Why do I keep running into these guys with just an SAFC, Vortech FMU, Walbro 255 and Base FPR, 2.87 pulley, STOCK INJECTORS and running RICH!?!?!

Ok we might have some stickies on this, old outdated stuff from the year 2001 type info. Anyway, I want the most current update with this. Jeff at Max tuning (maximus75) is doing it for over a year now and he boosts the car ALL THE TIME he said. Cmax has done it. My friend just went up this weekend and he has cartech fmu, and got his 2.87 installed with his Q45 fuel pump. Stock injectors on all these guys cars.

I spoke with Jeff, he even pointed out that the 370cc guys were running way too rich. ANd of course that robs you of power. WTH? Confused.

 

1000psi FP FTL

 

Ah, duh, silly me. Damn that was a simple answer, thanks.

 

No problem.

 

If you don't mind running 100psi+ fuel pressure it can be done.

SC guys also only see really high fuel pressure on these set up for 500 rpm's or so since boost doesn't peak till redline. As opposed to a turbo set up that would see insanely high FP for most of the power band.


I would also definately hardwire the fuel pump if one chooses to run like that.

 

no way man.. not stock .. what are u using for tune?

 

why would u want to hardwire the pump...

 

The stock wiring is pretty weak and under high load conditions with cars making decent amout of power with high flow pumps may not be able to keep up creating a lean condition at higher rpm's.

Just hardwiring my pump bumped up my base fuel pressure about 3 psi

 

You probably could do it within reason. Super high fuel pressure is the main limitation. I wouldn't go that high of boost wihtout better fuel management and probably some ignition retard. A good electronically based tune with high flow injectors will have significantly more power and be much safer on the engine.

 

Next question: Why are SCers going with anything over 370cc? You can run the 2.87 pulley with the 370cc injectors and a nice fuel pressure and it will still kick ***. Why are some guys overkilling with 550s?

 

B/c people would rather use accurate electronic tuning and properly sized injectors instead of just raising fuel pressure to no end with an FMU.

FMU = bandaid
It is cheap, effective, and easy to use. However using it for high boost and/or high Hp is very unwise.

Going over 10# and you might need to start to worry about ignition timing too and without a piggy back you can't do anything about it.

People are running rich because they would rather be overkill on the fuel setup and not blow their motor every other week than the other way around.

 

So technically, if you got 370cc injectors, and a J & S safeguard, all would be just dandy, right?

 

I think this might be the answer. I could be wrong though.

http://forums.maxima.org/showthread....hlight=550%27s

 

Thanks Dave! I'll check it out.

 

Because 550's and Z32 maf go together like bread and butter.

But seriously now, I got them because I didn't want to run a FMU. 370's at 80% duty cycle and a .6 bsfc cannot do more than 280hp at ~40psi of fuel pressure. I've switched to a 2.87 pulley to target 350hp. You could do it with 370's but duty cycle will be at or near 100%, which is no good.

 

Cool, from what i've gathered though, the 300zxtt injectors actually flow closer to 410cc than 370s. I also have a Cartech FMU. I see the FMU not being a part of the system is a pretty good reason to get em. I've got to post up my set up by the end of next month mod for mod and get a few more points/tips. Drop a few dynos and then track day June 24th. . Maybe then all my questions regarding stuff like this will be answered.

 

I had my 300 zxtt 370 injectors balanced and blue printed and they now average 395cc. I doubt if you'll get more but to make sure they are putting out at least 390 for a saftey margin you should send them to rc engineering.

 

OEM Nissan 370cc injectors always flow about 410cc

 

How can you say "always" when I just said I had them cleaned and blueprinted and balanced at RC engineering and their figures were 395 average??

 

It may depend on what psi the injectors were tested at. I don't have my Deatschwerks flow chart but when mine came back they averaged about 410cc like Mike said, I believe it was at 40 psi, the minimum flow was 409.

 

1. There is a difference between accuracy and percision

2. I said "about". No set of injectors will ever flow exactly the same.

3. 395cc is a variance of less than 4% of the more normal 410cc's.

4. You stated that RC said 395 was the average. So at least one flowed more than 395

5. Fuel pressure makes a difference.

 

at 10 PSI I was very lean with stock injectors. Lets not say 12. Really asking for a kaboom!