Quick question: for a power goal of a conservatively tuned 300whp, will four 850cc injectors running at 70-75% duty provide enough fuel throughout the entire rev range? I used the RX7.com 3rd Gen Injector Calculator, but I wanted to double check.

I assume this is correct because the secondaries come online and fire WITH the primaries, correct?

PS - I may have double posted. If this is the case, will a mod please delete one? Thanks!

 

IMO, if all you are going after is 300rwhp, leave the stock injectors alone and just upgrade the fuel pump. The fuel pump won't provide "more" fuel, but it will make sure that the fuel delivery doesn't drop off (like what has been noted with the stock pump at increased boost levels).

 

Rx7 .com also says you can make 380 hp on stock. I agree with the above statment, simple is better!imo.

 

Points well made.

I looked at 85% duty and thought it could be too high. It is, at any rate, on the bleeding edge of a "safe" duty cycle. Then again, I went out looking for instances of injector failure at that rate and didn't find any. I'll probably see about getting a pair of 84-85 GSL-SE 680cc's since I'm neurotic, but I guess I can take my time in finding a good set for a good price.

Must the fuel pump be replaced, or is it sufficient to simply rewire it, as Dale did in a recent writeup? Thanks for the help thus far.

 

IMO, its just best to replace the fuel pump rather than rewire it. You can get a drop-in replacement that will only take about 15 minutes to install.

 

You do not want 850 primaries as idle tuning is a PITA.
Rewiring the fuel pump can decrease injector duty cycle by 5-10%.
This has been posted by me years ago and more recently by others.