Is s4 alternator good enough for walbro225lph that is rewired
05-08-13, 07:22 AM
#1
Is s4 alternator good enough for walbro225lph that is rewired
I am installing a walbro 225lph and was hoping it was acceptable to use the stock alternator with it.
Car will be around 250-280 flywheel hp, to clarify my fuel needs , 550/720 injectors, 1.7 rtek, I haveno subs/amp causing more power to be drawn.
What way is the most safe to rewire the pump?
I founf this topic to quite controversial and opinionated upon searching and would like legit facts.
1)switch voltage between idle/cruise to low 9v iirc, and 12 v continuous on wot.
1.A)Can prevent fireballs from what I've read, idk if its true
1.B)Lowers fuel pressure on idle and cruise,increasing gas mileage, but could it cause lean spots , potentially causing you to blow the engine
1.C) is less demanding on the alternator
1.D)power might not switch between voltages properly and cause constant low fuel pressure or constant high, making whole point of this method pointless, taking away all the benefits of this method and potentially causing the engine to blow.
2) Continuous 12v with no switch
2.A)Peace of mind that you're always getting all the fuel you need.
2.B) decrease in gas mileage
2.C) more demanding on alternator
2.D) fireballs due to running rich constantly
I don't have any subs or amp in my car
Rotary > Pistons
Car will be around 250-280 flywheel hp, to clarify my fuel needs , 550/720 injectors, 1.7 rtek, I haveno subs/amp causing more power to be drawn.
What way is the most safe to rewire the pump?
I founf this topic to quite controversial and opinionated upon searching and would like legit facts.
1)switch voltage between idle/cruise to low 9v iirc, and 12 v continuous on wot.
1.A)Can prevent fireballs from what I've read, idk if its true
1.B)Lowers fuel pressure on idle and cruise,increasing gas mileage, but could it cause lean spots , potentially causing you to blow the engine
1.C) is less demanding on the alternator
1.D)power might not switch between voltages properly and cause constant low fuel pressure or constant high, making whole point of this method pointless, taking away all the benefits of this method and potentially causing the engine to blow.
2) Continuous 12v with no switch
2.A)Peace of mind that you're always getting all the fuel you need.
2.B) decrease in gas mileage
2.C) more demanding on alternator
2.D) fireballs due to running rich constantly
I don't have any subs or amp in my car
Rotary > Pistons
05-08-13, 08:39 AM
#3
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Your alternator, provided it is functioning properly, will handle it fine.
I would bypass the resistor relay and run continuous 12v since you are changing the performance of your engine and increasing boost.
1A. may prevent fireballs, doubtful because it shouldn't switch to 9v at high throttle/afm movement.
B. Does lean mixture out. Since you have performance goals in mind and the motor will be flowing more air I wouldn't use this system.
(The larger answer to your question)
C. Marginally less demanding on the alternator, considering that it uses a resistor to bring it down to 10-9v. Resistors change some of the electrical energy into heat. So instead of getting the full 12v, the system still pulls 12v until the resistor relay, which just slows the flow/voltage of electrical energy by turning some of it into heat.
2. Go rewire the pump and skip the resistor relay.
a. this is why. or atleast you will know the pump is not the culprit.
b. it could also lead to a mileage increase, if the car is making more power it could cause you to pull more vacuum at certain throttle and at cruising
c. marginally
d. fireballs again should be happening under heavier throttle/decel so the pump should be at 12v regardless of if the system is intact or not.
As far as which one. Do either Dale Clark's Rewire, 1300cc's rewire, or arghx's (after reading the comments to his thread).
I would bypass the resistor relay and run continuous 12v since you are changing the performance of your engine and increasing boost.
1A. may prevent fireballs, doubtful because it shouldn't switch to 9v at high throttle/afm movement.
B. Does lean mixture out. Since you have performance goals in mind and the motor will be flowing more air I wouldn't use this system.
(The larger answer to your question)
C. Marginally less demanding on the alternator, considering that it uses a resistor to bring it down to 10-9v. Resistors change some of the electrical energy into heat. So instead of getting the full 12v, the system still pulls 12v until the resistor relay, which just slows the flow/voltage of electrical energy by turning some of it into heat.
