Vaporworx / Rick's Tank Problem - dropping fuel pressure at high rpm?

[carbuff]

Carl,

Thank you for responding with so much information! Of all of the suggestions that you have provided, I think the following may be the one I need to focus on:

Originally Posted by CarlC

You may also want to check that the wire gauge to the relay(s) is 14ga minimum and that there is not a large voltage drop to the relay output. The Gen5 LS3 pump needs 12 amps.

I'm using the 'relay' from the Holley HP EFI kit, which supposedly will source 10A. I do have 12 or 14ga wire, I don't recall which at the moment. I unfortunately do not have a good way to measure the actual voltage at the pump itself, but if it requires 12A, then it's very possible that I have a limitation on the available current. I did not run an extra relay for the pump itself, since I was under the impression that the HP EFI could source it. That may be my mistake.

If I'm going to dig back into this wiring, then it may be a good time for me to go ahead and install your PWM controller instead of just a relay. I don't think it was available when I made this original purchase, which is why I don't have one now...

I will contact you via PM about acquiring one...

Thanx again!

[CarlC]

I'm glad to help Bryan.

If you want to to a check of the wiring remove the circuit that connects the relay to the fuel pump. Take the output from the relay and run it to BAT + (assuming it's +). Do the same for the negative, or confirm that the chassis ground is secure and has direct contact with the chassis material, i.e. no paint, corrosion, etc. It won't hurt the pump to connect it like this with the engine not running. Connect everything with the engine off, then try running the car again. Use an in-line fuse to protect the circuit. The circuit should be capable of 20A in either case.

In the end you may well find out that the LS3 pump is a bit small for the build. The ZL1 has almost identical form, fit, and function to the LS3, the only difference being that the ZL1 won't compress quite as much as the LS3 due to the taller pump in the module reservoir. This is only a factor if you have retro-fitted an older Rick's, Rock Valley, or stock tank since these are only 7" tall overall. All of the tanks fabricated by Rick's or RV have sufficient mouting height to accomodate either fuel module.

The basics of the PWM kits will interchange among the LS3, ZL1, an CTS-V single fuel modules. The LS3 and ZL1 kits are identical. The CTS-V has a different short harness since the wiring for the plug on the fuel module hat is different. In other words, if you have a PWM kit for an LS3 and want to use a ZL1, just put the new pump in and go. When running twin fuel modules, like that in Mark Stielow's latest builds, it requires a different controller tune to get the system happy when running both pumps at the sam time, plus there is a lot more wiring to tie in the second module.

[LowFlyin']

Originally Posted by carbuff

I'm using the 'relay' from the Holley HP EFI kit, which supposedly will source 10A. I do have 12 or 14ga wire, I don't recall which at the moment. I unfortunately do not have a good way to measure the actual voltage at the pump itself, but if it requires 12A, then it's very possible that I have a limitation on the available current. I did not run an extra relay for the pump itself, since I was under the impression that the HP EFI could source it. That may be my mistake.

If I'm going to dig back into this wiring, then it may be a good time for me to go ahead and install your PWM controller instead of just a relay. I don't think it was available when I made this original purchase, which is why I don't have one now...

I will contact you via PM about acquiring one...

Thanx again!

Hey carbuff, I was directed to this thread by a community member, I work for a fuel pump and injector manufacturer and was actually in the process of flow testing the stock LS3 pump from the 5th Gen Camaro.

From 30psi up to 100psi, it was using 10.6-15.2 amps @ 13.5 volts. If I'm reading your first sentence right, you are over extending the Holley EFI relay.

From the looks of it, the pumps is actually quite good. My numbers are showing for 675hp at the crank you'll need around 195LPH of fuel from the pump. At 60psi, the LS3 pump was putting out 220LPH by our testing equipment.

As Carl pointed out, you'll need around at least 45# injectors to keep the IDC's in the 80's with 675hp...and also a 44# injector at 58 psi will yield ~52#.

If your current injectors are essentially going static, I could see that being a source of your fuel pressure drop, as well.

[INTMD8]

Originally Posted by LowFlyin'

If your current injectors are essentially going static, I could see that being a source of your fuel pressure drop, as well.

If air/fuel ratio is correct that will not have an effect.

[carbuff]

Low,

Thank you for chiming in! Always good to have someone 'in-the-know' to offer help and information on these forums!

Originally Posted by LowFlyin'

From 30psi up to 100psi, it was using 10.6-15.2 amps @ 13.5 volts. If I'm reading your first sentence right, you are over extending the Holley EFI relay.

That seems to be the consensus. It is interesting to me that it will hold the 58PSI consistently though until I actually open the throttle and the RPM start to rise though. You can see that on the left and right of the picture below (the pink line).

From the looks of it, the pumps is actually quite good. My numbers are showing for 675hp at the crank you'll need around 195LPH of fuel from the pump. At 60psi, the LS3 pump was putting out 220LPH by our testing equipment.

That's obviously more PSI than I was seeing, but my measurements were after the injectors, so I don't know if we are actually comparing apples to apples...

As Carl pointed out, you'll need around at least 45# injectors to keep the IDC's in the 80's with 675hp...and also a 44# injector at 58 psi will yield ~52#.

If your current injectors are essentially going static, I could see that being a source of your fuel pressure drop, as well.

This touches on a subject that I need some education on, so anyone who can help, I would appreciate it!

