550cc -vs- 850cc primaries
 

I have a nearly stock 94 R2 except for full 3" exhaust (DP, HF cat, RP cat back), RP cold air intake and PowerFC. The car runs great except for a little boost problem that I'm working on at the moment (different thread).

As long as the UIM etc. is off solving the boost problem not only am I upgrading the vacuum pressure lines with Viton I thought I might as well upgrade the injectors and replace the fuel pulsation dampner (a known weak point).

My tuner has suggested going from 550x850 to 850x1300 injectors. 1300cc's for the secondaries makes sense to improve the high end and prepare for future upgrades. I'm planning on sending my existing 850's to RC Engineering to be bored out.

However, I'm not sure about his advice going from 550's to 850's on the primaries using lower fuel rate settings / duty cycle for low rpms. He claims it will allow him to provide better tuning in the mid-range including the 4500rpm transition and providing quicker throttle response after shifts. I haven't been able to contact his references as yet to validate. Does anyone here have any experience to back up or debunk these claims? If a good thing, is it worth the $250 for new 850cc injectors or is it more a case of splitting hairs?

Jon
;)

You don't need the 850primaries especially if your still stock twins. I run 10's on 550primaries, so I know there OK for you. The 1300cc secondaries are a good idea. And don't waste your money on new injectors if your sending them to RC anyhow.

Agreed. You won't need them. If your planning to go single, that's not a bad route to go...

The car will idle as well with the 850 s Stay with 550-1300 with twins

Vancouver, Wa.
who's your tuner?
Pineapple is right across the Columbia from you, have you talked to him?

Frank

Pineapple/Rob is excellent for motors and race chassis design but he does not have a dyno nor a solid background in ECU's. He and the rest of us use Ralph Friends at Xcessive-Motorsports in Aloha for dyno-tuning. Ralph is crack at both PowerFC's and Haltech. If you have a lamda sensor tapped into your cat-back he'll even do road-tuning as well.

Jon

From what I've heard, Ralph is very knowledgable. So is he the tuner you are doubting? I would think that he knows very well what he suggests. But of course, by the sounds of things from other forum members it may not be necessary, but if Ralph says it will work fine, just think of all the extra headroom you would have.

Frank

Usually people with the stock twins go either route-850sx4 (like my bud alan) or 550s/1300s like i did.

Chris Ott at RP is of the opinion that taking apart the injectors (like RC Eng does) isn't the best thing for reliability. He recommends just going with 4 stock 850s. Tuning isn't a problem....Steve Kan tuned alan's car at idle with the 850s at idle very easily.

Alot of it depends on your ultimate goals.

Use this link to access RP's FD specific fuel calculator:

http://www.rx7.com/cgi-local/3catalog.cgi?cat=11

According to it, with my setup I'm good until about 475 motor horsepower at 85% injector duty. I'm tuned rich enough that I consistently see 80-83% toward redline.

Are you ever planning on going single and making big power? If so, I say listen to your tuner :).

The goal for this car is sleeper stock (or at least the visual appearance of stock...think Concours de' Elegance in another 7 years after the body is brought up to show quality). Driveability and reliabitliy is as important as overall road performance.

I will stay twin and won't do anything special with the motor until he next time it needs to be rebuld (it's a Mazda reman under warranty with only only 2K miles on it now and it's a very nice running motor). However, I do need to be sure I beat the socks off the occasional challenger. Ideally I'll find the place the original engineers had intended for the FD before the priorities of federalization and warranties were applied.

I started out thinking 850x4 as Ralph has done with other cars. However, Ralph's thinking this week is he can more tune for a multi-use car better on larger capacity injectors because the lower duty cycles allow for more precise metering of fuel under all conditions. He told me this just befor leaving town (SEMA in Las Vegas). This is the main reason I bouncing stuff off the forum instead of just talking to Ralph about it because I'm not sure I really need the 850 primaries (and $250 is $250).

As far as any issues with RC's 1300's...Ralph says they are fine for except for sustained race conditions. If your going to race get a new fuel rail and top feed 1600's.

The only real technical catch for upgrading the primaries to 850 is for apply an interim map to the PowerFC so the car will at least run tolerably until I can get to the head of his queue (generally weeks and you have to be ready to go at a moments notice). Ralph says he'll fax me a map to use.

Jon
:)

Injectors for use with Anfini twin turbos
 

I'm having my injectors replaced due to possible cracks in the stock injectors. I'm thinking of upgrading the injectors (I think they're the primaries?).

Anyhow, what's the right size to use with Anfini Twin Turbos that I plan to use with a new KDR "secret sauce" motor, HMIC, CAI, and Apex PFC? Will I need to upgrade the fuel pump as well?

