How to adjust a "set" RRFPR thats too big.
 

So, I am running a 3-1 rising rate fuel pressure regulator. This worked great for up to 16 or so psi combined with the 550cc injectors. 16 * 3 = 48 psi + 43 = 90ish psi fuel pressure. When you combine this with stock 550 injectors, they come out to be 800 cc equivilents.....

But, when I modified the 550s to be 820s, and raised the boost to 22 psi, my fuel pressure jumped to about 110 psi! This makes the 820cc equivilent to 1300 cc injectors!!!! WAY TO MUCH.

So I pulled ALOT of MAF signal.... This helped but, still ran way way rich.

I didnt want to pull out the rrfpr, just get it to run less.... What to do, what to do....

So I installed the extra Greddy Manual Boost Controller I had in the vacumn/boost line to the rrfpr! Then I was able to simply turn down the boost signal till I got a better fuel rate. Pretty simple cure!

Re: How to adjust a "set" RRFPR thats too big.
 

find short rope and a tall tree!

Re: How to adjust a "set" RRFPR thats too big.
 

or just swollow this
http://www.seancoon.org/wp-content/p...hale-penis.jpg

Re: How to adjust a "set" RRFPR thats too big.
 

First off, what the ---- are you talkin about???? :3

Im not sure what kind of car/engine your speaking of, but anytime you crank up the fuel pressure to compensate for injector size, ITS NOT A GOOD THING!!!! Not an acceptable method of tuning.

INjector FLOW IS NOT LINEAR TO FUEL PRESSURE@!!!!!

ANything past 75psi on a fuel system not designed for it (street car) is dangerous and down right ignorant. Hince the "get a rope" comment. :1

Re: How to adjust a "set" RRFPR thats too big.
 

I was using this

http://www.witchhunter.com/injectorcalc1.php4

to do the injector sizing...

And my point was on how to bring the WAY TOO MUCH pressure down to an acceptable level so everything worked together. And its adjustable, a feature that is cool.

Re: How to adjust a "set" RRFPR thats too big.
 

you need to understand how an RRFMU work at the first place.

Re: How to adjust a "set" RRFPR thats too big.
 

I get how you figured those flow rates. Thats not what im talking about.

MY point is that using excessive fuel pressure to make up for the lack of injector flow is a piss poor method to control fuel on your car. I dont care if its a brand new civic or an 87 mustang. Not only are you NOT acheving your "calculated" flow, but you are putting your life and engine in danger by having too much pressure on the fuel system...Fuel leaks DO happen, and cranking up the pressure is a damn good way to achieve that.

Engine fires are not pretty.

Im not trying to run you down, but you must understand ive seen far too many engines scatered across the track because some retard was running a rising rate regulator or FMU and blew the fucker to hell just because he wanted to skip out on buying injectors.

Injectors+tuning=cheap engine insurance AND more power.

Have fun.

Re: How to adjust a "set" RRFPR thats too big.
 

i have 820 cc injectors, I don't think I am lacking.

And my point is how I am turning down the pressure, not up.

Why the hell do people install fuel pressure regulators anyway if not to adjust their fuel.

Re: How to adjust a "set" RRFPR thats too big.
 

whats the setup here? pics?

Re: How to adjust a "set" RRFPR thats too big.
 

a FPR and FMU are 2 completly different things

FPR's are 1:1, if fuel pressure is 49 psi, at idle its say 39 psi due to the vacuum
the right way is to put a check valve in, and have it NEVER exceed 49psi, and buy the correct size injectors for your turboed app

FMU's are avail in 2:1 up to 12:1 or more. this means you have your stock 49 psi and depending on your FMU your adding 2-12 more psi of fuel per psi of boost, so 15psi of boost into a 12:1 FMU your now adding an additional 180psi to the 49psi of fuel pressure you started w/. now doesnt 229psi going through rubber hose and your fuel rail and crappy injector o rings sound bad?

Re: How to adjust a "set" RRFPR thats too big.
 

