Guest lamar32 Posted December 10, 2003 Share Posted December 10, 2003 I found a pretty good deal on some rx-7 injectors the 440cc but do you think those are to big for my set up. 240sx tb 3" exhaust 2 1/2 down pipe I have the dawes device boost controler coming also a small spearco intercooler that flows to around 300 hp and I will be installing a bov. stock t3 turbo but might upgrade in the future. I was looking for some 370 cc but came across some rx-7 Thanks any help would be appreciated. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 10, 2003 Share Posted December 10, 2003 They are same as DSM, Honda I think. If that helps. Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 10, 2003 Share Posted December 10, 2003 Whether or not they "too big" depends soley upon your fuel management system. If you are using a stock ECU you need to use stock injectors. Using any larger size will not be compensated for by the ECU and the car will run poorly. I know there are hacks to get more air (unmetered) so that it won't be running too rich, but those will not work well across the entire fuel map. Aftermarket fuel management is the way to go! Check out Megasquirt: http://groups.yahoo.com/group/megasquirt Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted December 10, 2003 Share Posted December 10, 2003 I found a pretty good deal on some rx-7 injectors the 440cc but do you think those are to big for my set up.240sx tb 3" exhaust 2 1/2 down pipe I have the dawes device boost controler coming also a small spearco intercooler that flows to around 300 hp and I will be installing a bov. stock t3 turbo but might upgrade in the future. I was looking for some 370 cc but came across some rx-7 Thanks any help would be appreciated. Stock injectors work well with stock EFI, especially if you are limited to 300hp. Quote Link to comment Share on other sites More sharing options...
Jersey Posted December 10, 2003 Share Posted December 10, 2003 Aren't the RX7 injectors high impedance? For some reason i thought they were? Forrest, i'm going to have to disagree with you here - you do not NEED to use stock injectors with stock ECU. If you're a hack like myself, running the 370's with the stock ECU, you can tweek the AFM a bit to get her close enough to run smoothly. My Z surely takes full advantage of the extra fuel by the seat-o-da-pants dyno and actually runs very smooth thoughout the R's. Yes, my plugs are a little darker than that nice brown but, no stumbling and no pinging! The next most logical step for me to take is toward some type of fuel management as Forrest suggested, just to get her perfect but, i know it can be done with the 370's. 440's may require a bit more HACKING! LOL. Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 10, 2003 Share Posted December 10, 2003 I know several people who have done the AFM adjustment in order to use the 370's. (Most of them went to aftermarket EFI or took the 370's out, however.)Like I said, I know it works, but the amount of extra air and the amount of extra fuel you're getting is not porportional across the board. So its going to be rich at some places on the RPM/a-f curve. With 370's it's not too bad, but I would guess that with 460's if there is even enough air with the air bypass screw all the way out, the mixture would be much too rich in some ranges to run smoothly. But hey, why agonize over it? MS it for 140$ and a few hours of soldering. Jersey, if you're a hacker, MS was designed for you! Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 10, 2003 Share Posted December 10, 2003 BTW, I have a set of 460cc RX7 injectors, so let me answer your other question - they are low impedence. I'd heard the same thing, but Pallnet and I pulled several sets from the yards, and they are all low-impedence. Quote Link to comment Share on other sites More sharing options...
Jersey Posted December 10, 2003 Share Posted December 10, 2003 Actually, I figured out what i was thinking - the series 5 (i think mid '88 and up) RX7's and newer that use the 460 & 550cc injectors i believe are high impedence. With the 370's, it's not bad at all. They seem to have really woke my 240 up. Better a bit rich than a bit lean in my poor mans book I didn't have to adjust my bypass screw at all for proper idle either. I guess my Z must just have a mind of it's own. Not agonizing at all. Hopefully i'll get the time this winter to build the MS! Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 10, 2003 Share Posted December 10, 2003 Good deal man! It only takes a few hours to build - it's the research for application specific junk that takes a while. Mine is totally built and tested, I just have to make the underhood wiring harness. It's taken me way too long, if I wasn't such a slacker it could have been built and installed in a weekend. Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted December 12, 2003 Share Posted December 12, 2003 Humm I don't know...first arent those RX7 injectors O ring? We know the 370's will run on a stock EFI car, specially at wide open throttle. But I like consistancy, and I am very demanding on my car. Rich is not horsepower, not at all. I like stock injectors a FMU and a high pressure fuel pump. Get a stand alone a large injectors as soon as you can. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted December 12, 2003 Share Posted December 12, 2003 Somebody sell me a set of those "460's". My Nissan ecu doesn't care if the injectors are big. It always runs nice. Guess I wouldn't need my 370's anymore. 8) Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 I like stock injectors a FMU and a high pressure fuel pump. You're referring to the cartech RRFPR right? Why do people call them FMU's... confuses everything for me I'm glad you said that though that's exactly the setup I'm getting close to 'settling' on... the more I learn the more it seems this setup will work just fine on my stock setup running higher boost. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted December 12, 2003 Share Posted December 12, 2003 I like stock injectors a FMU and a high pressure fuel pump. You're referring to the cartech RRFPR right? Why do people call them FMU's... confuses everything for me I'm glad you said that though that's exactly the setup I'm getting close to 'settling' on... the more I learn the more it seems this setup will work just fine on my stock setup running higher boost. Honda's use "FMU"s, and that's what the setup is good for. There are better options available, but it seems as though Alex here is a one-recipe kind of guy. