MM, so what is the correct way to add injectors?

I currently have the setup that way (380/380/480) and its been fine, although maybe MM 'mucked' around with it to make it work.

From my understanding, you want to keep the Primaries and Secondaries at the same ratio and keep the Primaries low for idling purposes, which usually will mean keeping those two as they are. The Primary 2 slot can be as large as you want and come on only when needed, but if you switch from the yellow, things get complicated because the primary 2 and secondary share the latency table.

Easiest solution to meet all those: Stock Primary, Stock Secondary, Yellow Modified Primary 2

That is basically correct. The secondaries are best kept at 125%-ish of primaries, and the sec and p2 share a latency table....

So in a perfect world you up all three, keeping the ratio the same, along with latency. But it gets expensive. So most of us run big P2's and deal with the small latency issue.

^ This. :biggthump

Thing is - I have not had to do any "chicanery" . Could it be that the difference between 280 and 380 is not enough to upset the balance ?

When you transition into boost at a low RPM, do your fuel tables deviate more from your actual output lambda than they do after 4500 RPM?

you can tune around most anything. The issue arises when you change something significant enough and the amount of tuning required to dial it back in.

I have a 6% rich spike at 4000 relative to 3500 and 4500 so I guess the answer is yes .

And there it is.

Ok . I guess there is a small amount of tuning around it then .
I kinda like the idea that the P1s (which inject direct into the port) are supplying a little bit more of the total fuel .

The fuel that gets there from the P2s is just the same.
I like the idea that fuel getting into the chamber somewhat equally from both sides of the rotor leads to a more even burn.

The P1s are right on the port whereas the P2s are up stream somewhat .


which you would only get if you made the secondaries larger - not the P2s .

Doesn't really matter. In fact, I'd posit that the mixture is more homogeneous with the added distance.
It isn't like the P1 position is really "direct injection".


Not exactly. As a result of the OE staging strategy, the secondaries get leaned on pretty hard as the P1s get trailed off. Also, the air path is different.
You can see the result of fuel delivery if you dissect a very low-mile, undamaged turbo motor.

This is one of the areas that was giving me fits when trying to tune myself with my uncapped P2s. In the end I got it "close enough" but never really completely "got" it. It would be so much easier if the staging of the injectors was directly tunable.

True - I'ts as close as Mazda could get it without going the whole hog . I would have to believe there was a benefit to doing that though , as it would have been far easier for them to just mount all the injectors further upstream. What is the layout with the S2 engine ? The P1 is now 400ccs (same as what I now have;) ) but is the other injector a P2 or in the secondary air channel ?


which is what ?

great in theory, but probably not valid due to the air flow not being equal from both sides, within a certain range is likely to be inconsequential regardless

The primary injector positions are placed for emissions/efficiency purposes.



.

But they are equal under these relevant circumstances because of the location/shape of the ports.
This becomes apparent when you look at a low-mile motor as I suggested.

What's apparent is that you theorized your belief rather than actually tested it out in detail in a controlled environment with definitive feedback, such as a Superflow engine dyno. I can only surmise that you don't have any direct experience tuning with the 4 injector S2 intake manifold on a 6-port engine. Going back to you original statement, a more even burn is defined less by appearances and more by calibrated data.

You're pretty d@mn good at what you do, but don't confuse your Cobb AP talent with operating at the top of the world class rotary/Renesis knowledge base. There are people who have built, tuned, tested and torn down multiple hundreds of Renesis engines let alone decades of prior 13B experience.

You might have just opened a new orifice on your neck there with that one...

Just going through this with the uncapped yellows ATM . From the results i'm getting It seems they don't flow as much as they should . What settings did you have when you were "close "

Oh .... not again .... :cuddle:


Did you guys uncap your P2's on your own?

I like what these guys do ... http://kgparts.com/index.php?page=rx8modinject

Apparently they flow test them afterwards and send you a matched pair!

I am leaning towards this....

