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

[thedrew]

I have noticed with the air getting colder out, my CLT temps wont get above 120 degrees. And thats with all the tins and full thermostat. I can imagine as the ambient temps get into the 40's it'll get even lower

[Chip Birks]

Where is your sensor located?

[thedrew]

I use Mario's CLT temp sensor, on the #3 stud. My IAT sensor is in the top of my 3-4 filter top.

[Chip Birks]

Do you have the round rubber seals on your spark plug wires?

[Piledriver]

I use Mario's CLT temp sensor, on the #3 stud. My IAT sensor is in the top of my 3-4 filter top.

CLT location is the issue, that's in direct forced air flow at ~coolest and most massive part of the head.

You can't really compare that value to an under the plug TC etc.
(although if you had both you could establish a correlation)
It should still work for warm up, but may lag a bit due to the distance from the chamber and the mass of the head there.

I have seen pics of Marios sensors used on the intake manifold, still relatively cool there, but not in cooling airflow.
The manifold//intake ports temps probably provide a good relationship to fuel evaporation in the ports, which drives enrichment needs.

The hottest part of a T1 head is the exhaust port, but I cannot suggest a thermistor for that location as it may not be able to take the heat there. (may work, but I plead lack of data, I haven't had a T1 in ages so I cannot measure)

[Piledriver]

Yep, stock thermostat setup, but it can only do so much.

What do you mean by this statement pile. I thought john recommendation was to run all engine tin including the thermostat with his pistons.

I'm running all the factory tin and thermostat.
(and not running squishies at all, so YMMV, just mentioning the AFR vs. timing setup for comparison)

@19:1 AFR and ~ of 50 BTDC timing at 60 KPA it doesn't get hot enough on E70 at cruise under ~70f OAT.
It gets hot enough running E10, and when ~>70F OAT.

Squishies would likely need a little less max timing, but needs will still increase as pressure goes down.

Interesting observation, had to refuel between E85 stations last week, ended up at ~e45.
Won't pull 19:1 AFR running ~E50, but will at 64%.(lean miss at cruise)
Changed 19:1 area to 17:1 until I could burn it off and refill on E85 (E70 from the pump usually)

[thedrew]

Hey Pile and ChipB -- what do you think of this map...I was trying to smooth things out a bit

[Steve Arndt]

Looks pretty good. I run less timing than that at peak torque full load, then slowly add some back above 5000.

[thedrew]

so like 3700ish? (not sure where the fk8 peaks out torque)

[Steve Arndt]

It is really best to put it on a load bearing chassis dyno, we are all just guessing here for your engine. FK8 is pretty close to the 86B and 86A which I have ran both of at north of 12:1 on pump 91 with squishies. The engine is most sensitive between 2000 and 4000 to knock. I have a calibrated ear (joke, and a J&S safeguard for a read out). It gets pretty hard to hear knock above 4500 with our loud intakes and exhausts.

[thedrew]

Gotcha -- ya I know its a stab in the dark, but your guys' experience is invaluable!

i knocked 90 and 100 kpa back a degree and a half...how bout this



thanks again for your help!

[Steve Arndt]

That should be a very safe starting point. Below 35 Kpa and below 3000 RPMs you can bump the timing some. This will help drivability. When you lift off the throttle quickly and hit those super low pressures it will have extreme engine breaking if too retarded. I can actually chirp my rear tires just from compression braking in first gear letting off quickly.

[thedrew]

awesome. thanks so much!

[Piledriver]

I'm sure it will need a lot more timing at lower MAP, at least.
(as you have done)

Might also want top rescale that, 25KPA is deep into fuel cut range.

I added some smaller gaps between 80-95 KPA to allow it to switch between a very lean target area and rich for WOT with a sharp transition zone, with same bins for spark.

Very lean or very rich or low KPA may actually require far more timing than you might think.

Not running squishies, so just a general observation.