big-phil Posted December 14, 2007 Share Posted December 14, 2007 I've been searching but can't really find anything. I just got my 4 bar map sensor so I can run some big boost with my Meth injection (25+lbs) I now have 440cc supra low impedance injectors. my megasquirt will run a bigger resolution with high impedance injectors but I'm just not sure what to get. Although I would like to stay low impedance, I think?? my goal is about 30 psi at the max. I'm just not sure what size injector I can run, and have good idle? Any help? Thanks guys. Quote Link to comment Share on other sites More sharing options...
Guest 280ZForce Posted December 14, 2007 Share Posted December 14, 2007 i have 785s wired in now w/ a 14mm fuel rail from pallnet, i have yet to fire up the new setup yet as I've still go ♥♥♥♥ to do before I get to firing her up. but i do not see any reason why it won't work out. Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 14, 2007 Author Share Posted December 14, 2007 are they low impedance? Thats about the ball park I want to be in 700-750cc's or bigger. If you would just start that thing up you could help us both out:wink: Quote Link to comment Share on other sites More sharing options...
Guest 280ZForce Posted December 14, 2007 Share Posted December 14, 2007 hehe...yes low impedance. best deals on injectors i found was fiveomotorsport. http://www.fiveomotorsport.com/ I got the Rochester (75#) 785cc and the pig tails. And...I'm getting there.. just so much while I'm at it sh*t I'm doing lol. Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 14, 2007 Share Posted December 14, 2007 Phil you should ask Joel S. about idling problems. I think he was running 680's or 720's. You know, you shouldn't have to go nearly as large as you would without methanol...I'd spend the money on a computer to control your methanol spray instead. Better methanol control would let you push a lot farther with the same size injectors. Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 15, 2007 Author Share Posted December 15, 2007 Phil you should ask Joel S. about idling problems. I think he was running 680's or 720's. You know, you shouldn't have to go nearly as large as you would without methanol...I'd spend the money on a computer to control your methanol spray instead. Better methanol control would let you push a lot farther with the same size injectors. Thanks. I do need a good controller for the meth. If I'm going to buy injectors, I want to get the biggest I can run. I always seem to go overboard, so I don't want to get 650's if I could of run 750's with no major idle problems. Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 15, 2007 Author Share Posted December 15, 2007 hehe...yes low impedance. best deals on injectors i found was fiveomotorsport. http://www.fiveomotorsport.com/ I got the Rochester (75#) 785cc and the pig tails. And...I'm getting there.. just so much while I'm at it sh*t I'm doing lol. I was looking at that web site this morning! Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 15, 2007 Share Posted December 15, 2007 Thanks. I do need a good controller for the meth. If I'm going to buy injectors, I want to get the biggest I can run. I always seem to go overboard, so I don't want to get 650's if I could of run 750's with no major idle problems. Haha, I'm with you there. Overboard is my middle name. From what I've heard you'll have some idling problems with anything that large, but again, I'll leave that to people who have actually run them. Another option (which megasquirt supports with dual tables) is a second set of injectors. A friend of mine here is going to attempt that - he has Joel's old TWM setup and he's going to use the extra set of injector bungs AND the original set. I was looking at that web site this morning! If you're using the EV1 style connectors, don't buy your pigtails from them! I sell them for less than 30% of what they are charging (look on ebay). That's highway robbery! Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted December 15, 2007 Share Posted December 15, 2007 here is another place for injectors. i got the 77# ones for mine. i think i heard some one say that at idle the injectors squirt so much gas that it runs rough. i thought that mega can open an injector for a short period of time but it is more than the engine needs until you get going. i dunno. http://www.racetronix.com/ jimbo Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 15, 2007 Author Share Posted December 15, 2007 I did also think about sequential injection. I have a set of stock turbo injectors I could use. My 440's plus the 270's would give me 710's. I've been reading allot about it in the megasquirt manual?? Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 15, 2007 Author Share Posted December 15, 2007 does anyone have any experience with high impedance injectors and megasquirt? I understand with a program download I can run only high impedance, but I can get far better resolution so a big injector can be opened and closed about twice as fast?? Quote Link to comment Share on other sites More sharing options...
