slp223

using datamaster my inj dc will spike up in to 95% but then come back down to 77%. do i need larger injectors? i am using 30# svo and the car makes 430 wrhp

kmook

Um I think so. I'm expecting about the same power and using 42#s.

roadtrip120

i wouldnt think so, i have seen two turbo cars pu the injector dc at 120 !!

I think you are on the boarder line. You could if you want, for later on hp but i wouldn't waste your money yet. The 30lb will hold for awhile longer.

1racerdude

Unless your fuel pressure is set real high your injectors are to small.
With 36#@39psi & a 83.3 duty cycle you can make 480FWHP.

Deenasty

you can ask Fred, he has seen datamaster show false injector duty cycle. I wouldnt trust it..

kmook

What are you suppose to trust?

kmook

You know that they are not at 120% right? Something can't be open for more than 100% of the time, the ecu is just calling for 120%. Reference Here If it is calling for 95% he doesn't HAVE to upgrade, but he should.
Read here for more injector info-
http://www.rceng.com/technical.htm

1racerdude

[QUOTE=kmook]You know that they are not at 120% right? Something can't be open for more than 100% of the time, the ecu is just calling for 120%. Reference Here If it is calling for 95% he doesn't HAVE to upgrade, but he should.
Read here for more injector info-
http://www.rceng.com/technical.htm[/QUO
TE]

Ditto
If he wants to make the HP the engine is capable of and keep a descent A/F ratio he is small.
I have made over 600HP with 30# but the fuel pressure was at 90PSI+ and the distribution plate had been removed,which gives you a fit when tuning.
Most cars don't have the fuel pump to go that high with FP and deliver the correct volume.

slp223

My car on the dyno made 430rwhp with 30# injectors and 600rwhp on bottle with the same 30# injectors. yet my air fuel was never lean. I would asume the my duty cycle was un aceptable. i have had the same motor combo since may of 02. with what seem to have no adverse affects. I have not made many bottle passes so so who know what will happen I am going to make some run on the dyno tomorrow and see what happens on and off bottle.

1racerdude

You didn't say what your FP was.Like I said I have made a lot with 30# with the FP jacked WAY up and the injectors modified so they will deliver fuel but the drivabality went to s***,you can't control them.

slp223

fp is stock 43.5

1racerdude

If a bsfc of .50 is used your duty cycle is 98.0.Way to high,or you have the most effecient LT-1 in the world,but you can let them go static,just don't have a bad tuning day at the track and don't push that button.
Just not my way to get it done.

Injuneer

Were those injectors flow rated at 43.5psi, or were they flow rated at 2.7bar (39.15psi), like some injectors? That buys you 5% above rated, or 31.5#/HR at 43.5psi. For your NA HP, as noted above, you probably made it by the skin of your teeth, with the engine peaking "briefly" at 430rwHP. It's possible you have a BSFC on your NA tuning that is closer to 0.45#/HR/HP, if its a really good tune. That buys you a little headroom. But the thing I can't understand is why you feel its good to run a "too small" injector. How do you know that the spray pattern was not becoming unstable, and limiting HP at the 430rwHP level? How do you know you couldn't have made more HP with a decent injector? Its not going to show up in the A/F ratio.... its still using the same air and fuel, but its not using it efficiently. How do you know that the heat and instability of running the injectors at 100% duty cycle isn't wearing them out, and going to lead to a catastrophic failure when they go unstable and can't supply the fuel while your on the bottle?

And, what type of nitrous system do you have? If you have a dry system, and are claiming you made 600rwHP on the bottle, with 30# injectors at 43.5psi, I'll raise the BS flag as high as it can go. On the other hand, if your nitrous is a wet system, the extra fuel was supplied externally to the injectors, and the statement of how much power it made on the bottle is irrelevant to the question. Which system do you have - wet or dry?

slp223

I dont know what psi they are rated at they are svo 30# svo injectors. I never stated that i thought was a good idea to use to small of an injector. The point was not to try to use and injector that was too small. My swag (scientific wild *** guess) for what size injectors i need years ago was #30 the car runs fine and is not lean on the dyno there for I did not see any problem well ingorance is bliss. I used a data master. last night for the first time saw a possible problem. what why i posted the question. Fred real you bs flag back down. Like it says in my sig I have a wet kit its an NX kit with a stand alone fuel system (NX does not make a dry kit and you would not have a stand alone fuel system on a dry kit) but hey I apreciate you throwing that out there.

Injuneer

Then what was your point of posting that you made "600rwhp on bottle with the same 30# injectors"? People read these posts and believe this crap. Its not helping in any way to post irrelevant info like that, to make your case.