View Poll Results: If you've Overheated What is Your Stage Aero 1, 2 or 3
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ZO6 overheating issues ***MEGA Merge***
06-22-2015, 06:34 PM
#2841
One guy had a faulty reservoir causing overheating in normal day to day operation, and from just that one instance of a bad part I've seen at least two threads with people saying things like "a few reportedly overheating on the street".
Really people, stop just spouting b.s.
Really people, stop just spouting b.s.
06-22-2015, 08:51 PM
#2842
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https://www.physicsforums.com/thread...engine.701885/
The other thing I wonder is the vct affected by the oil temps as it's pressure dependent and can affect the dcr.
Last edited by PRE-Z06; 06-22-2015 at 08:55 PM.
06-22-2015, 08:58 PM
#2843
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This is my belief as well. The computer may pull timing with 91 octane. If so a slight loss of power should occur. Other factors impacting coolant levels will overwhelm this small change in power.
Throttle position and gear selection are likely 1000 times more important for coolant temps. Here we are talking about a few HP difference at 100% throttle. If there is a loss of HP due to low octane, I gather the engine will produce less heat not more. Either way, it can only be a negligible amount.
Throttle position and gear selection are likely 1000 times more important for coolant temps. Here we are talking about a few HP difference at 100% throttle. If there is a loss of HP due to low octane, I gather the engine will produce less heat not more. Either way, it can only be a negligible amount.
An example of that in my experience was a v8 vega I had with 12.5:1 scr/230 cranking psi, that when I limped around on pump gas with retarded timing of course making less power it ran hotter than when I ran full timing with av gas.
Last edited by PRE-Z06; 06-22-2015 at 09:39 PM.
06-22-2015, 10:49 PM
#2844
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I agree load(driver) and the track may have an impact, but see above link for how you can produce less power yet create more heat. Diablo claimed ~50whp difference, that ~8% in their dyno thread.
An example of that in my experience was a v8 vega I had with 12.5:1 scr/230 cranking psi, that when I limped around on pump gas with retarded timing of course making less power it ran hotter than when I ran full timing with av gas.
An example of that in my experience was a v8 vega I had with 12.5:1 scr/230 cranking psi, that when I limped around on pump gas with retarded timing of course making less power it ran hotter than when I ran full timing with av gas.
06-23-2015, 12:18 AM
#2845
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I can't remember the thread, but I thought vengeance mentioned it being more than that when taking into account all modifiers...what is the timing differences from max to min including hot ECT/iat and low octane?
06-23-2015, 01:21 AM
#2846
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Would have to really look at it and figure it out but it's not a number you'd ever see. The ECM will never learn all the way to the Low Octane Map, just a little bit off the Hi map towards the Low Map. It doesn't just click to the Low Map, that's what the learning process is for.
06-23-2015, 08:23 AM
#2847
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Would have to really look at it and figure it out but it's not a number you'd ever see. The ECM will never learn all the way to the Low Octane Map, just a little bit off the Hi map towards the Low Map. It doesn't just click to the Low Map, that's what the learning process is for.
06-23-2015, 11:29 AM
#2848
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Simply put,
base spark timing map + IAT modifier + ECT modifier + flex fuel, humidity, etc modifiers + EQ Ratio modifier +variable cam modifier will give you a pre-torque management spark number (for a given g/cyl and rpm combination).
Torque management will take over spark (and throttle) during idle, dfco, shifts, etc etc.
Under full throttle with a stock config on 93 octane I doubt you will see over 22 degrees or under 12. Part throttle and other activities could be anywhere. Mine idles at 8-10 because of torque management wanting to smooth out throttle oscillations, I wanted to get it up to 15 (like with the old ones) but then I was like....Why?? It idles great, no issues, just let TM do it's thing as long as it isn't limiting power output.
06-23-2015, 03:37 PM
#2850
Le Mans Master
8 degrees is WAY more then enough under load to cause massive heating. I've tested it. I don't know where people pull these opinions out of...