Can AT injectors be uncapped in the same fashion?
In that case, could you do this set-up, with increasing all of them at the same time as Kane said:

primary: yellow
secondary: stock blue
P2: uncapped blue

My injectors that KG flowed at 900cc had to be scaled more like 750cc to get things in line. I had initially offset them with the Maf scale which caused all kinds of wonkiness.

Yes - I've uncapped my own . (after the shop i gave 1 to totally destroyed it trying to get the cap off - fucktards )

if you have 4 blues why not go
P1: yellow
sec : blue
P2 : blue

that gives you the scenario Kane spoke of . Not sure it's that much of an issue though .

I mean ... i dont have 4 blues, BUT I have spent $160 on worse things http://www.discountfuelsystems.com/s...ry,universal:0)

Esp with how much I have put into this turbo build already, combined with the fact that I want to go bigger in the future...

However, can someone explain why the following is?






Also, what exactly does the latency table control? From what I understand it has something to do with the firing mechanism of the injector (hence the pressure vs battery volt. relationship) However, is this atmos pressure or fuel line pressure?

Finally, if I go for the yellow, blue, blue setup, can I just copy the table from my currently secondary/P2 injectors over into the primary table and get an A/T table for the sec/P2? Should be doable since the tables are NOT rpm based.....

Jeff, can you hook me up with that ^?

It has to do with transition.

The PCM normally knows when and how to bring the sec's online and drop the duration on the P1's - if you mess with this ratio, it won't work right. This is firmware, cannot be tuned out on the AP.

If you go Yellow, Blue, Blue, you should be able to copy "Yellow" Latency Map onto P1 along with the size, to get close. You will still need to scale. And also you could get the Auto settings if Jeff was willing to send them. Only a pro-tuner can tune auto's?

The latency is the amount of time to physically move the pintle open in injector. IE Injector ON time where no fuel is flowing.

Probably because the injector scaling value is not linear like it appears to be.

Guys--sorry to butt in here, but I am dialing back boost to around 7-8 lbs. I get around 310 grams per sec at 7.5K at that level in the weather here in Ga.
Before i was running the stock injector set up with it and really didnt have a problem, BUT I was feeling I was about on the edge. I have the 09 fuel pump in. No issues.
Would the reds, blues in P2 and the yellows in the secondary be a better choice?
Since I now have the Cobb-- i will be looking (with Steve Kan) at all this also, just want to get started right.
thanks
OD

Yellow, Blue, Blue is the best choice, all things being equal.

Does latency change or stay the same for uncapped vs stock injectors?

Was looking at the pdf doc for these injectors the other day.
Your injectors where flowed at 2.5 bar around (1 bar is 14.508 psi, I think) or 36.27 psi
I guess ideally they should have been tested at 60 psi ....

Understanding that the scaling is not linear (as mentioned already) I would not expect the scale to move down ...

Am I seeing this wrong?

Would the injectors not be flowing more fuel at 60 psi than 36 psi? Therefore the injectors should be at least scaled up .... to some magnitude?

I can attach the pdf if requested.

That is exactly the thinking that had me hung up for a while. I thought for sure having Flowtested injectors would mean one parameter i didnt have to guess at and if anything our fuel rails higher than tested pressure would mean MORE fuel. But it didnt work out that way. I tried to make them work as "900cc" but they just dont put out that much fuel. A 900cc injector calls for a setting in the AP software of ~1100. But they didnt hit target AFRs until I lowered the setting considerably. I just checked my last few versions of my tune. I was running them with a value of 850 in the Racetuner software(which is approximately the setting for a 700cc injector).

Thanks Kane--when are you going to be home?
So yellows--P1
blues on bottom rail?
Is that right?

Od out until he can contribute something--which may be a WHILE!

OD - yeah, yellow on one rail, blues (qty 4) on the other rail.

OD - if you are dialing back the power to well below 300 you would be better served by leaving well enough alone and sticking with stock injectors .

The man has a point.

Though I thought part of the allure was the better atomization of the blue injectors....

