Wargasm

whoa.. hold the phone...

Is there a settting you can toggle with the Datalogit that helps this situtation? Please fill me in if you can. I already put in a call to Dave, but I got his machine...

Dave rules by the way.. just thought I'd throw that in there.

B

FourtyOunce

iTrader: (15)

yes, there is a way to manipulate settings on the PFC so the 1600's can be used without resistors. email dave, that would be the best way to get in touch with him.

FDSteve

>> there is a way to manipulate settings on the PFC so the 1600's can be used without resistors.

No there isn't! I know this is an old post... but I thought i should clear up this mis-information.

The facts:

The injector driver in the PFC is a uPA1556A. It is rated at 3.5W (from the datasheet)

At 14V the standard 14ohm injector draws 1A. A 2ohm injector will draw 7A.

The driver resistance is ~0.25ohm. The power per channel dissipated by the driver, is I^2R - ie 1x1x0.25 = 0.25W per channel for standard injectors - but a whopping 7x7x0.25 = 12.25W per channel for 2ohm injectors.

This would be 25W for 2 x standard plus 2 x 2ohm at 100% ie far exceeding the 3.5W rating.

FourtyOunce, i wonder how warm your PFC is getting?

The saving fact is probably that the 2ohm injectors are secondarys, and aren't always on.

My Question:

2ohm injectors are peak and hold - ie designed to be switched on with ~7A but then dropped back to 1 or 2 amps to hold.

Running a 2ohm injector with 10ohms resistor means it will only ever get 1A. I imagine it will switch very slowly. Perhaps a 3 or 4 ohm resistor is a good compromise?

Steve

FourtyOunce

iTrader: (15)

hmm .. interesting... ive been driving my car now for about 6 months with the 1600s[no resistors] and PFC is still good to go. i am not the only one. all the fd's coming out of KDR running 1600's with PFC are not using resistors. silver93t aka ihor is one of them .. his car has been running 415rwhp now for about 2 months ..

spoolin

ok guys, one more time....from the top.
i emailed "oh great one" a while back and this was his response:

Hey Roy..with the datalogit you go to injector screen..if using 550
primaries you load the following

Pri frt 100% +0.04
Sec frt -- +0.12
Pri Rr 100% +0.04
Sec Rr -- +0.12

Inj Size Primary 550cc
Inj Size Secondary 1600cc

Pri/sec transition 40%
Sec mmsc 1.112

And away ya go...works well as a base to start from...hope this
helps...dave@KDR


any questions?
ask him

RX794

Well has anyone contacted Dave@KDR about this or what?

FourtyOunce

iTrader: (15)

RX794 .. take some initiative and call yourself .. 610-614-1214

Wargasm

Leave poor Dave alone unless you're planning on taking your car to him for work.

I ended up going with 10 Ohm 20 Watt on each positive wire going to the injector and this has been working out just fine for me.

Brian

spoolin

uhhhh RX794, if you read the fine print, that was his email response to me about this whole situation.......

READ IT AGAIN!

MOSTIN

Can some one tell me or post some pics on how to mount aftermarket large injectors on the intake manifold of a FD with a fuel rail.

Dragon

get the fuel rail from K2rd or the one the RX-7 store sells..

jspecracer7

wow...some of you are running Low impedance 1680cc injectors without resistors?...I think a major rx7 company in Japan did this...and burn out their injector driver on the circuit. Good Luck...I know my "little" knowledge of electronics tells me to use resistors.

fd3st04

i will sell them a set of injectors and k2rd rail for cheap, if they show me how to run the resisotrs with my power fc . i know jspecracer7 know something about it lol

lane_change

iTrader: (20)

I need to know as well since I am also running the 1600cc injector/fuel rail combo form RX7 Store for my T78. Still in the procees as of now, but I know the resistors will play a role in all this. Any help would be great.