2. Go rewire the pump and skip the resistor relay.
a. this is why. or atleast you will know the pump is not the culprit.
b. it could also lead to a mileage increase, if the car is making more power it could cause you to pull more vacuum at certain throttle and at cruising
c. marginally
d. fireballs again should be happening under heavier throttle/decel so the pump should be at 12v regardless of if the system is intact or not.
As far as which one. Do either Dale Clark's Rewire, 1300cc's rewire, or arghx's (after reading the comments to his thread).
05-08-13, 10:33 AM
#4
Your alternator, provided it is functioning properly, will handle it fine.
I would bypass the resistor relay and run continuous 12v since you are changing the performance of your engine and increasing boost.
1A. may prevent fireballs, doubtful because it shouldn't switch to 9v at high throttle/afm movement.
B. Does lean mixture out. Since you have performance goals in mind and the motor will be flowing more air I wouldn't use this system.
(The larger answer to your question)
C. Marginally less demanding on the alternator, considering that it uses a resistor to bring it down to 10-9v. Resistors change some of the electrical energy into heat. So instead of getting the full 12v, the system still pulls 12v until the resistor relay, which just slows the flow/voltage of electrical energy by turning some of it into heat.
2. Go rewire the pump and skip the resistor relay.
a. this is why. or atleast you will know the pump is not the culprit.
b. it could also lead to a mileage increase, if the car is making more power it could cause you to pull more vacuum at certain throttle and at cruising
c. marginally
d. fireballs again should be happening under heavier throttle/decel so the pump should be at 12v regardless of if the system is intact or not.
As far as which one. Do either Dale Clark's Rewire, 1300cc's rewire, or arghx's (after reading the comments to his thread).
I would bypass the resistor relay and run continuous 12v since you are changing the performance of your engine and increasing boost.
1A. may prevent fireballs, doubtful because it shouldn't switch to 9v at high throttle/afm movement.
B. Does lean mixture out. Since you have performance goals in mind and the motor will be flowing more air I wouldn't use this system.
(The larger answer to your question)
C. Marginally less demanding on the alternator, considering that it uses a resistor to bring it down to 10-9v. Resistors change some of the electrical energy into heat. So instead of getting the full 12v, the system still pulls 12v until the resistor relay, which just slows the flow/voltage of electrical energy by turning some of it into heat.
2. Go rewire the pump and skip the resistor relay.
a. this is why. or atleast you will know the pump is not the culprit.
b. it could also lead to a mileage increase, if the car is making more power it could cause you to pull more vacuum at certain throttle and at cruising
c. marginally
d. fireballs again should be happening under heavier throttle/decel so the pump should be at 12v regardless of if the system is intact or not.
As far as which one. Do either Dale Clark's Rewire, 1300cc's rewire, or arghx's (after reading the comments to his thread).
I'm still contemplating purchasing an adjustable fpr.
My theory is if I run rich with stock fpr, that's better then running lean setting lower, and only way to find out is by getting a wideband, or.narrow band and decide what to do then.
Rotary > Pistons
05-08-13, 12:37 PM
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I was just afraid of fireballs happening all the time, cops will definitely not prohibit it. So as long as I'm not.not rodding it and using minimal throttle, it shouldn't happen.
I'm still contemplating purchasing an adjustable fpr.
My theory is if I run rich with stock fpr, that's better then running lean setting lower, and only way to find out is by getting a wideband, or.narrow band and decide what to do then.
Rotary > Pistons
I'm still contemplating purchasing an adjustable fpr.
My theory is if I run rich with stock fpr, that's better then running lean setting lower, and only way to find out is by getting a wideband, or.narrow band and decide what to do then.
Rotary > Pistons
2. Why do you think you'll run rich with the oem fpr? if anything the walbro will be what causes you to run richer. But an adjustable one is good if you know what you're doing.
The only way to find out is a wideband. You won't get any useful data from a narrowband, waste of money.
