Type RZ

How much horse power or PSI can the stock injectors hold?? cause i dont know when im gonna upgrade mine, i heard the stock injectors can hold up to 16psi is this true?

Sidestick

iTrader: (1)

The general consensus is 12.5-13psi should be max for reliability, for injector duty cycles of 80-85%. However, some people say they've run their injectors at 100% without ill effects. It's said they max out at 14psi.

Trexthe3rd

I run 14.7 psi (1bar) on stock injectors using the Pettit unlimited ECU without a problem. It's actually still rich at that point.

Type RZ

COOL!! cause all i want to run is 14psi when im at the track and 8psi on the street! eggcellent!! thanks you guys

Type RZ

what is a duty cycle?? haha sorry for my ignorance

maxcooper

Duty cycle is the percentage of time the injector is open. The cycle time does matter in this figure, because it is just a percentage of whatever cycle at which the injector is running. Whether is it 95% of 0.01 seconds or 95% of 10 seconds, it is still 95% duty cycle because the next cycle starts immediately following the previous one. Hence, in either case the injector is open 95% of the time.

Run some numbers to see what your fuel system will support:
http://www.maxcooper.com/rx7/how-to/...tem/calcs.html

I haven't heard of many injector failures for the FD, and I know a lot of people are running them up around 100%. However, the real problem is that you lose tuning control at 85%+ because they just stay open. That is to say, you can't really run the injector at 95% because it is really just staying open 100% of the time if you give it a signal with a 95% duty cycle. I recall that somone had their injectors tested and they went static at 92-93%, which is above the 85% "rule of thumb", but if you are choosing replacement components, the rule of thumb is probably a reasonable guideline to follow.

-Max

Wade

iTrader: (1)

gsxr,

It has been stated that running injectors 100% for long could cause damage, possibly from overheating.

Considering the hundreds of people who have run their RX-7's in this manner, and the length of time they have done so (years), I don't think it is an issue. People have tossed around the idea that since the injectors on FD's and DSM's are side fed, the fuel cools them and keeps them from damage at high duty cycles. Also, if an injector hits 100% duty, it is normally only right near redline, how much time do you keep your car there? If you kept your car at WOT at redline for extended periods, I think you would have many other things fail before the injectors.

In short, I don't think it's worth worrying about. If you can't get enough fuel with your injectors to keep your desired a:f, then get larger ones.

To answer the original question, there have been many FD's that put out 370-380 rear wheel horsepower with the stock injectors and fuel pressure. I wouldn't consider an injector upgrade worthwhile unless your car is making more than 350 rwhp with your regular/daily setup.

Wade