What duty cycle are you guys running on your injectors? Mine are over 50% just to make 370rwhp on a heads/cam/fast 90 90 car. Theres more power in the car but I thought these injectors would be plenty big....? Im thinking theres a restriction somewhere in the fuel system but I have no friggin clue. I did find a GOOD AMOUNT of missing hp by adding a **** ton of fuel to my tune raising the duty cycle. Ive got a hair over 60psi of fuel pressure at wot. Walbro 255 pump, new fuel filter, man I dont know. Id really like to figure out whats going on

 

uumm... restriction in the fuel system.... at 370hp thats not that much for those 42#ers considering they are more like 48#ers at your fuel pressure

whats your AFR?

 

I'm running Racetronic 42s and their pump as well WITHOUT the included hot wire harness. I haven't had any issues spraying a 100rwhp+ dry shot on top of my heads/cam. However, i don't know what my injector DC is.

 

I think you're fine.

 

You are more than fine with the 42# injectors. My stock injectors handled more rwhp than your car is putting out with no problem. The 42# injectors are good to about 600hp.

 

I'm wondering if it would be too much for 375hp? I'm at 410rwhp, soon to be around 430rwhp. I'm worried SVO 42lb may be too much...? Ideas?

 

Actually, there is no such thing as "too much" unless you are having idling or low RPM issues. (Are you asking a different question: planning on going back to your stock injectors, and getting back what you paid for the Bosch, in which case yes the 42# are overkill for 375hp) You can always turn down your fuel pressure. You are fine.

 

I'm just curious as to how the 42lb would affect the idling. The TSP TQ2 doesn't cruise at low rpm all that great, but I'm worried that the 42lb would inject too much fuel at idle and unable to lean out.

I'm at 98 duty cycle now at 6800rpm.

 

No they are not too much injector. Your required pulse width at idle is over the 42's minimum pulsewidth so you are just fine.

 

You are at 370 hp on head.cam A4 with a giant stall, which eats up dyno HP numbers. On a M6 those mumbers would be well over 400 HP. You injector cycle seems to be on par.

 

Dunno the duty cycle on mine, but my car ran great for awhile with a H/C/I on 42's.

 

i wonder how long your factory wiring harness is going to last... i burnt the hell out of mine and almost lost the whole harness in the back.

your fuel pressure is around 60psi, more towards say 58psi. so is mine. I made 423HP and 431TQ SAE on 5lbs, no IC and I'm only running 64% duty cycle. I used Racetronixs' PnP kit, the whole thing. I am NOT using the boost-a-pump yet. I hold 58psi fuel pressure all day long

injectors can run up to 85+% duty cycle but is not recommended.
Those 42# injectors you have are plenty. GET YOUR AFR CHECKED, RE-TUNE and check.... ALSO check AFR on STREET versus AFR on DYNO

 

get the 42#ers, it will also give you breathing room for later mods.

DO NOT go out and buy 60# injectors...you will need a FAR BIGGER motor and idle airflow to control those suckers along with a FPR (fuel pressure regulator)

 

Well I don't really know what your trying to say. Everything was installed correctly, I did it myself. Looks like you had a run of bad luck.

Oh, I have been running this setup for over a yr and 10-11K, so, I don't think I have any problems...

 

The factory harness is ok, but the aftermarket hot wire kits just allow more consistent voltage to make it to the pump.

Im still on the factory harness with a 255 walbro, been ok for about 30k.

 

I just went from 30lb SVO's (at over 90% DC at WOT) to 42lb Lucas injectors and it actually runs better at low RPMs. I had to tweak the MAF tables a little in the lower flow cells. I haven't logged any data at WOT yet though.