I got to thinking and I want to make sure 460cc injectors aren't going to be a limitation on a new motor that is ready to go to the dyno. In hindsight 550cc might have been a better choice but since the 460cc are already in and balanced/blueprinted I'd like to stick with them.

13bNA - desired 230RWHP

According to RC Engineering calculator http://www.rceng.com/technical.aspx

285BHP (18% loss to 233RWHP)
4 Injectors
.50 Brake Specific
80% Duty
45PSI

Results show a 460CC minimum. I don't know how accurate this is and it's probably more geared to a piston engine.

Bottom line, will a 460cc be enough injector for my 230RWHP goal?

 

the corky bell turbo kit did almost 240hp with stock injectors, they did bump fuel pressure though, and put a big fuel pump in.

the other thing, a bsfc of .5 is too good for a side port engine, .65 is more realistic.

 

Yes, he used a rising rate fuel pressure regulator. This is widely frowned on these days, but it worked out pretty well. They still sell those units. That injector formula for pressure change and flow will help you determine the fuel pressures needed to attain your HP goal.

 

Even though the 460cc injectors will flow enough and they aren't at 100% duty cycle I'd still recommend the 550cc injectors. It all comes down to reliability. The larger injector will not work as hard to do the same thing. Years ago I built an injector cleaner with one of the early DIY ECU boards. All the board allowed me to do was open and close the injectors. A simple reostat type switch allowed me to control the duty cycle. While playing with some 460cc injector near 100% duty cycle I had two of them hang open. Yes, I was pushing them further than 80%, and yes they were out of a car that had 100,000 miles on it but it was a failure. YMMV.

 

^Thats good info. Hanging open is better than closed though, I guess.

 

According to RC and their worksheet, the answer to the question should be no.

RC says that .65 BSFC should be used on 2 rotor NA (.70 for a Turbo). Using the new BSFC number.

285BHP (18% loss to 233RWHP)
4 Injectors
.65 BSFC
80% Duty
45PSI

Results show a 598CC minimum injector, a far bit larger than 460cc. Guess I am going looking for injectors.

 

If you have any doubts about rc's calculator ..... Here you go.

http://www.rx7.com/cgi-local/2ndgencalc.cgi