Selecting fuel injectors S5 Tii
 

I could use some advice for selecting fuel injectors for our 90 S5 Tii. I searched of course but as noted before the noise-to-signal ratio on the forums search system is out of bounds.

The exhaust and intake are ported using the Pineapple templates and it has a 2.5" Rotary Performance Cat and Cat-forward along with a 3" Corksport cat-back.

I have an RTek 1.8 on its way along with an APEXi Neo SAFC and a Zeitronix wideband. So I need at least 720cc injectors.

I know from my searches that I'll need to wire in the resistors and apparently buy new FI connectors.

I'm not looking for huge power gains or swapping out the stock turbo but I may get the RTek 2.0 when it comes out. So is there any value in going with the 1600's or best to just stick with the 720s?

Any recommendations for vendors?

Thanks,

Jim

Bouncing around eBay, I found a couple of RC Engineering ones.

I know there is a thing about posting ebay links so I'll just share the item numbers:

Item # 360076469161
set of [4] 1200CC Low Resistance (Peak and Hold, Approx 2.5/3 ohms)
Flow Matched RC Engineering Fuel Injectors
RC Part # PL9-1200

Item # 360076469204
set of [4] 1000CC Low Resistance Peak and Hold (Approx 2.5/3 OHMS)
Flow Matched RC Engineering Fuel Injectors
RC Part # PL4-1000

They are $355.50 with clips and shipping. So why wouldn't you just get the 1200s? Doesnt that just give you more headroom?

And the included "clips" are the electrical connections, right?


thanks,

Jim

In searching the classified I noticed that someone mentioned that you had to change the fuel rails to work with non-stock injectors. is that always the case?

Continuing to converse with myself... :)

I'm gathering from a thread about injectors where the owner didnt know what kind or size of turbo he'd installed in his car that at least for the primaries I probably dont want to deviate much from the 720cc because of idle issues when you go bigger.

I would surmise that the bigger injectors can't meter down well enough. So you end up with trying to get a precise 1/8th of a cup from a fire house.

I've narrowed it down to getting (4) 720 - 800cc injectors. I've seen all the Venom stuff so I think I'll stay away from those. There are implications that the Venoms are remanufactured and being sold as new, at least that what's the thread seems to imply.

I haven't seen anything harsh said about RC Engineering but did find several references to them here in the forum (usually in people's signatures on what they have in their cars) using Google to search the site.

These RC Fuel Injectors Mazda RX-7 RX7 750cc 750 cc FC3S 13B are $355.50 delivered with clips and are high resistance. I saw where either RETed or Aaron said that the low resistance ones were better. And these seem to be above the threshold for high impedance injectors (which seems to be around 550cc or so).

They also have RC Engineering Flow Matched 1000cc Fuel Injectors which are low impedance but are bigger than the 720cc target for good idle.

So, suspicious high impedance 750cc or low impedance 1000cc injectors?

Will I be able to have a nice idle with the 1000cc injectors?

Are the 750cc injectors bored out beyond the performance envelope for high impedance injectors?

Appreciate your thoughts.

Jim

I think I've narrowed it down to either:

TRE Performance on ebay

• RC Fuel Injectors Mazda RX-7 RX7 750cc 750 cc FC3S 13B
• High Impedance
• $355.50 delivered with clips

Five-O Motorsport

• Siemens FI 11445 (3145) 750cc - Custom Milled - sold w/4 - EV1-Denso electrical adapters.
• LOW RESISTANCE
• $357.00 delivered (with adapters)

Here are the pros and cons as I see them:

1) Low impedance/resistance with a resistor is better - advantage Five-O
2) RC Fuel injectors are popular in the RX7 community. Siemens is well known and probably supplies OEM to German car companies. But the Siemens are "milled". - wash?
3) Price is a wash
4) Vendor reputation - Five-O has a lot of customer testimonials. TRE has a 99.4% rating on eBay and they even sell Venom injectors (which if you believe the threads here would suggest a huge risk) - So wash.

Am I missing anything? What would you do?

Thanks,

Jim

Email Turbo2up@aol.com

His name is Bob Mulligan and he got me the injectors I needed at a fair price, prespliced resistors, etc. He's also awesome at helping you plan your build.

