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

[Tor]

Originally Posted by solidONE

I'm not sure if you are running an oil cooler, but check out @DarkSunrise's logs. I'm not sure how much ignition advance he is sacrificing for the sake of having a knock resistant tune for the track, but it pretty damn solid if you asked me. I think a big contributor to this is his track oil temps. "Dem oil temps" "Dat knock resistance"

Track Data Log thread: http://www.ft86club.com/forums/showthread.php?t=108142

I don't think his oil temp is particularly low. But in any case I don't think FLKC and oil temp is directly related.

As I wrote a few posts back:

That our oil temps rise too along with the internals of the engine is given since both are dependant on how hard you run the engine. It doesn't mean that oil temp in itself is causing the knock.

Below one of my track logs. Oil never goes above 220 f (104 C), due to oil cooler and fairly low ambient temp. Still there is plenty FLKC. This log is taken from a Fomula 1 track, with long straights and lots of driving in 4th and 5th. I didn't log gear in this particular log, but you can see it from the speed (km/h).

What makes it hard to compare to his logs is that we don't know what gear he is in. From the rythm in the log I would suspect it's a short track and not in very high gears.

I think oil temp can be an indication of the temperature of the engine internals, but it doesn't have to be. As in:
- the engine internals may be significantly hotter than what the oil temp would lead you to believe. E.g. the log below.
- Or oil temp may be fairly hot due to ambient conditions, low speed (less cooling flow over the oil cooler), but the engine internal might not be as hot as the oil temperature would indicate (low gears, not that much strain on the engine).

http://datazap.me/u/tor/tor-2141-tra...ata=9-21-22-31

[solidONE]

Originally Posted by Tor

What makes it hard to compare to his logs is that we don't know what gear he is in. From the rythm in the log I would suspect it's a short track and not in very high gears.

I think oil temp can be an indication of the temperature of the engine internals, but it doesn't have to be. As in:
- the engine internals may be significantly hotter than what the oil temp would lead you to believe. E.g. the log below.
- Or oil temp may be fairly hot due to ambient conditions, low speed (less cooling flow over the oil cooler), but the engine internal might not be as hot as the oil temperature would indicate (low gears, not that much strain on the engine).

http://datazap.me/u/tor/tor-2141-tra...ata=9-21-22-31

That makes sense.. You are probably right, though do you have any comparable logs using the lower gears on the same tune? (on smaller track under similar oil/ambient temp operation?) Do they look less knock prone? Less kc?

It makes sense the 'same knock' would be more sustained or pronounced in higher gears since you hold those loads at the more knock prone rpms for a longer sustained amount of time (more work and heat in the moving parts for a given range of rpms. In this case past 6k rpms and up). Or, is it completely absent when you are running it in a similar fashion in the lower gears?

Another thing to consider is that your tune is likely less knock prone than what 90% of people are using on their 86brzs. But hey.. why not make it run better than 99.9% of the people that are running them on track. lmao

[Tor]

Originally Posted by solidONE

That makes sense.. You are probably right, though do you have any comparable logs using the lower gears on the same tune? (on smaller track under similar oil/ambient temp operation?) Do they look less knock prone? Less kc?

I was only on that one track with this tune.

Last year I was still on stock header and have some logs. The timing I used stg 1 was a lot more conservative:

The F1 track (Nürburgring GP circuit):
http://datazap.me/u/tor/track-0?log=...-19-27&solo=27

[ame="https://www.youtube.com/watch?v=2ynalp17k94"]Getting a grip on Nürburgring GP circuit (and GT86 vs. GT86) - YouTube[/ame]



And racepark meppen (mostly 3rd gear):
http://datazap.me/u/tor/track-logs?l...-22-31&solo=31

[ame="https://www.youtube.com/watch?v=7fJFfeIuM_I"]Best lap Racepark Meppen with GT86, 1:22 - YouTube[/ame]

[DarkSunrise]

Originally Posted by Tor

I don't think his oil temp is particularly low. But in any case I don't think FLKC and oil temp is directly related.

