Ok so lets start out by saying I have a 86 base model, ok my question is this, recentally I have ported the motor and it is treating me nicely, however everyone within our little rx-7 community says I should upgrade to 550cc secondarys(TII)

My car runs on low impedence injectors and my buddy gave me a full set(4) of S5 TII high impedence injectors. I have done a little searching and have come to the overall conclusion that inorder for me to run them I would have to remove the resitor pack.

Is this the correct theory ? and If so, where in the world is the resitor pack

and also, incase anyone is wondering I am useing the stock S4 ECU if that makes any difference

 

To answer you question, you would also have to switch out the injector plugs on the harness to use those injectors, as they are a different shaped connection.
Secondly, there is no need at all to upgrade the injectors. I have an 87 with a very large streetport and a ported exhaust, and it still runs rich up top with the stock maps.

 

I have the same as you basically, full exhaust from header, no ac, no ps, no airpump, no emissions and for some reason it will pull from 5-6 but after that feels like nothing especially in 3rd, where my power should be nice and dont even talk about 4th

 

Well, low power doesn't mean it doesn't have enough fuel. If you are running out of fuel, it would be pinging and you probably would already have lost an apex seal. The drop off is likely for some other reason. What are your compression numbers like? Did you use new housings, or resuse your old ones?

 

yea new housing and new rotors rebuild was about 2k miles ago, with 4 oil changes already lol

in reality I feel a loss because my buddy also has a street ported engine and his feels faster than mine with basically same mods

 

Weird. I would think with a street port and new housings, you would make power to 7k or so, maybe even higher. I guess at 2k its pretty much broken in, so that shouldnt be a problem. Maybe a clogged intake filter?

 

actually right after the rebuild, like 500 miles I got a ebay HKS lookalike intake filter, and a breather, I do not think that would be it

Like I said I have talked to a couple of guys, for example my one buddy who is a...well he is really into drag racing and is really old school (but coolest guy ever) he was running 14's on his street ported motor and told me some tricks, and mentioned to change my 460's to 550's for secondaries. Also have mentioned it to some other people and at first said it wont make that much of a difference, but after I mentioned the engine was ported, said with a smile, " Yea change the injectors"

besides that fact, perhaps the injectors themselves are getting..old, after all they are hitting 20 years now lol, just another theory

 

Yeah, it could be that the injectors are clogged. I still don't think you really need 550s, but you can use them if you have them. I guess if he is a drap racer and has experience doing that, then go for it. You might get a better flow pattern or something, I dunno. You would definately need something likm an safc to tune them down or your would be running pig rich up top, which would lose you power.

 

ok cool, so back to orginaly question, how would I make the high impedence injectors work and fit on the low impedence injector system I currently have

 

You would have to remove the resistor pack and replace the injector clips. S4's use a different style connector as the s5 injectors. I'm not sure exactly what to do with removing the resistor pack, try searching for "remove resistor pack" or something like that.

 

yea nothing came up of use to me, so I guess I am asking now, how would you do it exactly lol

 

i believe the resistor pack is next to the radiator on the passenger side right behind the headlight

 

I am still kind of...weary about doing this, I read some nice horror stories about injector impedence, has anyone else done this ?

 

DO NOT upgrade the injectors!

The injectors you have are capable of providing more fuel that your engine needs. Anybody who tells you your car will be faster or more powerful after doing this knows nothing about how EFI works. Even with porting, the stock ECU runs the engine rich at full load. Making the mixture even richer will lower power, not raise it. This has been proven time and time again.

If you want more power you need to increase airflow, not fuel.

 

ok cool thanks for that, but I still feel a loss at high RPM, maybe just get new 460cc

 

What you need to do is get a wideband and see what the car is doing at the rpm loss area.

 

Why do you think new injectors would fix that? There are plenty of other possible causes.

Also, professional cleaning will bring injectors up to near-new standard. Buying new stock injectors is a waste of money.

 

Yes.