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Project Ford Rally Focus: Part 3

Engine management, brakes and rally computer

Jared Holstein
Jul 18, 2002

Building a one-off Group 5 rally car isn't easy. There are no established formulas to follow, no experience from which to build. This is the unfortunate reality of any new car like the Focus. But things are looking up. With the abundance of Foci beginning to appear at U.S. rallies, our job with this car may soon be simpler.

Although the project flat refuses to maintain the schedule we originally planned for it, it is moving along. On the agenda this month are several bits, all critical to making any top-level competition car reliable; precise, programmable engine control, a reliable fuel system and a few other high-tech goodies.

Custom Engine Management
The easiest way to screw up an otherwise capable racecar is to use poor engine control. We knew this. We've seen too many street cars run poorly because of this kind of problem.

Further complicating the project was our decision to build the car to the Sports Car Club of America's Group 5 class rules. Group 5 is the most radical two-wheel-drive class. It allows for turbo or supercharging with a corrected displacement of up to 5.1 liters. To be competitive in Group 5, we would need a fair amount of power--more than we could get from a normally aspirated, two-liter Zetec. Our answer was to turbocharge the Zetec engine already in the car as we discussed in the last installment (SCC, Oct '01).

Turbocharging a factory, non-turbo engine leaves lots of room for poor engine management. We didn't want to deal with the problems that arise when you manipulate sensor signals, blindfold the stock ECU with piggyback devices or resort to other electronic trickery. In other words, we needed a stand-alone engine management system with a relatively simple user interface and durable hardware. The answer, thankfully, came from a system with some very elegant solutions.

Pectel, the same company responsible for the engine management on the Ford Focus World Rally Cars, offers a system perfectly suited to our needs. Pectel's T2 ECU is designed specifically for the U.S. Ford Focus and uses the factory sensors, ignition coils and injectors (although we used larger units from RC Engineering). Two temperature sensors are supplied with the kit and Pectel will supply boost control valves and MAP sensors for forced-induction applications. The T2's use of stock sensors eliminates the need to build a custom mount for a cam or crank angle sensor, as well as the hassle associated with sourcing and installing non-factory sensors.

The T2 can control the Zetec engine in parallel with the stock ECU, which drives the dash instrumentation; or, Pectel will build a custom harness to suit whatever needs a Focus racer may have. We went with the custom harness for several reasons. First, we didn't need the stock exhaust gas recirculation control and our car's stock harness had already been modified for other changes.

Additionally, we weren't using the stock Focus dash displays, so we didn't need the stock ECU to drive those instruments. Our choice for dash instrumentation is Pi Research's System 2, which is discussed later.

The T2 offers full control of fuel and ignition maps, idle circuit and boost control. Interface is through any Windows-capable PC using DOS-based software. Fuel, ignition and boost maps can be displayed in three-dimensional graphs or numerical tables. Building calibration files and using the system is easy, compared to many other engine management systems we've seen. T2 software comes from Pectel with two base calibration files--one for normally aspirated applications and one for turbo applications.

Pectel's software also allows simple user interface with hot-key access to minimum and maximum sensor values in saved datalogs. Datalogging memory is 125KB from up to 40 channels. Depending on sample rate, this amount of memory is enough to gain loads of useful information for most race applications.

The T2's biggest strength, next to its ease of installation and interface with stock sensors, is the flexibility built into its software. The ECU can be configured to begin recording data based on a series of parameters. We configured ours to start recording the first time engine speed exceeded 5500 rpm--which should only happen under race conditions in our car. Fuel mapping can be based on speed/throttle position or speed/density combinations and can be mixed via programmable balance tables to make the engine less sensitive to load changes at low speeds.

Additionally, Pectel Technologies supplies some of the most durable wiring harnesses we've seen in any application (see photos). Every connector is weatherproof and is labeled with a yellow tag describing its destination in the engine bay.

The real magic with the Pectel unit is the ease of installation on a street or racecar as well as the low cost. With a relatively small number of wires to run into the engine bay, the T2 box goes into the car very quickly. It's positioned in a stock car near the factory ECU and can be installed with a 10mm socket. The wires can be run behind the fender liner instead of through the firewall, making the job even easier. By itself, the T2 ECU sells for about $2,000. With the interface harness, four additional sensors and a wastegate control valve, the price is a very competitive $2,500.

By offering the ability to interface with the stock sensors, eliminating the hassles of building sensor mounts and pricing the ECU so competitively, Pectel has produced an effective, efficient and easy-to-use system--perfect for most Focus racers.

If you read last month's installment on this car, you know how pressed for time we were going into the Rim of the World Rally and the ridiculous stress levels we reached trying prepare the car. It's because of Pectel's technical support that the car was ready to race. Giles Denning, Pectel Technologies' president, spent at least one sleepless night making sure Pectel's parts would be ready on race day.

Data Display
As discussed, building a one-off rally car creates some unique problems. One of those problems on our car was the need to run a rollcage cross brace directly through the real estate formerly occupied by the stock dash and instruments. In addition, the lack of the stock ECU on our car made driving the stock dash instrumentation a prohibitive operation, at best. Plus, an array of 14 gauges documenting every engine vital is too complex and confusing on a rally car. We needed something simpler.

Luckily, aftermarket race parts suppliers cooperate with one another from time to time and we were able to find a remarkably simple solution from one of the best in the industry. Pi Research, Inc. builds a dataloging dash unit, which served our needs perfectly. The System 2 is designed for use in everything from rally and hillclimb cars to open-wheel racecars and shifter karts.

