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I believe knock retard is on of the most important things to look at regarding the "safety" of your tune. I have my car tuned to see no more than the occasional -3 on knock retard, mainly 0s with a few -1s and -2s on the street with 91 octane. At the track I run the same tune with a mix of 91/100 and while heavily heat soaked under load I still see no more than a few -3s. I would much rather leave a few hp on the table and run a safe tune with plenty of margin. You never know when you get a marginal batch of fuel and you want the ecu to have plenty of room for knock retard. We went though 4 versions of tune fine tuning it for my car. Dynojet numbers on 91 octane are 599whp/673rwtq, 100% emission legal with 100cell Emitec race cats.
Agreed, Safe is key while at the track. Knock, should be the first to log under these conditions.
I'll be honest, I don't fully understand "ignition angle." My understanding is, the top compression point of the cylinder compression to its relative ignition point. Not sure how it changes its actual angle (maybe under pressure, angle of ignition under compression?.) Maybe the actual gap of the plug? Maybe, the ignition timing reflects the piston TDC timing?
The ignition angle is just the angle between where the crankshaft is pointing and the top of the cylinder. Thus, when the piston is at top dead center, it's 0 degrees. The earlier it fires before top dead center, the larger the timing angle. The later it fires, the lower the angle. I drew a quick pic for reference. Sorry about the bad quality, it's from a bad webcam.
I believe knock retard is on of the most important things to look at regarding the "safety" of your tune. I have my car tuned to see no more than the occasional -3 on knock retard, mainly 0s with a few -1s and -2s on the street with 91 octane. At the track I run the same tune with a mix of 91/100 and while heavily heat soaked under load I still see no more than a few -3s. I would much rather leave a few hp on the table and run a safe tune with plenty of margin. You never know when you get a marginal batch of fuel and you want the ecu to have plenty of room for knock retard. We went though 4 versions of tune fine tuning it for my car. Dynojet numbers on 91 octane are 599whp/673rwtq, 100% emission legal with 100cell Emitec race cats.
that makes sense (leaving power on the table and keeping "safe"). Austin had mentioned in another thread that the stock tune can show timing retard of -12 iirc, which surprised me. Just wondering what people are seeing in the real world with their tunes. Different versions of my Cobb tune have had varying amounts of knock sensor activity. You could definitely tell it was the smoothest drive when there was no activity or very little activity.
that makes sense (leaving power on the table and keeping "safe"). Austin had mentioned in another thread that the stock tune can show timing retard of -12 iirc, which surprised me. Just wondering what people are seeing in the real world with their tunes. Different versions of my Cobb tune have had varying amounts of knock sensor activity. You could definitely tell it was the smoothest drive when there was no activity or very little activity.
I think this is what separates the really good tunes from the not so good tunes. It's easy to have a tune on the car that tries to extract the most power by relying on ignition retard but not so easy to have a tune that has the car right at the threshold before ignition retard starts to come into play to save the day. If you go too conservative you leave a lot of performance on the table. Ideally you want to be right under or at the threshold so that you have max performance combined with a lot of margin and safety left for the ECU to do it's job and save the day if need be. This can rarely be accomplished via canned tunes but rather through a lot of real time logging so that your files can be fine tuned for your application.
I think this is what separates the really good tunes from the not so good tunes. It's easy to have a tune on the car that tries to extract the most power by relying on ignition retard but not so easy to have a tune that has the car right at the threshold before ignition retard starts to come into play to save the day. If you go too conservative you leave a lot of performance on the table. Ideally you want to be right under or at the threshold so that you have max performance combined with a lot of margin and safety left for the ECU to do it's job and save the day if need be. This can rarely be accomplished via canned tunes but rather through a lot of real time logging so that your files can be fine tuned for your application.
I just did another run after adding some fresh 100 turbo blue (which may still be stale but at least it isn't watered down). The numbers look better. Can some of you expert tuners take a look at this and tell me what you think?
I'll be honest, I don't fully understand "ignition angle." My understanding is, the top compression point of the cylinder compression to its relative ignition point. Not sure how it changes its actual angle (maybe under pressure, angle of ignition under compression?.) Maybe the actual gap of the plug? Maybe, the ignition timing reflects the piston TDC timing?
The Crank spins 360 degrees in the case. As that happens the pistons are moving up and down in their respective cylinders. Ignition angle refers to the degrees (of crankshaft rotation) before the piston reaches top dead center (BTDC) that the ignition fires.
By firing the ignition "15 degrees BTDC" you're giving the air/fuel more time to burn and create cylinder pressure than if you fired the ignition 12 degrees BTDC. That's how you are picking up extra power.
There's a lot of variables - especially temperature and humidity that can change things. If you spend all day getting everything perfect, tomorrow things could be totally off. That's why the factory ECU has adjustment ranges. It sets a target, and then based on the conditions goes out and gets as close to the target as possible. People here tend to think that exact values are programmed and seem to argue while wearing their tuner of choice on their sleeve.
I just did another run after adding some fresh 100 turbo blue (which may still be stale but at least it isn't watered down). The numbers look better. Can some of you expert tuners take a look at this and tell me what you think?
Log ignition retard on EACH cylinder. That will tell a lot of the story. I suspect you are pulling a lot of timing in the mid to upper 3K range.
Log ignition retard on EACH cylinder. That will tell a lot of the story. I suspect you are pulling a lot of timing in the mid to upper 3K range.
Durametric does not support that and UMW/Cobb is just calculated. With 2 knock sensors the program applies the reading of the knock sensor to the cyclinder that is firing at the time - which is a bit of a guess.
OK I charted it out. There is a lot of other things you should be logging like short term fuel trims, long term fuel trims, timing corrections etc. Do you happen to know if you ROM id is a B742? Lambda is a little jagged but that could be due to the ROM you are running.
You are running around 22.5 psig at peak boost and it falls down.
Without logging timing correction (knock correction) it is hard to say if it is pulling timing but in the upper RPM's it looks to be holding good timing. 21 degrees at red line is a good amount at red line for 100 octane.
From what I see here I would say it looks to be running pretty good. Would like to see more data to be sure, but doesn't look bad.
Hope that helps,
-Mitch
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Wow, thank you, I appreciate the help interpreting these numbers! I'll try and get some of the other data in the future, but in the meantime I plan on getting one of your Accessport setups for my DD which is a BMW 335i. I think I've learned a good bit just scrolling through the tune options on your page. Thanks again!
Originally Posted by COBB Tuning
OK I charted it out. There is a lot of other things you should be logging like short term fuel trims, long term fuel trims, timing corrections etc. Do you happen to know if you ROM id is a B742? Lambda is a little jagged but that could be due to the ROM you are running.
You are running around 22.5 psig at peak boost and it falls down.
Without logging timing correction (knock correction) it is hard to say if it is pulling timing but in the upper RPM's it looks to be holding good timing. 21 degrees at red line is a good amount at red line for 100 octane.
From what I see here I would say it looks to be running pretty good. Would like to see more data to be sure, but doesn't look bad.
Durametric does not support that and UMW/Cobb is just calculated. With 2 knock sensors the program applies the reading of the knock sensor to the cyclinder that is firing at the time - which is a bit of a guess.
So we all know this statement isn't correct right...like at all
08-05-2015, 12:07 AM
