Any ideas for tuning a ka-t with an safc????

[Jookmasta]

with the safc tuning, if not in boost, DO set the low throttle at -27%. This may vary slightly from car to car but i personally run -30% on everyday driving. Now for high throttle, i honestly dont know since i havent been able to get boost yet. You would probably start increasing the fuel so it would go to -23% or -22% for high throttle. Im 100% sure for the low throttle part but i can't back the high throttle numbers.

Running at -10% will definitely cause the car to stall/bog if not in boost tho. Dont know where those numbers came from...............

[D1 guy]

Thanks man I appreciate it and all the info from everybody. The car is almost ready and I should be able to try and start it tomorrow or saturday.

[KFL]

Does anyone know which wire color from the safc2 goes to the ecu air flow signal.

[xatracing]

Hey guys take into account something else important when tuning with an AFC.. I do a ton of AFC tunes, Nissan ECU rom tunes.. standalones etc so I am very familiar with how a efi ecu works... look at the left most chart.. basicallly most ecus run a matrix.. rpm over motor load.. or in our case.. mass air quantity... Nissans mafs dont see boost just a higher quantity of air going in through the meter so the "boost" row you see in the picture is just for a refrence point. Anyways ... the important thing I wanted to mention is that when you use a afc for bigger injectors you are essentially lessening the signal coming in from the mafs. This in turn makes your ecu read from a earlier cell in the matrix... What you are looking at is the timing portion of a ka .. sr.. vg ..rb.. whatever ecu.. If it sees lower load it .. lets say 40... vs 72 because you took out that much with a afc... it will now give you 18 degrees of timing instead of 12.... not good in boosted situations.... esp on a KA because the timing is set up for a NA car.. The thing is .. up to about 260 rwhp you are ok if you just run your timing at 15 deg base.. After that you gotta back it off more with a device made for timing control.

MartinXAT Racinghttp://www.xatracing.com

[KATwo40]

***QUOTE***Setting it to -27% will make your 370 -> 270 across the board.

Sorry, but your math is wrong. To achieve the mimic of 270cc/min in a 370cc/min injector, you'd need to dial back to -37%. 270 is 37% less than 370.

That's why -27% makes it run rich...because you're NOT flowing equivalent to 270cc/min. You're flowing more than that.

At any rate, you'll be fine if you dial back to -27%. Whatever you do, please don't keep the stock pump. When I dyno'd my setup w/ wideband we found that the stock pump was tapping out around 4k rpm on 370's and the SAFC @ -15%. No matter what I did, the pump just couldn't keep up. And that was on 7psi. The best ratio we could obtain was 13.2:1ish.

[D1 guy]

Thanks for the aem windows. That will help a lot!!! You guys are awesome!

[Fulcrum]

Xatracing,

I see that you are using ROM Editor. What software/hardware so you use to burn the .bin's to the EPROM? Also, do you have the addresses for the KA24DE ECU?

Please bear with me.... All my experience is with Uberdata and Hondata. I'm still a newbie at Nissan ECU stuff.

TIA,Fulcrum

[SonyPete]

Hey KATwo40, Not so sure about your math. If you added 37% to 270 injectors you might get 370. But if you deduct 37% from 370 injectors you shoot way below 270.So I do believe -27% from 370 gets you down to 270. AM I missing something here this is simple math

[onosqv]

Hey KATwo40, Not so sure about your math. If you added 37% to 270 injectors you might get 370. But if you deduct 37% from 370 injectors you shoot way below 270.So I do believe -27% from 370 gets you down to 270. AM I missing something here this is simple math

HAHA, I knew 27% was right.

37% of 370 = 136.9 -> will bring your injectors to 233.127% of 370 = 99.9 -> will bring your injectors to 270.1

Boo YA!

In any case, this is pointless because your numbers may be very different since there are factors like state/condition of injectors, bla bla bla. You still need to tune in the end.

Good job Pete!

[KATwo40]

Bah, I need to refresh my math. Sorry about that.

[sil80drifter]

YES!!!! I WANT EVERYONE WITH AN SAFC TO READ THIS!!!!! TIMING GETS RETARDED WHEN YOU DECREASE FUEL TO ADJUST FOR LARGER INJECTORS!!!

