# SR20 injector upgrade
**URL:** https://forums.speedlife.net/t/sr20-injector-upgrade/81057
**Category:** SON240sx Automotive
**Created:** [May 27, 2004, 8:30pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057 "2004-05-27T20:30:47Z")
**Posts on this page:** 14
**Page:** 1
### Author:  [@sidewaze](https://forums.speedlife.net/u/sidewaze)
#### Post date: [May 27, 2004, 8:30pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/1 "2004-05-27T20:30:47Z")
Hey guys whats up.
I just wanted to let you guys (who don’t know) a great injector upgrade for your SR that won’t break the bank. You ready… :?:
Mazda RX-7 FC3S Turbo II
:shock: That’s right :shock: . The stock turbo 2’s flow 550cc and bolt right in and (supposedly) clip right up with no mod’s needed.
I’v seen them for $50.00 US on ebay for all four (4), so they can be obtained cheaply.
Simply get them cleaned and flow tested. It will be about $80.00-$100.00 for that and you have 550’s in your motor for less then the cost of one new injector from say Nismo.
Just wanted to pass this on. Have a good one.
Easy 8)
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### Author:  [@santas](https://forums.speedlife.net/u/santas)
#### Post date: [May 27, 2004, 11:14pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/2 "2004-05-27T23:14:42Z")
> [@sidewaze](#):
>
> Hey guys whats up.
> Mazda RX-7 FC3S Turbo II
>
> :shock: That’s right :shock: . The stock turbo 2’s flow 550cc and bolt right in and (supposedly) clip right up with no mod’s needed.
supposedly?
can anyone confirm?
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### Author:  [@Doba](https://forums.speedlife.net/u/Doba)
#### Post date: [May 28, 2004, 4:58am UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/3 "2004-05-28T04:58:18Z")
well if thats true…wow that would be awesome, better than spending 500$$ or so…trully great news (if true)
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### Author:  [@sidewaze](https://forums.speedlife.net/u/sidewaze)
#### Post date: [May 28, 2004, 11:30am UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/4 "2004-05-28T11:30:28Z")
Hey guys.
My buddy find out about this b/c he owns an FC and saw it on RX7club. com.
The S4’s are top feed and the S5’s are side feed. It is great news. It means the money saved can go to other things. 😃
Easy 8)
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### Author:  [@Titan](https://forums.speedlife.net/u/Titan)
#### Post date: [May 28, 2004, 12:41pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/5 "2004-05-28T12:41:57Z")
First off, you should let people know that they will need sidefeed injectors for the SR20. Secondly, and just as importantly, you will need to varify if they are low or high impedence injectors. I believe the SR has a high impedence (sustained) system, like the KA. Whereas, FC injectors came in both high impedence and low impedence (peak and hold) system I believe. Be careful to match yours up correctly. Running a low resistance injector on a high voltage system will fry it.
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### Author:  [@bing](https://forums.speedlife.net/u/bing)
#### Post date: [May 28, 2004, 12:49pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/6 "2004-05-28T12:49:56Z")
if you can find out the year and model of the injectors i can get factory rebuilds for at least half of retail.
that way you dont have to have then redone yourselves, and they would come with a warranty as well.
the rebuilders dont catlogue by chassis code however. they will go by year, model and engine variations
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### Author:  [@sidewaze](https://forums.speedlife.net/u/sidewaze)
#### Post date: [May 28, 2004, 12:51pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/7 "2004-05-28T12:51:25Z")
Hey.
Ok as instructed :lol: , S4’s topfeed low impedence, S5’s sidefeed high impedence.
The model years I believe were 88-91 Turbo II’s. The earlier having the topfeed. They come out of the same motor though. All RX-7’s then used the 1.3 liter 13b motor.
Hope that helps 😃 .
Easy 8)
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### Author:  [@yashin](https://forums.speedlife.net/u/yashin)
#### Post date: [May 28, 2004, 6:49pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/8 "2004-05-28T18:49:49Z")
Are you 100% sure about this?
I know that the FD injectors drop in with a little bit of work but have never heard of FC injectors fitting.
If they do it would be great. Did your friend test this on a KA24E, a KA24DE or an SR?
Thanks.
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### Author:  [@sidewaze](https://forums.speedlife.net/u/sidewaze)
#### Post date: [May 29, 2004, 8:10am UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/9 "2004-05-29T08:10:35Z")
According to the post’s and questions he asked, yes they are a direct fit when using the FC injectors. Someone on his board has or had a 240 with an SR and used them. These injectors are considered an upgrade.
The injector harnesses fit to with no mods.
Im also having him see if they fit RB’s too.
Easy 8)
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### Author:  [@Original\_Nutta](https://forums.speedlife.net/u/Original_Nutta)
#### Post date: [May 29, 2004, 10:54am UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/10 "2004-05-29T10:54:31Z")
> [@sidewaze](#):
>
> According to the post’s and questions he asked, yes they are a direct fit when using the FC injectors. Someone on his board has or had a 240 with an SR and used them. These injectors are considered an upgrade.
>
> The injector harnesses fit to with no mods.
>
> Im also having him see if they fit RB’s too.
>
> Easy 8)
They fit the RB25.
Rb25 injectors are the same as the Sr20s
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### Author:  [@sidewaze](https://forums.speedlife.net/u/sidewaze)
#### Post date: [May 29, 2004, 11:03am UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/11 "2004-05-29T11:03:28Z")
I figured as much. Well there’s an upgrade for those engines too! 😃
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### Author:  [@yashin](https://forums.speedlife.net/u/yashin)
#### Post date: [June 1, 2004, 12:57pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/12 "2004-06-01T12:57:47Z")
After some research I was told that S5 injectors are top feed. Can you clear this up?
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### Author:  [@sidewaze](https://forums.speedlife.net/u/sidewaze)
#### Post date: [June 1, 2004, 2:01pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/13 "2004-06-01T14:01:29Z")
Hey Yashin.
Well according to my buddy, who drives an FC, S4’s are topfeed and S5’s are sidefeed.
I may have missunderstood him though. It could be the other way around. I will try and get it confirmed or you can PM Oni-Kyan, here, about it. He is the one with the RX knowledge 😃 .
Easy 8)
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### Author:  [@slipperysilvia](https://forums.speedlife.net/u/slipperysilvia)
#### Post date: [June 1, 2004, 6:52pm UTC](https://forums.speedlife.net/t/sr20-injector-upgrade/81057/14 "2004-06-01T18:52:20Z")
YOU NEED A CUSTOM FUEL RAIL TO RUN RX-7 INJECTORS. ASK CP RACING, THEY HAVE 50 STOCK RX-7 INJECTORS LYING AROUND AND THEY PLAN TO SELL THEM WITH CUSTOM RAILS FOR SR ENGINES.