White specks on pistons and heads, also issues
09-05-2017, 10:31 PM
#41
Ethanol blends and pump gas are a different story. Race gas burns slow. C16 takes a surprising amount of timing and likes to be lean. Nothing like E85 or pump gas in my experience. Running it rich and retarded can cause problems.
But I do think you are going at it the right way. start low and work your way up watching plugs is always the only correct answer IMO.
As an example I tuned a 10:1 370 twin setup on C16. At the end of the day we left it at 24* and 25lbs 12.0 AFR. Plugs aren't even on the edge. 9 heat range. A2A IC.
Wiith race gas in general the only real reason to run lower than 15* or so is if you are fuel/octane limited or need to pull power near peak torque to keep weak parts together. Then it's usually added back after pk tq. With good fuel at the power levels you are shooting for that combo isn't octane limited on C16.. Nothing like E85 or pump gas in my experience.
But I do think you are going at it the right way. start low and work your way up watching plugs is always the only correct answer IMO.
As an example I tuned a 10:1 370 twin setup on C16. At the end of the day we left it at 24* and 25lbs 12.0 AFR. Plugs aren't even on the edge. 9 heat range. A2A IC.
Wiith race gas in general the only real reason to run lower than 15* or so is if you are fuel/octane limited or need to pull power near peak torque to keep weak parts together. Then it's usually added back after pk tq. With good fuel at the power levels you are shooting for that combo isn't octane limited on C16.. Nothing like E85 or pump gas in my experience.
Last edited by Forcefed86; 09-05-2017 at 10:55 PM.
09-06-2017, 12:13 PM
#43
Agreed. Yea, we are making some tuning changes. Fuel shouldn't be an issue. Might be a touch rich. And on timing, Game Ova your correct. same as fuel, it can be too safe and cause issues just like being too far the other way. Needless to say its like walking a tight wire.
09-07-2017, 01:59 PM
#45
Rule #1 (lol at #1) Don't assume anything
When I thought he is using 93 octane, I said I wanted to see the dyno chart at 7* etc.. along with EGT data. This is a given, we can collect this point on a graph, then we can plot the other points and chart a curve for behavior. Usually 9 degrees to 12 degrees is common between 5 and 18psi of boost pressure so it would not be uncommon for me to test these points as well near 9*, such as 7 and 5 if necessary. I wouldn't try 5 unless 7 gave me a reasonable EGT. I would try 3 and 1 and -1 etc... if I kept getting reasonable EGT.
Actually, I am glad you brought this up, thank you. What happens when timing is too retarded? A: Too much fire in the exhaust, and a high EGT is the result. This is why we use $80 EGT gauge from ebay-china as a minimum installed to the O2 bung temporarily to find the high EGT zone for timing which defines points on our graph from above.
800 horsepower without EGT, what I am saying is, in ordinary situations we would look at all the results like we are doing right now, to the best of our ability, which is lacking EGT data of course. So what else can we see: The IAT is incredibly low, that is amazing. The fuel is very high octane leaded racing fuel. The compression total (including boost pressure) at 20psi is considered very low (some are using 30psi+ with similar fuel). So this should be a very very safe condition to run the engine in, when we take everything into account. The only thing that stands out to me is the super-rich unnecessarily air fuel ratio of approaching 10:1 which was commented on about, and I hope that fixes it for you. If you avoid EGT data it is still possible to use traditional method of torque percentage increase per timing increment, although again I stress to examine the graph with smoothing=0 and use this as part of the equation for optimal timing
Example daily driver:
8* Engine breaks up, wont run
13* Engine runs normal. EGT is too high approachin 1610*F let off. Short run terminated.
21* Engine runs normal. EGT is 1440*F. Torque is smooth line. 500ftlbs
26* Engine runs normal. EGT is 1420*F. Torque is bumpy. 527ftlbs due to a jagged peak isolated event.
31* Engine runs normal. EGT is 1400*F. Torque is hard to read. 530ftlbs.
Then we look at temperature. The condition on the dyno hot, but not as hot as daily driver traffic, concrete Florida sun heat. When the temp rises the imaginary "graph" for temp vs effective octane shifts, because now combustion reaction is faster. So if I got the above results, I would still optimally want one more point on my graph, either to the left or right of 20*.
So one final pass immediately without cooling down:
18* Engnine runes normal. EGT is 1440*F. Torque is smooth line. 497ftlbs.
I would leave this thing at 18* and use IAT compensation to pull 1-2 more if IAT goes above 115*F as the max recorded IAT was 110*F after two or three consecutive pulls. Notice now my dyno graph is minus 50 or 80 horsepower depending on the max output of the engine (up to 1k) and that I could use smoothing=5 to cover up spikes in the torque graph which got me there.
If this were a race car we would consult with multiple engineers and consider things like risk and replacement engines etc... then push timing as far as possible against some probability that is costs us an engine and the labor to change it.