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 so he IS referring to the Cartech unit though right? Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted December 12, 2003 Share Posted December 12, 2003 I like the Vortech FMU's, the bring on fuel pressure on boost only, no idle adjustment. The FMU is a recipe I use on small injector cars trying to push the horsepower its what works so I recomend. Here's another I am sure you all have heard, try additional injectors SDS sells a nice controller I sell the units from Microtec, sorry I don't recomend crazy ass riggs that will make you chase your tail for hours, I leave that to others. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted December 12, 2003 Share Posted December 12, 2003 I know I sound like a broken record, and I'm not going to repeat my argument against using "FMU"s for Z cars. Suffice it to say for a speed density system not designed for boost, the RRFPR is a good fit. For a Z car with an AFM or a MAF, it is not. Lots of people just install the larger injectors, upgrade the pump and adjust the AFM, with excellent results. Installing the RRFPR will result in a "chasing of tails" and non-ideal fuel mixtures. I'm not trying to sell any products here - I want to keep people from wasting money on un-needed or inappropriate "mods". Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 the Cartech FMU is the same, it only adds pressure under boost. From what I understand, you can adjust both how much pressure you want it to add per each pound of boost, AND you can adjust at what point you want it to start coming on (say, no fuel increase over stock until boost hits 7psi or above). It runs in line with and after the stock regulator, so stock regulator still handles normal driving duties. Extra injectors are pricey... I'm a cheap bastard Cartech unit going for like $200 at MSA and less on ebay if they can be found. Quote Link to comment Share on other sites More sharing options...
Jersey Posted December 12, 2003 Share Posted December 12, 2003 This is why i made the decision on using larger injectors rather than increasing pressure to the stockers... weather my decision be right or wrong - You can only go so far with the stock turbo injectors. With the 370's, i have room to upgrade more components before spending more money in that department. You can get larger injectors for cheaper than $200 and not have them running at 100% duty cycle, spraying erratically, like you would eventually be doing with the stock injectors by squeezing increased amount of fuel pressure through them under boost. Just my opinion on the subject. I'm on the same page as Nathan. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 Sleeper - can you post a link to whatever topic(s) you have discussed this in before? You know I"m very open minded and always want to learn more... I'd like to hear the details as to why this type of FMU wouldn't be a good choice for my setup or how exactly it doesn't work 'right' for what I want it to do. To read the description of it on the Cartech page makes it SOUND like the perfect way to get some more fuel and some adjustability in there, but ONLY on boost, as opposed to a regular FPR which adjusts the whole range. I know I've heard/read from more than a few guys that have had good results with this type of unit. I'm steering away from larger injectors because it seems to me you could very easily get into the 'chasing the tail' thing with that setup... I"ve already been thru trying to tweak the AFM on other Z's that I had modified and NEVER got very good results... it was always a matter of adjusting the thing and "okay the mixture is better here but got worse there" this was tuning on a dyno. I can only imagine how it would play out with bigger injectors... I can't vouch for Jersey's good luck LOL but what I wouldn't give for a piece of it!! Everything seems to come together right on his car. To me it would be almost a requirement ot run some kind of programmable ECU or piggyback ECU if I were going to upgrade injectors.. and that is just so far out of my price range right now. Hell... the injectors themselves are out of my price range right now, unless I go for used JY units... which experience has shown me to be a gamble at best... I wouldn't be willing to install them w/o having them cleaned and flow balanced and that's another $100-200 at least right there... Bottom line is that it has been repeated many times that stock injectors are good up to about 250hp at the wheels, and this is the HP # I am shooting for, it's the goal # I have had set since way before I started this swap, so I really see no need to swap them. If the FMU is absolutely not needed in any way to help me reach that goal... awesome... $200 saved for other goodies. But I'd really like to know more about why it wouldn't help. So... should I just stick with the stock unit or should I get SOME kind of adjustable one? There's still the MSD one with boost/vacuum reference for like $50... just a 1:1 unit but adjustable. I dont trust my stock one anyways... thinking it's been on thsi motor who knows how long and probably isn't working as good as it should... so I'd feel better replacing it. If I remember right stock ones are pretty close to $50 too right? Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted December 12, 2003 Share Posted December 12, 2003 I know sleeper can't help but try to pick on me a bit. But I have tuned a couple of Turbo charged V8 Mustangs on a FMU, a couple of turbo crap Hondas and A few others. If you have a Z car with no bullshit ECM harness problem and runs great at 10psi a FMU should help when your going over 13psi. If your car runs like crap or super rich all around you got other problems and shouldn't be messing with fuel pressure. Oh and I do sell high performance parts for a living everyday from 8-12am non-stop. Take stabs if you like its what I do.... 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.