Biggest injector while running SAFC

[574-240sx]

Well I have some GTR injectors laying around. I think they are 440cc. Whats the largest injector size you can run with out running into idle problems and etc on the DOHC KA. Thanks. Nick

[SHIEF]

I believe around 550cc is the biggest the SAFC can control decently. I'm sure someone else can tell you for sure. I know it'll handle those 440's though.

[Structure240sx]

theoretically it could only do 540cc since stock is 270cc. you can mess with the dec air setting NE1 to lean it out some at idle without the maps leaning out. currently im running sr s15 480cc injectors. so you will be just fine

[Ricer240sx]

yeah, ull be fine i wil be running a First Gen(with the knobs) S-AFC with the 444cc GT-R ijectors!! it will work fine!

[574-240sx]

I might just go with 550s because the GTR injectors are low impedience and top feed. If I go with the 550 side feeds they are two less things to deal with and they shouldn't have any filiment problems. Where are decently priced side feeds found. Nick

[Checkered-Member]

You should run injectors that are within your intended power range…So 80% injector duty cycle of the maximum power you plan to run, this will insure good response thorough the RPM range

[Structure240sx]

people max out injectors all the time wihtout having response issues, i;ve never heard of that. i was corrected once this week tho so i could be agian. the only thing bad about maxxing out injectors is premature failure.

Nick- your looking at getting some tomei/nismo injectors. certain year sti injectors are 550cc and sidefeed's and can be had for close to $200. you just need the plugs to go with them tho. also rx7's use 550's as primary or secondary injectors and can be used with certain collars or spacers.

[bruinbear714]

I wouldn't run anything more than 370ccs. Although 550ccs would work, the MAF signal gets altered so much that it'll throw timing off.

[Chezedik]

Sorry for reviving a dead post, but this came up when I was searching and it had almost the exact info I need. Does anyone know how the max is affected when a Z32 MAF is used. Can you correct for the MAF and the 550s, without bumping up the timing? If anyone has done it, I would love to hear what and how you did it.

[nismofly]

afaik the mafs has no effect on the size of injector you could run with the safc, but i also think there are people running 550's with an safc, so theres something

wow, the stuff thats happened since this thread started...i almost **** myself when anthony said he was running s15 injectors

[Chezedik]

But by using the Z32 won't it change voltage to the computer. Also, since it is larger, the cooling effect will be less. What about the larger scale on it?

[Jookmasta]

well first off i think u mean retard the timing? cuz unless u have an upgraded ecu or standalone or emanage, u usually have to retard ur base timing unless ur running like 4 pounds of boost. As for correcting for it, the safc can correct for a z32 maf and 550cc injectors. to do it, u just put in the right in and out settings for the maf and then use a wideband or dyno to tune ur fuel settings.......

[Tims_240]

i always thought you could run 50% bigger than what your original injectors areso since stock injectors are 260, not 270... then you would be able to run 390cc injectors, this is at 100% duty cycle.now if you got a retuned ecu from enthalpy and you got your ecu tuned for lets say 550cc injectors you could run 825cc injectors.-tim

[fabio420]

Well, I'm running 550s and a z32 maf and an SAFCII and I'm not maxing out the correction. No problems at al. You wouldn'e know I had them in if i didn't tll ubtw thay are from deatchwerks. good price and they are a sponsor. Great customer service

[Structure240sx]

the safc can tune down injectors 50%. so if you put in 550's then it can cut them down to 275's close enough for a ka stock ecu

i used to run a stock ecu, 550's, and a z32 maf

the safc has in out maf settings to correct for the z32 maf so the proper voltage goes to the ecu. i also hit 385rwhp on that setup. my stock ecu was pulling timing on its own for some reason. we have found a few cars that do this

[KATwo40]

...now if you got a retuned ecu from enthalpy and you got your ecu tuned for lets say 550cc injectors you could run 825cc injectors.-tim

Wouldn't that kinda defeat the purpose of having a tuned ECU? I mean, wouldn't you just rather have it tuned for 825cc injectors?

