I haven’t posted this update on my350z yet…

As some of you may know I blew my engine at the drag strip this past February, mrg1981 helped me out and had my car towed back home and it sat in the garage for four months while I made all the arrangements for a motor build… During the month of June I dropped a spare motor off at Intense for the build, they ordered the parts, sent the motor out for machining, and two weeks later they began assembly. Within another two weeks they finished my build and after the engine was broken in I took the car to Jason at ProEFI for tuning.

Now, at the time I took the car in for tuning my fuel system consisted of Deatschwerks 600cc injectors (at 14 psi they were at 85% duty) and a Walbro 255lph fuel pump. I figured that without a return fuel system I should probably keep the power around 450whp, so Jason set the car up with 3 i-Boost settings:

i-Boost setting 1: 7 psi, 371 whp & 350 torque
i-Boost setting 2: 9 psi, 415 whp & 395 torque
i-Boost setting 3: 14 psi, 466 whp & 466 torque

I’m looking to add a RFS now and I was thinking about getting the CJM Stage 0 RFS and possibly modifying the fuel rails like some other members have. I’m happy with the power I have right now, I’m really just looking to make the car/fuel setup a little safer and more consistent… last time I did a highway pull at 14 psi in 5th gear the car had some very noticeable hesitation/jerking at WOT. The AFR’s seemed good, just a lot of hesitation. I figured it might have had something to do with the fuel system and the high temps that day (105+ AZ day), although I’m not 100% sure… Also, as far as the plugs, I’m running 1 step colder NGK iridium’s, I didn’t adjust the gap, just went with whatever they came out of the box with.

Would the CJM Stage 0 RFS be sufficient for my setup? Would I need to retune after I added the Stage 0 RFS too?

Thanks!

 

Hey I was in your place a while back. I actually made my own fuel system. I bought cjm correction kit . Than bought -8an braided hose for feed line and -6an for fuel return. Bought OBX fuel rails from eBay, fuel lab FPR and a fuel gauge from summit and a while bunch of fittings. So basically for a stage 2 fuel system I payed 500-600 bucks

 

It would be really cool if you posted a detailed DIY w/links on the forum, think about how much money the rest of us save. just a thought

 

I might actually do it this weekend. I have the engine pulled , and car jacked up so I'll take some picks

 

we have 100% updated pricing that will be made public on a new website in the next couple weeks. PM me if you want any quotes on stuff with the new pricing, everything has gone down in retail price pretty well since we have shifted to getting more retail orders versus dealer orders.

as for your questions:

A stage 0 kit will do very little for you in terms of improving fuel flow and max power capabilities. The stage 0 kit is called the stage 0 because its not so much an upgrade to the system, as it is just a return conversion with an adjustable regulator and 1:1 vacuum/boost reference (if hooked up). The stage 0 is popular because having the 1:1 w/ return makes it easier/cleaner to tune out larger injectors for idle/cruise and still get the most out of them under boost. If you are happy with the quality of your tune and do not need fuel headroom, I wouldnt bother with it.

Installation of a stage 0 kit, if you do not hook up the vacuum line to the regulator, in theory would not require a retune if you set the fuel pressure to stock. But if you hookup the vacuum line to the regulator, a full re-tune is required as you will now have radically altered your fuel pressure curve to a static differential rather than a static base. But then again, to run a stage 0 without a vacuum on the regulator offers very little benefit... pretty much the only thing it allows you to do is adjust your base pressure up/down if you feel you want to change your overall A/F a tad bit without going into your tune.

 

Thanks for the reply Charles! I sent you a PM for a few quotes…

Hmmm… I guess I first need to find out what was causing my hesitation on “high boost” in 5th gear…

Another question… So, if I don’t hook up the vacuum to the regulator any changes I make in fuel pressure via the regulator would consistently richen or lean out the tune throughout the rpm range? Increase in fuel pressure would cause the A/F to richen?

 

what do you need details of? you use the return correction piece CJ sells in place of the OEM FPR in the stock basket. Then you use the push on -6AN fitting on the stock basket. just run hoses to and from the front of the car. One hose has fuel the other is the return to the tank.

Its not complicated. CJ just makes a nice easy kit so you dont have to cut braided lines (which can be a pain without the proper tools), source the fittings, or buy parts from multiple vendors. Plus he uses teflon coated lines which are fairly expensive per foot.


with no vacuum/boost reference, it acts no different than the fuel setup you have now. they would be no changes to your tune.

 

So at what point does the return fuel line kit become worthwhile?

I ask because I just had this conversation with someone and they recommended the same stage 0 kit. More so as laying the ground work towards any future upgrades I may do I would assume.

 

charles lined it out in his post but i can re-iterate.

you have the ability to adjust fuel pressure. That is the biggest difference. Also, if you use vacuum reference then the car will idle at lower fuel pressure and the fuel pressure will increase as the boost increases (1:1) therefore it will allow more fuel in boost per the same injector. This will help people that are high duty cycle with an injector and don't want to upgrade to new injectors.

You can also make small injectors work better by just increasing fuel pressure some. This isn't going to work wonders but it helps if you need another 5-10% duty cycle.

Idling at lower fuel pressure helps run larger injectors while still keeping a normal idle.

Many benefits. if you have a good tune with no issues with duty cycle, fuel pressure, or idle (all relating to the fuel system) then you will have no gains from switching over.

 

I'm sorry but am I the only one who read this part? If the AFR is "good" and the car is jerking at WOT and full boost, I would be concerned. If it were a fuel problem you would see AFR spikes that correlate to the jerking. Do you have an overboost fuel cut? What is it set at? And what are your AFR's when this happens?

Could the ProEFI be sensing knock and pulling timing? Your comment about hot weather would support this theory, as the car is more likely to knock under these conditions.

Either way, if the car is jerking or hesitating to any extent under full boost, take your foot off it!

 

ya, detonation would cause jerking. If a/f is good then changing the fuel system won't do anything for the jerking problem.

 

48 box doesnt have knock control.

 

Yeah, the AFR looked good when I was making the 5th gear pull (high 11’s mostly if I remember correctly)… and I don’t have any knock control on my car, I don’t think there’s a over boost fuel cut either… any ideas on what else could’ve caused this issue?

 

i'd bet misfire.

 

or detonation

if there is no knock control then that means timing would stay advanced when it's detonating under high load.

pull the plugs and check for specks on the insulator. specks=detonation if none then probably someting else.