Standard Injector Performance

[blitza]

Hi All,

Just a quick question.... How many hp/boost can the standard R34GTT injectors (I think they are around 370cc) take, and safely run with???

Any help would be much appreciated.

[stolen_s15]

To be safe I wouldn't run them past 90%duty cycle at absolute max.

Should be goot for 225-240rwkw depending on the dyno.

[blitza]

i will have supporting mods like a fuel reg and fuel pump...would that make a difference. I plan to use this fuel setup for a GT3071 turbo.... I was kinda hoping that the standard injectors would do the job... final power output is 'planned' for around 275rwkw at something like 15psi.

[blitza]

i will have supporting mods like a fuel reg and fuel pump...would that make a difference. I plan to use this fuel setup for a GT3071 turbo.... I was kinda hoping that the standard injectors would do the job... final power output is 'planned' for around 275rwkw at something like 15psi.

[stolen_s15]

No way will they handle that power with any sort of reasonable rail pressure.Spend the money and get some nismo 550's.

Dont skimp on injectors mate, no fuel = lean out, lean out = popped motor, popped motor = alot mor expensive than $750 for injectors.

Oh and forget the fuel pressure reg, you dont need it.

What spec'd 3071 are you going to use? I would imagine you would need a bit more than 15psi to get 275.

[ellie]

An injector is just a solonoid controlled valve which can flow a certain amount at a certain rail pressure. So technically you should be fine to run them all the way up to 100% duty cycle but that puts a fair bit of stress on them running such high frequencies and with no margin for error, well stolen_s15 has covered that. Their will always be real world variables (basic condition of you fuel system components) so you need a small safety margin of about 5% (so 95% duty cycle) or 90% as abvove to be super safe. By my calculations the standard injectors are theoretically capable of 259rwkw best case senario on 100%duty cycle so you not going to get any where near what you want!

If you don't wish to buy larger injectors, you can remove yours and get them high flowed for approx. $60 each to pretty much any spec you want. But be consious of future power goals as Ive seen people go to small before.

Hope that was of some help

[pixel8r]

I have a GT30 turbo (hybrid - mated to standard R34 exhaust housing) on my S2 stagea and at my last tune it had ~180rwkw. Boost would spike initially to 12psi but fade off to 9psi by redline. I also only have minor supporting mods, so not enough to run higher boost in mine. A better fuel pump would get me to 200-220 rwkw but at the moment I dont have adequate tuning to compensate for lag so more boost at the top end is out of the question right now.

For your setup, you may get more than 180rwkw with the same boost as what I had but I'd guess around 16-18psi for ~280rwkw...

Good luck with it Just be aware that you'll lose some low-end response with this turbo. Big numbers for max power is all well and good but if you want overall responsiveness, I'd recommend no bigger than a GT28. Just my opinion, depends what you want. Its not that the GT30 is super laggy or anything, it should be good enough with the right tuning, but you may miss the almost-instant boost you get with the stock turbo.

Max boost with the GT30 is usually around 3500-3700rpm (maybe lower with better tuning). I believe max boost on the stock turbo is around 3000rpm depending on what boost you're running...correct me if I'm wrong...

I'm looking at getting a GReddy Emanage (probably just the blue - will do fine for what i need) sometime within the next 6 months which will hopefully significantly reduce lag and improve things a little. In colder temps, I have no issues with it, it revs to over 4000rpm before I'm all the way across any intersection....its just when its like 35 degrees with a/c on it takes longer to get onto boost...but again, your mileage may vary and I could have issues with my a/c. I dont know.

Edited December 21, 2007 by pixel8r

[Simon-S14]

heres my results... call BS if you like but the power was made on a KNOWN reptuable dyno, and a malpassi rising rate was used.

I made 283 rwkw on 20 psi with stock injectors. Rb25 with 3071R, bosch motorsport pump, cooler, AM performance exhaust and dump. and the AFR's were still in the 12's, there was still headroom left 283 also.

I run 16-17 psi now to keep it safe as its a drift car, makes 265 rwkw, still stock injectors.. perfect mixtues and gets well thrashed on the track.

[Lukaz]

heres my results... call BS if you like but the power was made on a KNOWN reptuable dyno, and a malpassi rising rate was used.

I made 283 rwkw on 20 psi with stock injectors. Rb25 with 3071R, bosch motorsport pump, cooler, AM performance exhaust and dump. and the AFR's were still in the 12's, there was still headroom left 283 also.

I run 16-17 psi now to keep it safe as its a drift car, makes 265 rwkw, still stock injectors.. perfect mixtues and gets well thrashed on the track.

Highflowed, not stock or happy dyno - no way stocko factory injectors will do 280+rwkw

[Simon-S14]

theres always one isnt there.

its not a happy dyno, in fact its the most accurate dyno in SA. and the injectors are 100% stock.