I was also unaware that we could run E85. Is the Z06 really a flex fuel vehicle? I didn't get a badge for it :-)
There's also an error in the math on that page. See if you can find it.
I was also unaware that we could run E85. Is the Z06 really a flex fuel vehicle? I didn't get a badge for it :-)
There's also an error in the math on that page. See if you can find it.
06-23-2015, 04:14 PM
#2852
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8 degrees is WAY more then enough under load to cause massive heating. I've tested it. I don't know where people pull these opinions out of...
I was also unaware that we could run E85. Is the Z06 really a flex fuel vehicle? I didn't get a badge for it :-)
There's also an error in the math on that page. See if you can find it.
I was also unaware that we could run E85. Is the Z06 really a flex fuel vehicle? I didn't get a badge for it :-)
There's also an error in the math on that page. See if you can find it.
Who said you could run E85 and the Z06 is a Flex Fuel vehicle?
06-23-2015, 04:32 PM
#2853
Le Mans Master
And yes, I've done extensive testing and recording of data on this. Granted only on a dual-roller dyno, not the track. I've already explained it in reasonable detail elsewhere, I'm not going to beat the horse. Believe it or don't, trust me or don't.
The logs only show deltas from the base timing map and the changes in AFR, IAT, and coolant. They show conclusively that backing off timing generates MASSIVE heat under load.
Furthermore, I set the engine mount shielding on fire and got ejected from the emissions place (I was trying to pass without cats at the time, which was the impetus for messing with timing).
But you guys just need bigger heat exchangers because superchargers suck at the track. We all know that from reading it here daily.
Edit: Whoa - just to be clear, I'm talking about 8 degrees of timing advance, not temperature. Someone's talking about 45 up there and that can't be timing...
06-23-2015, 04:59 PM
#2854
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I never said it could. Read my post - I was surprised to hear it (because I didn't think it was true but since moving out of my mom's basement in 1984 lost the need to correct everything on the Internet).
And yes, I've done extensive testing and recording of data on this. Granted only on a dual-roller dyno, not the track. I've already explained it in reasonable detail elsewhere, I'm not going to beat the horse. Believe it or don't, trust me or don't.
The logs only show deltas from the base timing map and the changes in AFR, IAT, and coolant. They show conclusively that backing off timing generates MASSIVE heat under load.
Furthermore, I set the engine mount shielding on fire and got ejected from the emissions place (I was trying to pass without cats at the time, which was the impetus for messing with timing).
But you guys just need bigger heat exchangers because superchargers suck at the track. We all know that from reading it here daily.
Edit: Whoa - just to be clear, I'm talking about 8 degrees of timing advance, not temperature. Someone's talking about 45 up there and that can't be timing...
And yes, I've done extensive testing and recording of data on this. Granted only on a dual-roller dyno, not the track. I've already explained it in reasonable detail elsewhere, I'm not going to beat the horse. Believe it or don't, trust me or don't.
The logs only show deltas from the base timing map and the changes in AFR, IAT, and coolant. They show conclusively that backing off timing generates MASSIVE heat under load.
Furthermore, I set the engine mount shielding on fire and got ejected from the emissions place (I was trying to pass without cats at the time, which was the impetus for messing with timing).
But you guys just need bigger heat exchangers because superchargers suck at the track. We all know that from reading it here daily.
Edit: Whoa - just to be clear, I'm talking about 8 degrees of timing advance, not temperature. Someone's talking about 45 up there and that can't be timing...
yes, severely retarded timing will generate increased temps vs optimal timing, that is well known. running 17 or 15 vs 20, in my experience, has not changed coolant temps by any measurable amount.
06-23-2015, 05:14 PM
#2855
Le Mans Master
i guess we just miscommunicated then. and the linked example was talking about 45 degrees of spark timing vs static cylinder pressure with no spark, which is all i was referencing with my example.
yes, severely retarded timing will generate increased temps vs optimal timing, that is well known. running 17 or 15 vs 20, in my experience, has not changed coolant temps by any measurable amount.
yes, severely retarded timing will generate increased temps vs optimal timing, that is well known. running 17 or 15 vs 20, in my experience, has not changed coolant temps by any measurable amount.
