I got my hands on some lsj injectors for practically nothing and I already have an aeromotive afpr. Is it safe to run the lsj injectors on a stock ecu as long as I compensate with lower fuel pressure. The stock injectors are 24 lb/hr at the stock pressure of 55 psi. I would be running the lsj injectors (36 lb/hr) at around 35-40 psi. using a injector calculator I figured that brings flow down to about 27-28 lb/hr. The only problem I figure would be the possibility of pooling in the head due to incomplete vaporization. Someone please double check my math and let me know if it would possibly work? Before I get flamed, comp stage 2 cams and the 2.4 manifold swap is in the works, I am not just putting bigger injectors in for fun.
are the stock injectors rated at 24 lb/hr at 43.5 psi or at 24 lb/hr at 55 psi ?
anyway ... i get a fuel pressure between 19.5 and 24.5 depending how they're rated ... seems a bit too low to get good atomization to me.
calculator here
14.82 @ 97 mph
See thats what I was unsure about, I'm not sure what pressure our stock injectors are rated at. If it is 43.5 psi, that means the L61 injectors are actually flowing from the factory a decent amount above their rating at around 27 lb/hr. I used this
calculator because it uses lb/hr not cc/min. Your right though. I re-did the math at 30psi the lsj injectors would be flowing 29 lb/hr compared to the stock 27 lb/hr. Thats not too much of a difference, the ecu should be able to handle it in closed loop. In open loop it would be on the rich side but i'm ok with running slightly rich with my current mods. The question now is, is 30psi too little? I don't think I would want to go any lower than that.
Listenting...
Is there a problem with doing it the other way around? By that I mean increasing the fuel pressure on the stock injectors, effecively increasing the flow rate? i know higher pressure is more stress on the pump, but what are everyone's thoughts?
Right now my stock l61 injectors are running on 65psi. When I dynoed my car afr was still running slightly lean at around 14 afr. This was with bolt ons, i/h/e. I have an 05 ecotec so that could be one reason. Turning up the pressure higher than 65psi might start locking injectors shut which I don't want to risk.
darestie wrote:Right now my stock l61 injectors are running on 65psi. When I dynoed my car afr was still running slightly lean at around 14 afr. This was with bolt ons, i/h/e. I have an 05 ecotec so that could be one reason. Turning up the pressure higher than 65psi might start locking injectors shut which I don't want to risk.
Doesn't the hahn turbo kit push near 100 psi at WOT, as it is tuned with an adjustable FMU? I know its not the ideal situation, but if it works for the hahn kit, i would guess it could work n/a. You're AFR won't change under closed loop - you'll need HPT to set the PE engagement conditions and then tune youre AFR's.
I don't feel like digging out my physics book - does double the fuel pressure on the same injector effectively double the flow rate? For example, injectors rated at 24lb/hr @ 50 psi would be 48lbs/hr at 100 psi? Just a general question...
oldskool wrote:darestie wrote:Right now my stock l61 injectors are running on 65psi. When I dynoed my car afr was still running slightly lean at around 14 afr. This was with bolt ons, i/h/e. I have an 05 ecotec so that could be one reason. Turning up the pressure higher than 65psi might start locking injectors shut which I don't want to risk.
Doesn't the hahn turbo kit push near 100 psi at WOT, as it is tuned with an adjustable FMU? I know its not the ideal situation, but if it works for the hahn kit, i would guess it could work n/a. You're AFR won't change under closed loop - you'll need HPT to set the PE engagement conditions and then tune youre AFR's.
I don't feel like digging out my physics book - does double the fuel pressure on the same injector effectively double the flow rate? For example, injectors rated at 24lb/hr @ 50 psi would be 48lbs/hr at 100 psi? Just a general question...
Yes but thats only while making boost, the majority of the time, the car is only running on low pressures. To be running 70+ psi on a stock pump all of the time will burn out injectors and fuel pumps fast.
I can see how it will shorten the life of the stock pump, but how does this destroy injectors? All the injector knows is a pulsewidth right? I guess the pressure could get so high such that they cannot close, but I haven't specifically heard of it. As far as the pump, it can be upgraded. So you could sqeak a little more out of the stock injectors and it would probably run, but you would still be stuck with the stock PE engagement.
All that to say, its easier safer and more efficient to upgrade the injectors and tune...