If you want to run out of fuel pressure sure.

A check valve will not let the FPR operate correctly under boost. if you boost 15psi with a check valve in place, the resulting pressure differential across the injectors will be decreased by 15psi.


NOT THE CORRECT WAY.

Re: How to adjust a "set" RRFPR thats too big.
 

You still havent told us what engine/car you are talking about. SRT4??? scooby? what??? Did you knock the caps off the 550s??

820cc injectors and a 3-1 RRFPR? I assume you are using some kind of piggy back since you said you pulled sig. from the mass air sensor.

And a very clever idea it was. MY point is that you shouldnt have had that problem in the first place.

MOST people seem to install regulators because someone else told them that they needed it, even if they didnt.

Only 3 reasons to install a FPR (notice I didnt say RRFPR)
1. Upgrading the whole fuel system, reg becomes a restriction.
2. Highflow fuel pump "outruning" the reg/weak reg. (common on dsms)
3. To maintain an accurate and predictable LINEAR pressure to ease tuning.


Im not saying that you cant make power with whatever setup your running. Im saying that you might want to rethink the way your tuning it. The more signal you pull out of a MAS the less accurately the ecu is going to be able to control fuel and timing. Hince the running rich even while tricking the ecu. The more you lie to it, the more it will NOT run right.

You should also consider that with a properly running fuel injection system, if your hack your MAS signal to lean out the mixture, 99% of the time, the ecu is going to ADD timing. Richen it up, and it will pull timing. You will hit your knock limit sooner.

Good luck with your setup. (no sarcasm i swear)

Re: How to adjust a "set" RRFPR thats too big.
 

CC-Fab anyone?

Re: How to adjust a "set" RRFPR thats too big.
 

ROFL :y

Re: How to adjust a "set" RRFPR thats too big.
 

see were talking about the RIGHT way, as in ohhh, i dont know, an engine management system that works. if you have injectors big enough to handle the amount of boost your running at the correct psi of fuel pressure, you dont need to ramp up fuel pressure under boost. the computer will see the boost, via map or maf, and supply the correct amount of fuel. the only reasons i run vacuum to the FPR is because a) its not insanly unsafe like adding fuel pressure is and b) with huge injectors sometimes you can't shorten the pulse with enough to not have your motor idle rich as ----.

so as you can see, this is the correct way. if were refering to correct as the absolute best and safest way

Re: How to adjust a "set" RRFPR thats too big.
 

http://www.vincentfurniture.com/phot...llingRRFPR.jpg


I don't get it.


1-1 is fine cause thats what EVERYONE uses.

But 1.1-1 will blow your motor up, cause fires and rape you mother.

God forbid you go to 1.5-1 rate!

What about a turbo that only boosts to 8 psi. The fuel pressure goes up 8.

Another turbo boosts to 24 psi, ie fuel pressure rises 24 psi, 3 times the amount.

Will the first motor blow up in a fiery death because he decided to use a 3-1 RRFPR (for whatever reason) and also raised his fuel preassure 24 psi?

Not.

Re: How to adjust a "set" RRFPR thats too big.
 

You don't get it even after I explained it. The FPR has to see boost. That way it cranks up the fuel pressure to compensate for boost pressure. ie 1:1 FPR.

If you have 40psi of fuel pressure, and then add 10psi of boost which putting pressure on the output of the injectors, the resulting pressure across the injectors will be only 30psi.

rail pressure - boost pressure = effective fuel pressure (just simple physics here, nothing complicated)

Now your fuel maps would be funky and ramping up to compensate for the pressure loss.


Now imagine boosting 30psi. Now the effective fuel pressure would only be 10psi. You would need some massive injectors to compensate.

With the FPR seeing boost and you have 40psi of fuel pressure combined with 30psi of boost. Now the rail pressure will be 70psi and the resulting effective fuel pressure will be 40psi. Now no matter the boost pressure you will have a predicable fuel pressure and normal looking fuel curves.