Project EVO X GSR- Upgrading the Fuel System With Cobb Tuning and RC Engineering

by Mike Kojima

When we last left off on Project EVO X, we had come close to maxing out the car's fuel system with our bolt ons up to this point.  Since upgrading the turbo to Garrett's drop in GTX3071 is in the plans, we must first bring our fuel system up to snuff.  On the EVO X this is a little more involved than earlier EVO's as the injectors we chose were not an easy drop in.  Don't fear, it still was not that hard, check it out!

To read more about Project EVO X!

RC Engineering supplied us with some of their 1000cc injectors for our project.  The RC injectors came with wiring pigtails and spacers for the fuel rail to make installing them into the car a snap.  The RC injectors are a high quality but low cost big injector.
RC injectors use deflected disc technology instead of the standard pintle and seat.  Deflected disc injectors have good atomization.
Compared to stock, the RC injectors have a longer body, hence the need for the long fuel rail spacer.
Deflected disc injectors don't have the same kind of multi hole spray nozzle that the stock injectors have.  No fear, they still have good atomization.
The RC injectors are low impedance peak and hold type injectors and the stock EVO X injectors are high impedance saturated coil type injectors so you must add resistors to make it all work.  Don't fear this is pretty easy and inexpensive.  We used the resistor box from a Toyota Previa van that was lying around Technosquare but a lot of people use the resistor box from a 88-91 Honda Civic/CRX or a 92-96 Prelude.  This resistor box is easily available from many places that sell fuel system upgrades or you can get one from a wrecked Honda in a junkyard.


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Wednesday, January 02, 2013 9:39 AM
From what I read some time ago, wouldnt it be better to use a Fuel injector driver box like from AEM, or FJO. It will decrease the dead time for the injector. You can also reduce the injector fuel map correction by about 10% compared to using resistors because of the reduced dead time.

Or skip all that and use Injector Dynamics :P
Wednesday, January 02, 2013 2:17 PM
Yup, I'd be all for skipping the wiring and PnP'ing some ID1000's.
Wednesday, January 02, 2013 7:05 PM
Man the Evo X IC piping is strange. I always wonder why people routed the IC that way and then remember that it is the stock routing.

That being said, although the wires are heatshrunk in badass raychem, it looks like you used zip ties to hold it all together. I know in commercial building standards that don't see anything like the vibration or heat from an engine bay they are unacceptable. We use velcro to meet TIA or EIA but I'm not sure how well that would hold up to heat either.

Mike Kojima
Mike Kojimalink
Wednesday, January 02, 2013 10:05 PM
The car runs fine with the resistor box. We wanted to show a typical lower cost DIY route of doing things but we agree going with high impedance ID injectors would have been the best solution.

Protodad, I see zipties used in in F1 cars and WRC cars so I don't think I would sweat that.
Dusty Duster
Dusty Dusterlink
Thursday, January 03, 2013 2:52 AM
Wire lacing (instead of zip ties) is mandatory for use in aircraft (per FAA) and in building communication wiring (per EIA/TIA, Telcordia, IEEE, NFPA, etc). There, it is being used with larger-gauge SINGLE STRAND wires, often in large bundles, and in securing wires to non-moving objects. Furthermore, a lot of the wire lacing requirements are designed for use with fiber optic cabling, which is much, MUCH more fragile than single-strand, MULTI-STRAND copper wiring used in automobiles. I've seen OEMs use zip ties, as well.

Hey, you just learned what my engineering day job is.
Dusty Duster
Dusty Dusterlink
Thursday, January 03, 2013 2:53 AM
*I meant to say single multi-strand wire per sheath used in automobiles.
Thursday, January 03, 2013 6:01 AM
Fair enough, I figured you guys knew something I didn't. I wasn't trying to imply that it was the wrong way to do it, I was just wondering if there was a better long term solution.
Mike Kojima
Mike Kojimalink
Thursday, January 03, 2013 8:20 AM
We also use 3M high grade metal tab zipties and 3M automotive grade high temp electrical tape.
Thursday, January 03, 2013 1:00 PM
Hey Mike thanks for the article, quick question, how do you scale the injectors when doing this conversion? I won't be doing this myself any time soon but would still like to understand the science behind it.
Mike Kojima
Mike Kojimalink
Thursday, January 03, 2013 8:03 PM
Instead of me writing something long, I suggest you go to the ECU flash forum of EVOM and do a search. It's not that hard, just a little time consuming to do a good job.
Der Bruce
Der Brucelink
Thursday, January 03, 2013 9:48 PM
I really enjoyed this affordable DIY approach which I bet results in GOOD gains with that drop-in turbo!
Sunday, January 06, 2013 10:22 AM
I'm curious about the 3 port boost control solenoid... in what way does it offer improved performance over the stock 2 port?
Tuesday, February 26, 2013 11:17 AM
The stock dual 2 port solenoids have proven to work just as well as an aftermarket 3 port. No matter what you do, the stock turbo won't be able to hold more than about 19-21 psi at redline (sealevel) unless you upgrade the actuator, and even then it doesn't get much better. It's time for a turbo upgrade at that point.

On a side note, I'm really surprised you guys went with such an inferior injector. Those RC injectors are 20+ years old technology wise and is like replacing a sniper rifle with a 105mm Howitzer. Power and gas mileage WILL suffer with inferior atomisation properties that these injectors undoubtedly have. I understand it's a cheaper alternative, but this is a new $40k car, so an extra $100 for injector seems worth it, plus you don't have to screw with a resistor pack.
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