Have a read of what i wrote, a Malpassi rising rate was used. if stock pressures were used i doubt i would have made the power i did. However i decided to use the RR FPR, then retune all the idle and cruise/down low mixtures to stop overfuelling.

the RR FPR isnt running massive pressure in the rail either.. its only something like 10% more then stock

[simor32]

my mate makes 300kw on stock rb25 injectors. hes on these forums actually. no bullshit

[Simon-S14]

i'd believe it, again a RR FPR would have to be used, the fact i made 283 and still had plenty of headroom left means that making near 300 wouldnt be out of the question.

I made 220rwkw on stock RB20 injectors when i had a 20 and huddy on this forum made 230 rwkw, both were with stock FPR.

[R31Nismoid]

Good to see people running grenade set ups

Do the math with 370cc injectors, you'll find that leaving no margin for error is dancing with the devil.

Also ECU dependant, if the ECU is batch firing (rather than sequential), of course you can run more than what you should as there is extra fuel sitting around doing nothing

[Adriano]

The base fuel pressure may not be that much different, but a 2:1 malpassi will add 60 psi to the idle pressure if your running 20 psi, so 40+60=100 psi, tell me thats not a lot of fuel pressure.

[Simon-S14]

Good to see people running grenade set ups

Do the math with 370cc injectors, you'll find that leaving no margin for error is dancing with the devil.

Also ECU dependant, if the ECU is batch firing (rather than sequential), of course you can run more than what you should as there is extra fuel sitting around doing nothing

my car is a drift car, it gets more thrashed then your car i can tell you right now.. My tuner is one hell of a awesome tuner and the whole combo is safe as anything.

the fact that 40 + dyno runs back to back during 4-5 hours in 38 degree temps in the dyno room, all with safe AFR's and not a hint of detonation... yeah its a grenade

[R31Nismoid]

I dont care whats going on to be honest

Your running unnecessary risk.

Get a build motor worth many thousands... cheap skating out on $700 worth of injectors is silly. Its as simple as that.

Anyone can run 11ty psi through the injectors, doesn't mean its the best way, nor the safest way to go about it.

Its no different to welding a diff. Does it work? Yes. Is it the best way? No.

Doing supporting mods, is just that. Injectors are no different to a stock cooler.

Did you upgrade the cooler to get the best cooling? So why not the same for injectors for fuel?

The guy is asking for safe figures. And in all honesty bumping the rail pressure that much isnt safe.

[UCD15R33]

^+1 i agree why put ur engine through stress it doesnt need??? Yeah I have seen some bull sh*it power from stock inj butt 1 know for a fact after a few time raping it, they pinning and in a few cases bang goes the engine. look for safety sake 300 hp is a safe with a good tune and plenty of fuel. and If u want more for fark sake bigger injectors and aftermarket ecu

[Simon-S14]

I dont care whats going on to be honest

Your running unnecessary risk.

Get a build motor worth many thousands... cheap skating out on $700 worth of injectors is silly. Its as simple as that.

Anyone can run 11ty psi through the injectors, doesn't mean its the best way, nor the safest way to go about it.

Its no different to welding a diff. Does it work? Yes. Is it the best way? No.

Doing supporting mods, is just that. Injectors are no different to a stock cooler.

Did you upgrade the cooler to get the best cooling? So why not the same for injectors for fuel?

The guy is asking for safe figures. And in all honesty bumping the rail pressure that much isnt safe.

wheres the unnecessary risk? everyone says its highly dangerous to run injectors over 80% duty but without any real proof. Sure the math's and reasoning says otherwise but in the realworld... theres no real reason why you couldnt push it harder.

[Sydneykid]

wheres the unnecessary risk? everyone says its highly dangerous to run injectors over 80% duty but without any real proof. Sure the math's and reasoning says otherwise but in the realworld... theres no real reason why you couldnt push it harder.

There is no magic here, it is simply a mater of increasing the fuel presure to squirt more fuel through the same sized hole. We do it all the time, when we only need a slight increase in flow. Big increases in flow (like this one) are not something we would EVER do.

Here's the problem Simon, you have to be running the injectors at higher than standard fuel pressure, much higher than standard. This means several things;

1. You need to have superior than standard fuel lines and fittings, a petrol fire is not pretty. The right stuff is not cheap.

2. You need to buy an ajustable FPR and tune it to the required pressure, there is a cost involved in doing that.

3. Your fuel pump is working at a pressure that is higher than its rated pressure, that means it has reduced flow. Plus its life will be much shorter. As a result I would hope that you bought a larger fuel pump than you really needed, that will have cost more

4. The big one, the injector solenoids are opening against much high pressure than they were designed for. One day one of them with fail, without notice, the solenoid will simply cease to function. Then you will have one cylinder gone west, the first thing you will know about it will be a plume of smoke.

The real quations is. have you realy saved any money by not buying larger injectors and spending it on an adj FPR, a larger than neccesary fuel pump and superior fuel lines and fittings? Not in my experience. Then factor in the risk and the cost when it fails.

Roll the dice by all means, but you will lose eventually, why? Because everyone else has.

Merry Xmas

Gary