As I wrote a few posts back:


Below one of my track logs. Oil never goes above 220 f (104 C), due to oil cooler and fairly low ambient temp. Still there is plenty FLKC. This log is taken from a Fomula 1 track, with long straights and lots of driving in 4th and 5th. I didn't log gear in this particular log, but you can see it from the speed (km/h).

What makes it hard to compare to his logs is that we don't know what gear he is in. From the rythm in the log I would suspect it's a short track and not in very high gears.

I think oil temp can be an indication of the temperature of the engine internals, but it doesn't have to be. As in:
- the engine internals may be significantly hotter than what the oil temp would lead you to believe. E.g. the log below.
- Or oil temp may be fairly hot due to ambient conditions, low speed (less cooling flow over the oil cooler), but the engine internal might not be as hot as the oil temperature would indicate (low gears, not that much strain on the engine).

http://datazap.me/u/tor/tor-2141-tra...ata=9-21-22-31

Thanks for the mention @solidONE

To clarify, that was a pretty short track (2 miles) mainly in 3rd and 4th gears, hitting around 120-122 mph on one straight in 5th. With a Perrin oil cooler, oil temps have peaked as high as 243 F on hot days.

It's hard to say how much of a correlation there is between oil temps and FLKC for the reasons you listed. It's also worth noting that Subaru built coolant temp and IAT based timing reductions into the ECU logic, but not oil temp so perhaps coolant and IAT are more closely linked to FLKC in most cases.

Personally I've found that using the coolant temp based timing reduction was most effective for eliminating FLKC. I also pulled timing out of the base map, mostly in the 6000-7400 RPM range. I was aiming to reduce FLKC to 1 degree or less (same for KC), but everyone's comfort level with knock is different. I'm trying to take care of this engine and am willing to de-tune a bit for track use.

[solidONE]

I figure both your exhaust setups are similar UEL (Tomei and Gruppe-S ?) while tuning for very similar purpose of knock resistance under track duty. Probably a good idea for you guys to compare tunes, data logs, notes etc.

[solidONE]

Originally Posted by Tor

I was only on that one track with this tune.

Last year I was still on stock header and have some logs. The timing I used stg 1 was a lot more conservative:

The F1 track (Nürburgring GP circuit):
http://datazap.me/u/tor/track-0?log=...-19-27&solo=27


And racepark meppen (mostly 3rd gear):

Was the Stage 1 ignition timing really that much more conservative? Looks pretty close (roughly +1.3* past 6800rpm on the STG 2) in terms of the amount of ignition advance when the throttle is pinned. While not really a fair comparison, stock header vs catless UEL , between these 2 logs the one with more kc activity was with hotter oil temps. Neither logs had kc exceeding -1.5* at any point.

Zoomed in in the Nür/STG 2 log (110*C oil, 29*C IAT):
http://datazap.me/u/tor/track-0?log=...5987-5993-6000

Zoomed in on the meppen/STG 1 log (99*C oil, 26*C IAT):
http://datazap.me/u/tor/track-logs?l...5756-5742-5727

[DarkSunrise]

Originally Posted by solidONE

I figure both your exhaust setups are similar UEL (Tomei and Gruppe-S ?) while tuning for very similar purpose of knock resistance under track duty. Probably a good idea for you guys to compare tunes, data logs, notes etc.

Yeah not a bad idea although that was a JDL catless header and I've now switched to FT86SF catted. Haven't done a track day on this one yet.

[Tor]

Originally Posted by Tor

I'll try these changes and see how it works:

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.

http://datazap.me/u/tor/tor-226?log=...zoom=3588-4520



By the way, does anyone know if our cars have per gear fuel enrichment programmed in the ECU? It seems to me that it always runs richer in 5th.

