Advice on RRFPRs

[CorvallisBMW]

I'm thinking of installing an RRFPR on the turbo car. I know these are kind of old-school and were usually meant to go with burned chips, like in the old Cartech/Kormann/TCD kits. I posed this question to Miller, and they responded with "no, totally unnecessary". But the ability to tune my fuel pressure, and have a gauge to monitor it as well, seems very attractive. I even noticed a lot of the Pro3 cars run them, and those are stock motors.

Am I crazy? Would an RRFPR actually gain me any kind of benefits, aside from the gauge/monitoring? Will a stock e30 pump even put out enough pressure to get up to, say, 50psi? I've been doing some reading on the BEGI (Cartech) RRFPR and it seems pretty sweet, but I'm hesitant to pull the trigger on something that expensive without understanding more about the pros/cons.

If anyone has thoughts/advice, I'd be happy to hear it. Thanks!

BEGI RRFPR

Cheap eBay RRFPR

Even cheaper eBay RRFPR

[downforce22]

I'm thinking of installing an RRFPR on the turbo car. I know these are kind of old-school and were usually meant to go with burned chips, like in the old Cartech/Kormann/TCD kits. I posed this question to Miller, and they responded with "no, totally unnecessary". But the ability to tune my fuel pressure, and have a gauge to monitor it as well, seems very attractive. I even noticed a lot of the Pro3 cars run them, and those are stock motors.

Am I crazy? Would an RRFPR actually gain me any kind of benefits, aside from the gauge/monitoring? Will a stock e30 pump even put out enough pressure to get up to, say, 50psi? I've been doing some reading on the BEGI (Cartech) RRFPR and it seems pretty sweet, but I'm hesitant to pull the trigger on something that expensive without understanding more about the pros/cons.

If anyone has thoughts/advice, I'd be happy to hear it. Thanks!

BEGI RRFPR

Cheap eBay RRFPR

Even cheaper eBay RRFPR

It seems you don't know the difference between a RRFPR and an AFPR. The A stands for adjustable which just means you can set the fuel pressure that the regulator controls. The rising rate has an inlet which is a vacuum port and some adjustment nozzles. The base fuel pressure is set (which is what the AFPR does) then you set the rising rate pressure with the adjustment screws based on the vacuum the regular sees (which an AFPR does not do). This allows the car to run normally with factory injectors when not in boost but then adds additional fuel when boost comes on to keep up with the demands of the engine.

This was commonly used on boosted engines before standalone fuel management systems were affordable and easy to tune. Now the entry cost of a new RRFPR is about a third of the cost of a plug and play standalone fuel system. The standalone is "better" according to certain people but they both solve the same problem. One forces more fuel through the stock injectors by increasing the pressure in the fuel lines so they can exceed their 100% duty cycle rating. The other adjusts the fuel maps and opens the injectors longer but keeps the fuel pressure the same. Two ways to get to the same result. Just one includes more trial and error (adjusting the fuel inputs on the BEGI).

And to be clear the stock m20b25 uses a 3 bar regulator (14.7 psi = 1 bar) which is already about 44 psi. Most guys I have seen use the stock pump with no problems up to 250 hp.

You don't have to have a RRFPR to gauge the fuel pressure in your fuel line. I would make sure this turbo car has a wideband oxygen sensor to ensure the fueling is not lean and truly determine whether you need to change the fueling. But with that said there are plenty of threads on e30tech where people had success using turbo chips which adjusts timing combined with a rrpr with great success and reliability. I was planning to go that route when I thought my turbo build would be a 'budget' build.

[CorvallisBMW]

Ah yes, I see what you mean. I guess I didn't read the eBay adds closely enough, I assumed that since they had vacuum nipples that they were set up as rising rate pieces. But now that I think about it more, even the stock FPR has a vacuum line.

I do have a wideband setup, so yes I can monitor for rich/lean conditions. I was just wondering if there's any performance to be gained out of an RRFPR if I'm already running an EM system (in this case Miller WAR/MAF) that can control fueling. It sounds like the answer is "no". I already have larger 36lb injectors which should work fine at the stock 3bar I suppose.

Thanks for the help.

[LowR3V'in]

I used the begi fmu.
Worked well to 13psi. It had perfect AFR where I wanted it.
Great unit. Just get a turbo chip which only retards timing like 5* or something.

Nothing wrong with it. Very simple and works well.
Don't have to mess with cold start or idle or any other settings. Good plan.

[CorvallisBMW]

I've never seen a turbo chip for an m30 setup, hence why I'm using the Miller stuff.

[LJ851]

The only reason for a RRFPR is for altering the "tune" of an engine that does not have tuning capabilities.

A turbo setup with a non tunable chip for example.


If you can alter the fueling with your ECU there is no need for the RRFPR. It could in fact make tuning more difficult since the RRFPR is analog and the ECU is digital.