Mods in Sig: Was cruising last night and I don't have my profec-b spec2 installed yet but it's in the garage, anyway, so I've been taking it lite and trying not to overboost by hauling ***. I decided last night to just punch it real quick from 4500rpm in 3rd and got a PFC reading like this: Boost = 0.85bars (like 12.5psi) and Injector Duty = 85.5%!! The injector duty kinda scared me. My question is, I have a Nippondenso Fuel Pump on order from the rx7store and was wondering if when I install it will that bring the injector duty down any or do I need to go ahead and put some 850s in as my primaries? Thanks

Brad

 

The fuel pump alone will not effect the injector duty cycle. The fuel pressure regulator is what regulates what the injector sees from the fuel pump. So, as long as the FPR is working properly, the pump will not make a difference as long as it can supply enough fuel to keep the required pressure.

It is possible to get a pump which is powerful enough to overpower the stock FPR.

 

Thanks Mahjik, so is 280lph powerful enough to overpower the FPR

 

The Nippondenso (if it's the Supra version) would be fine with the stock FPR.

 

Great!

 

Oh yea, so does that mean I do or don't need to go ahead and upgrade my primary injectors?

 

That depends on your philosophy on high injector duty cycles:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/what-situation-do-you-have-259912/

 

.85 bar on the PFC commander is more like 13 psi in reality. Get a separate and good boost gauge.

I would not want to go over 90% injector duty. The fuel pump will do nothing for you until you install larger injectors.

 

Awesome link. Thanks.

 

Thanks rynberg. I guess I'll purchase some injectors to. Also I have the Pettit Boost Gauge to along with the PFC. I was just going by www.onlineconversion.com for my conversion which stated it was 12.328psi but that's a whole other issue as I know some people use 14.7, 14.5 or even 14.66 to get the psi numbers.

 

It has nothing to do with the metric conversion, the Commander displays a low boost reading, the higher the boost, the less accurate it is. This is a well known problem with the PFC.

You only need bigger injectors if you want to raise the boost above what you are currently running.

 

Well then I'll have to upgrade injectors because I plan on setting and/or tuning my car for at least 14psi.