I have an 87'N/a with a mild street port, K&N intake & custom high flow exhaust and my friend just gave me his 550cc injectors that came out of a first gen rx7. I have stock primary injectors right now and had 460cc secondary injectors. Is it possible for me to use these injectors? Should I use them as primary or secondary? Also...what are the stock sizes of the S4 & S5 injectors.
Thanks a ton guys!

 

RouNdaBouT,

Seems like there's something about impedance or voltage that the stock setup will/won't work correctly.

Do a search on "injector" in this section and you should see the post.

 

 

What makes you think you need bigger injectors? The stock ones will support around 250hp, and won’t be getting near that without bridgeporting, so don’t worry about it.
Stock injectors (all four) are 460cc/min for NA and 550cc/min for Turbo.

 

Pardon me for saying so, but I believe that the first generation had not 550's, but had 680's. Racing Beat and Mazdatrix both, I believe, recommend these for the secondaries on a 2nd gen turboii. That would be with some type of upgrade, such as a downpipe with presilencer etc. I sure wouldn't put them in 2nd gen N/A without extensive modifications i.e. street porting. Now that we've given you our thoughts, how about helping us, and looking at the number on the side of the injectors you got from your buddy, and telling us what the number is. It should resemble a number like 19550-1370 or a similar number. Please.

 

Thankyou for the replies guys, I'm sorry I couldn't stay around the computer, I was at work earlier and couldn't stay on long and this is the first time I have had a chance to get near a computer now that i am at home.

Alright, I did a search and found out that my friend doesn't have a clue what he is talking about (seems to be the case more often than not!). Here are the specs on the injectors.
The number on the side reads : 195500-1370
I'm not sure if it is due to fading, but the caps are a light purple color.

 

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So I take it I won't get any sort of power increase by using injectors bigger than stock?

 

bUmP

 

Fuel does not equal power! Airflow, with the right amount of fuel, is what adds power. You need to remove the restrictions to the engines breathing to make more power. With mild mods the ECU will compensate for the extra airflow by adding the appropriate amount of fuel. Stock NA injectors can flow enough fuel for ~250hp of airflow, which you can't reach without internal engine work. So don't worry about your injectors for now, worry about exhaust and intake airflow.

 

Well I'll be darned. Those -1370 are 550's. So I'm puzzled why he had those in a first generation. If the first generation had 680s, why would he put 550's in????? Eternal puzzle. Best thing that ever happen to a NA car is the complete Mazdatrix dual exaust. Exaust is the best way to large hp gains. Intake sucks. Always has. Exaust first and if you have spare change left buy a Kand N for the intake. Small gains with intake.

 

I do have a mild street port as mentioned up top, Race Pipe from Rx-7.com, 2.5" dual catback with high flow mufflers, stripped emitions, no air pump, K&N...fresh rebuild.
They probably weren't from a first gen then. He got them a while back from some guy who supposedly said that he got them from a First Gen. That probably explains it.

 

One other thing....My car was made 11/86

 

Just put them in the secondary rail and see what happens. Takes much less than an hour. Just the secondaries though. Take a meter and ohm the two injectors and see if they are the same as yours. They should be approx 2.1 ohms. If the new ones are 12ohm....forget it. If its too much fuel for your car, when you get approx 5100 rpm your car will fall into a bog, then pick up the rest of the way on up. If it does that, put your old ones back in. Should take approx 15min to reinstall.

 

From what I gathered using the search feature, these injectors are low impendence 550cc injectors. Correct me if I am wrong, but it seemed that if the notch on the plug is centered, it is low impendence, and if the notch is off centered, they are high impendence. On mine, the notch is centered. Is my theory correct? So by rights, these injectors should be compatible with my engine...?

 

bUmP

 

Couldn't say it better myself. Tab in the middle= low impedence. Good for your car. Gonna bog on you though, but do it anyway. Don't trust anybody.

 

Thanks Hailers! I appreciate your help!

 

Hey Roundabout..... was curious if you ever tried swappin in the 550's in your secondaries? What was the outcome?

Matt

 

If he did, he'd lose power, foul plugs, and run rich.

 

so what would happen if he put the wrong ones in there as in different impendence?