Ok, everytime I search something to do with NA mods, anywhere, people recommend FPRs. I don't know f I really understand how something like this could increase power, so please, fill my head with knowledge!! lol

Well it's not so much for power, but something designed to remove the 'flat spot.' Turning up the pressure say to 40psi is sposed to increase the amount of fuel available, so when you're in flat spot range ( for me it's around 2500rpm) it resolves that problem. That is my understanding, i haven't installed mine yet. I would suggest you ask Lenda if he has noticed any difference since installing his. It seems to be a controversial topic.

They also help when the injectors are nearing 100% duty cycle as you can increase rail pressure and help achieve more from the injectors. In my "donkey" engine we had to wind up the rail pressure 10psi to help richen the AFRs up due to injectors being maxed out, this was done as a band-aid fix until i put the bigger injectors in.

Ok cheers lads. So I take it the factory one has a set pressure, and an aftermarket one basically allows you to just raise (or lower I guess) the fuel rail pressure?

what injectors are you guys maxxing out?

i only ask because i just replaced the injectors in my v8 with 42lb injectors, if my math is right this makes them 440cc injectors, smaller than i was planning for my magna build

Affirmative.

So please, fill my head with knowledge!! lol

In order to fill it, first you must empty it...Grasshopper ! :woot:

FPR R/R usually follow hand in hand with upgraded injectors and upgraded fuel pumps, cams, FI, boost etc.. as part of an engine performance build...by themselves they wont do much for performance, but usually included in your long term plan for engine performance upgrades ...pretty much what Jason says...he knows...:happy:

In order to fill it, first you must empty it...Grasshopper ! :woot:

FPR R/R usually follow hand in hand with upgraded injectors and upgraded fuel pumps, cams, FI, boost etc.. as part of an engine performance build...by themselves they wont do much for performance, but usually included in your long term plan for engine performance upgrades ...pretty much what Jason says...he knows...:happy:
1. Won't take long, Bill...
2. Yeah, you're not wrong there, I'll agree with that. :ninja: Don't tell him that though...

If your injectors are maxed, and you only require a little more fueling, then yes an aftermarket FPR is a cheap solution, as it allows you to raise the fuel rail pressure. A slight bump in pressure is ok, too much starts causing problems (e.g atomisation deterioates).

Apart from the above, I don't see any reason as to why you would wanto replace the factory unit. Yes I'm quite familar with RPW's spiel on why everyone should purchase a FPR from them..I don't buy it.

Fiddling with an adjustable FPR is a very crude way of solving tuneing issues, much better to do it properly via actual tuning with your piggyback/ECU.

l agree with Chisolm. When tunig a piggyback you are pulling fuel out. So unless you have a decent build the factory reg will do just fine. I am still using my factory reg with my setup

Yeah prob just RPW doing what RPW does best...

Yeah prob just RPW doing what RPW does best...

but they come in fancy colors!

Apart from the above, I don't see any reason as to why you would wanto replace the factory unit. Yes I'm quite familar with RPW's spiel on why everyone should purchase a FPR from them..I don't buy it.

Wait.....hold the phone reg,

You mean to tell me there's aftermarket parts for cars that arnt really needed? :surprised

Most cars run about 3 bar fuel pressure. Some are 2.7, a few 2.5 and even as low as 2.0(1 bar = 14.5 psi approx).

Ordinary injectors will supply more fuel up to about 5 bar max. Some brands will stall before that but generally Bosch and Denso are OK at 5 Bar.

Extra pressure increases fuel flow all through the range so the engine will be too rich unless the ECU is reflashed, or a piggy back is fitted. Increasing fuel pressure is usually done to make a small injector flow sufficient fuel so they are open no more than about 92% of the time, called the duty cycle(injectors overheat, become unstable or can burn out kept open too long)or so the engine doesn't lean out at the top end.

More pressure also helps fuel atomisation, although with modern multi-hole injectors that is not so important unless the engine is capable of turning very high rpm. F1 is now limited to 100 Bar and Moto GP is similar. Direct injection is generally around 120-200 Bar.

Cheers,
Alan

More pressure also helps fuel atomisation

Correct me if I'm wrong, but to my knowledge running far higher rail pressure than a injector was designed for results in poor atomisation/spray pattern.

Yes the higher the rail pressure the better, but only provided the injector used is actually designed for the pressure being used. Direct injection is a good example of this.

A magna injector might be 'ok' with significantly higher rail pressure than factory, but that doesn't mean it's atomising as well as it would at its normal operating presssure.

Happy to be corrected if I've got it wrong :)

Correct me if I'm wrong, but to my knowledge running far higher rail pressure than a injector was designed for results in poor atomisation/spray pattern.

Yes the higher the rail pressure the better, but only provided the injector used is actually designed for the pressure being used. Direct injection is a good example of this.

A magna injector might be 'ok' with significantly higher rail pressure than factory, but that doesn't mean it's atomising as well as it would at its normal operating presssure.
Happy to be corrected if I've got it wrong :)

Hence why im running high rail pressure but with the "12 hole" 380 injectors

Higher pressure helps atomisation. That's why big injectors operating at low pressure are a bad idea.

Manufacturers generally keep at 3 Bar as that allows them to fit small fairly lazy quiet fuel pumps and there are fewer issues with simple clamps on flexible hoses leaking etc, and you don't have to be checking hoses for cracking so often. Injector life can be a bit longer too at 3 Bar.

Pump volume drops considerably when the pressure is pushed up so you have to be careful that the pump is actually capable of suppling the required volume at the higher pressure. A good simple dyno check is at full load there should be fuel in the return line (disconnect back at the tank and carefully point return into a container, and keep an extinguisher handy).

Cheers,
Alan

When I was building the Turbo Rotaries I needed in many cases to run duel fuel systems due to the simple fact that we did run higher rail pressure and thus volume was an issue. Now we were running up to 15+ psi on the snails and running huge snails at that as well.

In a standard Magna or one that has moderate mods, I see absolutely no reason to run a FPR, the old way for a small increase was to "tap" the end of the existing reg (while hooked up to a proper guage) but this is a perm increase not temp

As Alan said, the increase is across all ranges and 2 things will happen, first of all you will run even richer in higher ranges that can cause power loss if you are not careful and 2 your fuel system may not handle the higher pressure.

If you are wanting to tune, either reflash or get a piggy back as this is by far the best option. If you are starting to get into serious stuff then by all means get a reg but make this part of your overall tune.


Yeah prob just RPW doing what RPW does best...
What, talking crap, than I agree with you 100%