[SHIEF]

the safc can tune down injectors 50%. so if you put in 550's then it can cut them down to 275's close enough for a ka stock ecu

i used to run a stock ecu, 550's, and a z32 maf

the safc has in out maf settings to correct for the z32 maf so the proper voltage goes to the ecu. i also hit 385rwhp on that setup. my stock ecu was pulling timing on its own for some reason. we have found a few cars that do this

Yeah I remember reading about that. It was awhile ago though. Wonder if maybe your knock sensor was causing the timing change. Any slight knock (to which your ears cannot hear) could cause this. Not saying the engine internals themselves were knocking, but maybe another cause. But who knows.

[Chezedik]

Yeah, but doesn't SAFCII have a log for knock sensor duty? Then you would know. I always thought that when the engine sensed an increased load it would bump timing, but I guess you are telling it that the load is actually less with the SAFC and turning down the duty on the signal to pulse. Am I getting the gist of it?

[Tims_240]

no it wouldnt defeat the purpose, you have a great tune, and then you tune it some more, its called nit picking. If you are looking to have a near perfect tune you are not getting it from a tuned ecu, unless you go to their shop and have it tuned. Plus different climate changes/elevation, will throw tuning settings off also.

[Structure240sx]

even with low boost and race gas it was still pulling timing, there could be no knock at that point

the point of having a tunned ecu is also to run injectors bigger than 550's and have a good timing map.

plus tunned ecu's seem to run a little better with cold start up and temperature change over a stock ecu with only a piggyback

[WDRacing]

Just to get back on topic...I helped tune a car with 600CC injectors. We had to lower the base fuel pressure down to 36 psi though. But we ha d arock solid idle at 14.4:1 A/F and enough injector to keep it at 11.3 or so with 24 lbs of boost and 7900rpm. This being an RB20 by the way.

So add a MSD BTM and I'd say you'll be golden. Careful with lowering the fuel pressure to much, the injector won't spray right at to low of a pressure. Also use a wideband to monitor the fuel all the way to redline.

WD

[Craving4Boost]

even with low boost and race gas it was still pulling timing, there could be no knock at that point

ive been thinking about something...since the SAFC is known to cause advance timing, could it also been the cause of your automatic timing retard? does every person who has the out of the blue automatic retard timing use a SAFC? so far i only know you and Geo.

sorry to get off topic. 550cc is the biggest safc can go..its a great unit..easy to use. simplest way it can be put..why cant people just face the facts. I dont even have to know how it works to use it, just subtract fuel and add fuel in the maps and its done(mostly)

[WDRacing]

550cc is the biggest safc can go..its a great unit..easy to use. simplest way it can be put..why cant people just face the facts. I dont even have to know how it works to use it, just subtract fuel and add fuel in the maps and its done(mostly)

Exactly...somthings are better, but this DOES work. People knock the air flow controllers all the time. Alot have more money to spend then I do. Alot also have a standalone installed and then tuned by someone else. This IMO does not give that person the right to post an argument, since the hands on knowledge is nill.

I'd still be boosting my 240 right now if my oil didn't fail and cause my motor to internally melt all the bearings...lol. SAFCII and BTM...great combo.

WD

[GEO]

Yeh my car was pulling 20 TIMING at WOT before I wetn turbo... We thought it was casue I had a bad O2 sensor and knock sensor.. we replaced them and it was STILL pulling 20 timing.. WERID. But now with the turbo installed and such, we noticed that ti now pulls 21 timing under WOT... ANd we did not knock timing down either, I probably should get an MSD to handle timing anyway jsut incase one day ti wants to go back to normal timing. Cool huh?

[Craving4Boost]

when we gonna see Geo up the boost damnit show us that AT power

[Jookmasta]

well isnt that weird............is ur car the same year as structure's geo?

[Structure240sx]

we both have obd I s14's

but i have found this out on a few different cars

[WDRacing]

I sure wish we could have figured that one out...I hate not knowing.

[Chezedik]

Has anyone seen it happen on the S13?