Tell him Andrew sent ya.

what resistors are you talking about? if you're talking about for the low imp injectors then you dont really need it if its a S5

Uh...NO.

S5 FC's all run high-impedence fuel injectors that spec out around 12 - 14 ohms.
Low impedence fuel injectors are typically under 4 ohms.
You *need* the resistors to compensate for the difference.
If you don't use resistors or something to compesate for the impedence difference, you're going to fry the injector drivers on the ECU.

If you're looking for around 720's range for fuel injectors, I recommend the Trust / GReddy (rebadged ND) 720's with the light blue tops.
Yes, these are low-impedence fuel injectors.
You need to use resistors with these fuel injectors.
Yes, you need to redo the electrical plugs, since the GReddy units use the older, Bosch style electrical plug.

I don't like using "redrilled" fuel injectors, as they can sometimes fail on you.
Remember, just because they drill the opening larger doesn't mean the "valve" seats perfectly anymore.
Sometimes they work well and sometimes they don't - I prefer not to gamble with my fuel system if I can buy fuel injectors already sized properly from the factory.

Other "multi hole" fuel injectors who claim they have better spray patterns than single orifice injectors clog easier due to the smaller, multiple holes.


-Ted

Why cant he just buy high impedance injectors? I know that S5 injectors are a drop-in replacement for the RB20DET, so there are options out there.

As far as the fuel rail goes, as long as you stay top feed of the same style (bosch) you wont need it.

Disclaimer: I am a nub at RX7's, with my Nissan background, but this makes sense.

High impedence fuel injectors over 550 cc/min are very rare.
If you do find them (i.e. SARD), they are very expensive.


-Ted

oh, makes sense. now that I think about it I dont know of any newer motors that use high impedance.

Definitely go with the Denso/Greddy Injectors. That's what I run in the primary spots... I've actually read that the they flow better than a lot of the other 720's out there.

Don't get 1600's, even the Rtek 2.1 can't control them all that well. Better off with a standalone for injectors that big.

Wow, this thread is like Texas weather. Long periods of drought followed by flash flooding! :lol:

Thanks for the advise and input guys. I'm going to order a pair of the GReddy's for the primaries and then I'm going to get a pair of the RC 1000ccs for the secondaries. The GReddy's are 50% more expensive than the RCs so I think that will be a good, cost-effective arrangement.

The RCs will come with clips so I can splice them in. For the GReddy's, are these what I need?

EV1 - Use for all pintle-type and Design II Bosch-style rectangle electrical connector replacements

They are exactly half way down the page on the left. Anyone know of another source for them? These are 4 for $23.

Then I'll put the 10ohm resistors in the cabin near the ECU so they arent exposed to engine heat.


Thanks again,

Jim

just checked the specs on the injectors and didnt noticed the ohms on them. yrs ago there was an ebay store that sold hi imp 750cc's+ injectors but i dunno if they still exist.


as to the op, good luck and let us know

rc injectors are pretty good I had a good experience dealing with them.

RC engineering ftw.

marren blueprinted and matched 1000 cc multechs suit jap rail FTW

marren make the balanced sets that can fit japanese 11mmm rails
( if you ask , PI code )
mail service is V good

personally, marren work very well , and fit straight in
( its imperative that rochester style multechs are sold as balanced pairs, marren do this for you )
the have a plug/disk, multihole design with excellent pattern
- lucas patent style disk ( RC ) are not a patch on them !

with your stock or Rteck ECU you have to add the resisters to peak hold injectors
( low ohming ) to limit current draw across the drivers
- they will not drive low ohming injectors with the correct peak hold current
as such, expect slight real life changes to tune to compensate their performance when compared to use with the right drivers
( those low ohming injectors work much faster with the correct driver types giving spike, then low sustained current )



750 cc-05750PI
870 cc- 005850PI
1000 cc- 051000PI
1680 cc- 051600PI

$95 USD

drop in fit ( 11mm top ) , early type ( s4 ) plug

http://www.injector.com/fuelinjectors.php




else - some more common choices
- sorry about the cut and paste from some of my other posts

Bosch
0280150845 680cc - Purple tops
2.8 ohms
( 14mm top, 16mm bottom )

