10-20-2011, 08:43 PM #1
AFR adjustment with RRFPR, using boost line restrictor or manual boost control/bleed
My ski is in storage now, but before I put it away I played with my RRFPR and AFR a bit. My setup in my sig is pretty mild with ET 137 and the Riva ECU and Riva 50s worked well for most of the year. Towards the end of the year as it cooled off, my WOT AFRs went up a bit and I hooked up the boost reference line. Low and mid leaned out a bit, but were still OK, but WOT AFR went to 10.5 range. I started to wonder about ways to reduce how much boost the RRFPR was seeing ...
Did a bit of looking online and saw a couple possible options ... installing a fixed restrictor in the boost line, but preferred to have a way to adjust it as needed based on boost and weather. I thought of putting an inline needle/seat valve or possibly a controllable boost bleed inline, but that would be basically a manual boost control valve.
A non-adjustable restrictor is simple, but may still allow boost to creep up if you stay WOT for a longer period. A manual boost control valve may be better since you can set it to start to bleed off boost seen at the RRFPR past a certain amount, ie, anything over 8 lbs opens the valve and bleeds so the RRFPR only rises a bit, rather than the full amount, keeping your WOT AFR from going too rich.
Just curious if others have done much in this area ... having an RRFPR AND a way to control the rise based on boost would give us double the control with just a static boost reference line.
10-20-2011, 08:47 PM #2
Probably a begi setup would be your best bet, I think
10-20-2011, 08:48 PM #3
Vern the best solution to manual control of fuel pressure at three points is the duel reg set up.
10-20-2011, 08:56 PM #4
10-21-2011, 05:23 AM #5
If you are worried about leaning out idle and mid even more do like Speedski says and hook your boost reference line to the tb and drop your base pressure a bit and you should be fine. If not switch to Bosch 48s. Don't overthink/overanalyze... Keep things simple.
10-21-2011, 07:38 AM #6
10-21-2011, 03:22 PM #7
I ran riva 50's and it was running leaner than I wanted at idle and mid.. hooked up reference line to throttle body and richened it up a bit. bought bosch 48's and just had to switch back the reference line as it's too rich low and mid now with 1 reg.
10-21-2011, 05:40 PM #8
There are so many variables to take care of first to get close, ECU, injectors, level of boost. But once you settle on a setup, and if it includes a RRFPR, for very little additional money, there are a few ways to get your setup tuned in even better.
1. If your setup without boost line attached is rich all the way up, you may be able to get very close just by adjusting the static fuel pressure down a bit. If it is lean all over, you can do the opposite and just up the static fuel pressure. It surprised me how much difference only a couple pounds of static pressure makes.
2. If your setup is good at low and mid, but lean on top, attach the boost reference line and your WOT will richen up quite a bit ... but your low and mid may lean out more than you like. This is what I was getting at with this post ... you can then install a restrictor in line and that will then help richen up your mid and lean out your top end a bit. IF you want more adjustability, you can use an inline needle valve fitting to allow some adjustability in restricting the signal to the RRFPR. Another option is to install the boost ref line before the throttle body blade, but your WOT may still be rich ... in that case you can still install a turbo MBC inline to adjust how much boost signal the RRFPR sees.
3. If your setup already includes the ref line attached, and WOT is too rich, but low and mid is good with the ref line attached, you can install a manual boost controller to reduce the boost signal the RRFPR sees. These are cheap and easily adjustable, example is: http://www.ebay.com/itm/NXS-MOTORSPO...sories&vxp=mtr
What I was getting at was that with very little additional money, you can have one more super simple easy option for fine tuning if your setup already includes a RRFPR. Some of us have pretty big swings in weather and temperature, and by using one of the above tools, you can adjust your AFRS by just turning a knob a bit.
The BEGI is a good option for some that really have unique setups, but for many of us, it is cheaper and easier to just add a way to control the boost reference signal. A turbo manual boost controller (or inline bleed valve), restrictor, or where you hook the reference line are very cheap ways to get your final tune where you want it.
10-21-2011, 05:55 PM #9
There is only so much adjustment you can do with a 1:1 regulator. I like the Begi as you have three distinct independent adjustments, In my case B-Wheel stock ecu Idle FP is Idle 20 psi Mid is 55ish and WOT is 72ish. You can put together the Begi set-up complete for less then $200 if you are patient.
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