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Old 03-25-2015, 05:53 PM   #21
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Quote:
Originally Posted by DNMakinson View Post
I don't think you will see it. Look for information about latency. I think the general recommendation is idle to 4K is sufficient.

Lock the timing, then rev engine and timing should not move with RPM. If it does, adjust the latency so that your tables are set to is what you get.
Yeah, I didn't specifically choose 6K, but I was doing it alone and my USB cable isn't long enough to look at the laptop screen and the timing light at the same time so I had to guess.

Oh, and one last step, don't forget to switch it back to table-based timing before you drive it!

--Ian
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Old 03-26-2015, 12:02 AM   #22
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Originally Posted by Chiburbian View Post
Is Harold (HHammerly) running an ATI Damper? What are his spark latency settings? Perhaps there is a common thread?
I have the stock dampner, triger wheel and sensor, the only change i made there was to install bigger dampner bolts. I will have my computer back tomorrow and will post my map and settings but my timing is even more RETARDED than yours.
I did not have this issue on my first motor but it came up as soon as i installed the new cam, maley roods (vs scott's) everithing else is the same on both builds.
Since seeing the need for low timing Iv checked base timing, TDC marks on the pulley vs piston position, cam timing, sent out the injectors for flow test, installed 4 EGT's (do not see high EGT as expected w retarded timing), dual feed rail, rising rate regulator and cannot find anything wrong, the car makes good power 337hp @ 18psi on the (happy dyno so that probably is more like 300)
Interested to see what you find ...
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Old 03-26-2015, 02:50 AM   #23
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So I rechecked the spark latency -- there's no "power cycle required" for it, and 100 usec makes a pretty small difference in the timing at 4K, something like 1 degree difference between 0 and 100. We tried a few values and decided that 50 was the best fit.

Braineack: When you saw that huge difference, was it an NA cam sensor or an NB crank sensor?

The good news is that I was able to advance it a bit from the massively retarded map above on the dyno without suffering massive ping. I dunno what the difference is exactly. I needed to add more fuel this morning, 3 gallons each of 100 and 91. That should deliver the same 95 as I had in the tank before, but...



The bad news is that the dyno results were disappointing, at 230 kpa it only made 275 each on torque and horsepower. It was actually able to reach MBT at 190 kpa and below, 215 was slightly ping-y at MBT, and 230 was spark limited.



I'll post further discussion about the power (or lack thereof) in my build thread.

--Ian
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Old 03-26-2015, 05:22 PM   #24
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Based on what you've posted, my guess is either those pistons are creating hot spots (known issue with super tech pistons, did you modify them?) OR your wideband is lying to you and you need more fuel. What is your AFR at peak torque?

FWIW, when I tune my car for a street car/DD and expect reliability, I keep spark around 5* retarded from MBT or whatever value = detonation, and keep the fuel in the low 11's. High tens when AIT's get above 120s *F. This is close to how OEMs tune turbo cars.

For testing I'd add some fuel and see if the detonation stops.
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Old 03-26-2015, 05:23 PM   #25
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Also only other thought of a cause could be sharp edges in cylinder head from machine work, is that a possibility?
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