Guest livewire23 Posted February 7, 2003 Share Posted February 7, 2003 Originally posted by BLKMGK: Big injectors idle and drive just like smaller injectors if you've got control of them. Injectors are NOT carb jets! I run 6 72lb injectors on a 3liter 2JZGTE motor and it idles 14.7:1 or leaner as I desire - no problem. I know guys running 1000cc injectors on the same type of motor daily driven idling just like mine. At some point you get so big the injector cannot be idled but that point is apparently fairly big. Is this true? I think its almost time for my L28 to get new injectors, but I don't want to buy new injectors now, and then get even bigger ones when I go turbo and bump up the boost. You know, the classic "while I'm at it" syndrome. So how big of an injector could I get now, and maintiain a nice not-to-rich idle and daily drivability? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 7, 2003 Share Posted February 7, 2003 There IS a point that injectors can get too large for a clean idle. Right now I'm running 550cc low impedance injectors in a batch fire mode. This is just about the limit on my 2.8 liter motor without going sequential or alternating mode. My idle pulse width is about 1ms flat and if I went any bigger I'd have to reduce my pulse width further. Depending on the type of injector, and the ECU drive circuit, below 1ms injector times may be too short and difficult to maintain stability at idle. Changing to sequential or alternating batch could allow me to ,as much as, double my pulse width for the same RPM/load settings. This would allow me to use larger injectors. The question you have to ask yourself is: "How much horsepower am I looking for". Getting injectors that support what HP you want, is all you need. Any bigger is just a waist and causes more problems. 550cc injectors can support over 400HP in a turbo 6 cylinder application and still maintains an 85% max duty cycle. Go to : http://www.rceng.com/technical.htm#WORKSHEET All of this supposes that you are using a programmable fuel management system. If you're going stock ECU, you'll run pig rich and hate it. Once you change injector size you're committed to programmable fuel control. Fudging the AFM or using a variable fuel pressure regulator is just a bandage fix that will never run the way you want it to. Gas milage will suck and tuning will be a nitemare. Just my thoughts... Good luck with your project. Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 7, 2003 Share Posted February 7, 2003 You must use programmable FI if you go to larger injectors. That being said, if the progammable ECU you are using does not have a fine enough fueling resolution, you will never get a smooth idle. Some systems have more resolution than others. I'm running 380cc/min injectors with my setup, and the idle is smooth. I know of others running the same ECU I am on a 4 cylinder with 500cc/min injectors, and it idles like **** . When picking injectors, I would first calculate the injector flow rate for a "realistic" HP goal, and then add 20%. This will give you head room in case you want to go to the next step. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.