Bernardd Posted December 15, 2007 Share Posted December 15, 2007 Phil you haven't stated what your horsepower goal is. That's a good way you to zero in on the size of injector needed. Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 15, 2007 Author Share Posted December 15, 2007 1 million? as much as I can get Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted December 15, 2007 Share Posted December 15, 2007 Phil, I would contact the boys at MS to find out how low you can go with the pulsewidth for size of the injectors. I know that idle can become a real sore spot with large injectors and many people have to reduce fuel pressure at idle to slow down the fuel from giant injectors. I think staged injectors or a true sequential EFI would be the right answer. Remember what happened when your cam was too big for the motor...it took all the fun out. Size appropriately don't get hung up on tape measure wars. IMHO. I am running high-impedance injectors. It's easy on MS-II. My injectors are already near the low pulswidth limit at idle and they are only 42# Ford Lightnings. -Dave Quote Link to comment Share on other sites More sharing options...
zguy36 Posted December 15, 2007 Share Posted December 15, 2007 I am not sure if it was this site, or the megasquirt forum, but I saw some opening curves comparing a high impedance and low impedance injetors. There wasn't really much of an difference to speak of, so I wouldn't get too stuck on staying with the high impedance. Your megasquirt will run a dual stage fuel map, so you can have your smaller injectors for idle and run large injectors for everywhere else. (That is not called sequential injection as you stated) If you do this with the squirt, you will have to run high impedance injectors though, as the squirt cannot drive that many low impedance. I have also tossed around the idea of using a single throttle body injector for this two stage setup along with the biggest injectors that you can still idle well with. This would save a lot of plumbing by only adding one injector instead of six. Quote Link to comment Share on other sites More sharing options...
Clifton Posted December 15, 2007 Share Posted December 15, 2007 I'm running 700's with MSII. On a 7M but it's a 3.0 with similar airflow 77 as an L. If you are only going for 30 psi, you can do it with meth and 550's. You idle PW will be better. I've run 30 psi on 550's with a T72. The inj were maxed and afr in the low 12's. Without meth you won't make it to 30 psi with 550's. With 700's I'm around 1.5 at idle. I've run 40 psi with those. If you think you might go higher than 30 psi one day, I would get larger than a 550. Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted December 15, 2007 Share Posted December 15, 2007 This is another good place to get injectors: http://www.racetronix.com/ Quote Link to comment Share on other sites More sharing options...
TimZ Posted December 16, 2007 Share Posted December 16, 2007 does anyone have any experience with high impedance injectors and megasquirt? I understand with a program download I can run only high impedance, but I can get far better resolution so a big injector can be opened and closed about twice as fast?? I guess I'm not that familiar with MS, but in general the high impedance injectors have considerably lower dynamic range than low impedance ones (i.e. ,low Z injectors take less time to open and close, so they have a wider range of usable pulsewidth). Is there some idiosyncrasy with ms that doesn't work well with low Z? Looking at one of the MS help pages, it looks like one option would be to go to simultaneous injection if you start getting down close to the min on-time at idle. Even though this is not ideal, it will allow you to only have to open and close each injector once per 720 degree cycle, which should alleviate the min pulsewidth problem. FWIW, I was able to run 72lb low Z injectors with my TEC2 without much of an issue. One technique for leaning out the idle mixture when you are near the min on-time is to run less advance at idle - say 10 degrees or so. Less timing tends to slow the idle speed so to compensate you set the idle bypass to allow a bit more air, which leans the mix out. Another useful trick if you don't need the full capacity of your injectors is to run your fuel pressure a bit lower, say 30 or 35psi. This will make the injector act like a smaller injector - a 72lb injector at 35psi will only flow ~65lb, for instance. This will get your idle pulsewidth up a bit, and have the side benefits of getting a bit more flow capacity from the pump, stressing the pump less and heating the fuel less. I wouldn't go much lower than 30psi though - you might start having atomisation problems. Quote Link to comment Share on other sites More sharing options...
510six Posted December 16, 2007 Share Posted December 16, 2007 If you use your staged injection controll for the methanol injection a couple of VERY large low impedence injectors could be used in the place of the methanol "misters" and would allow better controll of the methanol injected.Since the (1600cc) secondary injectors only come on under boost idle quaility is not affected. http://www.fiveomotorsport.com/Injector_SetsMODS.asp http://www.cardomain.com/member_pages/show_image.pl?bg=FFFFFF&image=http://memimage.cardomain.net/member_images/7/web/2071000-2071999/2071134_26_full.jpg Quote Link to comment Share on other sites More sharing options...
datman Posted December 16, 2007 Share Posted December 16, 2007 I have Rochester 650cc low imp injectors from FiveO. 2 bar fuel pressure ...no idle problems. 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.