I hear ya on that one-damn that factory connection

 

I'm going a different route, I am going to attempt running without a return setup for 500-550whp.....we'll see if it works

 

you wouldn't be the first

 

Just make sure you have a good stanalone engine managment, that would be your safest bet with out running a return style fuel system.

The returnless fuel system makes tunning more difficult and requires you to run higher fuel pressure. No recommended but I could work.

Good luck and let me know if you need anything!

 

I may get blasted for asking this, but what does a return fuel system gain you? I have seen the kits advertized and they are not cheap!

 

why would I have to run more fuel pressure if i'm running larger injectors? At stock fuel pressure, 550cc injectors or even 610cc injectors will provide enough flow for 500whp with ease.....no need to adjust fuel pressure, aside from the fact that I've got a walbro pump in there now.

 

Are you doing this with the stock fuel rails?

 

more than likely, the only aftermarket rails are fuel return rails. We'll see though. I've got to call JWT and talk to them about it.

 

A nice fuel return system offers many benfits in design to accomplish one very important task: To provide steady and equal fuel pressure to all 6 fuel injectors.

Each restriction in the fuel system (and the stock 350z / G35 contain many) will impede on the overall maximum capacity of the fuel pump at its given voltage. Many think that fluid dynamics say that a chain is only as strong as its weakest link, and increasing flow through some parts of the fuel system will not help if other parts are still more restrictive. Well, this is not a chain folks. Duration and count of restrictions DO MATTER.

The largest restrictions in the factory fuel system include, but are not limited to, every transitional joint quick-clip connector (very small inside diameters), and the pipeing that is feeding the factory fuel rails. The CJM S1 fuel system eliminates every single restriction in the entire system aside from just one remaining factory clip-on connector. The S2 system eliminates that final restriction.

Testing has proven that above 450rwhp, the factory fuel system starts to run into pressure maintainance issues, and you will start seeing substaintial pressure drops by redline... this limiting fuel system capacity.

The other issue addressed, as mentioned, is equal fuel pressure. Having uneven fuel pressure supplied to each injector is risky business. Since your A/F readings are an average of the cylinders in that bank, you do not see that some cylinders are running different A/Fs then others. This pressure gradient will not be visable during lower injector pulse duration moments, such as cruising and idle. But the closer you run to the max, the more this problem will exagerate itself. The factory fuel rail feed pipes are extremely biased and poor flowing. This will cause uneven pressure from one rail to the other, and then limit the rails ability to maintain proper fuel pressure when the injectors are rapidly draining the fuel. You are running risk of uneven fuel pressure from one end of the rail to the other.

The fuel return systems address this issue by substainally increasing flow to the rails and allowing the transfer of fuel into the rails to increase greatly. The second part of eliminating this problem is by putting the fuel pressure regulator after the fuel injectors, rather then before. This ensures that as long as your pump and lines are keeping up with your flow demands, your fuel pressure minimum at the end of the rails will be at your regulator setting. These systems also have a positive side effect of equal pressure balance between each rail. This takes place since the fuel source is split into 2 to meet the rails, and then joins back into 1 after the rails again. Having them connected side to side before and after the rails allows pressure balance.

Another benefit of the return fuel system is the 1:1 ratio regulator. The fuel pressure regulators will maintain an equal pressure differential between the fuel rails and intake manifold. This makes it easier to idle and tune for larger fuel injectors, since at idle your fuel pressure will drop, and in boost it will increase. Having fuel pressure remain the same at all times reduces top end capacity of the fuel injectors, and makes it harder to idle them since the higher pressure will be forcing too much fuel thru the injectors at their lowest responding pulse width.

Last but not least, a proper fuel return system offers you adjustable fuel pressure, which aids in A/F tunability... and also allows for minor end user adjustment to the overall A/F when needed... without having to always take it to the tuner or hook up the laptop and spend time tuning the EMS.

 

Wow! That was a great explanation and it makes perfect sense. Thank you for taking the time to write that.

It just amazes me how there is so much room for improvement for the VQ 35engine. Even in stock form this engine is awesome!

 

Charles...couldnt have said it better myself.

 

I like how Charles will give a ton of information, and yet it will have sence of being unbiased. He doesn't come out and say that ours is the best and that's it, you should buy it. He will give you the information to make the best decision on your own.

+1 to you Charles.

Ps. Thats quite alot of great info.

 

i just dont wanna get banned... sooo uhhh ya... i AM unbiased

 

lol

 

Just please don't call it "EXTREME!!"

 

Since everyone is into the over exagerated product naming around here we have come up with a list of ideas. Maybe we will have a vote which one it should be.

Extremest
XtraXtreme
Extremer Type R
XXXtreme GT-R
Ultra-Extreme Combat
Ultra-Mega Ninja Warfare
CJM Flow-Boy Stage 3
or my personal favorite, Super Nuclear Neutron Stage X

We'll leave it up to you guys.

 

Super Mass Flow Gas Pumper 3 - The final flowdown.

 

Winner---> Ultra-Mega Ninja Warfare

 

Im a slow learner and was afraid to ask the same question. Phunk well explained and to get Sharifs applause makes me feel more better about the fuel system. Been putting it off because things keep coming up but definately my next mod. Getting a new house in Nov so I won't be able to do it till February. So a fuel return system and new injectors is all I need or is there more? Thanks again for the education.

 

I think your Ultra-Mega Ninja Warfare system should come with a fuel tank that uses the full 20 gallons.