Thanks for the info .
The (NA now but later going FI) car i'm tuning at the moment has uncapped yellow P2s and to get the AFRs to be the same as when the stock injectors were in there I had to set them to 533 . Figure that one out ......

Nothing is linear..... makes the game fun I guess.

The problem is that pressure as a derivative is not particularly consistent. I mean one look at the MAF scale, IAT etc should clue you in on that.

Best thing to do would be flow test them at 60PSI, barring that, scale them the same way you scale the stock ones.

http://godwillbegod.files.wordpress....-wait-what.jpg


So... uncapping injectors has unpredictable flow rates and consequences???



Nooo .... that means I will have to scale my injectors regardless .... exactly what I was trying to avoid :/


New plan:
1) Get injectors scaled while NA, keep them stock for my power goal of 250whp, screw trying to get under the UIM until I HAVE to...
2) Install Turbo

translation for ppl watching this thread: moar actual tuning rather than discussion to come...

dannobre, can you still send me the blue latency table? thanks!

No more so than stock (unless you mess them up physically).

What I am saying is that a 200cc/min injector at 10PSI will not be a 400cc/min injector at 20PSI...unfortunately.

poop ... if that was the case we could simply increase the fuel pressure to increase fueling, BUT from high school physics we know that liquids are not compressible .... therefore we cannot increase flow with pressure as we can with Air (a gas)

Am I right?

Also, would it be safe to assume that my injectors now flow LESS rather than MORE than my ECU thinks they do?

Increasing pressure does increase fueling to a point, (think old school turbo tuning) it is just not linear really.

I don't know what you scaled the injectors too, my net is too slow to go looking. But scaling them NA before going FI is always a good idea.

I thought I gave pretty good instructions on how to factor out the anomalous injector scaling values in the seminar.

That said, here is my FUELING CALCULATOR

^^^ Thanks for that Jeff

Started a new thread specific to an issue I'm having with P2 scaling - any help would be appreciated .

https://www.rx8club.com/series-i-engine-tuning-forum-63/problems-scaling-p2s-209721/

well I just ordered 4 blues (reconditioned --but flow tested etc ) for $160 for all 4. Nice price.
I am dialing back, but I still feel I need a little more than what stock will give me and stay in the 80% duty cycle.
Stock is around total at aprox 2080 cc--right? If my calculations are right I need around 2000cc total flow. So with the oem set up that would be very close to 100% duty cycle.
The yellow and blue set would be 2680cc or which may be a bit much unless later I decide to use the power level?
Now if I went with reds in P1, blues in P2 and yellow in secondary then that would be 2280cc. That may be about right and still keep my idle and low in ok?
Blues to atomize more--heck the 09's do a better job than all of them.
I will probably start out with the reds/blues and yellows. Then see.
I think I will be over 300 gram/sec--prob between 310-320 is where I expect to be.
Wish I could put the 09 set up on.
OD

Yeah - that is right at the high point of the OE fuel injection system with no changes (2100cc).
That should equate to about 220 wheel horsepower on a 7 PSI supercharged car.

Wouldn't you be better to use the 4 blues.....the latency tables would be correct that way for all 4.......otherwise you have an error right off the bat for that :)

So yellow/Blue/blue??????

Well, I think that is what OD is doing now ... I am going to probably do that too ... I need to acquire the injectors first.

For now, I am going to practice with scaling for NA .... once I got my lazy ass out of my warm house and into the cold outside to do some logs....

but yellow/blue/blue is the idea for the future ... big thanks for the latency table btw

before I was getting around 275 rwp
I think i got my numbers wrong--recalculating for approx 325 crank HP(approx 275 at the wheels?) and max of 80% duty cycle and 55 psi fuel pressure I would need 2280 cc total flow.
The yellow/blue/ blue should be is right on?
Then no scaling issues like Dan mentioned?
I will see how that runs by next w/e--motor going in now but taking my time--lots of little stuff to do.

Less latency issues....scaling will still be off by whatever they could be off stock :)