safc settings

[wild_maxx]

ok i am finishing up my ka-t install and i wanted to know a safe rich safc setting for my motor so i can just drive it to a dyno place about 2 hrs away and get it fine tuned. i am running rx-7 460cc injectors and just wanted to know a safe setting to run them at. i have heard the guys with the sr injectors are running around -27 for their settings so should mine be around there or a bit higher? and is it the higher the - number the richer it will run or the lower the - number the richer it will run?

[wild_maxx]

any recomendations?

[blubottlemax]

Sorry, but every car is different. I tried using some else's setting recomondation, and it was way off for my car.

[wild_maxx]

i'm not trying to get an exact setting i just want a ballpark figure to set it at just so i can get it started up and drivable to the dyno tuning place.

[blubottlemax]

Okay, with 460cc injectors, if you run -41% on the SAFC, you will be at the stock injector rating. going negative obviously subtracts fuel, and adding well... you get it. Start it up and see how it runs. If it runs really rough smell your exhaust, if it smells like excess fuel, pull the plugs. If they are really black and covered in soot, your running too rich, turn it down a couple points and try again. In closed loop mode (low throttle while driving around) your ECU will try and get the vehicle to run at 14.7 AFR anyway. Just keep the throttle low and make sure you don't boost till you get to the dyno. What part of WA are you in?

[240DRFT]

who r u gonna have tune your car?

[WDRacing]

Get ahold of Toki, he cruises through here quitea bit, he has the same setup as you do and his car idle well.

[wild_maxx]

i am in ocean shores, WA i am not sure where to get it dyno tuned. any recomendations? i just wanted to get it started and work from there. thanx for the info.

[AN89HATCH]

so if the base seting is 41% on the SAFC, 41% should only be for 1k correct? then for 2k pluss, what should the safc setting be at just incase you hit alittle boost?

[Toahk]

Okay, with 460cc injectors, if you run -41% on the SAFC, you will be at the stock injector rating. going negative obviously subtracts fuel, and adding well... you get it. Start it up and see how it runs. If it runs really rough smell your exhaust, if it smells like excess fuel, pull the plugs. If they are really black and covered in soot, your running too rich, turn it down a couple points and try again. In closed loop mode (low throttle while driving around) your ECU will try and get the vehicle to run at 14.7 AFR anyway. Just keep the throttle low and make sure you don't boost till you get to the dyno. What part of WA are you in?

That calculation you used to get that % doesnt work. Base settings for 460cc injectors in a sohc are -22 on the LT across the rpm band, and -27 on HT across the rpm band. Thats a good base tune.

[:: orion ::]

Base settings for 460cc injectors in a sohc are -22 on the LT across the rpm band, and -27 on HT across the rpm band. Thats a good base tune.

-22 is not nearly enought...

-27 is the common "get it started" base tune for 370s...these 460cc injectors are 25% bigger than that...so the correction factor must be more than -27.

But, to see where all these numbers are coming from:

Stock KA injectors are 270cc.

To make a 370cc injector act like a 270cc injector, you remove 27% (-27)...or use 73% of it's capacity (1 - .27 = .73 or 73%).

The math: [ 1 - (270 / 370) ] = .27, or minus 27%.

...

So for 460cc injectors: [ 1 - (270 / 460) ] = (1 - .59) = .41, or -41...like "blubottlemax" said above.

...

Hope that helps - Brian

[AN89HATCH]

so when you guys say base setting, do you guys mean to set the low throttle 1k-7k to -41% just to get it to the dyno, or do you guys mean set the 1k low throttle to -41% then the 2k+ to a more rich setting, just incase you hit boost. would this sound about rite?

I set my low throttle 1k to -41% 2k to -43% 3-7k low throttle to lets say a -65% and on High throttle -70% from 1k-7k. would this be about rite, just to drive to get a dyno tune? and not hitting boost (but just incase I do hit alittle boost, on the way to the dyno my motor will not blow with these settings correct??

[:: orion ::]

No way to tell, unless you have a wideband.

It's all guess work until you KNOW the A/F ratio.

...

But for a baseline, I'd go for -41 low, and maybe -38 across the board for high.

BTW, you're math is backwards...-65 on high throttle is LESS fuel than -41.

The % is the amount of fuel you're CUTTING OUT from the injectors flow. To cut a 460cc injector down to ~270cc, you remove 41% of the flow. To to richen it up on HIGH throttle, you need a numerically lower number(nevermind the minus (e.g.: -41)...just think 41).

So -25 on 460cc is WAY more rich than -41...get it?

(Don't wanna see you blow it up first time the pressure gauge reads on the positive side...hehe).

