hondahater

iTrader: (2)

should I change my safc's settings somewhere if I have 720 secondaries? I was doing some searching and I found someone that stated that you did but nothing was in detail. Thanks.

2a+RoN

Its best to have it tuned on a dyno. I'm not exactly sure if that's what your asking, but oh well.

Ryde _Or_Die

I have been running 1 BAR with 720 secondaries and I had it tuned down I believe 10% for a while. Now I'll have all 720s and get it tuned on the dyno though.

NZConvertible

Why do you have those injectors? You don't need them with a stock turbo.

Ryde _Or_Die

Are you talking to me? My turbo is not stock.

mr_vaughn

iTrader: (1)

i will be getting an safc and 720cc injec next year for my setup and then a wide band o2 then i am done on engine upgrades.
then all i need is slotted rotorsfor the brakes and the car is performance complete

NZConvertible

No Mr. DeNiro, not you. The question was for hondahater.

hondahater

iTrader: (2)

I don't know the last guy that had the car put them on and also a huge *** fuel pump (prolly why I'm getthing about 4 miles to the gallon, lol).

Ryde _Or_Die

Thats what I thought JK

13B2QuIcKNy

who said u dont need 720's for a stock turbo?? with intake and complete exhaust and even without a street port... or fcd the car will run very lean on the high end..those 55O's gotta go.. specially with a street port

NZConvertible

You need to better understand how EFI works. Unless the injectors have reached 100% pulsewidth, engines don't run lean because the injectors are too small. They run lean because the fuel pump has reached its max flow (too much boost) or the ECU isn't compensating enough for increased airflow.

The higher the manifold pressure, the higher the FPR pushes up fuel pressure. The stock pump can't flow enough to maintain the required pressure at boost levels past ~10psi so the engine runs lean. This has nothing to do with the injectors. The pump needs to be upgraded well before the injectors do.

If you upgrade the pump you fix that problem but if you run high boost on the stock turbo (which you shouldn't anyway) the ECU's maps may not be suitable. This is when you use a fuel controller to enrich any areas running lean. You only need to upgrade the injectors if this tuning causes injector pulsewidths over 85%.

Your comment about the effect of the FCD isn't completely correct. On S4's the MAP sensor has very little to do with fuel delivery, but it does control ignition timing. On S5's though the MAP sensor does have an effect on fuelling. In either case, this is again a control issue than can be tuned using a fuel controller. But since you have no control over ignition timing, running more than 2-3psi higher than 8.6psi with an FCD is risky because the timing isn't being retarded as manifold pressure increases.

The turbo's efficiency drops off past 11-12psi anyway, so if you do run high boost on the stock turbo (with an FCD), then you'll have problems with high intake temps and over-advanced ignition, both of which will cause detonation. Detonation can be suppressed with rich mixtures, but that kills power and increases fuel consumption. Basically it's a very crude and inefficient way to "tune" an engine.

Again, injectors don't need to be upgraded unless you can't get safe mixtures without exceeding 85% duty cycle. Sort out fuel pressure and fuel control first. And if you're running high boost because of boost creep then fix it!

oregano

iTrader: (1)

"The higher the manifold pressure, the higher the FPR pushes up fuel pressure."

"Your comment about the effect of the FCD isn't completely correct. On S4's the MAP sensor has very little to do with fuel delivery"

So is the S4 from 1986-1987? And the S5 is 1988+?

If so, then hondahater's fuel delivery is controlled by the MAP sensor right? What controls the fuel pressure on the S4's, the MAF sensor? or does the fuel run a closed loop fuel map?

oh yeah, wut is an FCD? And can the ignition timing be adjusted by tweaking the crank angle sensor? If so, will this cause the car to run on closed loop?

J-Rat

iTrader: (2)

Fuel cut defensor. Prevents the ECU from cutting fuel when boost hits a predetermined level.

Jarrett

hondahater

iTrader: (2)

its 86 to 88 is s4 and 89 to 91 is s5. I don't think I need the injectors like nzconvertable always tells me but thats what I got so I gotta live with it. Hey nz I got a question for you. At what rpm does your secondaries kick in? And when they kick in should I tune the a/f ratio down to compinsate for the 720's over fueling for my setup? THanks.

J-Rat

iTrader: (2)

All secondaries kick in at 3800 (assuming stock ecu). And although NZ cautions against it, I am also running 720 secondaries. Actually, I will be going to 800+ secondaries and 720 primaries on a stock turbo (in preparation for the aftermarket turbo of course). But the SAFC is going to be turned WAAAAY down. And I also have a walbro, so fuel isnt a problem..Ever.

Jarrett

hondahater

iTrader: (2)

yeah I have the huge exspensive one off of rx7.com so I think I need to tune it way down.

oregano

iTrader: (1)

So is the FCD only for the turbo rx7 then?