With the ability to monitor, display and datalog vehicle speed, engine speed, oil temperature, water temperature, oil pressure, fuel pressure, voltage, lateral acceleration, and two user-selectable inputs, the unit offered the ability to analyze nearly as much data as Pectel's ECU. Plus--and this is the cool part--it interfaces with the T2 ECU via a single connector, greatly reducing installation time as all vital sensor information is supplied to the ECU through the stock sensors. The single-point interface did away with the need to connect multiple sensor inputs to the dash.

The System 2 has considerable flexibility built into its design to accommodate many uses in almost any competition vehicle. The fuel and oil pressure channels can be configured to measure boost or vacuum on cars with forced induction or carbureted engines. In addition, the user channels can record data from thermocouples, temperature sensors or rotary or linear potentiometers allowing users to record valuable data on everything including exhaust gas temperature, steering angle, throttle position and even shock travel. While this sort of data analysis is beyond the scope of this project, it's good to know these tools are there if we ever need them.

Logged data can be analyzed in three ways. It's most easily accessed through the dash itself, where it can be viewed on the LCD screen. Data can also be viewed after downloading to a computer using the Club Expert software provided with the dash. Alternately, data can be printed. Up to 105 minutes of data can be logged, depending on the sample rate.

The System 2 comes with an infrared beacon, which can be used to record lap times. While this isn't a feature we'll likely use on this car, it's conceivable to use two beacons while testing to record stage times. Because maximum and minimum sensor values are displayed by lap when using the Club Expert software, the beacon kit is a must-have. The System 2 will build a circuit map as well as graphs of engine and vehicle speed at any point on the circuit--invaluable data for developing a racecar and a feature we plan to report on in later installments.

Custom Lines, Fittings and Hose
SCCA rally rules mandate steel-braided lines any place fuel lines share interior space with the driver and co-driver. We took the Focus to Goodridge USA where the R&D staff spent time with tape measures designing our car's custom fuel system. Goodridge R&D man Jeff Cowan specified the company's 600 Series Teflon-lined, steel-braided lines for the engine's supply and return fuel lines. Unlike conventional steel-braided rubber lines, Goodridge's Telfon line prevents racing fuel vapors from permeating the lines and entering the cabin.

Cowan also sourced the company's 600 series Teflon-lined, steel braided brake lines. Flexible 600 series line replaced the stock hard lines from the firewall to the rear brakes. This allowed us to run the lines through the frame rail for further protection from rocks and debris. In addition, all four corners received 600 series lines. The new brake system and EBC brake pads from The Progress Group in Anaheim, Calif. improved pedal feel and feedback. The durability of the new system gives us some added piece of mind when on full attack with huge consequences.

Goodridge fittings are all machined to aircraft-quality standards; plating thicknesses are taken into account in the size of each fitting. In other words, each aluminum fitting is constructed slightly undersized so the addition of the final plating will allow each part to attain its specified size. This prevents galling and chipping of fittings, which are oversized due to plating thickness. Goodridge offers custom design and construction of fuel and brake systems to race teams and will install its products at its authorized installation center in Torrance, Calif.

Drivetrain Goodies
Our rushed schedule to finish the car for the Rim of the World Rally didn't allow time to install some of the more important drivetrain upgrades. We actually used a stock clutch at Rim and continued with it during our initial testing.

Since then, we've upgraded to Advanced Clutch Technology's heavy-duty street clutch. This upgraded unit uses a larger diameter (236mm vs. 225mm) Mazda disc and increases clamping load by about 40 percent. The Mazda disc has a stronger center and heavier springs and uses an organic friction material. ACT offers a race clutch for the Focus but, given the power we plan to make and the reduced torque load when racing in the gravel, we figured a street clutch would do the job without placing unnecessary stress on the rest of the drivetrain. While we haven't had lots of seat time using the new clutch, engagement and driveability seem equal to stock.

With the clutch, we installed Unorthodox Racing's lightweight flywheel--a part we've really been looking forward to using given the Focus' propensity for hanging onto revs between shifts. The flywheel is a gorgeous aluminum piece, which includes the crank trigger wheel. It is considerably lighter than stock. The stock flywheel in our Focus weighed 21.4 lbs. The Unorthodox flywheel weighs 10.5 lbs and it allows us to match revs easier. Big improvement.

Going into this project we knew we'd need a limited-slip differential appropriate for rallying. Because of our ambitions behind the wheel, we often find ourselves with one tire off the ground. Since our car drives the front wheels, we figure we'd better have a differential which would put power to the one drive wheel still planted and salvage some hope of finishing the race. The Kaaz limited slip does just that.

Once the tranny has been removed, the installation of the differential in Ford's MTX75 transmission is an extremely painless procedure. With the bellhousing facing upward, it's a simple matter of unbolting the case, pulling the stock differential, swapping the ring gear, pressing on new bearings and reassembling the whole unit.

Kaaz differentials require a break-in period which demands driving in a figure-eight for about a half an hour or so. To ensure proper seating of the friction material, the clutches must be forced to operate at different speeds initially. We followed the recommended procedure carefully as failure to break in the differential can lead to problems. During break-in, Kaaz recommends using less-expensive conventional gear-lube and replacing it with its petroleum-based high-grade gear oil before competition.

Kaaz differentials are adjustable but are set for 100-percent lock-up when new. We left ours in this configuration initially. However, adjustment may be necessary later depending on how the aggressive setting affects our car's turn-in on the gravel. According to Kaaz, adjustments to the clutch plates to change the locking rate can be made in about 10 minutes once the differential is removed. Small changes in the locking rate may also be made with a friction modifier additive.

Up Next
Look for further refinement of the drivetrain in upcoming installments of Project Rally Focus. Additionally, a new, fully built engine will give the car the necessary power to be competitive in SCCA's Group 5 category. We'll also discuss several cooling measures we've already taken so the engine survives in California's unrelenting summer heat.

By Jared Holstein
25 Articles

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