nategdizzle Posted September 5, 2006 Share Posted September 5, 2006 i have stock zxt injectors with a t3/t4 and ported/poished head and intake exhaust manifold with lt8 standalone efi.. how much of a load can i put on my injectors..how much fuel pressure should i run..i built a fuel rail, kinda like pallnet and rsk makes, my fuel pump is good for like 125psi and it seems like i read that the zxt injetors make their best spray pattern at 80psi..is it a good idea to run that much psi? any suggestions? Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted September 5, 2006 Share Posted September 5, 2006 I doubt very seriously that Nissan would have put injectors whose best spray pattern at a psi the ECU wouldn't allow them to achieve. I have heard the opposite as far as spray patterns and higher fuel pressure go - I heard they get worse and inconsistent. Size your injectors according to the many calculators out there, and leave it at that. The stock injectors are good to ~ 260 HP at stock FP levels. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted September 5, 2006 Share Posted September 5, 2006 What Brad Man said. Dave Quote Link to comment Share on other sites More sharing options...
nismopick Posted September 5, 2006 Share Posted September 5, 2006 Just get a rising rate FPR, or slightly larger injectors. Ford 370cc injectors work the magic. Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 5, 2006 Share Posted September 5, 2006 Stock idle fuel pressure is 38psi or so, and full boost pressure can be well over 60psi depending on how much boost you are running. Run the stock pressure at idle, and either get a rising rate FPR, or add more injectors and an addition injector controller. Just increasing pressure will make it run rich except for full boost if you can adjust the pressure. See this thread for more information about changing injectors and or pressure. http://forums.hybridz.org/showthread.php?t=114278 Quote Link to comment Share on other sites More sharing options...
nategdizzle Posted September 7, 2006 Author Share Posted September 7, 2006 thanks guys Quote Link to comment Share on other sites More sharing options...
spork Posted September 7, 2006 Share Posted September 7, 2006 With the standalone you can do just about anything you want. If you don't upgrade the injectors, you can up the pressure, but just use a regular adjustable fuel pressure regulator. There is no need for a rising rate regulator. They just make your standalone that much harder to tune. You didn't name what pump you had, so 125psi doesn't really mean anythin if it can't flow much fuel at that pressure. You'll be fine to up your base pressure some tho. You're going to run out of injector very quickly with that setup if you want to run any kind of boost at all. 45-50psi base pressure would be fine. That only puts you at 65-70psi if running 20psi of boost. If you need more fuel, up the pressure a little more. I'm running a base pressure of 60psi on my 52pph injectors and then 25psi of boost. (plus some methanol since the injectors are maxxed out). All of that said, eventually you're going to want to upgrade injectors. 550cc or so would do you great with that setup and they will still give you a nice idle. Quote Link to comment Share on other sites More sharing options...
nategdizzle Posted September 8, 2006 Author Share Posted September 8, 2006 how much boost do you guys think i will be able to run be i max out my injectors..i wont be able to buy any injectors for awhile since my truck just got ran over by a tractor and inusrance wont cover it so i want to push these as far as i can..can i just turn the duty cycle up until the injectors are open all the time pretty much or is that a no no, my fuel pump is the high output msd that is supposed to flow like 500hp...also i was wondering if anyone might be able to tell me about how much rwhp i may be able to achieve with this setup..ive got arp bolts throughout the engine and its freshly rebuilt with stock dished pistons 24x12 fmic 3in dp mandrel bent 3in exhaust 60mmtb and head work with undercut tuliped valves but its still a stock n42 cam and port matched manifolds...also i dont know how much of a limiting factor my to4ob compressor will be with compressor wheel i have..they came from a tractor haha..hope im not asking too much from you guys haha Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 8, 2006 Share Posted September 8, 2006 The stock injectors are good for around 250WHP at 100% duty cycle using the stock FPR. So for reliability reasons, you want to stay below 90% or so for a street engine, and probably less than 80% for a race engine. So I would start with 10psi and monitor you duty cycle. I'd say you can probably make around 225WHP while keeping the duty cycle below 90%. I'd pick up a set of used 380cc/min or larger injectors and be done with it. Then you can tune once on the dyno. Quote Link to comment Share on other sites More sharing options...
nismopick Posted September 8, 2006 Share Posted September 8, 2006 To go along w/ what Z-ya just said, I'm gunna share a lil secret w/ ya nategdizzle... You can get Ford 370cc injectors for oh... say... $60-$80 for a set of 8 (usually sold in sets of 4) from ebay. Why, there's some on ebay right now! http://cgi.ebay.com/ebaymotors/2-3-Ford-Turbo-35lb-Brown-Top-Injectors-Mustang-SVO-TC_W0QQcmdZViewItemQQcategoryZ33554QQhashZitem130023215861QQihZ003QQitemZ130023215861QQrdZ1QQsspagenameZWDVW And look.... slightly larger than those! http://cgi.ebay.com/ebaymotors/36lb-Turbo-Ford-brown-top-injectors-Turbo-Coupe-SVO_W0QQcmdZViewItemQQcategoryZ33554QQhashZitem330025899876QQihZ014QQitemZ330025899876QQrdZ1QQsspagenameZWDVW Quote Link to comment Share on other sites More sharing options...
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