Hey guys, I just got my Accel system ordered and now it's time to get some injectors to go with it. I've noticed that they get really expensive when you get the big ones. So here's my question. Can I just get some big ones that I will more than likely use in the future and tune them down or should I buy two sets one now and one later when I upgrade.
I'm looking at running 8psi on a 396 for starters and I've got 30# injectors right now. I'm not so sure those will cut it. I'm planning on going up to 15psi and adding an intercooler eventually. I found a guy that is selling a set of 72# injectors for cheap. Can I just get those since I'll probably need them anyways for my 600rwhp goal in the end. Or should I get some 42 or 50's now and 72's later?
I would say that you could run the 72 pounders now if you take your time and tune them down to your current horsepower goals. this would be much safer then pushing the 30#er's. I am going to use the seimens 57lb high impedence injectors with my setup because i am planning on retaining the stock ECM for engine management. i say why spend the extra dough twice..
here is a thought... kinda off topic but hey ideas are nothing but that.. something to think about and maybe make work.
what if you ran an extra injector or two up front similar to the setup mentioned in the other posts, perhaps right in front of the TB.. and ran a hobbs or other pressure switch to close a circuit from one of the existing injectors as the pulse feed. this way until boost hit a certain psi, the injector did not fire but once the pressure hit mark X, the pulse from the ECM would feed the extra injector. you could tap the fuel pressure test port with a fuel feed line to a small fuel rail. i think with the extra single injector only being pulsed at higher boost levels, a better then stock system should be able to keep up! just throwin rocks at the wall. kick it around.
also MN, ever see if a large single will fit down there? I am back and forth between twins and single every hour... when the new tig welder gets here along with the bundle of pipe i ordred i guess i will have enough to experiment with manifolds for both setups.. then pick which one will be most effective and have the least negatives. keep me posted.. sure wish some of you guys lived closer by.. we would be in serious trouble i'm sure...lol
Get the 72# injectors (they should be good to 800 rwhp). Think about upgrading your serpentine drive system to an 8-rib or cog for the higher boost levels.
Good luck!
CT
72's will not work unless you use a converter with the stock ECM.... the seimens 57 LB injectors are the largest high impedence injectors available that work with the stock ecm with no modification besides tuning.
72's are low impedance, Stock injectors are high impedance, you would need to get a converter box to do this, but it is possible.
LC, I did take some measurements and I think a big single will fit. I didn't actually borrow one and put it on there, but it should. That's the plan anyways.
As for adding the extra injectors up front I think for me it would be more hassle than it's worth. I'm getting that Gen 7 kit and it should do everything I would need. If I wasn't swittching cams and didn't want the wideband O2 feedback I might think of using something like that though. But it still seems kinda like a bandaid fix to a problem though.
Did you say TIG welder?? Man you went all out didn't you. I just bought a little Lincoln Electric flux welder that I can upgrade to MIG. Are you doing everything in stainless? I also ordered my J=bends yesterday. Hopefully they should be here by the end of the week and I'll be starting to cut and weld next week. Things are starting to fall into place :yesnod:
If you are using the 72s with that new ACCEL system there is no need to worry. The ACCEL box has low impedance drivers installed already. So you are good to go. what is your goal for now? The reason I am asking is that with your current boost levels you don't need 72's. In my 8.1L suburban I am running 8 PSI of boost with 42's and have absolutely no fuel problems.
If you do go with 72's you may have some idle problems in tuning for idle stability at those RPMs. LJ, a friend of mine uses a convertor box with a GM PCM and doesn't experience any problems. But his engine is a 383 @ about 9 PSI with a Vortech YS trim blower running high 9's right now.
I am running 50's in my Vette now and haven't had or seen any noticable fuel problems. My AFR hits 11.2 to 11.5:1 @ WOT, but there again I am still running relative modest boost levels for the street @ around 8 at the intake. That may change later with the new T Trim. But the intent is to keep it around 8 @ the intake and 10 @ the blower discharge. I figure a 2 PSI drop across the intercooler.
I wasn't planning on running a box with my accel system, however, with a stock ecm you would need a box to run low impedance injectors.
Current goals are 8 psi, non-intercooled on my 396. If that works and the kinks are out of the system I'm bumping up to a bigger turbo and an intercooler and hopefully 15+psi. I would like to hit that 600rwhp mark without the nitrous. I think the 72's will be overkill for now but may be the ticket later on. I'm thinking I may have to lower the fuel pressure to help idle quality which kind of defeats thepurpose of bigger injectors, but for the price I couldn't beat them. I got sent the check for my set $300.
But with these injectors I could switch the nitrous to a dry system and let the accel control all of it. This might be a better match with the wideband feedback.
Yeah... tiggy wiggy tiggy wiggy...lol can't wait... figured if ya gotta weld dammit be able to really weld... my buddy has a wire feed mig flux core setup and it is alright for mild steel, welded up a stock exhaust setup to long tubes with reducers and the such for my wifes car so she could hear people on her cell phone around town. she still has the monster 3" SLP system ready to bolt up for dyno days and track events.
I plan on using 304 stainless steel for the headers.. the 321 will be later..much later down the road as it gets quite pricey when ya start figuring up whats needed. also i wanted to be able to weld up some aluminum tubing for the intake side and the intercooler. and whatever i see layin around.. im sure i'll be welding everything in sight for the first couple of weeks its here!
Corvette Store
Injector Sizing
