Yes with a 950cc injector, a 340lph pump, and a stage 0 kit, you shouldn't have any trouble achieving in the 500s. There are not enough samples of built motor results yet to give extremely accurate estimates. However, its a cost effective system that is easily upgraded to our larger stage kits down the road if you run into any pressure drop issues.

Hahaha, yeah reminds me my '90 Civic Cx base model with the 60 amps alternator, could barely run every electrical accessories at the same time.

I agree it would pull a lot of power from the alternator just to keep up, but really, thats the price to pay to pump more fuel into the engine, there's just no getting around it. Plus, most newer cars have very large alternators to keep up with all the powered accessories.

That being said, I think it would be interesting to use a twin pump setup for high HP engines. I'll elaborate a bit more on what I meant by 2-stage. Imagine having 2 pumps each hooked up on a separate relay. First one could be an OEM sized pump that's on all the time like a regular fuel pump. The second one on the other hand, would be a high output one and could be wired to a relay which would be energized by a fuel pressure sensor on the fuel rails similar to an oil pressure sensor but set for 50 PSI. So essentially, the second and bigger fuel pump would only come on if the pressure was dropping below 50 PSI. This way, when your just cruising around, your not drawing 25+amps all the time and moving massive amounts of fuel heating it up, you'd only pump it when its really needed. Add a little timer on the relay to keep the pump from cycling ON-OFF for nothing and you're good to go.

One of OEM's reasons for keeping the pumps small are very strict EVAP emissions regulations. This is also one of the several reasons for a factory return-less fuel system.

What you mention about a twin pump setup.. that is very close to what is already being done. The Nissan GT-R uses 2 pumps from the factory in a comparable configuration.

We offer a twin fuel pump unit to our customers. We always recommend that people wire it to be staged, where one 255lph pump is on full time, and the second pump is energized at higher engine load.

It isnt a good idea to wait until fuel pressure drops to engage the secondary pump.

Based on your post, there is a product series I believe you may find interesting. Fuelab has a line called "Prodigy". The prodigy pump is controlled by their fuel pressure regulator. The regulator monitors volume of return fuel. It has a target volume it tries to meet, and it will increase or decrease pump speed to achieve as close to that return volume as within its range. This means the system is providing the "just right" amount of fuel at all times, proactively, before there is any pressure drop or increase.

We have been waiting to see how the Prodigy line up proves itself for reliability before designing any fuel system kits that depend on it.

Very interesting about the EVAP emissions regulations, didn't think of that one. I guess the more you move fuel, the more vapors will be created in the gas tank, but I don't see why a return-less system might be better tho?

Haha, just as I thought, I knew they were smarter people than me that thought about that one way before I did.

Well if OEM specs are 52+/- PSI @ idle on our Z, I thought it wouldn't be that bad if it was dropping to 50 before turning on the second one. I'm sure it drops more than that on most guys' FI setup running in the high 500's whp?

That being said I agree it wouldn't be the most elegant way of doing it. The electronic fuel pressure regulator from Fuelab you're talking about would be a much more efficient way of doing it.

Thank you for that very interesting info good sir :tiphat:

Odds are, I'll be contacting you around next spring. I'm contemplating doing a return system conversion on my Z before I get tuned next year.

A return line generates a small, but measurable amount of evaporative emissions since the fuel traveling through the line will permeate through the line over time. Therefore, it would require more expensive material that prevents permeation known as SAE J30R7 rated hose. Even then, the longer the line, the more surface area that the fuel can permeate through. Therefore, it is ultimately less expensive to use a returnless fuel system to keep evaporative emissions low enough to pass EPA and CARB mandates. When it comes to OEM's, saving a few pennies per car translates to big savings over tens of thousands of cars.

Small but measurable amount of evaporative emissions??:bowrofl: Ch*@$, they really are going ape sh!t with all those emission standards. I wasn't even aware fuel lines were permeable before today... I guess you learn something new everyday.

