low impedance injectors, use resistors?
#1
Elite Member
Thread Starter
iTrader: (11)
Join Date: Apr 2008
Location: Texas, 'Murica
Posts: 2,497
Total Cats: 0
low impedance injectors, use resistors?
i have a 95 with the ms pnp and i was planning on running 440cc injectors from a turbo supra, from what i gather they are low impedance. So would it be better to use the resistors or the pwm feature? i searched but i didn`t really get my question answered, thanks!
#3
Hey this is something I may need to do soon as well. I have wondered for some time what sort of resisters will I need? Figuring out the correct resister value to reach an ohm load I can handle, but often I see people selling injectors with resisters and they have four little aluminium finned blocks. I realise those little blocks are the resisters but are they really necessary? Couldn't one just wire in normal resisters as available from radio shack and the like? How hot do they really get? What wattage will we need?
I have been around long enough to know that anything that is anodized blue aluminium Just HAS to make it go faster, and will therefore find its own buyers. But are they just snake oil or is there a real need for that level of cooling?
I have been around long enough to know that anything that is anodized blue aluminium Just HAS to make it go faster, and will therefore find its own buyers. But are they just snake oil or is there a real need for that level of cooling?
#8
Elite Member
iTrader: (10)
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,979
Total Cats: 356
Most injectors flow about 1A of current through them during use. Lets assume 2A to be safe. P=V*I=14*2=24W. Remember, you are not constantly running them at 100% duty cycle, so they will be cool at idle with no load. Not so for 4k rpm boosted. Ever touched an injector that is shorted to ground accidentaly? Its hot like ****. You can easily burn yourself. So yes, you do need the resistors with the heatsinks on them.
Jim
Jim
#9
Elite Member
iTrader: (14)
Join Date: Sep 2009
Location: Birmingham, AL
Posts: 2,101
Total Cats: 180
I'm at this point too... I've got the 430cc from my 7mgte (2.9ohms?) and am trying to decide on adding resistors or using the PWM feature. Some searching said that if you use the PWM feature, you might also want to add a direct ground line (to the MS ground location) from the grounded side of R37/R38 to prevent noise... is this right? Also, can't defintetly find what our peak hold amps are for our application, so saying 2 amps is a 'safe' figure, we'd need about a 4.1ohm ~25watt resistor per each injector, or 11.1ohm for a 1amp current (according to DIYauto calculator a little more than 1/2way down the page) calculator
So far you guys are saying go the resistor route... so why NOT use the PWM feature on the MSPNP? What is being overlooked/wrong?
So far you guys are saying go the resistor route... so why NOT use the PWM feature on the MSPNP? What is being overlooked/wrong?
Last edited by GeneSplicer; 01-30-2010 at 11:33 AM.
#16
Boost Czar
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,501
Total Cats: 4,080
or
Needed when using low impedance injectors (such as DSM injectors). Gold anodized finish with solder lugs. 10ohm / 50 watt, no heat sink needed (built-in). Install 1 resistor inline with each injector on the positive side.
TA048 Set of 4 resistors- $19.99
JGS Precision Turbo
or
Honda resistor box.
Honda resistor box.
#20
Supporting Vendor
iTrader: (33)
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,659
Total Cats: 134
3 ohms is the minimum required to where you shouldn't damage the injector drivers in the MS. It all depends on how much current you feel comfortable running through the injectors, but prudence dictates running a bit more resistance.
It doesn't matter where the resistor falls in circuit.
It doesn't matter where the resistor falls in circuit.