I plan to run no more than 10.8 psi max!

My thinking is that in order to provide maximum flexibility for tuning you should go 850 primary x1300 secondary. I believe keeping the approx 1.5:1 ration of secondary to primary is important to keep the duty cycle and injection pulse timing symmetrical (at least for a PFC). Even if you don't the headroom the injectors will be more precisely and run cooler with lower duty cycles (i.e. reliability). In any case with a PFC you'll either need a professional tuner with the Apexi Excel tools or the Datalogit plus an air/fuel meter (preferably with an add-on 4 point Lamda sensor in your exhaust system) in order to get your setup running to it's full potential.

I took my stock 850's and sent them RC Engineering for conversion to 1300's ($350 plus shipping) and bought new 850's for the primaries ($250 plus shipping from RX7Trix.com). Once I programmed my PFC with new baseline injector information the car started right up and is running pretty well. I havent' been to the tuner yet.

Jon

Can I get a copy of that temporary map ?

Thanks,
:-) neil

There is a lot of great info on this thread for you. I strongly recommend you NOT to bore out the injectors. I sent out my injectors to RC to have them bored and they failed on me within a few thousand miles. Luckily it didn't destroy my engine. :D

Regardless of how many miles on them? 115K mile 850's + RC Engineering = like-new 1300's?

I listened to Chris at RP and went with the 850X4 route, the car idles without any problems at all and I now have the fuel to support more power than I will ever want

do any of you know how much it costs to just have RC clean the 850's?

28.98 per injector... 10% if you mention rx7club.com

I just got mine back from them.... however there is another shop i guess that does it a lot cheaper...

Amel

what number do I call or.... whats the procedure?

Do a search for Witchhunter...he does an excellent job and for much cheaper price. $15 per injector.

Man,

I just got mine back from RC, but I didn't know about the 10% discount. Just the same I wouldn't have sent mine to someone that couldn't possible have all the equipment to do the job right. Russ Collins is very reputable, go to the page and read all of it. They supply some pretty big customers. I can remember watching that guy run multiple engine drag bikes at orange county drag strip in southern California back in the 70s. My 2cents.

Terry7

Forgot, they provide brand new o rings with theirs too! See how much Mazda charges for those!

I run 850's/1600's
 

using a Wolf 3d and twin Cosmo pumps. The challenge for your tuner is to get the fuel pressure and injector settings just right, since the 850s drip gas on startup. You need enough fp to get the gas to atomize, but not too much. I have found that you have to run ~2K rpm for the first 15 or 20 seconds on cold start before you can let off the throttle and have it idle, at least when it is less than 50 F ambient, and I run ~ 40 psi base fp. When the temps are higher than 50 F, only about 5 to 10 secs of 2K rpm is needed before idle sets in nicely.

Needless to say, I have all the fuel I need......

Beast

I have 850cc primaries, and my FD starts right up and idles at 900 rpm without problems, even in these NJ winters when my coolant temps are around 0 degrees upon startup.

Anyone?

I am going with 4x850. I have heard too many people with failed 850 bored to 1300 injectors. To me just one problem is too many for something this vital and I have heard alot more than 1 injector stuck. Unless I was going for some crazy HP numbers that is what I would recommend, and if that isnt enough fuel go with 1600cc aftermarket injectors.

I'm running the stock 850cc injectors in the primary position and 1300cc secondaries. I also have stock twins running at 14psi and am pushing 320 to the wheels. My primary injector duty cycle is at ~64% using a PFC and a safe (high 11s AFR) tune. The low rpm response is great and i would say that 850s are fine for primaries, as long as you have them properly tuned. I really don't need the large secondaries, but wanted to keep my options open for going single sometime in the near future. The biggest you'll ever need with stock twins is 850x850, or even 550x1200 would work fine. The beauty of the PFC is that you can custom tune your injectors so that the secondaries will kick in earlier or harder and make up for a bit of lack on the primary side. You just tune it so the primaries run up to 80%, and then the secondaries provide any extra fuel that you need from there. Sounds like your guy knows what he's talking about. Whatever option you choose to go with, just make sure to get a proper dyno tune and that your tuner knows what he's doing. If he does, he should be able to make most any combination work well for you.

I tried a search and nothing is coming up.

Do yourself a favor.. and leave the primaries alone.
and Just go ahead and bite the bullet and get New 1600 secondary
injecters.

Because down the road, Your either gonna either go Single turbo, or start
pumping up the boost on your twin. Or what ever.
Never hurts to over kill on the fuel system, Now and for future mods.

