[Joshinator99]

Originally Posted by JANNETTYRACING

Not trying to argue trying to educate.

You presented a chart for electric pump which is accurate, stating that higher pressure means less volume.

True for electric pumps.

Reason for that is more about the resistance to pump motor RPM falling as pressure is requested.

Which is why Amp draw goes up with requested pressure.

However with a positive displacement piston pump that is not the case, UNTIL you try to exceed the displacement.

In order to have higher pressure you must have higher volume with a PD pump.

The PD pump pressure is controlled via the volume allowed in to the piston chamber.

Volume = pressure.

So in summary your chart is not relevant when speaking about PD pumps.

Open for discussion.

Ted.

Hi Ted,

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

[JANNETTYRACING]

Originally Posted by Joshinator99

Hi Ted,

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

I agree, I never said anything about trying to increase pressure when past PD displacement.

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.

[Megahurtz]

Originally Posted by JANNETTYRACING

I agree, I never said anything about trying to increase pressure when past PD displacement.

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.

On a side note Ted. Have you found that increasing the solenoid open time on LT4 cars benefits volume/pressure? Since the LPE is based on an LT1 pump and the LT1 OEM config has longer solenoid opening times than the LT4 config, I typically increase the values on LT4 cars. Pretty sure I was able to see more flow this way but no one really talks about this or if it's bad for the pump or engine at higher RPM to raise these values. Curious if you have any knowledge to share here.

[KingLT1]

Originally Posted by Megahurtz

On a side note Ted. Have you found that increasing the solenoid open time on LT4 cars benefits volume/pressure? Since the LPE is based on an LT1 pump and the LT1 OEM config has longer solenoid opening times than the LT4 config, I typically increase the values on LT4 cars. Pretty sure I was able to see more flow this way but no one really talks about this or if it's bad for the pump or engine at higher RPM to raise these values. Curious if you have any knowledge to share here.

That is a great question and something I would be curious to know more about as well.

[JANNETTYRACING]

Originally Posted by Megahurtz

On a side note Ted. Have you found that increasing the solenoid open time on LT4 cars benefits volume/pressure? Since the LPE is based on an LT1 pump and the LT1 OEM config has longer solenoid opening times than the LT4 config, I typically increase the values on LT4 cars. Pretty sure I was able to see more flow this way but no one really talks about this or if it's bad for the pump or engine at higher RPM to raise these values. Curious if you have any knowledge to share here.

Both LT1 and LT4 have 130 Degrees max.

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.

[Megahurtz]

Originally Posted by JANNETTYRACING

Both LT1 and LT4 have 130 Degrees max.

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.

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.

[JANNETTYRACING]

Originally Posted by Megahurtz

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.

It is my understanding ( I could be totally wrong but testing has proven my theory so far)

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.

[Megahurtz]

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.

[JANNETTYRACING]

Originally Posted by Megahurtz

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.

With the LPE pump you do not alter the table just multiply the Y Axis by the percent the pump volume is larger than the stock one which works out to about 30% if my memory serves me, so multiply by 1.3

If you use a larger lobe 32% for example then 1.62.

[Megahurtz]

Originally Posted by JANNETTYRACING

With the LPE pump you do not alter the table just multiply the Y Axis by the percent the pump volume is larger than the stock one which works out to about 30% if my memory serves me, so multiply by 1.3

If you use a larger lobe 32% for example then 1.62.

Do you mean 30% if its an LT1 or 10% if its an LT4? Based on volume over stock.

[JANNETTYRACING]

Originally Posted by Megahurtz

Do you mean 30% if its an LT1 or 10% if its an LT4? Based on volume over stock.

Not really

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.

[Megahurtz]

Originally Posted by JANNETTYRACING

Not really

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.

That's exactly how my conversation started out lol. Saying that the LT1 data seemed more relevant to the LPE pump when used in an LT4. That's why I modify the LT4 data in the leading edge table (I leave the axis stock).

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.

[JANNETTYRACING]

Originally Posted by Megahurtz

That's exactly how my conversation started out lol. Saying that the LT1 data seemed more relevant to the LPE pump when used in an LT4. That's why I modify the LT4 data in the leading edge table (I leave the axis stock).

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.

Copy the whole table and both axis from an LT1 then multiply the Y Axis by 1.3 or 1.62 if using a 32% lobe.

[Megahurtz]

Originally Posted by JANNETTYRACING

Copy the whole table and both axis from an LT1 then multiply the Y Axis by 1.3 or 1.62 if using a 32% lobe.

That makes more sense lol