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Location:
Melbourne
Registered:
August 2003
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RX7 Injectors
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Thu, 22 April 2004 04:30
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Just wondering if anyone out there knows of any good sources for cheap RX7 Injectors.
So far the best price I can get them for is for $80 each through Rank Rotary... Which normally would be fine, but for the project I am working on, I would prefer to get some for half that price.
I am preferably after the 460 cc/min High Impedance injectors (I think they run around 13.5 ohms) that have a red top with a square plug & the notch for the plug is offset.
Otherwise, the 550cc injectors will have to do, but they only seem to come in a low impedance version, which would mean some extra tweaks to get them working "harmoniously" with my ECU.
Cheers,
3T-GTE
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Location:
Christchurch, New Zealand
Registered:
March 2004
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Re: RX7 Injectors
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Thu, 22 April 2004 06:53
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550's do come in high imp, I have a set and tried them on my 3tgte, but the buggers where far to big to get any sort of decent idle, something like 4% duty cycle and still far to rich and lumpy at 1400rpm, but i mostly put that down to crappy injector controll on the older model link im running. I think the prefect upgrade is st165 440's, only topfeed injector of the 3s-gte range. Mate is running VR4 440's, rasing rate reg, and big holley pump on his 3tg with 2tg head and vg30 T3 and 20 odd psi of boost and has no fueling problems.
Logan
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Location:
Terrigal
Registered:
May 2002
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Re: RX7 Injectors
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Thu, 22 April 2004 07:27
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I have series 5 injectors in my 3t-gte. They were $50 each. I run 20psi boost and these 550cc injectors are almost maxed out.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: RX7 Injectors
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Thu, 22 April 2004 11:06
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anyone know if these injectors would fit in a standard 1jz/2jz fuel rail?
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Location:
hobart
Registered:
November 2002
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Re: RX7 Injectors
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Thu, 22 April 2004 13:03
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3T-GTE email a bloke called Gerry on gboulch@hn.ozemail.com.au or PM him on toymods, his Author name is gerryb and he will have some or he'll be-able to get them for you. Nice bloke and good to deal with.
Cheers Chris 
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Location:
Melbourne
Registered:
August 2003
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Re: RX7 Injectors
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Fri, 23 April 2004 00:01
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Thanks for all your replies & information.
I will be contacting Gerry shortly.
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Location:
Brisbane
Registered:
May 2002
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Re: RX7 Injectors
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Fri, 23 April 2004 01:26
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| Chris Davey wrote on Thu, 22 April 2004 21:06 |
anyone know if these injectors would fit in a standard 1jz/2jz fuel rail?
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No they won't.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: RX7 Injectors
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Fri, 23 April 2004 08:05
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if the injectors are about 2.4ohms, you could run resistors in line with them to reduce the current flw thru each, and thus have them act like high impedance ones..
for 1.5 amp, you'd want something like 25W, 7.5ohm
for 1 amp, maybe 25W, 10 ohm.
the "ohmite" heat sink resistors available around the place look the goods about $25-30 for a set of four. you'd need one per injector.
or you could just nick a resistor pack from a wrecker 
Cya, Stewart
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Location:
Melbourne
Registered:
August 2003
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Re: RX7 Injectors
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Fri, 23 April 2004 09:37
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Hi Stewart...
This may be a little off-topic, but very relevant to my current project....seeing you know a "little" about the MegaSquirt ...
Can you tell me if there is any disadvantage to running in line resistors vs using the Flyback board that can handle the low impedance??
Cheers,
3T-GTE
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: RX7 Injectors
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Fri, 23 April 2004 11:49
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| 3T-GTE wrote on Fri, 23 April 2004 19:37 |
Hi Stewart...
This may be a little off-topic, but very relevant to my current project....seeing you know a "little" about the MegaSquirt ...
Can you tell me if there is any disadvantage to running in line resistors vs using the Flyback board that can handle the low impedance??
Cheers,
3T-GTE
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http://www.megasquirt.info/index.html
then click on "Injectors and Fuel Supply" on LHS menu.
looks like you can use up to 4 2.4ohm injectors using only PWM in the MS. more than 4 injectors requires resistors or flyback board (to be safe)
apparently injuector opening and closing is a little faster with the flyback board installed, but running resistors does not make it any worse than if you were using high impedance injectors anyway!
the only disadvantage to running resistors with big injectors (relative to the motor size, ie 550's on a 2L) is that the minimum opening time may not be small enough to give you good resolution at idle speeds. flyback board is only $35, and 4 resistors is about $25-30...
i'd be happy to run either, but i think i'd prefer to run the flyback board...
Cya, Stewart
| Quote: |
Pulse Width Modulation
Injectors are either high impedance or low impedance. High impedance injectors (usually about 12-16 ohms) can take a 12 supply directly, without a form of current control. Low impedance injectors (generally below 3 ohms) require some form of current limiting. With MegaSquirt, you can use resistors to limit current, or you can use Pulse Width Modulation (PWM), which is a software solution built in to MegaSquirt.
PWM works by switching the 12 volt ground to the injector on and off very rapidly (in about 0.000059 seconds!). The ratio of the "on" time to the "off" time determines the current through the injectors. However, the easiest way to think of the PWM% is as a percentage of the supply voltage, so 50% PWM on a 14 volt supply becomes effectively 7 volts on average, 28% would be 4 volts, etc.
Remember that pulse width and PWM% are two different things. Pulse width is the total duration of the signal whereas PWM% is the ratio of 'on-time' to 'off-time' within the pulse. So in the above illustration, the pulse width for both is the same, but the PWM% for the first is 50%, while for the second it is 25%.
The PWM% you will be able to use depends on the flyback circuit you have. Version 2.2 hardware generally requires about 55% to 75% PWM. Often the engine will run with lower values, but will not have enough voltage to re-start. Note that using embedded code version 2.986 or higher will disable PWM during cranking, allowing somewhat lower PWM% values. The FlyBack Board allows you to lower the PWM% dramatically, generally to 30% or less. It also helps close the injectors faster.
With better flyback control, you can reduce injector opening times (recall that the injector opening time is really the sum of the opening and closing times), and increase the duration of the 'controllable' part of the pulse width (i.e. after the opening time),
To exceed the recommended number of injectors (see below) either requires resistors in series with each injector or a modified flyback setup.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: RX7 Injectors
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Fri, 23 April 2004 16:06
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and i should add that for the Aussie GB's, we use TIP42C's instead of TIP32C, so the 'onboard' flyback current of the MS is 30A instead of 20A. the onboard flyback circuit deals with both injector banks.
with the flyback board, again TIP32 is specified, and it uses one for each injector bank... so that increases flyback current capability to 40A, but we will be using TIP42's again, so the aussie flyback boards will do 60A of flyback current.
Cya, Stewart
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Location:
Melbourne
Registered:
August 2003
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Re: RX7 Injectors
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Sun, 25 April 2004 23:19
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Hi Stewart,
Thanks for the info. I'll definitely be using the flyback board. I am helping out a friend build a MS system, & get him up & running before I build up my own.... so I will probably wait until the next group buy. (Got too many other things to spend $$$ on at the moment!)
I have also contacted Gerry & he can certainly help me out with finding the injectors for a really good price... so thanks for putting me on to him Chris.
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