When I thought he is using 93 octane, I said I wanted to see the dyno chart at 7* etc.. along with EGT data. This is a given, we can collect this point on a graph, then we can plot the other points and chart a curve for behavior. Usually 9 degrees to 12 degrees is common between 5 and 18psi of boost pressure so it would not be uncommon for me to test these points as well near 9*, such as 7 and 5 if necessary. I wouldn't try 5 unless 7 gave me a reasonable EGT. I would try 3 and 1 and -1 etc... if I kept getting reasonable EGT.
800 horsepower without EGT, what I am saying is, in ordinary situations we would look at all the results like we are doing right now, to the best of our ability, which is lacking EGT data of course. So what else can we see: The IAT is incredibly low, that is amazing. The fuel is very high octane leaded racing fuel. The compression total (including boost pressure) at 20psi is considered very low (some are using 30psi+ with similar fuel). So this should be a very very safe condition to run the engine in, when we take everything into account. The only thing that stands out to me is the super-rich unnecessarily air fuel ratio of approaching 10:1 which was commented on about, and I hope that fixes it for you. If you avoid EGT data it is still possible to use traditional method of torque percentage increase per timing increment, although again I stress to examine the graph with smoothing=0 and use this as part of the equation for optimal timing
Example daily driver:
8* Engine breaks up, wont run
13* Engine runs normal. EGT is too high approachin 1610*F let off. Short run terminated.
21* Engine runs normal. EGT is 1440*F. Torque is smooth line. 500ftlbs
26* Engine runs normal. EGT is 1420*F. Torque is bumpy. 527ftlbs due to a jagged peak isolated event.
31* Engine runs normal. EGT is 1400*F. Torque is hard to read. 530ftlbs.
Then we look at temperature. The condition on the dyno hot, but not as hot as daily driver traffic, concrete Florida sun heat. When the temp rises the imaginary "graph" for temp vs effective octane shifts, because now combustion reaction is faster. So if I got the above results, I would still optimally want one more point on my graph, either to the left or right of 20*.
So one final pass immediately without cooling down:
18* Engnine runes normal. EGT is 1440*F. Torque is smooth line. 497ftlbs.
I would leave this thing at 18* and use IAT compensation to pull 1-2 more if IAT goes above 115*F as the max recorded IAT was 110*F after two or three consecutive pulls. Notice now my dyno graph is minus 50 or 80 horsepower depending on the max output of the engine (up to 1k) and that I could use smoothing=5 to cover up spikes in the torque graph which got me there.
If this were a race car we would consult with multiple engineers and consider things like risk and replacement engines etc... then push timing as far as possible against some probability that is costs us an engine and the labor to change it.
Last edited by kingtal0n; 09-07-2017 at 02:06 PM.
09-07-2017, 02:27 PM
#48
09-07-2017, 02:40 PM
#50
Oh, well in that case...its simple. Timing that is too retarded, could lead to the same basic end result. A pile of junk under the hood, AKA hurt motor. Much like too much fuel can be as bad as not enough, as with most things.... there's a balance.
09-07-2017, 04:54 PM
#51
Only if you don't have an EGT sensor. Or some confidence in the engine otherwise.
For example, I dont have an EGT On my current LSx turbo. I also am using 87 octane since thats all we have here atm. How can I tell the engine is safe?
1. Pulling plugs constantly
2. Using low/no boost (approx 3psi max)
3. Using minimal timing, current 12* at 3psi of boost seems to work great
4. Watching coolant temp for clues
5. Laser temp reads make sure nothing under the hood is getting too hot
eyes and ears work. If coolant temp got hot after a highway run I would suspect an issue with high EGT, for example. The fact the motor pulls the car strongly and there is no sign of elevating coolant temp means either my cooling system is super over-kill (it isn't) or the engine isn't producing a whole lot of "secondary heating effect" due to a retarded timing setting. Nothing on the plugs besides the typical carbon and cleaning also tells me its running good. What else can we do.... Think of more examples.
I put 220 miles on it with 87 octane in the last two days. Last night I had the differential come apart. The front of it sort of "slipped out" of the differential. I limped it to a friend's shop and he happened to have an exact replacement differential, took an hour to put that in. So, no troubles with the engine or transmission so far. Only nissan parts.
09-07-2017, 05:09 PM
#52
LOL between you and kingtalon I'm not sure who is more full of ****. Too much timing will cause detonation breaking ringlands, lifting heads, pushing coolant, torching heads/headgaskets/blocks, etc. Too little timing will make it have higher EGTs but it will generally be just fine. I've yet to see a motor come through a shop that was hurt by being "too safe" on timing but I've seen plenty that ramped in too much timing and the end result is VERY different.
09-07-2017, 05:50 PM
#53
LOL between you and kingtalon I'm not sure who is more full of ****. Too much timing will cause detonation breaking ringlands, lifting heads, pushing coolant, torching heads/headgaskets/blocks, etc. Too little timing will make it have higher EGTs but it will generally be just fine. I've yet to see a motor come through a shop that was hurt by being "too safe" on timing but I've seen plenty that ramped in too much timing and the end result is VERY different.Super fun to drive this 5.3/4l80 gtg drive it some more l8z
09-07-2017, 07:14 PM
#54
LOL between you and kingtalon I'm not sure who is more full of ****. Too much timing will cause detonation breaking ringlands, lifting heads, pushing coolant, torching heads/headgaskets/blocks, etc. Too little timing will make it have higher EGTs but it will generally be just fine. I've yet to see a motor come through a shop that was hurt by being "too safe" on timing but I've seen plenty that ramped in too much timing and the end result is VERY different.
