Injector cycle duty? 87-90% in 3rd @ wot on To4s.
09-18-11, 06:41 PM
#1
Injector cycle duty? 87-90% in 3rd @ wot on To4s.
Hey guys I search the forum but I am not those fit my setup, anyway with my current setup (fuel) 550 primary and 1300 (new injectors) and SARD fpr, walboro pump, I am seeting 87-90% injector duty cycle in wot? Is it time to worry or starting thinking of new fuel system all togther? Or if i swap my fuel pump to aermotive 340 will that help?
09-18-11, 06:52 PM
#2
Original Gangster/Rotary!
iTrader: (213)
Hey Khris,
what boost level?
I'd say you're fine as-is if you're not going to turn up the boost, especially on the street. The side feeds supposedly run cooler due to their design (being cooled as the fuel passes through them) and it's not like you're going out on the road race track and really going WOT lap after lap.
If it ain't broke don't fix it
what boost level?
I'd say you're fine as-is if you're not going to turn up the boost, especially on the street. The side feeds supposedly run cooler due to their design (being cooled as the fuel passes through them) and it's not like you're going out on the road race track and really going WOT lap after lap.
If it ain't broke don't fix it
09-19-11, 10:10 AM
#7
Hey thanks for the input, well I do want to push the car more to get more hp and I want to see if that particular setup can make 400hp or little more, so before i go and get a retune I might as well partial upgrade my fuel system and then get the retune.
Khris
Khris
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09-19-11, 10:18 AM
#8
What is your base fuel pressure? If its 36 to 38 you could turn it up to 40 or a little more if you wanted to, and if The pump isn't rewired you can hook up a relay, all this and some tuning because you will be running rich, will then lower your idc and allow you to turn up the boost later. And get that aeromotive drop in replacement fuel pump, I might do that soon, should be a little better than the supra pump.
09-19-11, 12:04 PM
#11
I've seen good reviews on the aero. Stealth 340, not any bad. I actually just ordered one. Good lower price, easy install, and they have been tested to flow more than the Denso supra pump, which has supported about 500 hp for my current setup with 24 psi boost.
09-19-11, 12:24 PM
#12
if you want more i'd just swap in some cleaned 850's to replace the stock 550 primaries. no way around pushing it further without a retune anyways.
upping the fuel pressure and volume only slightly will also only slightly increase the amount that the injectors will be pushing. so in effect if you up the pressure by 10% then you will only be able to ramp up your peak horsepower by about the same level before you're right back where you were before. so if you're around 350whp now for example, then expect the system to peak out again at just shy of 380whp, which isn't at your goal level. if you're at 380whp now then you should be fine with only trying to squeeze a few more hp out of it with increasing the pressure to where it should be, if it even is. i wouldn't crank it up much over 40psi though because most regulators will start stressing at higher pressures.
upping the fuel pressure and volume only slightly will also only slightly increase the amount that the injectors will be pushing. so in effect if you up the pressure by 10% then you will only be able to ramp up your peak horsepower by about the same level before you're right back where you were before. so if you're around 350whp now for example, then expect the system to peak out again at just shy of 380whp, which isn't at your goal level. if you're at 380whp now then you should be fine with only trying to squeeze a few more hp out of it with increasing the pressure to where it should be, if it even is. i wouldn't crank it up much over 40psi though because most regulators will start stressing at higher pressures.
Last edited by RotaryEvolution; 09-19-11 at 12:30 PM.
09-19-11, 01:39 PM
#13
I just increased my fuel pressure from 36 up to 40, and did the fuel pump rewire with a relay in the hatch (battery in hatch, 13.8 volts now at the fuel pump wire harness), and I was able to turn up my boost from 18 psi up to 23-24 and now have the same idc of about 85-90% as I did before with 18 psi.
