fuel system managment question/poll

[fabio420]

So I have been getting contradicting opinions as to what is necessary to use 550 injectors with the KA. I have been told that an SAFCII will do the job, but that it's at its limits. Someone else told me to get a fpr that drops the fuel pressure while not boostin, and brings it back to normal when boost kicks in. The one person I personally have seen with this size injectors around me only uses an SAFCII and says it's worked for him no problem. So which is right? It seems that the person with the running KA is proof of what the SAFC can and can't compensate. BTW, If u guys would, I'd appreciate to learn what kind of fuel managment people are using with what size injectors and turbo size w/ psi. That would be most helpful in giving me ideas where to go next.

[Jookmasta]

well i know rick near us runs 550s with his safc2. is that who u are referring to?

[Iamjohnhayes]

Im not currently running my set up yet, because i am still in the process of fabing/aqquiring my hot and cold pipes. However i am going to use e-Manage Ultimate for my fuel management and Ignition Timing. AT the momet i plan on using 460cc injectors from my brothers '88 FC RX7 (He is also going turbo soon and is giving them to me for free). I am also going to use an inline fuel pump rather than the usual walbro , but that is because i plan to use a fuel cell eventually.

[fabio420]

yep. He's my shinning example

[Jookmasta]

lol. yup, good example. out of curiosity what numbers are u shooting for?

[fabio420]

It so depends. At the moment I have 370's in and I'm gonna tune for 10 psi(it's a new/old engine). Whatever that yields, and then I'll try to use the 550's. But I'm trying to hit 300rwhp. Not with the 370's but with the 550's. With the 370's I'm hoping to get 240?rwhp @10 psi.( I don't wanna be too disapointed, u know?)

[240SicknessX]

i dont know why you are even going to mess with the 370 injectors.

One of the issues that i am facing is if i put a walbro in my car its going to up the base fuel presure from 43.5 to around 58-60psi. Now with the factory nissan 1:1 fpr and factory fp (43.5psi), wot full boost im at -46% w\ my 550's. If i install the walbro for future goals while retaining the factory fpr i wont be able to lean the car out enough with the increased fp that is inherent with the 255lph pump for a desirable afr while at full boost.

To avoid any issues that you will have using the 550's with your safc just do either of the following options: 1. run factory fuel pump and fpr. 2. run a walbro and adjustable fpr and leave your fp at 43.5psi. *Factory s14 fuel pumps lean out at 14 psi from my t04e 60 trim* I wouldnt run more then 12psi though on a factory pump becuase there isnt enough margin for error.

[fabio420]

I have a walboro. So I should use an aftermarket fpr?

[Jookmasta]

yea it wouldnt hurt to run one anyway as u can definitely alter the a/f's based on ur fuel pressure. i personally will also be looking to get one in the near future. i hear aeromotive is the best out there. although i am curious about the aem ones........

[240SicknessX]

so you dont run into any issues with being unable to lean the car out into a considerably good a\f ratio, yes get an adjustable fpr and some way to determine what your fp is, in car fp gauge, after fuel filter, on the fpr.

or just run your s14 pump w\ your factory fpr.

[TurboChargedSE-R]

370 cc/min Nissan injectors will get you right at the 300whp mark, but you will be walking a very thin line. FWD SR20 guys (SE-Rs like mine) run the 370s with a bored stock MAF (53.5mm) and a JWT tune for that specific setup. I ran mine to 282whp on 11psi of boost with a GTi-R T28 setup. A couple other guys have gone just over 300whp. My 282whp was at about 97% duty cycle on the 370s, according to my Techtom.

[Turbo 510]

Get an adjustable FPR to run with the Walbro. They are relatively inexpensive and do what the stock set up can't. I would also put in an AFC as the wolf program is extremely conservative (rich) and a reflash after every dyno session gets annoying, expensive and takes forever due to JWT's backlog.

[fabio420]

I got an SAFCII, I just gotta get the fpr.

[C-Kwik]

So I have been getting contradicting opinions as to what is necessary to use 550 injectors with the KA. I have been told that an SAFCII will do the job, but that it's at its limits. Someone else told me to get a fpr that drops the fuel pressure while not boostin, and brings it back to normal when boost kicks in. The one person I personally have seen with this size injectors around me only uses an SAFCII and says it's worked for him no problem. So which is right? It seems that the person with the running KA is proof of what the SAFC can and can't compensate. BTW, If u guys would, I'd appreciate to learn what kind of fuel managment people are using with what size injectors and turbo size w/ psi. That would be most helpful in giving me ideas where to go next.

Any decent fuel management system should be able to accomodate 550cc injectors. I'd stay away from lowering fuel pressure below OEM. A little bit of fine tuning is fine, but if you drop the pressure too low, the injector won't spray properly. Proper spray is important in promoting good fuel atomization.

Personally, with large injectors, I'd probably be more concerned with part-throttle/high boost circumstances. The O2 sensor feedback is active in this circumstance and can dangerously lean out fuel. During full throttle, the O2 sensor is ignored so the ECU will run it based on the Mass-Air signal so a piggy-back works great here. The E-manage Ultimate would appear to be a better solution here as it can be wired to drive the injectors completely on it's own. It's a bit more expensive, but the best solution available now short of a full stand-alone.