Typical fuel hose from the 90s would permeate but I don't believe the modern nylon and Teflon hoses they use will permeate. I at least know that if it does permeate, it's a small fraction. But I cannot say with certainty that it doesn't at all. I believe that the evap of a return system has more to do with the heating of the fuel that is effectively cooling the rails and bringing the heat to the tank. Then again, the evap in the tank gets vented to the intake manifold eventually other than the pressure that escapes when you open the gas cap.

This forum is probably the wrong venue to get proper details on emissions systems since it's the last thing most tuners think about or study!

That's exactly why I find it funny that government regulations are giving the OEM's trouble over the extremely small permeability of the fuel hoses when you vent everything to the atmosphere by opening your gas cap. :ugh2:

That is a great point, lol! :tup:

I've just begun to research the idea of a two staged fuel pump energizing system for my CJ Motorsports twin fuel pump with a full return fuel setup.

Any recomendations? I do like the idea of a RPM based trigger

Zat

When it's an option, I would always try and use a standalone EMS' configurable output to ground a relay for this. But I understand that isn't really an option in a 370z since nobody runs a standalone EMS.

There are some secondary methods it could be done. If you were looking for an RPM based setup, there are many simple RPM window switch products available.

I believe what is most popular is to use a pressure switch that will engage the secondary pump at a specific boost pressure level. I commonly hear of Hobbs Switches being used. I believe there are also other similar types of pressure switches out there.

Be sure of one thing... use the pump that is closer to the over-tank siphon hose barb on the bottom of the twin pump as your primary pump. That is because this pump is what actually runs that siphon in our assembly. We do not "power" the venturi with return fuel like that OEM sending unit. That would cause far too many problems with the volume of return fuel a pump like that provides.

All of that about our electronic regulator is true. However, the pumps have other means of controlling the speed without an add-on such as the regulator. That electronic regulator is fairly new- it's been out about a year an a half or so. We have had only one warranty return/repair since their release. They have been working out really well for us. The regulator can also control more than one pump. We have several guys in the drag racing world that are running on straight methanol (much more flow needed). They are using a pair of our big 42402 pumps and controlling them with one regulator. With that said, you can control the pumps via other, potentially less expensive ways. The electronic regulator gives you variable speed operation. Another way to get the variable speed operation is via a PWM signal from an aftermarket ECU (some factory ECU's can do this as well, but that's pretty rare). If you can feed the signal terminal on the pump a PWM signal that's been 500hz-1500hz, it should work just fine. That would require a bit of tuning/setup unlike the plug and play regulator- but people have been doing that for years (long before we designed/released the regulator. Another option that works well would be a simple switch, RPM window switch, WOT switch (like what's used in a lot of nitrous systems), a Hobbs switch, etc. Those options would give you a simple high/low operation, rather than variable speed. Leave it on low for street driving and flip the switch for racing and things of that nature. In the case of a Hobbs switch, the pump would be in low speed mode until the Hobbs switch sees the engine come up on boost- when that happens, a signal would be sent to the pump to tell it to go into high speed mode. It goes without being said, but our pumps will work with any regulator- our standard and mini regulators, the electronic version, or any other brand out there. Our EFI pumps cannot be setup as a returnless or deadhead type system, although our carb line of pumps can (not that carb pumps are of any use to you guys here).

The pumps have a very simple wiring setup. Power and ground just like any other pump. There is a center terminal that controls the speed of the pump. If that center terminal sees ground, the pump will operated in a pre-programmed low speed mode (40%-60% flow, depending on pump model number). When that ground is taken away, the pump will operate in high speed mode.


If anyone has any tech/install questions- feel free to contact me. No sales questions please- just keep it tech related. I'm just here to help from a tech standpoint with fuel systems in general (doesn't have to be our brand).

Josh,

How about an in-tank version of the 42402? Or are we perfectly clear to submerge the existing inline model? If so, do you have a pickup filter that attaches directly to the inlet of the pump?