05-08-13, 01:04 PM
#7
the alternator will be fine IF it is healthy.
to properly rewire a fuel pump it should look something like this
new fused battery wire to a 40A pump relay located near the pump with 12gauge wiring to relay input pole, 30a fuse located near battery
feed pole on relay to pump power wire
cut original pump power wire and use it to control the trigger circuit of the relay
ground wire to opposite control circuit of the relay jumpered to a ground point nearby
to properly rewire a fuel pump it should look something like this
new fused battery wire to a 40A pump relay located near the pump with 12gauge wiring to relay input pole, 30a fuse located near battery
feed pole on relay to pump power wire
cut original pump power wire and use it to control the trigger circuit of the relay
ground wire to opposite control circuit of the relay jumpered to a ground point nearby
Last edited by RotaryEvolution; 05-08-13 at 01:07 PM.
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05-08-13, 02:50 PM
#8
Senior Member
^ 
that's mongolian to me. schematic would be nice 
only time i've experienced shot gun blasts from the exhaust is when I didn't have the smog pump and control valve in place. put them back on and has never happened again.
although never dyno'd, my TII is so equiped for 300+ whp. my pump wiring is still stock. my fuel pressure gauge stays fixed at max pressure throughout the RPM range.
hook up a gauge then determine if you need rewiring.
that's mongolian to me. schematic would be nice only time i've experienced shot gun blasts from the exhaust is when I didn't have the smog pump and control valve in place. put them back on and has never happened again.
although never dyno'd, my TII is so equiped for 300+ whp. my pump wiring is still stock. my fuel pressure gauge stays fixed at max pressure throughout the RPM range.
hook up a gauge then determine if you need rewiring.
05-08-13, 04:23 PM
#11
I had a walbro 255 running on the 9/12v switching system. Fuel pressure was still in the 40's at idle. So all the benefits you're listing from using the stock system aren't going to happen. At least not enough to prove. My car only backfired back when it didn't have a cat. Stock pump and walbro pump with no cat would backfire. Walbro or FD pump with cat never backfires.
My gas mileage didn't noticeably change after going to the FD pump, but the exhaust definitely smelled better.
My gas mileage didn't noticeably change after going to the FD pump, but the exhaust definitely smelled better.
05-08-13, 05:15 PM
#12
Senior Member
i run no cat (+ smog pump and control valve) and never backfires.
i'm currious, iirc, as to why a fuel pump upgrade was NOT an HKS required item as part of any of their performance upgrades for the TII including their 350-360 hp "Stage 5" ?? I just did it because seemed that's what had to be done.
Last edited by Clubuser; 05-08-13 at 05:20 PM.
05-08-13, 06:17 PM
#13
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so since neither HKS or Mr Bell wanted a fuel pump (or injectors) one can wonder why that would be, and there are a few reasons.
1. the gasoline is different, we've got an ethanol blend, and its does require slightly more volume than 80's gasoline.
2. the fuel pumps don't die, but it is pushing a quarter century old, when you couple that with a weak alternator, bad staple in the charging harness you have a recipe for an under performing system
2. everyone is running on worn out used engine parts. the better the chamber sealing, the less exhaust gasses leak chamber to chamber and the less hot exhaust gasses in the intake stroke the more detonation resistant the engine is.
Mazda left some margin, a stock car will be fine, but when you're trying to increase power by 50% these things matter a lot.
05-08-13, 07:27 PM
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Ben (RotaryEvolution) speaks perfect Mongolian..as well as wtfyatakkinaboutian..and yougottabekiddinmeian..
usually answered in his favorite language..Heresthescoopyouknobian!..
..as usual he is a Great source of info!
Thanks Ben..STYX.
usually answered in his favorite language..Heresthescoopyouknobian!..
..as usual he is a Great source of info!
Thanks Ben..STYX.
05-08-13, 11:47 PM
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its like wiring an amp, you're using the stock fuel pump power to trigger the relay so you can get big power to the pump
05-09-13, 12:00 AM
#17
Rotary > Pistons
05-09-13, 11:52 AM
#20
Senior Member
me too a little confused.
i interpret the yellow arrow as IGN 12V being sent to ground when the AFM closes the circuit.