[fabio420]

Personally, with large injectors, I'd probably be more concerned with part-throttle/high boost circumstances. The O2 sensor feedback is active in this circumstance and can dangerously lean out fuel. During full throttle, the O2 sensor is ignored so the ECU will run it based on the Mass-Air signal so a piggy-back works great here. The E-manage Ultimate would appear to be a better solution here as it can be wired to drive the injectors completely on it's own. It's a bit more expensive, but the best solution available now short of a full stand-alone.

That's how I blew my first engine. Hit 14 psi at 33% throttle and leaned out followed by detonation and putting a hole in my 4th piston.

[Jookmasta]

not trying to infringe on any commercial posting rules but i found a great deal on SARD FPR's. raretrick is having a special on em for 100 bux. i know some people here use the megan racing but from what i've researched, the sard, aem and aeromotive are the best units out there. if anyone wants some technical data on the sard fpr, ill forward the email.

[240SicknessX]

That's how I blew my first engine. Hit 14 psi at 33% throttle and leaned out followed by detonation and putting a hole in my 4th piston.

note: before i was turbod, i was watching the total timing of the NA tuned ka ecu and i watched the total ignition timing go to 38 and 40degrees btdc at 1\4 and 1\3 throttle. If you are running a factory na ecu try not to get into much boost part throttle becuase the na ecu advances TOO much timing and will detonate a hole in your piston as fabio knows. Its actually more dangerous to part throttle your car and hit full boost on the highway, lots of load, probably a lean tune at part throttle and low rpms. I specifically took careful note of this when i was initially tuning my car, my total timing and afr while at a certain amount of boost. If i want to pass someone or speedup on the freeway i dont give it enough gas to make more then 5psi in 3rd or 4th while im part throttle. Pass em slow or pass em WOT.

na tuned ecus advance timing to gain fuel effeciency and aid in driveability.

[240SicknessX]

370 cc/min Nissan injectors will get you right at the 300whp mark, but you will be walking a very thin line. FWD SR20 guys (SE-Rs like mine) run the 370s with a bored stock MAF (53.5mm) and a JWT tune for that specific setup. I ran mine to 282whp on 11psi of boost with a GTi-R T28 setup. A couple other guys have gone just over 300whp. My 282whp was at about 97% duty cycle on the 370s, according to my Techtom.

i recently help jookmasta work with his wideband on his car, t3 super 60 ka-t 370cc and a z32 fp. at 11 or 12 psi he was in the 13.90's and 14's for afr, WAY TOO lean. He dynoed at 246 whp at 11-12psi. We turned his boost down to 7-8 psi and still was a mid to high 12 through out the powerband. (safc correction +50%). Still lean for my taste according to reliability.

[Jookmasta]

id like to see the dyno chart with 300whp and sr 370cc injectors..........also include their a/f's cuz its near impossible to have those numbers with nice 11-12 afr's. and yes 480s here i come.............

[TurboChargedSE-R]

We are kind of comparing apples to oranges. The 370/4-bar/bored MAF combination the FWD SR20 guys like to use is setup for a T25 or (preferred) T28 from a GTi-R, on a 2.0 liter engine.

There's enough differences between that and a 2.4 liter engine with the Super 60, etc. that I'm not sure the comparison is completely valid.

The reason I made the post is to show that -with a specific setup- that 300whp (and maybe a few HP beyond that) is reachable with 370cc/min injectors at 4-bar.

Let me see if I can find my dyno sheet somewhere....Ah yes, there it is. Ignore the blip on the chart at the end of the run; the dyno software apparently freaked out, but it really didn't affect the reading. With the T28, all the damage is done (torque) in the 4-5,500rpm range, and there's little to be gained by going beyond 6,500rpm. The A/F is bumping high 12s on that one, and that's why I said "walking a thin line". I'd never daily drive the car with that setup, only at the track/dragstrip. On the streets, the car ran 8psi (stock wastegate) and made about 240-ish whp.

The bored MAF program from JWT is simply to allow another 30-40whp while staying on the 370 injectors, and no more.

[fabio420]

Maybe I just don't know how to read rthis chart, but the a/f seem ridiculously lean. With that a/f I can probly push over 300 with the 370's and the walboro.

[Jookmasta]

gross oversite on my part as i completely missed the SR part that u mentioned. obviously with a stock NA ecu, u cant run aggressive timing since the NA ecu likes to advance it. on the sr's, u dont have that issue since the ecu is already programmed up for the boost so the comp will keep ur timing in check hence y those numbers can be doable..............still too lean for me but i see what u mean. nonetheless, a KA-T can't reach that 300whp mark with sr 370s and have a nice afr

[TurboChargedSE-R]

I completely agree, Jook. The .4 liter added displacement and a slightly bigger turbo would rule the 370s out on a KA, compared to a SR.

And Fabio, you are correct. The a/f was in the 12.5-12.8 range in the meat of the powerband. Walking a thin line...

That setup was good for 12.80s @ 110mph in the 2,500lb car, btw.