J-Rat

iTrader: (2)

yes

NZConvertible

hondahater has an S4, so fuel delivery is calculated from airflow readings by the AFM. Even on S5's, the AFM still does most of the work, with the MAP sensor used at high boost.
Fuel pressure is controlled by the fuel pressure regulator. It is a purely mechanical device than is not controlled by the ECU. As manifold pressure goes up, fuel pressure goes up by the same amount. This is to keep a constant pressure differential accross the injector, so that fuel flow when the injector opens is constant regardless of load.
Closed loop is a whole different topic. It's not relevant here.
Yes, but that alters timing across the entire rev and load range, not just at high load when you want it. If you retard the ignition by turning the CAS you'll lose power across the entire rev range as a result. It also has the same effect on fuel injection timing, which can't be a good thing.
Again, seperate issue. Closed loop isn't affected.

The secondaries start firing at 3800rpm. Above this point you'll be injecting 18% more fuel than with the stock injectors, so you need to use a correction of -15% to get back to stock mixtures. You still need to get it dyno-tuned to make the mixtures are correct. Most likely you'll be further leaning out the rich factory mixtures.

I don't caution against it, I just think it's a waste of time if you don't actually need them. In my experience most that have them don't need them. I've also never seen anyone post that they actually measured injector duty cycle to see if they were really needed.
Why bother putting them in before you need them? You'll just have to get it tuned, and then retuned again when you put the turbo on. There'll be no gains from those huge injectors, just unneeded hassle and expense to get the car running right. Plus the S-AFC is not sophisticated enough to smooth out the hiccup caused by the transition to mismatched secondaries. I wouldn't want that unless I had no choice.

J-Rat

iTrader: (2)

This is all true, but honestly, my turbo is spinning to 14 PSI. Do we all know that its bad for the turbo? Yes. Do we know its bad for the motor? Yes. Do I care? Not really. I am just buying the stuff as I get money, and installing it. Its not tuned, but it will be in the new year. So what am I sayin? I know its probably overkill, but I dont care.......

But since I have your attention, what would you recommend for a TO4B? 4x720s? 2x550/2x720?

This would affect my decision.

Jarrett

gsracer

if you're going stand alone why not go the stock primary large secondaries (1200cc etc...)

It depends on your power goals. 4 x 720 is a lot of fuel and would probably do fine for lower - mid 300 rwhp. I remember tony was at 385 rwhp and running the injectors at an injector duty cycle of 99 percent.

J-Rat

iTrader: (2)

My HP goal is 350. So I believe the 4x720s would probably do the job.

oregano

iTrader: (1)

"Fuel pressure is controlled by the fuel pressure regulator. It is a purely mechanical device than is not controlled by the ECU. As manifold pressure goes up, fuel pressure goes up by the same amount. This is to keep a constant pressure differential accross the injector, so that fuel flow when the injector opens is constant regardless of load."

Really? Did not know that it was mechanical. Could you elaborate on how this device works NZ? Fuel pressure is created by the fuel pump, right? So is it a mechanical sensor that tells the fuel pump to create more pressure?

"If so, will this cause the car to run on closed loop?"

"Again, seperate issue. Closed loop isn't affected."

That's true. But while we are at it, I'm still curious. How sensitive is the rx7 to little tweaks like that? In other words, how easy is it to throw the car into closed loop? I know my mom's protege is running closed loop cuz the O2 sensor is busted

oregano

iTrader: (1)

nice avitar J-Rat
What is that thing anyways?

NZConvertible

If that's flywheel horsepower you're correct. They're good for about 380hp.

No, generally the fuel pump runs at a constant speed and pressure. The FPR is simply an adjustable restriction at the end of the fuel rail. A diaphram inside is acted on by manifold pressure, and as the manifold pressure increases the restriction is made smaller. By increasing the restriction to the fuel flow, the upstream pressure is increased.

S4 turbos and all S5's have an ECU-controlled system that reduces the voltage to the fuel pump unless the engine's under load, to increase pump life. This has the effect of reducing fuel pressure. The ECU's fuel maps are programmed to account for this.
Close-loop is entirely controlled by the ECU. Under all conditions other than light-load cruising the ECU refers to it's internal fuel maps to calculate fuel requirements, and the O2 sensor is ignored. Only under light-load cruise does the ECU used closed-loop tuning, where it uses the O2 sensor to determine whether the mixture is above stoichiometric or below it. If the mixures lean it adds fuel and if it's rich it reduces fuel. As long as the engine load remains low (and constant), the ECU keeps trying to maintain a stoichiometric mixture. This reduces both fuel consumption and emissions.

Mods should have little effect on when the ECU goes into closed loop.
No, without the O2 sensor working the ECU can't run in closed-loop, and will always run in open-loop.