FLKC in high gears (e.g track). What is acceptable?

[solidONE]

Originally Posted by Tor

I tried gooling a bit around. Next question is if running a lower temp thermostat would increase friction on the cylinder walls? I think it's probably pretty complicated all together.

If you do go ahead and do this, it would be very interesting to see your results!

For now I'm just trying to figure out why I seem to be getting more knock corrections even though I reduced base timing and increased the amount of transient retard. Got to check my exhaust hardware and torque everything. If anything, I'll install an oil cooler before I look into changing thermostats.

[Tor]

Originally Posted by Tor

So what worked? The reintroduced and increased MY17 TCPC or the 10.6 AFR?

Max -1.3 pulled in 5th, compared to -3.2 before. And look at the the last pull 5300 to redline in 5th, only -0.65 pulled at 6500.

To answer this question I tried zeroing out the TCPC again.


https://datazap.me/u/tor/tor-2351-no...-1265-965-1003

This time I recorded the pulls. As you might see it's a pretty steep uphill (look at the fences at 2:30) for the first series of pulls and I can't even keep the speed in 6th gear. The last 5th gear pull is level or maybe even slightly downhill as you can see by the sharper rise in the rpm and speed. Here it knocks a bit less so how long it's "stuck" in those rpm the more it knocks, probably like Wayno explain earlier that the exhaust is piling up.

[ame="https://www.youtube.com/watch?v=K3peKYD4wo4"]Autobahn WOT pulls - YouTube[/ame]

In 5th above 6800 rpm, TCPC definitively makes a difference. In 4th it's less important and in 3rd it's unnecessary:

https://datazap.me/u/tor/tor-2351-no...&zoom=973-4830

So for anyone that can't legally rev it out in 5th I think you might as well zero it out. Or you can do it anyway and keep in mind not to rev it out past 6800 in 5th if it's on a steep incline or whatever your logs tells you.

So the next question is this: How much work would it be for someone with the proper knowledge to hack a tune so that TCPC activates according to gear instead of ECT?

[Tor]

Originally Posted by steve99

@Tor
Bit of lateral thinking
....
But maybe we can use coolant temp. The knock seems to get worse as coolant temps exceed about 87 degrees.
...
now their is a coolant temp threshold for activation of the per cylinder timing compensation tables it set to 60 degrees


so if we set that to say 88 so per cylinder timing comp only active above 88 degrees coolant temp
...

Originally Posted by Tor

It an interesting idea, but unfortunately I think there are too many factors influencing ECT and the variations are too small. It also seems there is a delay and it might apply the retard too late.
...

It seems I was a bit too fast to dicount that idea!

I had a look at a lot of logs. Warning a lot of pictures below!

It seems it could indeed work for my application. It seems ECT always goes above 89 deg above 6800 rpm i 5th gear. Sometimes it wil of course go above in lower gears too, see below.

Anyway, so I could edit my tables to look like this:



Street:

At slow speed/lower gear it will go above 89 deg, but will drop down again when speed increases so most of the time it will be below 89 degs in 3rd gear above 6800 rpm (or a lot lower or the whole pull) and in 4th gear it's only sometimes. This is almost regardless of ambient temps.

In 5th gear it will always (as far as the logs I looked through) be above 89 deg at above ca. 6800 rpm as stated above.

Track:

On a slow tracks, it will be permanetly above 89 deg (checked at medium and hot temp). In this case it's tough luck and not required, but at least safe side.

On a fast track when it's hot same applies, but it this case it would probaly FLKC in lower gears in any case. So permanent TCPC would maybe mean it can pull less FLKC.

On a fast track, at low temp it switches around 89 almost as described for street. Which leaves most 3rd gear below 89 and most 4th/5th above, which is ideal.

Evidence as follows:

Street:

Cold 3rd, 4th, 5th gear pull (ECT goes above 89 deg thus activating TCPC):


Cold 3rd gear pulls (ECT goes below 89 deg, thus deactivating TCPC at high rpm):


Hot 3rd gear (ECT drops below 89 deg, same as cold):


Hot 4th gear (ECT goes above 89 deg at very high rpm):


Hot 5th gear (ECT goes above 89 deg before reaching 6800 rpm - prior to this fast (cool) cruising in low gear):


Hot 3rd, 4th, 5th gear pull:


Track:

Slow track, max 140 kph (85 mph) (ECT always above 89) Buhu:

(Same applies with a log with around 20 deg C IATs)

Fast track at low temps 10 deg:


Fast track at low temps 10 deg another example:


Fast track at low temps 15 deg:


Fast track on hot days I only had logs with stock header, here ECT was above 89 deg most of the time.

For those who want to copy this, keep your problem rpm area and ambient conditions and goals in mind - i.e check your own logs if this will work for you. In my case the goal is to only reduce timing in 5th gear above 6800 rpm.

Thanks Steve, for giving me this idea. This could maybe work almost as per ger timing.


(edit: added another screenshot, and see that I need to check this for a single 5th gear pull, after cruising at high speed in low gear during cold conditions).

[Tor]

And... it works!

TCPC -1 deg on C + D and -2.46 on A and B. Activation ECT set to 88.8 deg.

Look how beautifully it cuts in during the first 5th gear pull and lowers the timing with 2.46 deg with no FLKC at all!!

Ambient temp around only 10 deg C and IAT 12 deg.

Second 5th gear it doesn't "cut in" since 88.8 deg is reached earlier, so it's gradually phased in from 0 at 6400 to -2.11 at 6800 and -2.46 at 7000 rpm, (A+B and -1 at B+C)

FLKC during second pull -0.65, which is a helluva lot better than the -3.8 that I had before.

This is after cruising at fairly high speed in 6th:


https://datazap.me/u/tor/tor-2352-tc...zoom=6854-9144

Here 3rd and 4th gear pulls where TCPC is not applied:


https://datazap.me/u/tor/tor-2352-tc...537&mark=12481

[Baron_T]

Originally Posted by Tor

And... it works!

TCPC -1 deg on C + D and -2.46 on A and B. Activation ECT set to 88.8 deg.

Could you please post pix of your TCPC tables? I think I lost track of which places you've zeroed them and where you've pulled a bit of timing.

(For those of us who live in places where we can't legally cruize at 160+ klicks, and so can't just go and repeat your runs ourselves.)

Thanks!

[Tor]

Originally Posted by Baron_T

Could you please post pix of your TCPC tables? I think I lost track of which places you've zeroed them and where you've pulled a bit of timing.

(For those of us who live in places where we can't legally cruize at 160+ klicks, and so can't just go and repeat your runs ourselves.)

Thanks!

Here you go. But I think this is not universially applicable, you need to take your own timing/fuel quality into account. But it's probably not a bad starting point.

As for the temperature (191.8 f), we tried it on another car which has the Forrester heat exhanger and here the temp 88.8 c/191.8 f was too low. Either the heat exchanger raises the ECT a bit or there is variation in the thermostats. So you might want to experiment to find your sweet spot.

You would want to set it high enough that ECT stays below the threshold (or drops below before 6400 rpm from the cooling effect of the increasing speed) during the pull.

And low enought that the heat buildup during high a gear pull (where the increased engine temp exceeds the cooling effect) causes it to activate before 6800 rpm.