, stoplight to stoplight cruising, but made 240whp at 8psi with only 20 degrees advance on the dyno.

I ran a cam similar to an 86b on pump gas at one point and it. Looks like I was all in by 3000 rpm running about 22 degrees of advance just before it went under pressure. Cruise areas I ran more timing and a leaner burn, similar to what the old vacuum advance distributors do.

This is not even sort of a one size fits all thing. Obviously my setup is totally different from yours and has different needs. Best thing to do is start conservative, and add timing where it tells you it wants it. Get it on a dyno if possible.

[mrblyoung]

I am going to watch this thread heavily. My super squish motor is at the engine builder right now. Very similar to the OP's motor.

I'm building a 2276, 86B, Steve Tims Stage 2 heads, 10.5:1

Look forward to seeing your final results!

[mrblyoung]

I don't know many people running the Squishies N/A at the moment. I know Chip and Eric are running them boosted. I tried getting ahold of Steve Ardnt regarding his fuel/spark maps to use as a baseline for my tune (being that our engines are pretty similar), but he never got back to me.

Chip, care to share a snapshot of your spark table? Would be awesome to save as a reference.

[thedrew]

Thanks for the help you guys. Once I get things wired up and my MS fired up, I'll check back with some timing maps.

[Steve Arndt]

I sort of crashed my car and haven't had time to fire it up and take screen shots...

I'm listening though!

[mrblyoung]

I sort of crashed my car and haven't had time to fire it up and take screen shots...

I'm listening though!

Ahh nuts dude! That sucks. Sorry to hear that!

Being that I am a newb to Megasquirt, I didnt know you had to fire it up to see the table. I figured it would have been saved onto your computer and was just a matter of sending it as a picture. I will definitely be patient then....

[Chip Birks]

Steve is a Redline guy.

[mrblyoung]

Steve is a Redline guy.

Ahh gotcha...

[Steve Arndt]

Chip's advise is spot on. I run at high altitude quite often (over 6000ft, barometer below the low 80 (Kpa)), you can run more timing at the lower pressures like that.

Heat soaked handles much less timing than a cold cylinder head on my setup. I run 91 octane, and super high compression. I with I could run e-85 (cheap) or 104 octane, then I could throw some timing at it. I'm knock limited on timing everywhere when heat soaked on pump 91.

If I build it again I will get Tims stage 2s (or mini wedge ports) and set the compression closer to 11:1 instead of north of 12. That should really open up the tuning window and make it drive a bit smoother.

[Chip Birks]

I don't know many people running the Squishies N/A at the moment. I know Chip and Eric are running them boosted. I tried getting ahold of Steve Ardnt regarding his fuel/spark maps to use as a baseline for my tune (being that our engines are pretty similar), but he never got back to me.

Chip, care to share a snapshot of your spark table? Would be awesome to save as a reference.

My spark tables are a mess. Definitely not optimized with dyno time, and built by an idiot that is just willing to try stuff out. That it's the beauty of these fully mapable setups, build it how you want to, then tweak tweak tweak till you are both happy. It's not really hard, start conservative and add timing to get things happy.

[thedrew]

Chip, do you have a knock sensor installed?

[Steve Arndt]

I have a J&S safeguard that I use for monitoring knock but not controlling timing. I've played with the J&S for around 10 years now, they work well.

[thedrew]

Heres a hack at my first timing table, following what John @ ACN was advising.

6 degrees at idle, 26 full advance, coming in around 2500rpm

I have my rev limiter set to 6200 so range should be fine.

I don't know how my MAP range is yet since I'm waiting on my trigger wheel to hook it up.

please chime in!

[Steve Arndt]

I idle at around 10 degrees when fully warmed up. (timing based idle speed control allows 10 retard, and 20 advance from that)

22 advance at torque peak when fully heat soaked (handles any amount when cooler) on 91 octane.

Cruise under vacuum I throw 35 or so at it. About 5 percent change in TPS at cruise takes me from vacuum to full load on the map so I have to quickly pull timing from there. I want to build a real manifold and ditch the ITBs so it cruises better.

s