06-23-2015, 05:16 PM
#2856
I never said it could. Read my post - I was surprised to hear it (because I didn't think it was true but since moving out of my mom's basement in 1984 lost the need to correct everything on the Internet).
And yes, I've done extensive testing and recording of data on this. Granted only on a dual-roller dyno, not the track. I've already explained it in reasonable detail elsewhere, I'm not going to beat the horse. Believe it or don't, trust me or don't.
The logs only show deltas from the base timing map and the changes in AFR, IAT, and coolant. They show conclusively that backing off timing generates MASSIVE heat under load.
Furthermore, I set the engine mount shielding on fire and got ejected from the emissions place (I was trying to pass without cats at the time, which was the impetus for messing with timing).
But you guys just need bigger heat exchangers because superchargers suck at the track. We all know that from reading it here daily.
Edit: Whoa - just to be clear, I'm talking about 8 degrees of timing advance, not temperature. Someone's talking about 45 up there and that can't be timing...
And yes, I've done extensive testing and recording of data on this. Granted only on a dual-roller dyno, not the track. I've already explained it in reasonable detail elsewhere, I'm not going to beat the horse. Believe it or don't, trust me or don't.
The logs only show deltas from the base timing map and the changes in AFR, IAT, and coolant. They show conclusively that backing off timing generates MASSIVE heat under load.
Furthermore, I set the engine mount shielding on fire and got ejected from the emissions place (I was trying to pass without cats at the time, which was the impetus for messing with timing).
But you guys just need bigger heat exchangers because superchargers suck at the track. We all know that from reading it here daily.
Edit: Whoa - just to be clear, I'm talking about 8 degrees of timing advance, not temperature. Someone's talking about 45 up there and that can't be timing...
Dialing back the timing under load will likely increase heat AFTER the charge starts down the exhaust path because the fuel could possibly still be burning as it leaves the cylinder during the exhaust stroke.
Conversely with increased ignition timing (increased meaning closer to perfect) the cylinder temperature will increase due to a more complete burn of fuel at the optimum moment. This will likely transfer more heat to the cars cooling system (coolant) because this heat will be closer to were combustion was designed to occur. As opposed to in the exhaust tubing.
So from where I sit you are both perfectly correct but talking temperature increases at different places.
06-23-2015, 05:18 PM
#2857
Dave/Higgs I think if you clarified where the excessive heat is created you all may come to an understanding.
Dialing back the timing under load will likely increase heat AFTER the charge starts down the exhaust path because the fuel could possibly still be burning as it leaves the cylinder during the exhaust stroke.
Conversely with increased ignition timing (increased meaning closer to perfect) the cylinder temperature will increase due to a more complete burn of fuel at the optimum moment. This will likely transfer more heat to the cars cooling system (coolant) because this heat will be closer to were combustion was designed to occur. As opposed to in the exhaust tubing.
So from where I sit you are both perfectly correct but talking temperature increases at different places.
Dialing back the timing under load will likely increase heat AFTER the charge starts down the exhaust path because the fuel could possibly still be burning as it leaves the cylinder during the exhaust stroke.
Conversely with increased ignition timing (increased meaning closer to perfect) the cylinder temperature will increase due to a more complete burn of fuel at the optimum moment. This will likely transfer more heat to the cars cooling system (coolant) because this heat will be closer to were combustion was designed to occur. As opposed to in the exhaust tubing.
So from where I sit you are both perfectly correct but talking temperature increases at different places.
06-23-2015, 06:25 PM
#2858
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Great thread you guys rock!