09-08-2017, 11:21 AM
#57
Just to throw this in there it’s typical to drop timing into the 3-4* range for traction control on turbo LS setups. I do it all the time.
I’ve run as little as 0* of advance at peak torque on pump gas. Ramping back to 10-12* at redline… 34lbs of boost. (small engine stuff) I’ve personally never hurt a motor with too little timing.
To my knowledge, EGT’s go up to a point, but you aren’t running the engine in that range for long and its making so little power/cylinder pressure in that area. So it’s usually not hurting anything. I’m sure there are extreme cases and I wouldn’t suggest running extremely low advance for extended high load periods… But I seriously doubt you’ll hurt much.
Assuming you were flooding the cylinders and got the valves hot enough to self-ignite I could see some sort of serious damage happening. But I can’t see ever being in that scenario with a tune…unless you were totally clueless.
I’ve run as little as 0* of advance at peak torque on pump gas. Ramping back to 10-12* at redline… 34lbs of boost. (small engine stuff) I’ve personally never hurt a motor with too little timing.
To my knowledge, EGT’s go up to a point, but you aren’t running the engine in that range for long and its making so little power/cylinder pressure in that area. So it’s usually not hurting anything. I’m sure there are extreme cases and I wouldn’t suggest running extremely low advance for extended high load periods… But I seriously doubt you’ll hurt much.
Assuming you were flooding the cylinders and got the valves hot enough to self-ignite I could see some sort of serious damage happening. But I can’t see ever being in that scenario with a tune…unless you were totally clueless.
09-08-2017, 12:33 PM
#58
Just to throw this in there it’s typical to drop timing into the 3-4* range for traction control on turbo LS setups. I do it all the time.
I’ve run as little as 0* of advance at peak torque on pump gas. Ramping back to 10-12* at redline… 34lbs of boost. (small engine stuff) I’ve personally never hurt a motor with too little timing.
To my knowledge, EGT’s go up to a point, but you aren’t running the engine in that range for long and its making so little power/cylinder pressure in that area. So it’s usually not hurting anything. I’m sure there are extreme cases and I wouldn’t suggest running extremely low advance for extended high load periods… But I seriously doubt you’ll hurt much.
Assuming you were flooding the cylinders and got the valves hot enough to self-ignite I could see some sort of serious damage happening. But I can’t see ever being in that scenario with a tune…unless you were totally clueless.
I’ve run as little as 0* of advance at peak torque on pump gas. Ramping back to 10-12* at redline… 34lbs of boost. (small engine stuff) I’ve personally never hurt a motor with too little timing.
To my knowledge, EGT’s go up to a point, but you aren’t running the engine in that range for long and its making so little power/cylinder pressure in that area. So it’s usually not hurting anything. I’m sure there are extreme cases and I wouldn’t suggest running extremely low advance for extended high load periods… But I seriously doubt you’ll hurt much.
Assuming you were flooding the cylinders and got the valves hot enough to self-ignite I could see some sort of serious damage happening. But I can’t see ever being in that scenario with a tune…unless you were totally clueless.
09-08-2017, 02:21 PM
#59
And this is exactly what I was getting at, during an extended pull with ridiculously low timing across a broad number of cells in the upper range of rpm. Not the brief amount of time that traction control may be actively retarding timing, or the cell or two at peak torque.
as to the problem at hand: something else I can add, I thought of, if the trigger is bad or setup wrong, the timing can scatter, especially when high rpm and some kind of limiter is in use. I would say the trigger is the #1 most important aspect of the computer, and if its been changed around (the wheel removed/installed) or the wiring has been de-shielded for some reason (custom harness) just pay close attention to how the computer is getting its crank/cam info is what I am saying. If I setup a megasquirt ECU for example I twist the wires and shield them manually and inspect every inch of the wiring to make sure its golden, and if possible get an oscilloscope on it and use something to spin it at a high RPM to make sure the signal is correctly shaped.
09-10-2017, 07:34 PM
#60
As for the EGT and not having one. Its not a matter of affording one, its a matter of getting an EGT system that reads every cylinder and getting my headers setup with them. I don't run the truck often yet, haven't had a lot of time to mess with it and I have a second car which is a road race car that has also been needing work. Pulled the heads yesterday due to a blown head gasket and installing a Wilwood big bake kit on the front next weekend. We have a race in November coming up.
The truck will get an EGT setup as well as traction control installed. But for now, as forcefed stated, its not in any certain load area for long. While I do like my engines to run as perfect as possible, I am also learning EFI, Turbo and tuning with an ecm system. So for now I know enough to know I need to ask questions and seek some help.
The truck will get an EGT setup as well as traction control installed. But for now, as forcefed stated, its not in any certain load area for long. While I do like my engines to run as perfect as possible, I am also learning EFI, Turbo and tuning with an ecm system. So for now I know enough to know I need to ask questions and seek some help.