I received my kit from the RX-7 Store and it had 3 ohm resistors instead of the 10 ohm that is mentioned in many threads. The Bosch injectors are 5.1 ohm and the stock ones are 14 ohm.

Has anyone else received and been using 3 ohm resitors with their 1600s with a PFC without problems?

 

If anyone has the same kit, what size resitors did yours come with?

 

Many times it's been debated that the 10 ohm resistors are really more resistance than is required to add to the 1600's, and that this only increases injector lag. Several folks run with no resistors. If you do the math you will find that the 550/1600 with no resistors is only in the territory of burning out the injector drivers at very high duty cycles (which is why some folks can get away with it.) By adding the smallest amount of resistance, like 2 or 3 ohms, you will be operating safely without adding any more lag than is necessary.

Most folks run 10 ohms because they are easier to source. I have 10s in there because at the time there wasn't a good public understanding of the issues. If I were to do it again I'd be running less.. not because I have significant tuning problems but because it's a step in the "more correct" direction.

Hope that helps.

Dave

 

If you cannot source any 3 ohm or anything lower than a 10 ohm, you can very easily wire a second 10 ohm resistor in parallel with the first one, for an overall 10.1 ohms DCR with your measured injector DCR. Keep in mind that the impedance will and should change depending on the frequency compared to the DCR.

 

Stock setup (volts/resistance=amps)12v/13.8=.87 amps
just make sure that the PFC sees less than 2 amps total.
The 3omh resistors should be fine

 

I went with one of these:



It's $325, but it does not introduce any lag as resistors do. It allows full power to the injectors, as the larger / low impedance injectors need more to get them to open initially.

I talked with a person there and they were extremely helpful.

Unfortunately, I haven't used it yet since the car isn't running!

 

i got the rx7store kit, 550/1680's been running a year now with no problems.

 

Thanks to you all. I'll just stick with the 3ohms that came with the kit.