Also I have 460s, and when I set my idle fuel to -20 or below, my car starts stumbling, leaning out and dies.I don't knwo how you can run -30, but thats how it is. This may have somethign to do with the timing issue, but also with the exponential increase in injector flow, since most cars idle the same, the difference in the initial pulse width between a 270CC and a 460cc injector is NOT proportiona to their respective sizes. NOT NOT NOT. a 14:1 AFR will be achieved higher than -27, say around -20 to -18.I have done this personally on my KA, and that's how it worked.also look into figurign otu how high impedence injectors work, and you'll see that they ncrease flow exponentially and not linearly as everyone thinks. So at 100% flow, yeah the 460cc will dump 460cc and 270cc will dump 270cc (their respective ratio being 1.7:1. 460cc being 170% larger than 270cc)), BUT at 10% flow their ratio of fuel injected will be much closer, say 1.2:1 or so. The latter number is a but speculative, but I knwo what % decrease worked on my car with the SAFC so I'm guesstimating it.

sil80

[Jookmasta]

sil80 has a very very valid point. up to today i was noticing how my car does stumble at idle sometimes with the safc set at -30%. Strange how my car didnt do this when i was NA and running the 370s but i thought about what sil80 said and it makes perfect sense. When i was NA, i was running around 22 or 23 degrees of timing. This explains y i didnt stumble at idle since if i was using -30% on the safc, the retarding of timing wouldnt be bad due to my advanced timing. Now that i am turbo, my timing is around 13 or 14 degrees and with the car at idle and the safc set at -30%, the car will stumble a little and catch itself..............it will continue to do this until the turbo timer shuts off but since my timing is already retarded and since timing is being further retarded due to the setting on the SAFC, hence my stumbling and even dying of the car at idle.............

[Jookmasta]

well i did some chatting with a friend and it seems that my thinking was a bit off track. when leaning out with the safc, the maf signal which the ecu receives is being decreased. Although this signal is decreased, the TPS signal is not altered. This means that the ecu is seeing great load with little airflow. To compensate for this, the ecu will advance timing (not retard it). So whenever the correction factor is negative, the ecu will advance the timing. Its only when the correction factor is in the positive that the ecu will retard the timing. I myself have some portions of my high and low throttle maps in the positive as this was required for me to get my desired afrs.

So for my previous post, my guess as to why i stumble at idle is not b/c of me leaning out my fuel and causing the ecu to retard timing, but instead the stumbling issue was mainly due to my lack of thinking on my part. With the T3 that im running, i technically get spool with little rpms. This can be seen with my vacuum at idle. When i was NA, i got -.72 hkpa at idle. Now that im turbo, i am getting -.45 hkpa at idle. This is a 5 psi difference in the amount of airflow at idle. To rectify this, i will need to add more fuel as now i have more air being ingested at idle. In other words, -30% on the SAFC was fine for NA, but with the turbo ingesting even slightly more air, the lean conditions that are produced have caused the car to stumble and catch itself at idle.

[240SicknessX]

yes you are correct about the added airflow at idle from the turbo promoted a lean condition and you add to compensate by adding fuel to regain a constant idle.

you were under the impression that when the safc's values are the in negitives the ecu retards the timing, but your baseline timing was already advanced from running NA so it was belived that it didnt have much effect on your idle. Once you had the turbo tuned, the baseline timing was bumped back to 13 or so. you were under the impression that with the baseline retard that you gave the car for boost in addition to the misconception about the retard in the neg values of the safc resulted in a crappy inconsistant idle. Well as you said before, your vac decreased after you installed the turbo therefor increasing overall airflow and with keeping the same -30% safc 1k setting it would make it lean, and thats why you had a inconsistant idle.

btw, if the ecu sees the mafs signal as being lower then normal when compared to the NA timing map at a specific TPS volt then the ecu will add timing to gain more power, and increase the airflow to be proportional to the tps signal.

jookmasta and i discussed this over aim just a while ago and decided to post about it.

[240SicknessX]

sil80, what do you have your timing set at?

im going aginst what you said about the safc retarding the timing in the negitive correction values, i belive that because of the reduction in the mafs signal strength (volts) when compared to the TPS imput the engine will read that the driver wants more power, but the mafs is not responding with the correct voltage of where it should be, there for the ecu adds timing to try to make more power and make up for the lost airflow signal. based off what i said, if you already have your timing slightly advanced a few degrees, and after the installation of the safc it happens to advance it more becuase of the negitive correction factor for your larger injectors. well it could be advancing the timing too much causing it to not run smoothly, possibly getting spark knock at low throttle imputs.

now a genral tuning question, to reduce knock during NA tuning........you already have the timing advanced can you simply add more fuel to supress detonation; or becuase you are running more timing, you need a slower burning fuel so that it dosent pre ignite. or change cam overlap if possible.

[sil80drifter]

My timing was exactly at base timing, the ECU does advance it based on MAF signal.

The turbo does NOT give any additional airflow at idle. If anything it's a restriction. Mine doesn't even really spin at idle (mayeb one revolution per minute). Not because it's a bad turbo, but because there isn't enough gasses to make the turbine spin.

sil80

[240SicknessX]

well in jookmastas case, the turbo dose supply more air flow at idle. before he had -.72 hkpa NA (180 compression across the board), and now he bolted on the turbo and is reading -.45 hkpa (and has 180 compression across the board). so hes not loosing vac from the rings not seating properly from detonation or w\e. the less vac = more airflow. so in his case it would cause a lean condition as i described before at idel.

