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Discussion Starter #1
ok some books and info. that i have read say that the stock fuel system could support 7-8 psi. of boost i can't seem to get a straight answer on whether or not it will. i have a 92' hatch with the z6 and am getting ready to boost it. my current car is an 88 mx6 gt turbo running 16 psi on an ihi rhb5 with stock injectors (310's) and a walbro 190 fuel pump, i have absolutely no problems at all, i know the cars are different but it seems that since i only want to run 7-8 psi. the stockers would be ok. everyone seems to be going to the 450's but that seems like overkill to me. i have a buddy that is running 527cc injectors on his 2.0 neon making 400 hp. i only want to be in the 175-200 hp range, so why do i need such large injectors? i just don't want to lean the car out under boost and fry something, but i also don't want to put the 450's in there and lose the idle and drivability of the car. thanks
 

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stock injectors max out at about 170 WHP (the 240cc ones). I ran those at 9psi for one year (25K miles) at 97% duty cycle with no problems.

if you add walbro fuel pump, you could get some 5 or 10 WHP more, but that's about it.
 

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Discussion Starter #3
i have some 255cc injectors that i could throw in there, and i already have a walbro 190lph fuel pump. the turbo i will be running is a ihi rhb5 vj11 (small turbo) off a mx6 gt turbo and stock actuated boost of 8 psi. so you think with the 255's and and the walbro i would be fine? when you say duty cycle what does that refer to? is that something that you can set, or is that just what a particular injector is set at. sorry for so many questions! thanks
 

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The duty cycle refers to how long the injector is open 90% basically means 90% of the time. The only way to increase flow when the injector is close to maxed out is to increase the fuel pressure a bit.

You cannot directly set the duty cycle, normally you just set the how long the injector is open. My old Zdyne I think used milliseconds but I am not sure what other tuning tools use for this time.
 

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Discussion Starter #5
wouldn't putting in a high flow fuel pump raise the fuel pressure? or do i actually have to use a tuning tool to set this?
 

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What are you useing for fuel management??
You can't run bigger injecters in a Honda unless you have a way to control them, liked a chipped ECU.
With that small turbo and only 8PSI you could run a boost dependent fuel pressure regulator and be just fine with the stock injecters.
 

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wouldn't putting in a high flow fuel pump raise the fuel pressure? or do i actually have to use a tuning tool to set this?
high flow fuel pump will raise pressure, but how much really depends on which model you get. Walbro makes both high pressure and low pressure aftermarket fuelpumps.

For your setup, only wanting to make around 170-200.........a Walbro 190lph LOW pressure unit will suffice just fine.....hell, a gsr pump would prolly be enough (pretty sure they flow more)

If you go with a high pressure unit, you may find that you need to updrade to an aftermarket adjustable fpr (fuel pressure regulator.).

The main thing we need to know is the type of management you plan on running in order to tune your setup. I would HIGHLY reccomend looking into a chipped ecu (p28 ), and finding a tuner for crome, or even uberdata. They are both free, and depending on the tuner, will make you car run outstanding.

IF, you do decide to go the chipped ecu route and tune with crome, then just buy some dsm 390cc injectors. They will fit your setup perfectly, and wont be anywhere near maxing out their duty cycle. They will give you a better piece of mind, and also the ablility to run more boost if you ever decide the need is necessary.

good luck:TU:
 

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you could probably find some dirt cheap i got my 450's for like 50 shipped
yep........thats about right for the 450's

the 390's obviously are alot less. You could prolly pick some up from between 30-40 bucks :TU:
 

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DSM cars, 390cc injectors of from the cars with automatic transmissions, the 450cc injectors are from the manual transmission cars.

DSM= Diamond Star Motors, AKA the Plymoth Laser, Eagle Talon, and Mitsubishi Eclipse.
 

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ditch the stock injectors and go as described above. dsm 450's, resistor box and some good management like crome or uber.

thats what i've been running for 2 years DD. cheap and effective :bigthumbup:

-Luke
 

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Discussion Starter #14
ok you guys keep talking about resistor boxes? what is this and what does it do. i have modded many cars (but am new to hondas) and i have never had to deal with these resistor boxes. where can i get one. i have called some shops around here and people want mad money to put engine management on, one shop said 500 for hondata and 400 to tune it!!??? 1000 seems like quite a bit for that is there not an easier (less expensive, safe) way or do absolutely have to have some type of engine management. i am also a little confused about the chipped p28 ecu what can this help me with? i have had two turbo mazdas and did not run engine management on either with no probs. i already have all the parts to turbo except for the mani. and now the only thing holding me up is this fuel/engine management/ecu/injectors stuff. so any info is greatly appreciated! sorry for all the noob questions.
 

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The DSM injectors are low impedance injectors, and in order for them to work with OBD1 ECUs, you need a resistor box to increase the impedance (resistance) of the circuit, or the ECU will throw a hizzy and not work. So, you need to take a resistor box from another car (it doesn't even have to be from a Honda) and wire it inline with the injectors. There are many write-ups on what is necessary to run the injectors. Another option is to just purchase large injectors of the high-impedance type. These you simply plop in and go. http://injectorclinic.com (if I remember the URL correctly) has good prices on new injectors.
 

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its always better to have more fuel than to little so making sure you have the fuel side covered should be top priority. 7-8psi with a stock set up should be fine. alot of companies sell kits that you bolt up to a car with a stock fuel setup so I'm sure you will be cool. from what i hear a chipped ecu and a tuning program like "crome" would be good but I dont see why a safc wouldnt work.

whatever you decide, make sure you do more research and not just on the forums. most forums are full of suggestions from people that just followed behind what everyone else did instead of learning why they should or shouldnt do something. hence the reason why you havent gotten a clear answer to your question. It all in good fun though, good luck.
 

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WOW, someone with a WBO2 that can actually see the a/f on stock injectors chim in!!!!!!!

There was a thread on hmt a while back, where someone bumped up the fuel pressure to as far as it would go on a b&m I think and was able to get 4-5psi. don't remember exactly. but then you would have all the extra pressure not in boost...... if someone actually had a wideband to test the theory.
 

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The DSM injectors are low impedance injectors, and in order for them to work with OBD1 ECUs, you need a resistor box to increase the impedance (resistance) of the circuit, or the ECU will throw a hizzy and not work. So, you need to take a resistor box from another car (it doesn't even have to be from a Honda) and wire it inline with the injectors. There are many write-ups on what is necessary to run the injectors. Another option is to just purchase large injectors of the high-impedance type. These you simply plop in and go. http://injectorclinic.com (if I remember the URL correctly) has good prices on new injectors.
i think the url is www.fuelinjectorclinic.com

they have great prices. I went with dsm injectors though because a set of 500cc's brand new was $200 shipped.....not bad so i went with it and saved about $80.
 
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