Hi all,

Just thought I'd share with you my recent experience with installing DSM 450CC injectors in my RS...

OK, I'll cut right to the details...
Injectors - 450CC DSM injectors from a 1G turbo.
O-Rings - Standard 2GNT injector O-Rings (Top and bottom).
Fuel Pressure - Way low... :thumbsup
Resistor pack - custom resistor pack, using 2 x 20 Ohhm 50W resistors in paralell for each injector.
Engine - RS 420A, with a custom turbo kit, running at 10 PSI.

Hows the car running? Absolutelly great... its so much happier han with the stock injectors...
If anyone else wants to hear any more details let me know... I'll post some mor elater....

Lee.

Thanx for the info! That really helps and eases my tensions about that a little, because I'm going with a simular set up. Except I got a first gen resistor pack that I'm going to use instead of resistors like you used.:thumbsup

Yea I'm probly going the same route, but I am a bit standoffish about using the cartech unit with those injectors.
How much did all your parts cost in total?

can you do a "how too" because i want to go this route too. with a step by step with pics ,that'll be cool if you can and you would help alot of people that can't afford bigger injectors

nice work on getting the resistors to work. for some reason i still feel that a transformer would work better to match impedance...maybe i'll design one. resistors match the impedance by adding resistance to the fuel injection circut so that too much current isn't drawn, but resistors can get quite hot and i'm willing to bet that there's a better way. the characteristics of a resistor changes with frequency, any 50 ohms (or any value for that matter) resistor from can look like a capacitor, an inductor, or a perfect resistor depending on the frequency applied. transformers on the other hand usually have a more predictable self resonant frequency (the frequency when reactance goes to 0 and it's neither a capacitor or an inductor) and are more consistant with impedance matching.

anyways, if anyone knows the exact impedance (DC resistance, which is good enough) of stock 2GNT injectors and stock 4G63 injectors, please reply here and whatnot. it would be pretty easy to design a transformer that would do a better job than resistors - in theory.

Spec on saturated injectors as a whole is 12-16ohms. Peak and hold injectors are 2-3 ohms.

thanks dino. sounds like one would need a 5:1 or 6:1 transformer (impedance ratio) with a capability of handling a decent amount of power. it's easy for me to get a high quality transformer which is designed for R&D with high frequency stuff, however they are surface mount components that can't handle crap for power... maybe some type of audio transformer (definately can handle the power) has a 5:1 or a 6:1 impedance ratio...

Hwo the hell did you get the injector origns to fit, we couldn't get it to work!

Change out the o-rings

>Hwo the hell did you get the injector origns to fit, we
>couldn't get it to work!

What can I say... I tried using the 2GNT O-Rings with the 450CC onjectors... and it worked.
One was a bitch to get in though... you have to be REAL carefull.
I was afraid they would leak, but so far so good...

Can you post some up close picks of the resistors and how they are mounted?

maybe but i missed it.... but whats your fuel setup, other than injectors? what turbo? at what psi? stock internals? :+

My Setup:

Custom Turbo setup, Ported Mitsu Big 16G, Custom exhaust manifold, custom downpipe, custom intercooler piping, 1G sidemount, 2G BOV modified to for more boost, SAFC, custom MAP voltage limiter, Autometer gauges...
Running at 8psi as of today, on stock internals.

And of course the 450CC injectors.

The resistor pack is pretty ugly right now, being just a prototype, its pretty much just sitting between by BOV and battery. I'll take some pics later today if I get a chance.

I have some other electronics that I'm working on for the engine.. I'll keep you all posted.

Oh yeah, I'm using a piece of crap Cartech FPR right now... and yes I have it running super low fuel pressures, and have it modified to run at about a 2:1 or 3:1 ratio....:thumbsup

I plan on replacing the cartech as soon as possible, just havent decided with what yet...

Can you post up some pics and explain how to install them. I am putting in the 450's this week and need a diagram or something.

top, inquirying minds want to know

James

This install is straightforward. I don't know what kind of a diagram you want for the injector install, but it is easy as shit. 2GNT O-rings on 450CC injectors, injectors in the manifold, rail on injectors. done. The resistor pack isn't all that tough, either. There are 5 wires on a DSM pack. Four of them are one colour. One of these goes to each of the injectors, and the other coloured wire is the ground. All injectors have a common ground, meaning that all four injectors ground through one wire in the end.
-=B-=

P.S. Oh yeah, solder everything!

so, basically, i can put the resistor pack on just the ground and it will give the correct ohms throughout all of them? do you know the color of the ground wire or is it just black?

which resistors would you recommend? i found these on radioshack.com, they are the largest they have.