--------------

Bosch
0280150842-1580cc -Indy Blue tops
## unusual 4.5 ohms
( 14mm top, 16mm bottom )
apparently also marketed as -
* Accel 74160
* FAST 3016000
* Marren 05160
* Marren 051600PI ( 11mm rail fit )

US Ford motorsport fit part

--------------

Bosch
0280150846 - 1650 cc -white tops
( 14mm top, 16mm bottom )
## unusual 4.5 ohms
is reputedly similar as the earlier blue
[ but alcohol, CNG and LPG vapour compatible ]
( some tests rate them as only 1300 cc )
the blue is a ford USA motorsport item, hence the indy term
the white is a specialised alcohol injector, with heavy pintle , a little slower than the rest
Ford PN:
Ford XL3E-C9A / Ford XL3Z-9F593A
motorcraft - MICM4980

US ford CNG fit part

-------------

Bosch
0280150839-1600cc -Aqua tops
( 14mm top, 16mm bottom )
## unusual 4.5 ohms
[ alcohol, CNG and LPG vapour compatible ]
US Ford CNG fit part

---------------

Bosch
0280150837-1580cc-Brown tops
( 14mm top, 16mm bottom )
## unusual 4.5 ohms
[ alcohol, CNG and LPG vapour compatible ]
US Chrysler CNG fit part

-------------
===================

seimens deka 3105 , 850 cc ( or siemens 83 ) or lately the -# FI11405
( beware, pencil/ lazer stream, only for high airflow conditions )
Static Flow Rate: 86.2 lb/hr = 10.87g/s = 888 cc/min (+-/ 4%)
Dynamic Flow Rate 2.5ms PW @ 100Hz: 19.5mg/pulse (+/-4%)
Coil Resistance: 2.35 Ohms / Low Impedance / Low-Z (Peak/Hold driver circuit required)
Spray Pattern: Pencil
Connector: Minitimer
( known as Bosch EV1 or jetronic minitimer, but same square as early rx7 )
( 14mm top, 16mm bottom )

----------

siemens deka 3145
750cc, same specs as above

-----------
==================

lucas disk
numbers for lucas have changed a few times in past years, they are a little hard to identify
but feature there own disc design
these are also sold under several manufactures/ suppliers
such as RC and venom in the US
these, more than any MUST be balanced and grouped into blueprint sets
they have very wayward quality reputation
which rather lets down in execution what on paper should have been the most effective of designs

some of these come as lazer or jet sprays, and are not good for idling as such
- intended to jet directly onto rear of inlet valve for cooling
- or split into two jets to feed either sides of port runners

these however will come in the hard to find 1000 cc / 1600cc gaps
and are considered very fast reacting when working well

RC will match them up
( if willing to gamble when there are other choices )
and products coded with a D at end of part code indicate an denso type top seal that can be fitted to 11mm rail
RC PL4-0750D ( Denso style ) 750cc low ohming
RC PL4-1000D ( Denso style ) 1000cc low ohming
RC PL4-1200D ( Denso style ) 1200cc low ohming
RC PL9-1200 ( 11mm mazda top ) 1200cc low ohming
RC PB2-1600 ( 14mm top ) 1600 cc 4.5 ohm
( appears to be a pintle bosch copy )
RC PQ2-3200 ( 14mm top ) ( Gaseous Injector ) low ohm hydrogen capable
2.0 grams/second @ 18.5 PSI LPG
2.0 grams/second @ 43.5 PSI CNG

Yeah, the same ebay store that has the RCs above has 750cc RCs but with high impedance and the right clip. But as RETed noted, most high impedance injectors peak out at 550cc. So I think it is reasonable to assume that those are on the edge of the high impedance envelope, maybe beyond it.

Thanks

Thanks, Bump. Good information. All of this would have been great in the Archives.

A couple of points I pulled from your post:

To fit the stock fuel rails you need an injector with the following dimensions (good illustration here):

• (upper o-ring) 0.430 inch 11 mm
• (o-ring to o-ring length) 2.5 inch 63.5 mm
• (lower o-ring) 0.630 inch 16 mm

Connectors: Bosch-style plugs == EV1 == jettronic minitimer == old square RX7 plug all of which are different than the oval Nippodenso style found on S5s thereby requiring new clips (aka plugs)

For a drop-in 720/750cc injector, you recommend the 05750PI for $90 from Marrin (injector.com) Marren will ensure they are balanced before shipping them which is critical.