My car currently has 39# injectors. As best I can tell, that rating is at 3 BAR, or 43.5PSI. I'm running my system at 58PSI (at least when it keeps up), so using the formula which I've found online, that converts to about 45# equivalent.

So your statement above, that I need 45# injectors, does that mean that I have them? Or are you saying that I need 45# injectors, rated at 3 BAR?

I attempted some math to determine if I am going static or not. What I came up with is this. At 6500 RPM, each revolution takes about 9.2 mS, and 2 revolutions takes 18.4 mS. I'll paste another screenshot from the Holley Datalogger below. It's telling me that the Injector Pulse width is running consistently in the range of 16.0 - 16.3mS. If that, and the above 18.4mS at 6500RPM is correct, that would be about 87% duty cycle at 6500rpm.

Also note in the new picture below that my actual AFR is hanging at almost exactly what my Target AFR is (after recovering from Acceleration Enrichment, caused by the rate-of-change in my TPS and MAP), which was set to 12.5:1 for this run. This is also the run which shows the rail fuel pressure dropped to 44PSI.

I find several things about this interesting. First, the Injector Pulse width stays almost constant throughout the RPM range. Maybe that makes sense if I'm requesting the same AFR at all times (which I believe I am, and the Target AFR line appears to show).

So... Do I need to increase my injector size? Based on AFR, they seem to be keeping up. And do I need to keep worrying about this, if my AFR is keeping on target?

I have decided to install one of Carl's Vaporworx PWM controllers, if for no other reason than to get a clean voltage to the pump that isn't limited by my ECU. I'll be curious to see what differences that makes on my readings!

Thanx!

[LowFlyin']

Originally Posted by carbuff

This touches on a subject that I need some education on, so anyone who can help, I would appreciate it!

My car currently has 39# injectors. As best I can tell, that rating is at 3 BAR, or 43.5PSI. I'm running my system at 58PSI (at least when it keeps up), so using the formula which I've found online, that converts to about 45# equivalent.

So your statement above, that I need 45# injectors, does that mean that I have them? Or are you saying that I need 45# injectors, rated at 3 BAR?

That statement was you need 45# worth of fuel coming out of the injectors to be in the 80% duty cycle range. I know the whole nominal flow vs. actual flow thing can be a little confusing.

I think your injectors are spot on as most injectors are controllable up to 92-3%, so you do have some headroom available.

Originally Posted by carbuff

I attempted some math to determine if I am going static or not. What I came up with is this. At 6500 RPM, each revolution takes about 9.2 mS, and 2 revolutions takes 18.4 mS. I'll paste another screenshot from the Holley Datalogger below. It's telling me that the Injector Pulse width is running consistently in the range of 16.0 - 16.3mS. If that, and the above 18.4mS at 6500RPM is correct, that would be about 87% duty cycle at 6500rpm.

Also note in the new picture below that my actual AFR is hanging at almost exactly what my Target AFR is (after recovering from Acceleration Enrichment, caused by the rate-of-change in my TPS and MAP), which was set to 12.5:1 for this run. This is also the run which shows the rail fuel pressure dropped to 44PSI.

I find several things about this interesting. First, the Injector Pulse width stays almost constant throughout the RPM range. Maybe that makes sense if I'm requesting the same AFR at all times (which I believe I am, and the Target AFR line appears to show).

So... Do I need to increase my injector size? Based on AFR, they seem to be keeping up. And do I need to keep worrying about this, if my AFR is keeping on target?

I have decided to install one of Carl's Vaporworx PWM controllers, if for no other reason than to get a clean voltage to the pump that isn't limited by my ECU. I'll be curious to see what differences that makes on my readings!

Thanx!

I think the speculation comes back to the fuel pump. I measured flow at the outlet of the pump. There will be some flow/pressure loss as fuel travels through the system, but shouldn't be too significant. The question I have is if the fuel pump assembly itself has any kind of internal restriction that may decrease the numbers I was measuring.

Are you using the complete LS3 fuel pump assembly, with the bucket and fuel pressure regulator?

Also, if you'd like, you can check out the fuel system calculators available on our site > http://www.deatschwerks.com/resources/fuel-calculators/

[CarlC]

Low,

Thanks for coming in. Here's a flow table performed by RC Engineering for the LS3 pump at the outlet of the module. Bryan is running the complete module in the car. A bit of re-scaling is needed to adjust the BSFC accordingly.



At the same time ZL1 and CTS-V fuel modules were also flow tested. The results for the CTS-V are very similar to those obtained by Kinsler for a CTS-V fuel module, so the flow numbers should be good.

One part of the equation that may be missing in yours is the fuel draw required to drive the venturi pumps in the fuel module. If you are taking the flow readings from the outlet of the pump instead of the hat outlet then your flowrates will be higher. Did you remove the pump from the manifold housing for testing?

I was looking at your DW300 last week for a potential project. It's a heck of a pump. Very efficient and nicely packaged.

[LowFlyin']

Originally Posted by CarlC

One part of the equation that may be missing in yours is the fuel draw required to drive the venturi pumps in the fuel module. If you are taking the flow readings from the outlet of the pump instead of the hat outlet then your flowrates will be higher. Did you remove the pump from the manifold housing for testing?

I had to hook the venturi part of the bucket to the LS3 pump to get a good flow reading out of the pump. With the venturi supply line disconnected and flowing free into the tank, it only supplied 150LPH @ 40psi.

[glassman]

So Bryan, what was the result?