Fuel Injectors
Fuel Injectors
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Well I am running 440's and those are good to about 10 PSI effectively. Beyond that they are going into the > 80% duty cycle world and that wears out the injectors faster. 550's should be good to about 16 PSI which is really the max you can do on the stock RS 2.5 block. Though I DON'T recommend it, as this will cause your head gaskets to start leaking.
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Hell yeah Power Enterprise! Those guys build some very good stuff. They also ship directly to the US so any individual call call them up and place an order. They shipped me some parts before the same day that I ordered them. Tomei was still the quickest for a headgasket. I ordered it and got it the next day.
I got mine from Shiv originally with the TEC-II setup. (Vishnu)
The injector you run depends on the turbo and CR....its not driven by boost pressure as a standalone unit.
A 440cc injector is enough fuel for roughly 300 ish HP.....a 550 cc will get you to 400 hp reliably, and from there, it depends how "big dog" you want to go.
As for PE, they will not ship directly to a customer in the US....they direct you to an authorized dealer, but luckily, we are one
As for IDC, be careful how you measure it...i can post the formula to figure it out if anyone wants (tey should make it a sticky by now). 80% true IDC is a good safe, reliable place to ahve the injector live. 90% is actually where the injectors generally are at their greatest efficiency overall, and IDC's over 100% during very short bursts are accepetable as well...but 80% again is a nice safe place...no chance of the injector "locking up" (which almost never happens anyway), but the spray pattern is wide enough and fine enough that good atomization happens.
That being said, I never got around to doing injectors on my GC8.....stock '99 RS units, a 2:1 Magnetti Marelli adjustable regulator, Supra pump, an SAFC (monitering 02 voltage), and an ITC. Fuel was never an issue for my car, turbo was a T3/T04, Spearco top mount, and I ran....well, more than 10 psi daily. However, this was on a strict diet of 94 octane only.
Adam
Z-1 Performance
A 440cc injector is enough fuel for roughly 300 ish HP.....a 550 cc will get you to 400 hp reliably, and from there, it depends how "big dog" you want to go.
As for PE, they will not ship directly to a customer in the US....they direct you to an authorized dealer, but luckily, we are one
As for IDC, be careful how you measure it...i can post the formula to figure it out if anyone wants (tey should make it a sticky by now). 80% true IDC is a good safe, reliable place to ahve the injector live. 90% is actually where the injectors generally are at their greatest efficiency overall, and IDC's over 100% during very short bursts are accepetable as well...but 80% again is a nice safe place...no chance of the injector "locking up" (which almost never happens anyway), but the spray pattern is wide enough and fine enough that good atomization happens.
That being said, I never got around to doing injectors on my GC8.....stock '99 RS units, a 2:1 Magnetti Marelli adjustable regulator, Supra pump, an SAFC (monitering 02 voltage), and an ITC. Fuel was never an issue for my car, turbo was a T3/T04, Spearco top mount, and I ran....well, more than 10 psi daily. However, this was on a strict diet of 94 octane only.
Adam
Z-1 Performance
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Also depends on the fuel pressure you want to run, and what your Brake Specific Fuel Consumption is.
550's will need to be pushing near 90 pounds of fuel pressure to reach that 400 HP mark, oh yeah, what fuel pump are you running?
Cause unless it is high Pressure specific, most of them fall on their face at 90psi. The walbro seems to be a popular drop in unit both in 190 and 255lph variants. Both flow only around 45-50lph @ 90psi. 550cc's will eat about 8 gallons per hour, which doesn't leave much headroom for the pump which maxes at 12gph@90psi.
Better off going with the Walbro HP 255lph pump, which is what I chose, it will keep flow sustained up into higher pressures.
But that is just my 2 cents that I used when I decided to get the injectors I did.
First off, I am running an Autronics SM2 ECU, so I don't have any problems associated with stock ECU's. The Autronic is capable of running very large injectors in very precise and small opening cylces. Something a stock ECU can't do.
So because of this I decided to go with the 850cc@43psig injectors, which will give me my 400Hp @ 80% duty cycle at 43psi. At 43 psi the pump will flow ~60gph, so basically it won't be breaking a sweat.
Also for future enhancement if need be the pump will flow 37gals/hour at @90psi which will allow the injectors to support 575Hp @ 80% duty cycle, although I will never reach these figure, my main point is keeping the fuel pressure low and relying on precise injector control for proper fueling. (The stock fuel pump would probably provide enough flow at 43psi to support these power levels)
-Paul
oh yeah, my injectors came from RC Engineering- Custom Sized
550's will need to be pushing near 90 pounds of fuel pressure to reach that 400 HP mark, oh yeah, what fuel pump are you running?