You like multihole injectors while RETed feels they are at greater risk of clogging. I have no idea what you mean by "lucas patent style disk ( RC ) are not a patch on them !" :Wconfused

Pencil sprays are bad in RX7s, except (and I'm surmising here) in the secondaries where you have "high airflow conditions".

Thanks again to everyone who has responded.

there is two common ( different patent ) disc injectors on the market
- one has a wayward rep for pattern quality and batch quality
( yet has a reputed fast response )
- the RC

one has wayward rep for quality of batches, and longevity concerns when used with aggressive solvents
- the multec ( marren )


when blueprinted, the shop has matched the flows up, so the pairs flow 1 % of each other
the batches are sorted and matched, the same 1000cc marren injector body is actually sold as the marren 870
( 870-s are obviously the poor flowing 1000's all matched together )
- the multec are wet cooled windings, some earlier GM ones have a bad rep for dying after being used with harsh injector cleaners
( apparently better now, but i dont recommend solvent cleaners for them , its design however includes an anti clog feature )


taking all that in, and seeing it applied practically
- you will see some RC and LOTS of venon ( lucas style )
having all sorts of complaints about batch variance, and poor spray pattern
you will not see many complaints about the marren ( multech, rochester )

- marren have done favours and fitted the rochy with the correct top, and a universal fit base rubber

- and a bloody good spray pattern superior to all but the latest generation of new injectors


as for the siemens pencils
i would only contemplate them in the secondaries, or on custom inlet applications
( they are intended to pencil or multi pencil jet/s at the rear or an inlet valve/s to splash cool the valve and atomise the fuel )

with the rtech, and its use of saturated current drivers, you are best finding hi ohms
( cause even the low ohms will be run with a slow opening compromise )
i recall that some siemens and some RC's came as high ohm to around 800 cc
( actually i think there is a 900 )
but that is a rare bird, as large saturated current injectors move with exceptionally poor injector dwells
( peak hold currents open peak hold injectors that are larger, sooner )

-----------------------

its the atomisation of the fuel, and its distribution that is highly critical to your idle performance
- hence what on paper are bigger injectors ( marren 1000 )
with slightly more dwell than stock
actually idle superior to stock !
( when used as peak hold application )
closed loop haltech e8 with great definition certainly helps !

am i the only one thinks that he wont go so far with that stock turbo????

and a stock turbo takes about 4 hours labour to swap for a highflow
- and hes got the upgraded fuel system FIRST

whats so wrong about that method ?

I'm not looking to build big power with this. If I want crazy power I'd put an APC (s?) twin turbo system on my G35 Coupe MT6. But for the vert I think strong, reliable power is more like it. And as Bump noted I'm more interested in making it easy and cost effective to incrementally add power should the desire arise.

So for example, when I rebuilt the engine, I did the Pineapple Racing turbo port. This makes sense to do while the engine is out and all apart.

And since I put a Tii into a vert, I had to get an exhaust. Might as well get a free flowing one.

Rob at Pineapple said that to make sure I dont go lean with the extra flow from the porting, I need to lower the AFR. So that would lead to an SAFC, RTek or a standalone. Well, not interested in crazy power my first choice would be an RTek 2.0 because what I really want to see is all the outputs from the various sensors plus I appreciate that DigitalTuning supports this little community. But 2.0 isn't available for S5 Tiis yet. So I got a SAFC Neo and the RTek 1.8 which requires at a minimum requires 720cc injectors on all 4 holes.

Coincidently, I have the UIM off checking for any kind of air leaks so might as well put them in now.

If I decided to later, I could always BNR or monkey Aaron's project, get a standalone, FMIC or WCIC, etc. But again as Bump said I can do all later should I decide to.

The internals are done right. Anything else is bolt on.

But thanks again for the info and contributions.

Im working on the same thing. sounds ike you're plan is solid. You should really be careful with such lrg injectors(800cc) on the stock ecu. standalone recommended above 800cc. good luck!