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F002%5F014%5F004&product%5Fid=271%2D132

do you just wire all the resistors together and splice them into the ground wire?

thanx

james

i guess i just need to know if i should put 1 resistor on each of the 4 power wires, or 4 resistors on the negative side?

James

I would only add resistance to the circuit after the injector. An OEM (Honda or DSM) resistor pack would be easiest, as you could go with one wire per imjector, and use the common ground like your normally would.
-=B-=

>I would only add resistance to the circuit after the
>injector. An OEM (Honda or DSM) resistor pack would be
>easiest, as you could go with one wire per imjector, and use
>the common ground like your normally would.
>-=B-=

so, would you put the resistor on the positive or negative side of each injector?

Since you are saying put the resistor on after the injector, does that mean the negative side?

I went out and bought those radio shack resistors mentioned above and ran the ohms with the injectors and resistors inline, and they came out to 13ohms, but would you suggest running an oem resistor pack or will this method work the same?

if you have some time, i would love to give you a call and talk to you about this on the phone. if you want to give me your phone number, ill call, just send me an email to james@antsmarching.org or hit me up on aim at dmbonirc if you would be so kind. :)

thanx
James

here are some better questions

are the injectors being switched on the positive side or ground side?

are all these injectors being pulsed at once or are the seperate?

thanx
James

I recall this discussion once before and with a DC circuit you do not have reactances like inductance or capacitance.

Terry

bump

Ive been doing more research and found that the injectors are negatively switched and the injectors are getting a constant 12v. A few people I have talked to who are good with electronics and what not, say that the resistors should go in place on the negative side, but when i search around the web, other people are saying the positive side.

As soon as I know which side I should splice the resistor in, I can try out the mod.

James

You've got mail. They are negatively switched (the ECU fires an injector by turning the ground on or off). Because of this, I would keep the resistor on the negative side of the injector.
-=B-=

in theory, it doesn't matter which side the resistors go on, as long as it's still wired in series. all the ECU wants to see is the correct total impedance, which should be around 13 ohms or so.

3 ohm DSM injector + 10 ohm resistor pack = 13 ohms total
10 ohm resistor pack + 3 ohm DSM injector = 13 ohms total

Your calculatios are correct with the ohms. however the ECu does nto see the impedance as ohms it "see" the amount of currect that is drawn from it. So leads you own the path what currect can the ECU put out so you can optimize the highest available current toget your injectors to operate faster and more accuratly. here we use ohms law:

I=V/R so

I=12V/13ohms...so your current on stock injectors is .92 amps. no lets look at a turbo config 2-3 ohm injectors with a 7 ohm resistor pack. I=12v/10ohms....1.2 amps. now we know our ECU wil work on 1.2 amps as many have done already on various boards. Now the question of where do you place the resistor...on the ECU neg side or the Pos side ofthe injector. You have to think of dc current as direct currect in that it flows in a direction of Neg to pos. Currect stays the same over a circuit and is calculated by the voltage devided by total resistance. Voltage is another factor. voltage does not remain constant like currect. voltage begins to drop off after the first resistor. So if you place the resistor on the pos side the injector sees (turbo injector and turbo resistor) 12v 1.2 amps from the ECU. if you place the resistor on the Neg ECU side the injector only sees (V=I*R so V=7ohms * 1.2) 8.2v falloff so the injector only sees 3.8 volts. now if you made a resistor and used 3 ohm turbo injectors and a 10ohm resistor your current is .82 and you voltage drop accross a resistor installed on the ECU side of the injector would cause the injector to see 8.2 falloff and result in the injector seeing 3.8 volts. So now it should be obvious as to why you cannot put the resistor on the Neg side or the ECU side as it is correctly called. So all prevouse statements about it should not matter are incorrect.

I would go into why a transformet cant be used but this post is long enough.

Terry<~~~~never stops studying elec engineering working for the power company

Turbo resistor pack is 7 ohms not 10

The resistor has to go on the positive side due to voltage drop over resistance...use ohms law. I made my harness and setup about three months ago just too lazy to install.

Terry