JapTastic

Hi,
Just about to kick over a freshly rebuilt bridgeported 13bt motor in an fc rx7 series5. Its got the ApEngineering Power FC. Its got 800cc Power Enterprise injectors which according to their website/catalogue, have a lag time of 1.6ms. Using them for primary and secondary injectors.

Does this mean that I should be putting in 68.76% for correction value, and -0.85 for the lag time?
The lag time value doesnt seem right (excessive) considering the other posts Ive read concerning 850s.

Anyway, I just want to get the thing started and idling so I can check for potential leaks, issues, before flatbedding it to the dyno and tuner. Any advice would be great. cheers.

arghx

iTrader: (3)

the big question is, 1.6 msec at what battery voltage?

JapTastic

Sorry forgot to mention that, after some google searching it seems they're 1.6ms at 12V. The PE website doesnt mention voltage at all :/

As for how that effects the pfc correction values I have no idea.

arghx

iTrader: (3)

This is the TH800A injector? Top feed 800cc, high impedence, hole type?

Or is it the TL800A? Top feed 800cc, low impedence, pintle/needle valve type?

The reason why I ask is because I'm trying to figure out whether that number of 1.6msec makes any sense at all given the design of the injector, and especially at that battery voltage. Different types of injectors tend to be more or less laggy than others. For example, low impedence injectors have much lower lag times than high impedence injectors.

Tight now I'm thinking that's a useless/nonsensical number for 12V. The stock FD 850cc injector is a high impedence side feed and its lag time is 1.048 at 12 volts.



And here's your default AP engineering settings.



it looks like AP Engineering was lazy and didn't actually test the s5 injectors for their real lag. They just used the FD 550cc settings for both primary and secondary.

I have trouble believing that even top feed high impedence 800's lag would be so much higher than the stock FD 850 cc side feeds. Besides, what matters the most is the lag at 14V. That's what Apex'i is using when they are doing they are calculating the injector trim value.

JapTastic

Yep, they're the TH800A's, twin hole, high impedance, top feeders.

Keeping in mind, I just have the commander, no datalogit software. The dyno I'm getting it towed will will have that.

Is it worth just trying to get it to idle using a lag setting somewhere inbetween the odd sounding PE lag value and the value specified by sidefeed 850's? inspect for any probs and then I can get my tuner to work the rest out and redo if need be?

thanks for you help so far btw

arghx

iTrader: (3)

I just don't trust that number... it doesn't pass the "sanity check." It just seems so far off compared to what injectors are doing at similar battery voltages. Look at this chart: http://injector-rehab.com/kbse/lag.htm So here's what I would do.

set your injectors to 800cc and use the 68.76% scale. Then leave the lag to 0, or maybe something like -.10 . It's not going to make a huge difference for your purposes. You're just trying to start the car up and check for leaks, then let somebody else deal with it. Whatever setting you put in there your tuner is going to change anyway. I'm worried that if you use some extreme value (either + or - value) you're going to have trouble idling at all.