[Tor]

Originally Posted by solidONE

Was the Stage 1 ignition timing really that much more conservative? Looks pretty close (roughly +1.3* past 6800rpm on the STG 2) in terms of the amount of ignition advance when the throttle is pinned. While not really a fair comparison, stock header vs catless UEL , between these 2 logs the one with more kc activity was with hotter oil temps. Neither logs had kc exceeding -1.5* at any point.

Zoomed in in the Nür/STG 2 log (110*C oil, 29*C IAT):
http://datazap.me/u/tor/track-0?log=...5987-5993-6000

Zoomed in on the meppen/STG 1 log (99*C oil, 26*C IAT):
http://datazap.me/u/tor/track-logs?l...5756-5742-5727

They are both stg 1. These two logs are the same tune and stock header on different tracks. What I meant was that I ran more conservative timing when I was still on the stock header. I.e. I tuned for no FLKC on street. The one with more FLKC was the one with higher speeds/gears (and yes oil temp too). Though I think the higher gears are the reason for the more FLKC which is what I wanted to point out with these two logs as a comparison (the Meppen log mainly FLKC at lowish rpm).

With the stg 2 tune I run now, I accept some FLKC on street and subsequently have a lot more FLKC when tracking (that one time so far this year):
http://datazap.me/u/tor/tor-2141-track-logs
(now 15+ tune revisions ago)

[solidONE]

Originally Posted by Tor

They are both stg 1. These two logs are the same tune and stock header on different tracks. What I meant was that I ran more conservative timing when I was still on the stock header. I.e. I tuned for no FLKC on street. The one with more FLKC was the one with higher speeds/gears (and yes oil temp too). Though I think the higher gears are the reason for the more FLKC which is what I wanted to point out with these two logs as a comparison (the Meppen log mainly FLKC at lowish rpm).

With the stg 2 tune I run now, I accept some FLKC on street and subsequently have a lot more FLKC when tracking (that one time so far this year):
http://datazap.me/u/tor/tor-2141-track-logs
(now 15+ tune revisions ago)

I can confirm that kc does seem to increase at the upper ranges (load/rpms) in the higher gears. I have plenty of logs that show this. Though whatever the case may be, be it friction or sustained loads increasing the heat it seems pretty obvious that heat is a major contributor to knock corrections. Regardless where the oil temps are at relative to the knock you are seeing or which gear you are in, cooler relative oil temps (down to a certain level) will always increase the knock resistance.

For instance, you are seeing the same kind of knock at 220*F oil temps that DarkSunrise only sees when he goes beyond 240*f. By maintaining the oil temps under 240*f, DarkSunrise can increase the knock resistance in his particular setup and tune, just as you can do the same keeping it under 220*f. One thing seems pretty constant across the board. Keeping cooler oil temps will more often than not increase the knock resistance for the setup short of pulling timing. If you dont want to see that much KC yet you are unwilling to sacrifice ignition advance or change anything else in your tune
(ie. increasing temp/load regulated ignition retard), then your other option is to increase the cooling capabilities under the same circumstance. One of the best ways to do that is an oil cooler. (though obviously you'd still want it warm enough to have the oil working at optimal temps etc)

Know what I mean?

Edit:
Just to illustrate I tried to do a couple of 5th gear pulls to redline after work just now at different oil/operating temps.

Below 210*f oil in 5th:
http://datazap.me/u/solidone/5th-gea...1&zoom=189-456

Above 220*f oil in 5th in the same log:
http://datazap.me/u/solidone/5th-gea...zoom=2982-3322

Unfortunately we don't have anything like autobahn so I couldn't quite hit redline in 5th safely. It's the same log so you know conditions are almost identical between the 2 pulls besides the oil temp. Also the gear status is not logging correctly on OFT, so you're just gonna have to take my word for it that the pulls were in 5th. lol

[Tor]

Originally Posted by solidONE

I can confirm that kc does seem to increase at the upper ranges (load/rpms) in the higher gears. I have plenty of logs that show this. Though whatever the case may be, be it friction or sustained loads increasing the heat it seems pretty obvious that heat is a major contributor to knock corrections. Regardless where the oil temps are at relative to the knock you are seeing or which gear you are in, cooler relative oil temps (down to a certain level) will always increase the knock resistance.