- Brian

[wild_maxx]

damn this is getting more and more confusing every post but i think orion cleared things up. thanx for the help everyone

[blubottlemax]

You should search around in your phone book to see if there are any performance orientated shops nearby, think chevy or ford high performance. I'd ask them if they know of a local dyno, if you can't find one in your phonebook. Ive found that the local hot rod guys are a lot more helpful for information than calling up any ricer parts shop, but thats just my opinion. Otherwise, you can go to http://www.horsepowerfreaks.com (866) HPF-5600 in Portland, or http://www.intecracing.com in Kent, WA. I don't know how much HPF charges, but Ive heard good things about them. Intec charges $120 an hour for tuning, which can add up fast. The old owners used to be cool, but I haven't worked with the new guys yet, though they moved in and jacked prices WAY up on everything. Anyway, both are kinda far from you, but they are options if you need them. Good luck.

[AN89HATCH]

No way to tell, unless you have a wideband.

It's all guess work until you KNOW the A/F ratio.

...

But for a baseline, I'd go for -41 low, and maybe -38 across the board for high.

BTW, you're math is backwards...-65 on high throttle is LESS fuel than -41.

The % is the amount of fuel you're CUTTING OUT from the injectors flow. To cut a 460cc injector down to ~270cc, you remove 41% of the flow. To to richen it up on HIGH throttle, you need a numerically lower number(nevermind the minus (e.g.: -41)...just think 41).

So -25 on 460cc is WAY more rich than -41...get it?

(Don't wanna see you blow it up first time the pressure gauge reads on the positive side...hehe).

- Brian

thanks!!

[deezlins]

Try to find a shop with a Dyno Dynamics or Dynapack dyno. They are the best for tuning (and really just the best period).
Modified by deezlins at 1:19 AM 4/6/2005

[Turb0wned]

how did u get the rx-7 injectors to work? they didnt fit right in right?

[wild_maxx]

ya

[Turb0wned]

what year rx-7 injectors are they and was it from the turbo one?

[wild_maxx]

88 rx-7 460cc non turbo i think the turbo one had 550cc injectors. look around ebay or junk yards for a set and send them off the be cleaned out and flow tested. what car are you putting these on?

[Turb0wned]

sr20det so are u sure that the non turbo ones came with 460's??

[wild_maxx]

the sr20det uses sidefeed injectors. the 460cc rx-7 are topfeed high impedence. if you are using a top feed rail it might work.

[:: orion ::]

...and the RX-7 side feeds (~550cc) need a spacer on top of them to fit into a stock SR/KA rail.

FYI...

- Brian

[wild_maxx]

ok i set up my safc with the base low at -41 and it wont even startup. its really rich. i can smell gas comming off the engine. i pulled the plugs and only one of them was black. looked like it was covered in oil or something so i pulled them all out and did a compression test and got 185 across the board. the engine was cold because i didnt get it started at all. it has not been started in about 2 months. should i lean the injectors out more so it doesnt flood my engine everytime i crank the key? i have a walbro 255lph fuel pump in and the 460cc's and i hear the pump kick on when i turn the key but it stays on for about 15 sec. is that normal? and while cranking the engine over it will just lock up and and stop cranking over. is that cause there is too much fuel in the cylinders? please help me

[huguetpj]

ok i set up my safc with the base low at -41 and it wont even startup. its really rich. i can smell gas comming off the engine. i pulled the plugs and only one of them was black. looked like it was covered in oil or something so i pulled them all out and did a compression test and got 185 across the board. the engine was cold because i didnt get it started at all. it has not been started in about 2 months. should i lean the injectors out more so it doesnt flood my engine everytime i crank the key? i have a walbro 255lph fuel pump in and the 460cc's and i hear the pump kick on when i turn the key but it stays on for about 15 sec. is that normal? and while cranking the engine over it will just lock up and and stop cranking over. is that cause there is too much fuel in the cylinders? please help me

[huguetpj]

ok i set up my safc with the base low at -41 and it wont even startup. its really rich. i can smell gas comming off the engine. i pulled the plugs and only one of them was black. looked like it was covered in oil or something so i pulled them all out and did a compression test and got 185 across the board. the engine was cold because i didnt get it started at all. it has not been started in about 2 months. should i lean the injectors out more so it doesnt flood my engine everytime i crank the key? i have a walbro 255lph fuel pump in and the 460cc's and i hear the pump kick on when i turn the key but it stays on for about 15 sec. is that normal? and while cranking the engine over it will just lock up and and stop cranking over. is that cause there is too much fuel in the cylinders? please help me

Can you install the stock injectors back and eliminate the SAFC just to try it out? You might wanna take out some variables to see what the problem is.

[wild_maxx]

i would rather not do that because it is all soldered together. the would mean i would have to cut the wires again and resolder later. i will mess with the timing and make sure i have the distributor set right.

[wild_maxx]

also, i was cranking the engine and my oil pressure gauge was climbing as i cranked it. that does mean that oil is flowing through the motor right? is there was to check if my turbo feed line is getting oil also?

[huguetpj]

i would rather not do that because it is all soldered together. the would mean i would have to cut the wires again and resolder later. i will mess with the timing and make sure i have the distributor set right.

yep... too much hassle.

To check if oil is getting to your turbo (although this has nothing to do with the ability to start the engine) just disconnect the oil feed line from the turbo, put the open end into a canister and crank the engine... no better way I can think of.