[sil80drifter]

Going from -0.75 to -0.45 means that the engine is now sucking in LESS air than before. There is less vacume, and not as much air getting sucked in. In other words it isn't sucking air in as hard as it used to. If ANYTHING there is less air going in. Hence a richer mixture. The turbo acts as a restrictor. There is now something IN THE WAY OF AIR (the turbo) as it goes from the intake through the compressor wheel, through the FMIC, and into the intake manifold.

sil80

[240SicknessX]

Going from -0.75 to -0.45 means that the engine is now sucking in LESS air than before

you are correct to an extent, vacume isnt airflow, its the density of the air. the turbo is aiding in the air delevery to the engine, therefor less vacume. vacume is the draw that the engine creates with hte movement of the pistons.

There is less vacume, and not as much air getting sucked in. In other words it isn't sucking air in as hard as it used to.

correct, the turbo is suppling air to the engine which is decreaseing the vacume, the only way it can decrease vacume is if it increases volume.

sil80drifter, we all know that if you have a greater negitive number that means that there is less of something, vacume is read in the intake manifold.

-.72hkpa is < -.45hkpa, when looking at an analog boost gauge, the vac numbers are - and the boost numbers are +. now picture the values on the gauge, which number is closer to the boost side? well we all know boost is flowing more air then vacume.

there for as i stated before, the turbo aids in providing the engine with air, by keeping the same 1k safc correction setting, you have just created a lean condition in jookmastas case.

btw about your turbo spinning at an estamated 1rpm at idle............... was that a typo?

Modified by 240SicknessX at 7:17 PM 3/30/2005

Modified by 240SicknessX at 7:19 PM 3/30/2005
Modified by 240SicknessX at 7:20 PM 3/30/2005

[sil80drifter]

no it wasn't.my turbo literally doesn't spin much at all. it's not supposed to either unless it's a ball bearing or t28 or below. The mass of the exhaust wheel is too great and the size of the exhaust housing is too large, so that exhaust gets by without spinning the wheels. My exhaust A/R is about 1.0. Hence, since the compressor wheel doesn't spin, it's only in the way of air trying to get by to the intake manifold. So for me (and most others) the turbine, at idle is a restriction, and will not cause leaner idle mixtures. Even if the compressor wheel barely spins or spins visibly (but not quickly, it is more likely to be spun BY the air being sucked in by the engine (vacume) than actually be spinning and making ANY kind of positive compression effect at idle. I understand your explanation about -0.75 < -0.45, but all it tells me is that now the effort of the engien is spent suckign the air through the restrictive piping than on actually making enough vacume to operate as if under normal N/A conditions. Again. leading to a richer (if anything) mixture.

sil80

[240SicknessX]

I understand your explanation about -0.75 < -0.45, but all it tells me is that now the effort of the engien is spent suckign the air through the restrictive piping than on actually making enough vacume to operate as if under normal N/A conditions. Again. leading to a richer (if anything) mixture.

sil80

i dont understand what you are saying there so i let someone else read the above quote and they said: " i think he means that the decrease in vacuum is due to restrictive piping" ( and fmic) if this is true....... at idle, any restriction in the air pathway will result in a higher vac compared to when that restriction wasnt there. for easy explanation, a stock 240 lets say has -.72ish hkpa vac with the stock air filter, stock airfilter dosent flow much, which is a restriction. now if you replace the stock airfilter with one that is more free flowing then you will reduce the restriction, resulting in a lower vacume.

is that what you were trying to say? maybe?

im going to leave this topic/ discussion about the turbo being a restriction or aid to flowing air at idle alone. there are different varibles, some smaller turbos will supply airflow at idel and some wont, its all based on the setup. so ppl just get a freaking wideband and make sure you have appropriate afrs at idle if this is a concern for you.

[sil80drifter]

deal

although i'd like someone with more knowledge than us to chime in and maybe shed some light. always good whent he gurus stop by and break it down.

sil80

[Jookmasta]

calling any mod or anyone that knows more than us to break it down one time (no pun intended)

[deezlins]

Im glad people realize that changing afr on a piggyback will affect timing. BTW AFR doesnt really affect power much at all (as long as youre in a certain range, like not ridiculously rich or lean, the range will usually be more narrow with higher hp cars), it might make a few hp difference or so, really not enough to make much of a difference, afr is mostly for safety and fuel economy. The whole thing about leaning out the afr to make power got started because people didnt realize that changing the afr on piggybacks affects timing, so when they leaned it out the timing advanced and they though that leaning the afr out was giving them more power when it was really mostly the timing. I just thought i'd share that

btw, the vacuum should increase with more restriction (like dirty air filter), but a low vacuum reading can mean lots of things like leaks and timing, etc. I dont know how much air, if any, the turbo would flow at idle though, it might depend on the turbo, and it might just be a restriction, interesting, i'll have to look into it.