BTW: 1300 secondaries are bored out 850secondaries and have a reputation
of sticking, and POPing Motors..

Do a search on injecters and make the right choice.

If they are high milage, then just get new ones. That way your safe.

i have 1680 secondaries and just got the rest of the kg kit with the primary 850's what is the procedure to setting up for the 850's in the pfc? ernie... kevin...?

Its been years since I had the Power Fc, but Im pretty sure you need the data logit to change your injector size, but I do know the pwr fc doesn't go up to 1680cc, but have your tuner do it for you so your safe anyhow.

...if you're planning on running 850cc primaries, consider milling an ~1/8 off the top of your primary rail to get the injecter lower into the rail and better prevent leaking past the o-ring. Some people just add a smaller o-ring behind the bottom o-ring to push it lower. This does not always work, especially if you fuel pressure exceeds 38psi. If you're running a 1:1 rising rate FPR they will most likely leak without this mod...in my experience. also if you decide to go with the smaller o-ring trick, use one that is not affected by petrol...

I have 850 primaries and the car runs fine, but it's pig rich at idle (10s), with or without the narrowband hooked up

I also tried letting the car idle for 10 minutes ("learn" function) and that didn't help, either

what is the best way to confirm leakage past the o-ring?

The best way to run 850 primaries is to get KG's primary fuel rail.

Ern, Keith's rails are for top feed injectors, which necessitate splicing resistors into the injector wiring because of their low impedance. You also have to modify the fuel diffusers, which I most definitely did not want to mess with. I've heard there are ways around both of these problems, but I prefer the simplest method using oem parts and mounting.

I didn't want to mess with that, so went the stock side-feed route: brand new 850cc injectors (stock secondaries) in a milled primary rail. Works perfectly without leaking etc.

Also, my AFRs at idle are in the mid to high 13s with these injectors, so it is possible to run proper AFRs at idle. Mark, sounds like you need some tuning.

Out of the car fuel leakage test...page F-107 in the service manual

...I used an extenal power source to simulate the rising rate voltage/amps to the fuel pump and tested to a maximum of 60PSI.

...in a stock set up "key on" max is 36-38PSI.

...I may be wrong, but assuming that the stock ECU controls voltage to the fuel pump for a 1:1 rising rate, then @10PSI boost that's 38-42PSI minimum that "I think" you should test at...if your fuel pump/regulator set up is stock.

if you ground f/p at the diagnosis connector, you can get 71-107PSI from the fuel pump.

car is tuned (and running great at about 11.2, 14 psi), but there is no adjustment for idle using the datalogit that I know of, it is reportedly set automatically by the PFC (unless I have the wrong information)

thanks led

rich id like to know how you achieved the "13s" afr at idle with 850 primaries. . . im tired of the 10.9-11.x afr on my car. . . care to explain?

i have the kg primary rail now... keith never said anything about splicing in resistors i dont have any resistors for the 1680's! i guess i'll have to go round two with mr. gibbons and ask him what the deal is with this setup. there is no specification to modify anything here its suppose to be pretty strait forward. thanks for the info guys as usual. and rich i'll be checking that shortblock for a price for you but how did you want to go about getting it? i would rather you come and pick it up so you can also check it out to make sure its to your liking. you can also see my new motor and all the work im doing in my shop :)

would you need to change primaries from 550 to 850 if you plan on runing the bnr stage 3 turbos sequentially? i wanna try and get around 350 rwhp, no more then 400. Can the 550 handle this with out to much load?

It's been discussed on the Datalogt yahoo group and in the PFC forum here but from what I recall, you play with the injector lag times. Some including Ralph from Excessive use a negative lag time (I believe -0.04) for 850 primaries. Be warned that once you change the lag time, the rest of your map will need retuning.

Jack

Bump for a good discussion of larger injectors.

I was planning on doing 850cc's x 4 and having things tuned with the Power FC.

So how many people have actually had leaks useing 850cc injectors as the primaries?

Thanks,
Justin Wade

After 1+ years, no leaks so far.

I had my primary rail milled down, so no issues with sealing, and PFC tune by Mr. Kan.

:-) neil

I heard there was actually a debate between damean the track car guy and someone else that the resistor way is the wrong way and he had specified some kind of little box that adjusted the impednce properly

The PFC maps run rpm on the x axis and vacuum/pressure on the y axis. Thus, you can tune for idle.

right there on the first page

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fuel-system-upgrade-how-write-up-kgparts-kit-404091/

A driver for the injectors

checked for leaks today by pulling the stock primary rail out and running a jumper on the fuel pump...no leaks, so hopefully I'm good

the primary rail has not been milled

so why did you bring back an old thread if you have no problems?