I'm still not convinced. I think the main factor that you see a difference in FLKC in your log is rather that your cylinder head temperature (CHT) / piston temperature has increased between the two pulls.

That oil temperature increased as well might simply be a because the engine is warmer between the two pulls. Obviously, oil temperature is a good indication of the general temperature of the engine. But still, I think this is a discussion like the chicken and the egg.

In the European GT86 VLN series, which is run exclusively on the Nürburgring Nordschleife, they run only a 6 row cooler oil cooler and 10W60 oil as far as I recall. As far as I know, commen wisdom is that a higher oil temperature (and oil that will maintain the proper viscosity at that temp) will yield more power due to less friction losses. So the question is if they have the same CHT as they would have had if they ran a 16 row cooler and a lower viscosity oil.

My point being, I think the general statement "cooler relative CHT temps will always increase the knock resistance" would be more correct.

If lower oil temps contribute to lower CHT to a degree that makes any difference to FLKC I can't say. Or if you reach the same temperature in the combustion chamber given the same loading up of the engine regardless of oil temperature.

I know this doesn't prove anything, has way too much other factors and the differences are too small. But take e.g. my recent log for entertainment:
http://datazap.me/u/tor/tor-2141-tra...ark=12153-8346

I marked two places. Both 6500 in 4th. With 102 deg oil, it pulls -1.8. Later on, in the log, it pulls more -2.5 with less 100 deg oil temp. My oil cooler setup is sufficient at those ambient temperatures to maintain a fairly constant oil temp, but CHT is probably varying depending on how much it was loaded prior to the instance.

Another log (same day) with 7000 rpm in 3rd, -3.22 and 105 C vs. -4.17 at 102 C.
http://datazap.me/u/tor/tor-2141-tra...rk=12192-10986

Of course I know both above doesn't prove anything at all. But what I am trying to say is that although an oil cooler is a good idea for a number of reasons, it might be easy to overestimate the benefit with regards to knock?

[Kodename47]

Is this a place to suggest a lower temp thermostat? Cosworth have always claimed this is worth a couple of degrees worth of timing advance as engine will run a little cooler.

[solidONE]

Originally Posted by Tor

That oil temperature increased as well might simply be a because the engine is warmer between the two pulls. Obviously, oil temperature is a good indication of the general temperature of the engine. But still, I think this is a discussion like the chicken and the egg.

My point being, I think the general statement "cooler relative CHT temps will always increase the knock resistance" would be more correct.

That makes perfect sense, actually. What I'm suggesting is that lower oil temp = less knock, which may very well be lower oil temp -> lower CHT leading to less knock, .

Originally Posted by Kodename47

Is this a place to suggest a lower temp thermostat? Cosworth have always claimed this is worth a couple of degrees worth of timing advance as engine will run a little cooler.

Interesting.. Since Tor's oil temps already look pretty decent under track abuse this may be worth looking into. Keeping the temps stable and low can only help, I'd think, however this is achieved. Oil cooler, thermostat, hood vents, shrouds to direct cooling air, etc etc. The more the merrier without overcooling for your specific application.

[Tor]

Originally Posted by solidONE

That makes perfect sense, actually. What I'm suggesting is that lower oil temp = less knock, which may very well be lower oil temp -> lower CHT leading to less knock, .



Interesting.. Since Tor's oil temps already look pretty decent under track abuse this may be worth looking into. Keeping the temps stable and low can only help, I'd think, however this is achieved. Oil cooler, thermostat, hood vents, shrouds to direct cooling air, etc etc. The more the merrier without overcooling for your specific application.

From the things you list, the thermostat may well be the more effective of the things with regards to knock as the coolant is probably the main factor in keeping the internal engine temperature down.

But what are the disadvantages?