Thread: Afr/Rrfpr ?
01-20-2013, 07:17 PM #1
Have a question and looking for some input...if your off boost afr's are dialed in what would the regulator set up as rising rate do to your afr's under boost? Would the afr stay the same since the fuel and air added are equal? TIA
01-20-2013, 07:22 PM #2
Any time your under vac it would lean them out a tad IF you are tapped into the manifold.. IF you use your throttle body port everything would be unaffected until the boost comes in.
01-20-2013, 07:28 PM #3
01-20-2013, 08:23 PM #4
The pressure in the fuel rail will rise 1 psi for every pound of boost. So, your engine will get additional fuel because injector flow rate is based on the fuel pressure. More pressure more fuel pass for a given time open. So, if your engine needs to have its fueling tables reflec that your injector flow rate is higher under boost.
Real life example. I got a tune from Vtech, dont know if Jonaton missed me saying I had a rrfpr or I didnt mention it. But the tune I got was for a normal setup not a RRFPR set for 1 psi for 1 pound of boost. So what happened my AFR was 13.7 at idle but when I went in to Full throttle I had 9 to 1 AFR which is way to rich. So I unplugged the vacuum line from the manifold and plugged it. Now my AFR was 12.3 at wot which is perfect. So why have a RRFPR because if you throw a larger charger on there you will get more fuel out of the stock injectors when you need it most. Plus you can dial up RRFPR pressure if you need even more fuel.
01-20-2013, 10:08 PM #5
01-20-2013, 10:52 PM #6
actually a rrfpr does not add more fuel
it just keeps the SAME fuel flow at any boost level
and you can add a begi and get up to 5:1
so every pound of boost you get 5 psi more fuel psi
that is how you get MORE fuel
01-20-2013, 11:11 PM #7
01-20-2013, 11:25 PM #8
if you dont want your rrfpr to see vacume you can use a inline check valve
01-20-2013, 11:27 PM #9
01-20-2013, 11:35 PM #10
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