Last night I was reading through an article in the latest Sport Z magazine that I missed when I first got the mag. The article is titled "The Secrets of Grand-Am Cup Racing Unclassified" and is an interview with the folks from Performan Nissan's pro racing team.

It was a very interesting article, especially regarding handling in the Z, but there was one thing that really got my attention: Jackson Stewart, owner of Unitech Racing and crew chief of the Performance Nissan team, said the biggest power issue in the 350Z is the fuel supply system. He said that the fuel system cannot safely provide enough fuel for sustained WOT runs of over 300 crank HP. They basically had to replace the entire fuel system and upgrade the computer with a complete stand-alone unit in order to manage a sufficient supply.

Wowsers. I had not heard of fuel supply issue before. Did this little tidbit of information catch anyone else off guard when they read the article? I've seen a lot of people on these forums doing significant upgrades and make 260+ whp, which I would guess translates to over 300 crank HP, all without touching the fuel system.

 

i guess it depends on who you talk to...in another thread, someone said a nissan engineer told him the 350z was DEtuned to 287chp.
ps: what about the 05 z? 300chp. new fuel system? i think not.

 

But isn't the 05 Z just at 300 chp? The guy in this article said much over 300 is an issue. But even then, he said extended WOT runs. They particularly addressed people running 340 chp, and how that's not a good idea on the stock fuel system for any sort of extended WOT run.

But anyway, I certainly don't know. I was just taken aback by the statement in the mag, especially since it was made by a pro race team. Seems like they'd know what they are talking about, being that they beat the crap out of their cars on a regular basis, and having stuff not break is vital to their success.

 

What the article does not reveal is what does "inadequate over 300 hp" mean? The one thing lacking in the Z is an adequate fuel pump...the stock one pumps an incredibly miniscule amount of fuel given the size of the engine because it runs higher than "normal" base fuel pressure.

if you do some quick math, you'll see that with an 80% duty cycle (which is well within the "safe" zone, you would need roughly a 300cc injector to make 350 crank hp......and that's a 300cc injector at 43.5 psi of pressure. Our cars run higher base pressure than that. Our injectors are 290cc. As I said, the stock fuel pump is where the issue lay IMHO - it flows roughly 90 liters per hour at 12 volts.

I'm going all NA on my car as we speak, and already plan on upgrading the fuel pump and possibly adding a more conventional return line into the system to ease the tuning we'll be doing.

I know I have logged IPW and fuel pressure on my own car a few times, and even at my current power level (269 at the wheels), I am no where near out of injector, and even the pump is able to cope (fuel pressure not trailing off as rpm's increase)

That being said, I certainly would not rely on the contents of a SCC artcle for anything more than pictures

 

Sport Z magazine.

 

if your looking into a Fuel System upgrade, look at our AAM Fuel System upgrade....

https://my350z.com/forum/showthread....67#post1232167

Ben Yavari
Altered Atmosphere

 

rather then 300hp I would say more around 375 to th wheels and at that amount of power it's more of a necessity due to the amount of power,you have to look at the air & fuel ratio espeacialy if the car is a track car.

 

what good is an upgraded fuel system if our miserly ecu's gonna control it?

 

Get an AAM reflashed ecu then .

 

HP to the wheels, you might need to change some of the fuel system, but I think the stock will hold up. Flywheel hp, 300 is a cakewalk...

 

Ben, I maybe should be PMing this question to you, but maybe everyone should know. Here's a quote from Darryl from Ultimate Racing talking about their fuel system:

"The fuel system we've released is quite extraordinary. I honestly don't think any of the competitors, whether it be Turbo or Supercharger, have done enough testing. When we originally designed our Twin Turbo Kit, we tested to see if the stock fuel pump was up to par. Fuel pressure began to drop fast while in boost so we decided to upgrade the fuel pump (standard procedure when designing a turbo kit). With the fuel pump installed fuel pressure still began to drop! This told us that a fuel return line was definitely necessary. We went ahead and installed a boost dependant fuel pressure regulator as well. This should've did the trick, but it didn't. We were left scratching our heads for several days. After tearing apart the factory fuel system, we found the problem. For the most part it has to do
with the dual fuel tank design. We made some modifications, changed the fuel pump (again) and there it was, rock solid fuel pressure."

Just for comparison, is this how your fuel system works based off of what he says? Does it give rock solid fuel pressure? I'm asking cause those guys seemed to have solved the fuel system issue, and wondering if your return fuel system is the same thing or if it is different in any major design sort of way?

their kit includes:
-Modified Fuel Pump Assembly (Assy from Passenger Side Fuel Tank)
- Modified Intank Fuel Pump 255lph High-Pressure
- Aluminum Fuel Y-Block
- Modified Fuel Rail Assembly (Modified for dual inlet/outlet)
- Dual Port Boost Dependant Fuel Pressure Regulator (Assembled with High Quality Diaphragm and Viton O-Rings)
- Fuel Feed Line
- Fuel Feed Lines (Y-Block to dual inlet fuel rail)
- Fuel Return Lines (Dual outlet on fuel rail to Dual Port FPR)
- Fuel Return Line (Outlet from FPR to Fuel Pump Assy)


I'm asking cause Ultimate Racing doesn't seem to be responding to my emails and doesn't list their fuel system on their website, and also that they're from another country, makes me weary about buying from them.

Also, I think I read about some people having 2 fuel pumps instead of two. Is this possible with your kit or with the Z? It seems more reliable to have two pumps - especially if they're the walbro pumps with many of them failing out of the box

Didn't someone say they're redesigning the gas tank to overcome some issues?

I'm getting a misfire code and I'm not comfortable with it. I'm hoping upgrading the fuel system, injectors, ignition, and ECU wiring similar to the APS turbo kit wires will solve it... I have the TS ECU flash