For what its worth. I use to drag race Polaris snowmobiles in the 80s and early 90's in Pro stock and Mod classes. Our Pro stocker 3 cly. had 230 lbs compression @ 10,500 rpm's, extreme pressures for sure. We ran 123 + Octane from Sunoco and a oxygen additive which was not legal!
Our motor builder always said the super high octane created less engine temp than regular fuel. We use to temp meter every pipe within 3 inches of the cylinder. I do remember the ability to run much larger jets as the octane increased. We could also run much more timing with the higher octane. The comparisons to the lower compression mod sled.
I think some of this correlates with our Z06 engine temps and higher octanes, kind of makes some sense, to me with my experiences.
For what its worth. I use to drag race Polaris snowmobiles in the 80s and early 90's in Pro stock and Mod classes. Our Pro stocker 3 cly. had 230 lbs compression @ 10,500 rpm's, extreme pressures for sure. We ran 123 + Octane from Sunoco and a oxygen additive which was not legal!
Our motor builder always said the super high octane created less engine temp than regular fuel. We use to temp meter every pipe within 3 inches of the cylinder. I do remember the ability to run much larger jets as the octane increased. We could also run much more timing with the higher octane. The comparisons to the lower compression mod sled.
I think some of this correlates with our Z06 engine temps and higher octanes, kind of makes some sense, to me with my experiences.
06-23-2015, 06:50 PM
#2859
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Dave/Higgs I think if you clarified where the excessive heat is created you all may come to an understanding.
Dialing back the timing under load will likely increase heat AFTER the charge starts down the exhaust path because the fuel could possibly still be burning as it leaves the cylinder during the exhaust stroke.
Conversely with increased ignition timing (increased meaning closer to perfect) the cylinder temperature will increase due to a more complete burn of fuel at the optimum moment. This will likely transfer more heat to the cars cooling system (coolant) because this heat will be closer to were combustion was designed to occur. As opposed to in the exhaust tubing.
So from where I sit you are both perfectly correct but talking temperature increases at different places.
Dialing back the timing under load will likely increase heat AFTER the charge starts down the exhaust path because the fuel could possibly still be burning as it leaves the cylinder during the exhaust stroke.
Conversely with increased ignition timing (increased meaning closer to perfect) the cylinder temperature will increase due to a more complete burn of fuel at the optimum moment. This will likely transfer more heat to the cars cooling system (coolant) because this heat will be closer to were combustion was designed to occur. As opposed to in the exhaust tubing.
So from where I sit you are both perfectly correct but talking temperature increases at different places.
but we are all good now.
06-23-2015, 07:29 PM
#2860
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Don't have to log to figure it out, you just look at the spark tables to find out the highest and lowest the ECM will command.
Simply put,
base spark timing map + IAT modifier + ECT modifier + flex fuel, humidity, etc modifiers + EQ Ratio modifier +variable cam modifier will give you a pre-torque management spark number (for a given g/cyl and rpm combination).
Torque management will take over spark (and throttle) during idle, dfco, shifts, etc etc.
Under full throttle with a stock config on 93 octane I doubt you will see over 22 degrees or under 12. Part throttle and other activities could be anywhere. Mine idles at 8-10 because of torque management wanting to smooth out throttle oscillations, I wanted to get it up to 15 (like with the old ones) but then I was like....Why?? It idles great, no issues, just let TM do it's thing as long as it isn't limiting power output.
Simply put,
base spark timing map + IAT modifier + ECT modifier + flex fuel, humidity, etc modifiers + EQ Ratio modifier +variable cam modifier will give you a pre-torque management spark number (for a given g/cyl and rpm combination).
Torque management will take over spark (and throttle) during idle, dfco, shifts, etc etc.
Under full throttle with a stock config on 93 octane I doubt you will see over 22 degrees or under 12. Part throttle and other activities could be anywhere. Mine idles at 8-10 because of torque management wanting to smooth out throttle oscillations, I wanted to get it up to 15 (like with the old ones) but then I was like....Why?? It idles great, no issues, just let TM do it's thing as long as it isn't limiting power output.