Engine Prep

Engine preparation

If you are new to the sport, you don't need to go crazy and a stock engine will most likely be the more reliable option. Eventually get a mild tune but more importantly stay on top of the maintenance schedule and replace fluids and all wear parts in time. If you have a turbo car, you will most likely require a restrictor:

• • Turbo restrictor 30mm for novices, 32mm prod class in Canada, 33/34mm limited/open class ARA, 36mm limited ARA with boost limit (~$200 at Aze Performance in Canada but also check Paul Eklund at Primitive Racing): if you use the stock ECU there are 2 things to be aware of: there is a risk of overspinning the turbo to try to make boost over 5500rpms, leading to a shortened life span for the turbo. Issue 2, running rich will dilute the oil, leading to main bearing issues, which is already a weak point in the motor, so you need to change your oil more often.

  • The restrictor just sits in front of the turbo inlet and will be checked at tech with an inspection camera and a gauge for proper size and fitment.

• • Turbo inlet hose: The stock turbo inlet hose is made of hard plastic that doesn't age well with the heat and the turbo restrictor will also enlarge the end of the hose which will make it fail prematurely. We recommend using an aftermarket silicon hose like the Cobb Tuning inlet v2. With the restrictor in place there will be very little room to clear the TGV housing and the inlet hose will inevitably fail over time with the rubbing with the TGV. Use some Flex seal tape to protect the hose where it contact the TGV.

  • Engine tune: If you are installing a restrictor you can still run on the stock ECU that will adapt but this is not ideal. Consider a tune using a Cobb Accessport but the software only supports emission compliant cars. We also recommend installing an AEM wideband sensor and gauge (https://www.amazon.com/gp/product/B00N3VGPYS) to log data more accurately (see install video below).  We use this bezel (https://www.amazon.com/gp/product/B000CMJ74Q) to hold the gauge in the cluster.

• • Fuel lines: Stock fuel lines are acceptable, just make sure they are routed inside the cage and not between the cage and the chassis. You can also consider switching to braided stainless steel lines, in this case you will need:

    • PTFE hoses with AN-6 fittings (https://www.amazon.com/gp/product/B077BBMW8R): do not use rubber lined ones they get eaten by the ethanol in gas pump. You need one hose for the feed line and one hose for the return line.

    • Alternative: 2 x 15ft PTFE hose (https://www.summitracing.com/parts/SUM-220996), AN-6 fittings for the hoses: 2 straight (https://www.summitracing.com/parts/AER-FBM1103) and 2 angled (https://www.summitracing.com/parts/AER-FBM1112), you might need a 90 degree angle one for your fuel pump (https://www.summitracing.com/parts/AER-FBM1122)

    • Inline fuel filter is good to have: https://www.amazon.com/gp/product/B000CPJIBU (you'll need a female/female adapter like this one https://www.amazon.com/gp/product/B000CPCODE)

    • 4 Russell/Edelbrock 644113 adapter fittings to connect AN fittings to your stock fuel rail and fuel pump (https://www.amazon.com/gp/product/B005C6KTBW). Some fuel pump housings use 3/8" instead of 5/16" tubing so you might need a couple of Russell/Edelbrock 644123 adapter fittings for those bigger lines (https://www.amazon.com/Russell-644123-6AN-Quick-Adapter-Fitting/dp/B005C6KTNK/ ).

On the pics below from left to right:
Simple feed/return setup with no inline filter (top is feed/bottom is return), using the Russell/Edelbrock 644113 fittings. Fuel pump side with Russell/Edelbrock 644113 fittings to connect to the existing fuel lines. one connector is 180 degrees and the other one 45 degree angle.

Complete system with inline filter, note that the Cobb Flex Fuel kit and Cobb Fuel pressure sensor are no longer available. Lines to the injectors are wrapped with Mylar radiant matting (https://www.amazon.com/gp/product/B000CEQBX4). The fuel pressure sensor to AN-6 fitting is this one: https://www.summitracing.com/parts/SUM-220675

Charcoal canisters that are part of the EVAP system don't withstand very well rally abuse and the charcoal breaks down in small pieces clogging all the vent hoses. It could be a good option to remove this system if your state inspection regulations do not require them as part of the emission testing

• • Oil pickup: Some STi engines have had bad batches of oil pickup that will fail at the weld and results in complete engine failure. We recommend to upgrade to the Killer B oil pickup (https://www.killerbmotorsport.net/ultimate-oil-pickup-ej25-152.html.html) and baffle (https://www.killerbmotorsport.net/oil-baffle-windage-tray.html.html) for peace of mind.

If you have a turbo AWD car and plan to run events of the American Rally Association, you will have to prepare the car for the ARA Boost monitor (see Bulletin 2018 - 5, download rules and bulletin at https://www.americanrallyassociation.org/2018-rules).

We made a video explaining how to prep the car for the boost monitor:

Here are links to products used in this video:

- 1/8" NTP plugs (pack of 4): https://www.amazon.com/gp/product/B003C01DPG

- 9mm caps for intake hose: https://www.amazon.com/gp/product/B071W12W49

- Battery tender quick disconnect: https://www.amazon.com/Battery-Tender-081-0069-6-Terminal-Disconnect/dp/B000NCOKZQ

• • Air intake: the standard airbox can trap water in case of a big water crossing or watersplash. If the water goes through the intake, it is not compressible and will induce engine damage. The Cobb SF intake and airbox still provide good heat insulation but will not retain water as long as it is used in conjunction with an hydrophobic sock (https://www.amazon.com/gp/product/B00YXHCYSC). We recommend modifying the closing mechanism for the box by using a pop riveted hinge and a rivnut to hold the cover in place with 1 bolt.

Exhaust noise can be an issue: Too loud and you could not pass tech, too quiet and you won't hear the engine during the race which makes it hard to know if you are in the right gear. Most stock exhausts will be too quiet but you can find cheap catback exhausts (you usually still need to run a catalytic converter) on eBay. Nicer catbacks like Cobb significantly reduce droning which can be quickly annoying on transits.

Heat management is also key especially with the headers. Here is the solution we use for heat shieleding and engine temperature management.