Cause unless it is high Pressure specific, most of them fall on their face at 90psi. The walbro seems to be a popular drop in unit both in 190 and 255lph variants. Both flow only around 45-50lph @ 90psi. 550cc's will eat about 8 gallons per hour, which doesn't leave much headroom for the pump which maxes at 12gph@90psi.
Better off going with the Walbro HP 255lph pump, which is what I chose, it will keep flow sustained up into higher pressures.
But that is just my 2 cents that I used when I decided to get the injectors I did.
First off, I am running an Autronics SM2 ECU, so I don't have any problems associated with stock ECU's. The Autronic is capable of running very large injectors in very precise and small opening cylces. Something a stock ECU can't do.
So because of this I decided to go with the 850cc@43psig injectors, which will give me my 400Hp @ 80% duty cycle at 43psi. At 43 psi the pump will flow ~60gph, so basically it won't be breaking a sweat.
Also for future enhancement if need be the pump will flow 37gals/hour at @90psi which will allow the injectors to support 575Hp @ 80% duty cycle, although I will never reach these figure, my main point is keeping the fuel pressure low and relying on precise injector control for proper fueling. (The stock fuel pump would probably provide enough flow at 43psi to support these power levels)
-Paul
oh yeah, my injectors came from RC Engineering- Custom Sized
Guest
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paulnose,
without doing the maths, I think your figures for 850s are somewhat very very conservative. As a rule of thumb (and it has been proven time and again, on rolling roads and engine dynos) Subaru engines need about 5.5cc of injector flow per BHP. With an 850cc setup you should be able to push 525 BHP at 85% duty and 3 bar differential fuel pressure (the idustry standard), if you aren't making the power then there is something else going wrong... most often it's the fuel pump running out of puff, but if you already have the Walbro then it's unlikely that it's the pump that's the issue.
Personally I wouldn't like to run an injector much beyond 5 bar differential pressure (about 72 psi). Of course the actual fuel pressure may well be higher (you could, for example, be running 3 bar boost already, to give you 8 bar fuel pressure). Of course it's the differential pressure that propels the fuel out of the injector, not the absolute, but you need to be careful with high absolutes because the upper injector seals in the rails may give up. I've tested mine up to about 145 PSI and they held, but I wouldn't like to guess how long they would take that abuse.
440cc injectors should be fine for most people's needs; with a 1.7:1 rising rate reg, you'll get 480cc out of them at 1 bar boost, or you can adjust your reference differential pressure from 3 bar to 4 bar to get them up to 550cc., which will be fine for a comfortable 340 BHP at 85% duty, which if memory serves correctly is more than a 100% increase in power as compared to a stock EJ25, and I certainly wouldn't recommend pushing one that hard for very long, at least not without going internal and uprating the rods and pistons.
If I'm not mistaken, the RS uses Phase II injectors, which are the same as Skyline and RX-7 injectors, as well as MY99-MY00 UK and Aussie Turbo2000 / WRX models, so should be reasonably inexpensive to buy (just getting a quote from a breaker right now, I need a set for my 3.3).
Hope this helps,
Pat.
without doing the maths, I think your figures for 850s are somewhat very very conservative. As a rule of thumb (and it has been proven time and again, on rolling roads and engine dynos) Subaru engines need about 5.5cc of injector flow per BHP. With an 850cc setup you should be able to push 525 BHP at 85% duty and 3 bar differential fuel pressure (the idustry standard), if you aren't making the power then there is something else going wrong... most often it's the fuel pump running out of puff, but if you already have the Walbro then it's unlikely that it's the pump that's the issue.
Personally I wouldn't like to run an injector much beyond 5 bar differential pressure (about 72 psi). Of course the actual fuel pressure may well be higher (you could, for example, be running 3 bar boost already, to give you 8 bar fuel pressure). Of course it's the differential pressure that propels the fuel out of the injector, not the absolute, but you need to be careful with high absolutes because the upper injector seals in the rails may give up. I've tested mine up to about 145 PSI and they held, but I wouldn't like to guess how long they would take that abuse.
440cc injectors should be fine for most people's needs; with a 1.7:1 rising rate reg, you'll get 480cc out of them at 1 bar boost, or you can adjust your reference differential pressure from 3 bar to 4 bar to get them up to 550cc., which will be fine for a comfortable 340 BHP at 85% duty, which if memory serves correctly is more than a 100% increase in power as compared to a stock EJ25, and I certainly wouldn't recommend pushing one that hard for very long, at least not without going internal and uprating the rods and pistons.
If I'm not mistaken, the RS uses Phase II injectors, which are the same as Skyline and RX-7 injectors, as well as MY99-MY00 UK and Aussie Turbo2000 / WRX models, so should be reasonably inexpensive to buy (just getting a quote from a breaker right now, I need a set for my 3.3).
Hope this helps,
Pat.
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