Ben notes to send to ground directly (?).
Do we want the pump to come on once the IGN is hit with the AFM no longer playiing a role?
i interpret the yellow arrow as IGN 12V being sent to ground when the AFM closes the circuit.
Ben notes to send to ground directly (?).
Do we want the pump to come on once the IGN is hit with the AFM no longer playiing a role?
Last edited by Clubuser; 05-09-13 at 11:55 AM.
05-09-13, 12:01 PM
#21
the simplified version still uses the stock fuel pump circuit but it is used to trigger the relay.
ie, when you crank the engine the AFM door opens, the fuel pump circuit triggers and feeds power to the pump. cut the wire to the pump and use the voltage supplied to power the coil circuit of the relay at pin 85, pin 86 wired to ground to complete the circuit to power the coil and trip the relay on. this bridges the contacts from 87 and 30 to feed power from the battery directly to the pump.
a relay has 2 basic halves, the coil and the bridge connection(contacts).
85 and 86 are for the coil, one needs 12v and the other needs ground to power up the coil and close the contacts in the relay. the bridged contacts simple allow voltage to pass through the relay(87 and 30, pin 87a will feed power from 87 out when the relay is not power on and shuts off that voltage when the relay is turned on. it is an auxiliary bridge for various purposes depending on if you need it or not. for the most part you can disregard pin 87a as it isn't used for many purposes but it can be used as a reverse switched power, ie battery power supplied to a device only when the relay is off).
the relay does not take much to trip on, so using the original wiring to trip the relay just makes life easier. it also allows you to retain stock functionality of the pump, meaning it won't run constantly with the key on.
the picture is only confusing if you read the yellow as a positive battery input, which it isn't it is a switched ground in the diagram. all we're doing is making the other pin 85(fuel pump 12v switched) do the switching and pin 86 is constantly grounded. since apparently the subaru forum i snagged it from supplies the pump with constant 12v and uses a switched ground to turn their pump on(opposite the FC).
this is the simplest i can describe:
87- fused battery wire
30- wired to pump (black/white wire on top of tank)
85- original wire leading to pump (chassis side of black/white wire)
86- ground
it's actually very simple, regardless of my jibberish.
ie, when you crank the engine the AFM door opens, the fuel pump circuit triggers and feeds power to the pump. cut the wire to the pump and use the voltage supplied to power the coil circuit of the relay at pin 85, pin 86 wired to ground to complete the circuit to power the coil and trip the relay on. this bridges the contacts from 87 and 30 to feed power from the battery directly to the pump.
a relay has 2 basic halves, the coil and the bridge connection(contacts).
85 and 86 are for the coil, one needs 12v and the other needs ground to power up the coil and close the contacts in the relay. the bridged contacts simple allow voltage to pass through the relay(87 and 30, pin 87a will feed power from 87 out when the relay is not power on and shuts off that voltage when the relay is turned on. it is an auxiliary bridge for various purposes depending on if you need it or not. for the most part you can disregard pin 87a as it isn't used for many purposes but it can be used as a reverse switched power, ie battery power supplied to a device only when the relay is off).
the relay does not take much to trip on, so using the original wiring to trip the relay just makes life easier. it also allows you to retain stock functionality of the pump, meaning it won't run constantly with the key on.
the picture is only confusing if you read the yellow as a positive battery input, which it isn't it is a switched ground in the diagram. all we're doing is making the other pin 85(fuel pump 12v switched) do the switching and pin 86 is constantly grounded. since apparently the subaru forum i snagged it from supplies the pump with constant 12v and uses a switched ground to turn their pump on(opposite the FC).
this is the simplest i can describe:
87- fused battery wire
30- wired to pump (black/white wire on top of tank)
85- original wire leading to pump (chassis side of black/white wire)
86- ground
it's actually very simple, regardless of my jibberish.
Last edited by RotaryEvolution; 05-09-13 at 12:16 PM.
05-09-13, 12:17 PM
#22
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