Ready for Fuel System Upgrade..!!

[rn240sx]

Ok guys, ive been at 7 psi for the longest time and im ready for some more boost...I just wana be sure that I get the right brands and parts here.MSD 72lb injectors (have to send off my ecu for re-prog)96 300zx MAFWalbro 255 LPH fuel pumpJWT fuel railNISMO adj fuel pressure regulator (to lean up the ultra rich jwt setup)

Does anyone have any bad issues or experiences with the above brands..?? Am i missing anything..??Any places where u think i can get them for a descent price..??

ThanksRobert98 240sx ka-t

[klattr1]

Ok guys, ive been at 7 psi for the longest time and im ready for some more boost...I just wana be sure that I get the right brands and parts here.MSD 72lb injectors (have to send off my ecu for re-prog)96 300zx MAFWalbro 255 LPH fuel pumpJWT fuel railNISMO adj fuel pressure regulator (to lean up the ultra rich jwt setup)

Does anyone have any bad issues or experiences with the above brands..?? Am i missing anything..??Any places where u think i can get them for a descent price..??

ThanksRobert98 240sx ka-t

That all sounds good.Dont forget those pesky resistors for the injectors.As far as the mafs goes, here's a brand new cobra mafs for sale real cheap compared to JWT pricing:freshalloy cobra mafs link

[klattr1]

just dont expect to boost 10lbs higher right after you install the above items.Make sure and dyno first before you mess something up. Especially on a less forgiving stock internal motor.I've been through 3 different JWT chips to get my air fuel ratios right but Im like a "special case" according to Jim Wolf.

[Nathan]

Unless you allready have that jwt fuel rail, you can get basically the same basic thing from http://www.jgycustoms.com and I think heavythrottle too for a good bit cheaper You can also get the ecu cheaper from those guys.

[MarkEmark]

Ok guys, ive been at 7 psi for the longest time and im ready for some more boost...I just wana be sure that I get the right brands and parts here.MSD 72lb injectors (have to send off my ecu for re-prog)96 300zx MAFWalbro 255 LPH fuel pumpJWT fuel railNISMO adj fuel pressure regulator (to lean up the ultra rich jwt setup)

Does anyone have any bad issues or experiences with the above brands..?? Am i missing anything..??Any places where u think i can get them for a descent price..??

ThanksRobert98 240sx ka-t

About that nismo adjustable FPR---You said you want to use it to lean out the JWT setup. I think mine's rather rich right now too...Can the nismo fpr lower the fuel pressure BELOW what the stock pressure is to lean out the a/f, and how much? And how much would lowering the fuel pressure translate into @ the injectors? Is there some formulal for the flow @ a certain pressure? I guess you'd need to dyno it with a/f charts to really see how lean you can get from lowering the fuel pressure. Sorry for the hijack, but I may add a nismo fpr sometime....

[klattr1]

About that nismo adjustable FPR---You said you want to use it to lean out the JWT setup. I think mine's rather rich right now too...Can the nismo fpr lower the fuel pressure BELOW what the stock pressure is to lean out the a/f, and how much? And how much would lowering the fuel pressure translate into @ the injectors? Is there some formulal for the flow @ a certain pressure? I guess you'd need to dyno it with a/f charts to really see how lean you can get from lowering the fuel pressure. Sorry for the hijack, but I may add a nismo fpr sometime....

You can lower the fuel pressure above or below as long as you have only an adjustable fuel pressure regulator. If you use a universal fpr on top of a stock fpr, you can only raise pressure above stock fuel pressure(43.5 psi idle with vacuum hose disconnected).A stock fuel pressure regulator and a nismo fpr are both 1:1 ratio.Basically if you boost 10 psi, your fuel pressure should be 53.5 psi.If you boost 5 psi, your fuel pressure should be 48.5 psi. This is all assuming that the stock fpr or adj. fpr is set or rated at 43.5 psi at idle...etc.Typcially with Jim Wolf setups, their programming tends to be rich so you can lean out your air fuel ratios by dropping the base fuel pressure but you have to realize that it will affect the whole air fuel ratio curve typically. Some people have gotten away by leaning out Jim Wolf programs with adj. fpr but it might be better to use a S-AFC to trim at certain rpm points.Jim Wolf fuel rails have the location for use of stock fpr. So either you have to run a Nismo fpr that will bolt into the same location or you have to cap off with a plate and run a universal adj. fpr at the end of the fuel rail. Jim Wolf gives u the option and JGY will do either or.

[MarkEmark]

I may just use a bosch fpr that's 1:1 that I have sitting around...it's a 2.5 bar instead of a three bar, and it gets rid of the OEM one, and if my injectors are 400 cc like RCEngineering says they are, the lower fuel pressure would effectively make them more like 370cc injectors--if they aren't really 400 cc, the lower fuel pressure would lean it out a good amount (it'd be 6.75 psi lower @ all points). I'd want to see what the a/f ratio was on a dyno, however, since it's basically speculation as to how the car would run with the lower fuel pressure; and I'd rather be rich than lean.

[rn240sx]

klattr wrote:just dont expect to boost 10lbs higher right after you install the above items.Make sure and dyno first before you mess something up. Especially on a less forgiving stock internal motor.

Well, regardless if i dyno it or not, if the air/fuel mixture's are not correct the 1st time, im gonna blow it on the dyno anyway..!!!Am i right or wrong..??

Next thing i would like someone to explain to me... I understand the 1:1 ratio on the fpr...But when the dyno sheet comes out and it reads like 12-14:1 on the air/fuel curve.. what exactly does that mean..??

[klattr1]

the 12:1 or 14:1 literally means how much air to the amount of fuel. Generally people try to stay out of the 12:1 and above air fuel ratios. The higher the first number, the leaner you are getting. Some people tune their cars for a max air fuel ratio of 11.7:1 in boost. You can get away with lean mixtures at idle and low rpm throttle.You can have the exact same air fuel ratio at 7 psi that you could have at 15 psi but that doesnt mean your engine is gonna blow at 7 psi. I was running lean air fuel ratios in the 13:1's and 14:1 with my first JWT program but it didnt blow at all at 7 psi but the pistons sure took a beating at 15 psi.The higher boost levels you are running, the more airflow.

[huguetpj]

Wasn't 12.3-.5 a better AF for turbo?

[klattr1]

i guess it just depends on how much of the powerband is running at that air fuel ratio and how long you want your motor to last.

[rn240sx]

Well, as i look at the dyno sheet on my previous S13 this is how it came out...3600 rpm 17:14000-4400 rpm 14:14800-5400 rpm 13:15500-redline it maintained 12.5:1

The owner of the shop that ran the dyno test and came to me personally and said, "Just to let you know, your running VERY rich"Its funny how he came to me and said that with a very serious face and solid tone to his voice..!!

And from what u said earlier, the higher the 1st number, the more air there is to fuel... But in this case he had to have been wrong... Right..??

[Nathan]

Was he used to dealing with NA cars? They tend to run leaner than us weird turbo folks.

[klattr1]

you can get away with alot leaner mixtures with a naturally aspirated cars.He prolly meant you were running a little richer mixture in the higher rpms. Basically you could have gotten away with 1 point leaner from like 5000 rpm up on your NA s13.Check out Secret Services Rom Tune graph of before and after and observe their mixtures. Now remember this is a naturally aspirated car, so keep the tuning of NA cars and turbo cars separate.