01-18-2024, 07:05 AM | #15 | |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
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As an HVAC Engineer I can comfortably say ALL pumps are subject to the laws of physics. So as I mentioned, as you attempt to raise pressure through the HPFP, you’ll reach a point where volume cannot keep up when you reach the physical limits of the pump. I have extensive experience with the LPE V2.0 pump in this regard. Attempting to increase volume through a fixed orifice will result in increased pressure, so that is what’s happening with the injectors. Again, great for a band aid on smaller injectors. But the pump itself, as you continue to request more pressure, will reach a point where the volume through the pump will not keep up and you’ll see the correlating rail pressure drop like a rock, likely due to cavitation within the positive displacement pump. Most people will not see this as the injectors are typically not big enough to max out the LPE’s output (with a bigger cam fuel lobe). Add +52 or +65 injectors and you reach the pumps pressure vs volume limitations pretty readily. Josh
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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01-18-2024, 07:21 AM | #16 | |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
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Your statement of higher pressure means less volume, then showing the electric pump chart, is incorrect in this case which I pointed out. PD pump volume = pressure and Pressure = volume. We log solenoid opening time, which controls the volume entering the piston chamber which in turn controls pressure and available volume. Ted.
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01-18-2024, 08:52 AM | #17 | |
Snackbar Tuning
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01-18-2024, 09:06 AM | #18 | |
Drives: 2016 1SS NFG A8 Join Date: Aug 2017
Location: 46804
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2016 NFG 1SS A8
Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA |
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01-18-2024, 09:41 AM | #19 | |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
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I have seen some trucks listed at 132 degrees but I don't know if that is a math problem in the software template. It is obviously being used to fill the chamber as low side pressure drops we see this number increase and vise versa. I raise inlet pressure and the duration goes down. Again we are dealing with Positive displacement, repeat it in your head Positive displacement, Hard limited, when it is full, it is full. We can only reduce it's displacement by limiting the opening time or limiting the inlet pressure or both. Ted.
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01-18-2024, 02:26 PM | #20 | |
Snackbar Tuning
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Let me rephrase. If you look at the leading edge table for an LT1 vs an LT4, the LT4 commands smaller values as fuel demand goes up. The LT4 isn't anywhere near 130 degrees at high RPMs and high fuel demand. I change the LT4 values in the highest demand areas to be close to where the LT1 would be and I thought I noticed an improvement in maintaining commanded pressure with high ethanol %'s on LT4 cars. I am curious if there is any concern with pushing the solenoid open time higher for high rpms and cams with larger fuel lobes and was asking if you had an experience to share on this. There isn't any information on if doing this could put too much load on the pump internals or the cam lobe itself. I haven't seen any issues yet but that could mean its just fine or it hasn't broken yet lol. |
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01-18-2024, 02:40 PM | #21 | |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
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The Leading Edge table is Provided by the pump manufacturer to Characterize the pump similar to how we are provided characterized injector data, so it can control pressure and make it as stable as possible based on fuel demand. When this table is off we see massive spikes in pressure in either direction depending if the table is too high or too low from actual. For example if we are controlling 2 Identical pumps on stock cam lobes on the same car we would just double the Y Axis and have perfect control of pressure. Knowing, what I think I know I don't mess with the values in the table unless I am changing pumps. No different than changing provided injector data that we know is right. NOTE: there are adaptive strategies running in the background that will likely wash away any changes you make to this table. Those adaptive strategies are there to compensate for wear over the life of the pump, I don't know how much range it has because I don't think we have the PIDs to log. Again same as injectors. Doing a little reading I believe the Leading edge has to do with current for the Solenoid to deliver the fuel at the right time, I also believe it references Crank Degrees for each cycle of the lobe. Ted.
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Celebrating 37 years Performance parts, Installation, Fabrication, Dyno tuning, Remote custom tuning, and alignments. 203-753-7223 Waterbury CT. 06705 email tedj@jannettyracing.com Last edited by JANNETTYRACING; 01-18-2024 at 02:50 PM. |
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01-18-2024, 03:30 PM | #22 |
Snackbar Tuning
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yes the only PID I know of references degrees and it seems to be crank degrees. Or maybe its cam degrees divided by the number of fuel lobes although that may not make sense.
LPE doesn't provide any data with their LPE pump. If the values in the leading edge table reference current to the solenoid, than upping the values for the LPE if installed into an LT4 engine with the stock LT4 lobe seem to be the correct thing to do. If you installed the LPE BB in an LT1 car with an LT1 fuel lobe, the OEM table would command more current/duration vs just installing the LPE BB in an LT4 car and leaving the stock values. Anyhow I appreciate the replies. I'm not arguing anything at all. I've never seen anyone discuss this topic before. So I'm not suggesting any of my points are absolute. They are just the comments to the best of my available knowledge and a little bit of theory. Thanks for discussing with me, Ted. |
01-18-2024, 03:37 PM | #23 | |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
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If you use a larger lobe 32% for example then 1.62.
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01-19-2024, 09:01 AM | #24 | |
Snackbar Tuning
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Do you mean 30% if its an LT1 or 10% if its an LT4? Based on volume over stock. |
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01-19-2024, 09:20 AM | #25 | |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
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I believe we should use the Leading edge table/original data of the pump in question even if that pump has been modified. So in LT4s with big bore pump we use LT1 Data then adjust the Axis as needed.
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01-19-2024, 11:01 AM | #26 | |
Snackbar Tuning
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So you're suggesting use the LT1 axis and leading edge values for the LPE? I saw some spikes in pressure when lifting the throttle using the LT4 axis. Maybe the LT1 axis would be better. |
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01-19-2024, 12:07 PM | #27 | |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
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01-19-2024, 03:02 PM | #28 |
Snackbar Tuning
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