Leaning Out At Low Rpm Problem ...and Some Other Stuff
03-26-2009, 01:01 PM
#21
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Vehicle: 1999 Hyundai Tiburon
Fuel pump - Walbro 255 lph (GSS342 if I remember correctly)
FPR is just regular (Autotecnica)
Regarding FPR I have a Vortech raising rate FMU which I can throw into the system. Could that help?
FPR is just regular (Autotecnica)
Regarding FPR I have a Vortech raising rate FMU which I can throw into the system. Could that help?
03-28-2009, 02:52 AM
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Vehicle: 1999 Hyundai Tiburon
^^Yes Socks is right I have an Aftermarket "usual" FPR mad by Autotecnica. But I was thinking of throwing that FMU into play also only thing is that I am not sure if I would gain anything by putting it in and I cannot find any good info on the net about using the FMU in conjuction with piggyback
03-28-2009, 06:36 AM
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Vehicle: 2006 Pontiac GTO
Unless you're going very high boost, using the FMU would be more or less equivalent to increasing fuel trims in your map (by some fixed percent for every psi of boost). I don't think you'd gain anything by using it at this point.
03-28-2009, 04:27 PM
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^^
This is the explanation of RRFPR which I have found. According to your way stock FPR would also be a rising rate? As far as I have figured it out stock FPR also gives you 1:1 as well as aftermarket adjustable FPR's hence both being fixed rise adjustable units. Well, in that way both of them are rising rate only the stock one is not adjustable fuuel pressure while aftermarket is. WHen lloking like thatyou can say that I currently have an adjustable 1:1 rising rate FPR installed.
When it comes to RRFPR I think more of the units like Vortech's or B.E.G.I.'s FMU and similar which can give you more fuel (3:1,4:1,5:1....12:1 etc.) per every 1 psi of the boost it senses. Basically, "Rising Rate" implies an FPR that increases fuel pressure at greater than a 1:1 rate relative to boost pressure.
Am I correct?
EDIT: Another way of looking at it is following:
QUOTE
a rising rate fuel pressure regulator increases fuel pressure when it senses boost. A 5:1 rrfpr will increase fuel pressure by 5 psi for every 1 psi of boost. If you are running 5 psi of boost, then you will get an additional 25 psi of fuel pressure.
Note - the stock fpr and aftermarket adjustable fprs will increase fuel pressure with boost at a 1:1 ratio. The only reason you would need a rising rate fpr is because under boost (with stock injectors at least) you may need a lot more fuel pressure (depending on how much boost you are running).
Adjustable fprs are just that, adjustable. The stock car comes with the fuel pressure set at about 30 psi at idle. If you have a high flowing fuel pump, the tiny stock fpr will become overworked and feul pressure will rise up to 40 psi at idle. If you have an adjustable fpr then you can lower it back down to normal. The only way you can gain power from an adjustable fpr (like weaponR) is if you are running lean at the top end, you can crank up fuel pressure and regain the power you lost because of the lean condition. However, this has the adverse side effect of raising fuel pressure everywhere in the power band (including at idle) and you will most likely have to deal with a rich idle. Something like an AFC gives you more control over where extra fuel is added.
Note - the stock fpr and aftermarket adjustable fprs will increase fuel pressure with boost at a 1:1 ratio. The only reason you would need a rising rate fpr is because under boost (with stock injectors at least) you may need a lot more fuel pressure (depending on how much boost you are running).
Adjustable fprs are just that, adjustable. The stock car comes with the fuel pressure set at about 30 psi at idle. If you have a high flowing fuel pump, the tiny stock fpr will become overworked and feul pressure will rise up to 40 psi at idle. If you have an adjustable fpr then you can lower it back down to normal. The only way you can gain power from an adjustable fpr (like weaponR) is if you are running lean at the top end, you can crank up fuel pressure and regain the power you lost because of the lean condition. However, this has the adverse side effect of raising fuel pressure everywhere in the power band (including at idle) and you will most likely have to deal with a rich idle. Something like an AFC gives you more control over where extra fuel is added.
This is the explanation of RRFPR which I have found. According to your way stock FPR would also be a rising rate? As far as I have figured it out stock FPR also gives you 1:1 as well as aftermarket adjustable FPR's hence both being fixed rise adjustable units. Well, in that way both of them are rising rate only the stock one is not adjustable fuuel pressure while aftermarket is. WHen lloking like thatyou can say that I currently have an adjustable 1:1 rising rate FPR installed.
When it comes to RRFPR I think more of the units like Vortech's or B.E.G.I.'s FMU and similar which can give you more fuel (3:1,4:1,5:1....12:1 etc.) per every 1 psi of the boost it senses. Basically, "Rising Rate" implies an FPR that increases fuel pressure at greater than a 1:1 rate relative to boost pressure.
Am I correct?
EDIT: Another way of looking at it is following:
QUOTE
manufacturers use all sorts of terms to refer to these devices. in the end, they're all basically the same thing, with different degrees of adjustability. whether you call it a fuel management unit or fuel pressure regulator or rising rate fuel pressure regulator it's the same thing. it restricts the fuel return line, causing the fuel pressure to go up. all that's different is how adjustable they are and what the range of "restriction" is.
I think this is the most accurate explanation ;-)