[DRIFTEADOR]

double negatives....vacumm=negative pressure. so negative -.75 (-10.8psi, i dont do the metric )<-.45(-6.5psi) means theres more positive pressure now not more vacumm. however, i believe sil80 is right, with a turbo at idle there should be the same or more vacumm/less air than stock. are you sure you dont have a leak somewhere on the manifold? -6psi, roughly 12in/hg vac sounds really low. should be closer to 20in/hg

[onosqv]

it might depend on the turbo, and it might just be a restriction, interesting, i'll have to look into it.

Ok, time to clear things up hopefully .

I'm no expert like a lot of the members on this forum, but I have done a lot of research (just a term paper on turbochargers). A turbocharger itself is ALWAYS a restriction on the exhaust system... relatively speaking. Everything must flow through the exhaust turbine to exit, except the air through a wastegate which isn't that much anyway, etc. Once it starts to go into boost, the flow created outweighs this restriction. An easy way to think of turbocharger as a restriction in this case is to imagine a system w/ the same amount of boosted airflow but no turbine (although no really possible, but use it for an example). The exhaust system w/ the same air w/ no turbine has much better flow.

It DOES NOT matter how big your turbine is. There is ALWAYS a restriction. Air MUST pass through the turbine.

I believe Corky Bell, or one of the other main authors of other turbocharger/supercharger books, noted that your fuel economy, even w/ spectacular tuning, will be about 10% less city driving, 5% less highway driving. That has to do w/ a lot of other factors, but exhaust system restriction may be one of the smaller ones - just a lil something extra .

Anyway, to further back me up and since I don't have the books or my research paper in front of me, I'll quote Squires Turbo Systems:

For certain normally aspirated or supercharged systems, stock exhaust is somewhat restrictive and can cause backpressure in the system and rob HP. However, with turbocharged applications, the turbocharger is the biggest restriction in the exhaust system. All of the exhaust gasses (except the ones that are vented out the wastegate) pass through the turbine housing. The inlet hole in the turbine housing is about 2"x3", however, as it scrolls around the housing it gets smaller and smaller causing the exhaust gasses to increase in velocity. At the smallest point where the gasses exit and hit the turbine wheel, the hole is no bigger than about 1" in diameter. This tiny hole will create backpressure in the entire exhaust system prior to the turbo and clear back to the exhaust valves.

[WDRacing]

I don't know man, this topuic is open for debate. I leaned out my Sklyine and ran alcohol and made a ton more power then with a leaner Af mix then with a typical 12/1. I ended up with a 13.2 or so and made considerably more power.

It boils down to octane/compression and timing curve in situations like this. So a blanket statement like AF's don't make more or less power isn't really correct.

Sit on a dyno with C16 and raise the boost over and over. You'll see the mix lean out and the numbers on the graph will change drasticly.

And this was done way before SAFC and other piggy backs. We were doing this with carbs when you had to pull your plugs to check for detonation and a personal wideband wasn't even a thought.

The cool thing about the SAFC is the two maps you can build. One for running acohol and one for running pump gas. Or one for running 87 and one for running 93. Just in case you have to use a bad tank of gas for whatever reason.

WD

[DRIFTEADOR]

no doubt the turbine is a restriction. but a bigger restriction is the distance the intake air has to travel from the compressor inlet, to the tb. btw, corky can suck my left one, theres a bunch of mis-info in his book. and about fuel economy, city driving after turbo may increse/decrease fuel economy depending on your driving habits, but on the highway, at least in my case, it incresed fuel economy. turbochargers increase a motors volumetric efficiency.

[sil80drifter]

Leanign out WILL affect power but not as much as timing will. And you cannot possibly make gas mileage better by adding a turbo charger. The best gas mileage will be achieved by tunign an NA motor for the best AFR/timing to save the most gas. After you turbo charge that same motor, the best you can do is get back to that same AF/timing combination. It will never be better because the best AFR you can get for fuel efficiency is 14.7:1 on accel and up to 20:1 on decel. A turbo can push more air into the engine, and to achive the above AFRs you'll nee to add more fuel, but it'll never be "better" than an NA application tuned for economy. Volumetric efficiency has to do with power more so than economy. Corky has some good points, I have yet to see something in that book that is mis informing.

sil80

[DRIFTEADOR]

http://www.honeywell.com/sites...e.htmthats the first link that came up

a turboed motor will make the same amount of power more efficiently than a n/a motor. while cruising you only need so much power to reach a desired speed. therefore, at the same speed the turbo motor will require less fuel. i guess the correct term for this would be brake specific fuel consumption not volumetric efficiency.

and i'll rephrase about corky's maximum boost. the book has good basic info, but much of the material is outdated.