09-19-11, 07:25 PM
#15
I just increased my fuel pressure from 36 up to 40, and did the fuel pump rewire with a relay in the hatch (battery in hatch, 13.8 volts now at the fuel pump wire harness), and I was able to turn up my boost from 18 psi up to 23-24 and now have the same idc of about 85-90% as I did before with 18 psi.
To Karack I never rewire my pump because I did not want to mess it because it was working fine. Also for hp wise at 18 psi I am making 384 hp, I thought at those cycle duty % i need to update fuel system?, but I guess even thought I turn up the fpr to more fp I am still limited to the total output of the injectors because their only flow 1300, i just want to be safe than living on the edge.
Last edited by Rx7aholic; 09-19-11 at 07:34 PM. Reason: more info
09-19-11, 07:41 PM
#18
Yes, the stock wiring for the fuel pump is very thin and when it heats up the voltage drops which equals fuel pressure dropping under boost. Not to mention its going through a resistor which drops the voltage under light load which becomes a possible failure point due to its age.
thewird
thewird
09-19-11, 07:50 PM
#19
Are you talking about this thread here. And you can pull out the fuel pump relay at the front of the car and put in a jumper wire to bypass that resistor.
09-19-11, 07:55 PM
#20
You can bypass the resistor but that won't change your stock wiring. It might be fine for a few pulls. But I've seen it happen more then once. AFR's are steady for a fuel pulls and they start to slowly lean out. Ask the owner did you rewire the fuel pump, NO, get it rewired and problem is gone. Depending on how much fuel your demanding, it can be a slow creep of getting leaner or it can be a fast drop in fuel pressure and gets dangerously lean during a pull. Its most worse on the denso supra pump since it seems to draw a lot more amperage then the other pumps.
thewird
thewird
09-19-11, 08:10 PM
#21
injectors will flow more at higher PSI of fuel pressure, their rating is at static which should be at or near stock fuel pressure. rewiring the pump increases the volume it can produce, upping the fuel pressure increases the volume that the injectors can flow maximum.
the fuel pump will start to taper off it's fuel pressure and actually start to drop once you have reached and surpassed it's maximum volume flow, resulting in leaner AFRs. upping the voltage to the pump will buy you more "pump" from the increased volume output it is now producing.
there is even fuel pump superchargers out there, as the kenny belle boost a pump that i have installed in a few vehicles that needed a kick in the pants for fuel flow. these fuel pump superchargers increase the voltage from standard 11-13.5v up to upwards of 20volts, increasing the fuel pump output by as much as 50% or more depending on the pump.
the fuel pump will start to taper off it's fuel pressure and actually start to drop once you have reached and surpassed it's maximum volume flow, resulting in leaner AFRs. upping the voltage to the pump will buy you more "pump" from the increased volume output it is now producing.
there is even fuel pump superchargers out there, as the kenny belle boost a pump that i have installed in a few vehicles that needed a kick in the pants for fuel flow. these fuel pump superchargers increase the voltage from standard 11-13.5v up to upwards of 20volts, increasing the fuel pump output by as much as 50% or more depending on the pump.
Last edited by RotaryEvolution; 09-19-11 at 08:13 PM.
09-19-11, 08:28 PM
#23
Original Gangster/Rotary!
iTrader: (213)
Khris, this has been discussed many times before on the forum.... a simple search will give you the answers you want. Believe it or not you're not exactly blazing any trails here 
09-20-11, 11:10 AM
#25
thicker gauge wiring the better, but beyond a point is overkill. generally 12 gauge is a good medium but if you can fit 10 guage it is better, but the relay will still be the weak point in the system. the shorter the wire from the battery to the relay then to the pump the better, longer = higher resistance, more voltage drop and more points for possible failure. problem with the original wiring is the relay and wiring are now 15+ years old and generally give less than adequate voltage and often times erratic voltage readings because the contacts inside the stock relays do not last forever.
any good quality 30 amp bosch style relay is what is typically used.
any good quality 30 amp bosch style relay is what is typically used.
Last edited by RotaryEvolution; 09-20-11 at 11:12 AM.