I want to run 1680 primaries on pump gas.

I'm trying to go cheap and just use what I have in the bin to get the car back on the road, I realized that just 2 x 1680's are enough to meet the motors power goal of 325 HP (max) easily.

I know crispeed and a few others have done this, any advice for me?

Understand, I am merely trying to do this because I can put something together in a couple of hours to make this work without spending money.

 

Wow, I know you have the haltech so you will be able to idle them fine, but do you not have some stock 550s laying around? I guess 1600s are cheaper than getting the stock 550s. Tearbo2 runs 1600 x 4 on his e11v2 without problem, and his car idles well also. Just out of curiosity, what are your secondaries?

 

I was initially running 850-1300, then one of the 850's died , so I went to 550 1300, now one of the 1300's died (locked open ****** actually hydo locked the motor which I didn't think possible).

So now realizing that I can throw together a way to do just a pair of 1680s in the primary position with parts I have and plug the secondary holes, and that this is enough fuel for this motor's short term power goals. I'm thinking of just doing 2 injectors.

 

Oh, wow! I didn't think you were doing that. First, what awful luck with injectors, sorry to hear that. Did you have them cleaned and flow tested prior to installing them? Second, it looks like the fuel calculator at this website, http://www.rx7.com/cgi-local/3rdgencalc.cgi
Says that you can do 355 flywheel horsepower with 1680 primary at 70% duty cycle, and no secondaries. It only says 338 hp for the second gen calculator with the same inputs.

I am very interested to see what the gurus say. I never really thought about not running secondary injectors, would really simplify things for 300 rwhp or under cars. O.o

(update: Make sure to check your oil, you might have a lot of fuel in it if THAT much fuel was just sitting in your motor. Don't want it to get too thin)

 

Actually you can make quite a bit more than that, as its perfectly safe to go up too and beyond 80% DC, following that very link it says not to go over 85% at which point it says you have fuel for 430 FW that's close to 400 WHP, its safe to say that following the same guidelines with just 4 stock 850's, slightly more fuel than 2 1680's you could make or even surpass 400WHP.

There is no reason an FD and FC should be different they should have about the same BSFC.

 

I think they might be different because of the FD's newer possibly more efficient and better tuned ECU. But I don't know.

I really am liking the idea of only having a primary fuel rail, but I have to wonder why mazda didn't do that from the factory. I really think they would have done it if they could have. It would of illiminated a lot of cost. Maybe they didn't do it because the stock ECU wasn't high definition enough to make two 1000 cc injectors idle well?

 

I have a set of FD 550 side feed primarys that you could have.

 

With the E-8/11 you'll be suprise how lean they will actually run.
Haltech's resolution couple with good injector driver control enables that.

 

How good where you able to get them to run/idle, I know this is subjective, but could you tell while driving that it didn't have stock injectors?

 

Update: I ghetto rigged an S5 primary fuel rail to fit the S6 engine by slotting the bracket bolts and using huge spacers, welded cosmo FPR to the blank side of the rail and rigged the injector grommets to seal.

messed with the fuel map a bit and started it up, was able to get it idling at 750 rpm at about 12.6-1 within half an hour or so. Its amazing how well this works.

Wanting a permanent solution that would not be fire prone I called and ordered the KG parts primary rail, on the phone with KG, the guy tells me that the 1680's have better flow characteristics on the low end than GSLSE injectors!!