850cc secondaries able to tune down 720ish?
 

so finally figured it out im getting to much fuel when secondaries come on so no boost for me. have a new streetported t2 engine rtek 1.7 and running 550/850cc inj..question is can i tune down the secondaries to be more equivilent to 720cc with a safc? im planning on bigger and better mods in the future and just got new 850cc so im not trying to keep swapping injecters.
sorry for being vague any more info needed to tell me if possible just request and ill provide..
thanks

You should ask this in the Rtek Section Todd...Personally I don't think that the 850 can be run on the 1.7 as the settings are only for 550/720..and If that is the case,I "think" that the 850's would be Seen as 720's...but WTF..I am wrong most of the time..So HI..Just sayin HI!..heh.

yes you could tune them down with a SAFC, however if you turn them down at the transition point be very careful to ensure your not leaning it out right before the transition point when you do so!

Isn't that the place you want to be with injectors a little bigger so you can tune it. From reading on the forum seems like the average injector puts out less than it's number. Should be perfect for tuning. But like mister, I am just trying to learn a little. Maybe someone that knows from experience will chime in.

yea i knew that they are rtek was programed running 550/720 combo but im planning on running on bigger mods in the near future which will require more fuel so im asking if the apexi safcII has enough tunability to turn down the fuel spray to make my 850cc act more like 720 for the time being instead of purchasing another set of 720cc to run for a couple months ya know.. thanks for the input and i listed the thread in the SAFC thread too..

Then Todd,I would be looking at the Rtek 2.1 It has the capability of Tuning,and also you can run 550/550,550/720,or 720/720..They are all presets..you can also Vary the primaries and Secondaries and go with Say 750/1000...as Long as you stay within a Guideline of Percentages (say 23-28%) between Primary and secondary Injectors,then your Car should Run decently.
Here read this(off the Rtek forum),It is very informative and makes the 2.1 look very good for it's price! https://www.rx7club.com/rtek-forum-168/what-injectors-size-combinations-besides-presets-can-work-rtek-2-1-a-787164/
and as I said,go to the forum,grab a coffee and Read!..
I got a 2.1 and I had no clue..I'm Getting all my Info off of the "Gurus' There.
Cheers STYX!~
Oh..I don't Know where that BOLT goes!..got a PIC?..(just kidding!)

i had a knightsport chip, Apexi AFC neo, and 4 550cc secondaries (1100cc on each bank) and was able to tune it to where i wanted up top

you do realize when you lean a car out with an SAFC it advances the timing? the ECU thinks the motor has less air flowing through it (less engine load) and will advance the timing. I'm not saying you're going to automatically blow your motor up, but it's definitely not the safest way to do things, especially if you are going to run the car hard and let intake temps increase for a higher chance of detonating.

If it were me I would keep it the way it is until you can get an Rtek 2.1 . It gives you more precise control over fuel and timing as well as updated injector staging code. There are people running 720/1000 with it.

Todd,

I have an RTek 1.8 (rated for 720,720) on my S5 Tii vert with 720cc Densos in the primaries and 1000cc RCs in the secondaries. I have an SAFC-Neo and a Zeitronix w/b.

You can use the SAFC to "turn down" the secondaries. The SAFC tricks the ECU into thinking there is more or less air flowing thru so it adjusts the fuel accordingly.

Note that you can't tune with the SAFC unless you have a w/b or take it to a tuner shop with a dyno and an external w/b sensor.

One other thing to keep in mind is that the RTek 1.x is tuned assuming an otherwise stock engine with stock intake and exhaust. Mine is ported and I'm running a free-flowing exhaust so that at a given RPM my engine is pumping a lot more air than normal. What I found via the Zeitronix is that I had to use the SAFC to richen up the mixture pretty much across the board and by 20% in the 3-4k rpm range. And even though the secondaries are almost 40% bigger than the 720s the RTek is tuned for, we arent running super rich above 4000 like you'd think.

So IMO the answer to your question is "yes." I would have gotten the RTek 2.x which would have obviated the need for the SAFC but sadly they arent available for the S5's yet.

Good luck,

Jim

yeah it definitely isnt the best way of doin things, mine was my "rig job setup" so i could drive it this year, i put over 7000kms on it this summer made 313whp 289ft-lbs at 15psi, but i know what im doin, and made sure i was always keepin on eye on everything,

tuning 850cc inj down to 720cc is nothing, i was pulling out alot more fuel then you,and my engine still runs perfect, fires up after sitting for a couple weeks almost as fast as you can turn the key

people say it pulls out timing......but riddle me this, your boost pressure sensor is still hooked up yes/ no .....hmmm i thought the majority of the timing control was comming from what the boost pressure was reading and the fuel was being controlled by the volume of air entering into the intake system.......hmmmmmm

if you have the SAFC connected to the boost pressure sensor then yes thats the case with the timing but if hooked up normal it has very minimul effect to the timing

The timing maps are load-based. From Digital Tuning, the makers of the Rtek 2.1 :

http://www.digitaltuning.com/index.p...S4T2#timingmap


From Mazda factory training manual, Fuel and emissions control system section, page 4-50 :

https://www.rx7club.com/attachment.p...1&d=1230571477

The point here is not that leaning out your SAFC will automatically blow your motor, although the less airflow the ECU sees the more likely it is going to run unsafe timing. The Rtek chips do pull additional timing compared to the stock ECU, so the risk is less than say putting 550/1000 in a stock ECU, leaning the thing out 20%, then running 12psi.

I have used an SAFC to lean out a car before (both turbo and nonturbo FC's), but that was in 2005. There are better (but still affordable) options out there now, and when you are dealing with engines that are notorious for going kaboom you really should just do it right.

yea i know i was planning on going 2.1 but wanted to do everything @ once ie buy 2.1/wideband in a little bit...i will just buy the 720cc now for the secondaries so everything works accordingly with the 1.7 for now...just seeing what is easier since the price is about the same SAFCII and new 720cc inj...
thanks for the responses very informative just dont wanna play with tuning just as of yet wait for the 2.1

yes i do understand taking out fuel will cause advances in timing. However his injector size increase is quite mild, so he will only be taking out a small amount. This should not be enuf to cause timign to become an issue. mainly timing problem soccur when very large injectors are used and turned way down with the safc.