Project Focus SVT Part III

Look up a turbine's backside and you can see the problem you have if a flat flange is used. If the round hole on the left weren't there, exhaust coming from the wastegate valve would have to shoot out sideways and squeeze in with the turbine exhaust.

Look up a turbine's backside and you can see the problem you have if a flat flange is use

The oil pump
The PTE kit is very unusual in that the turbo is mounted so low the oil can't drain out of it and return to the pan without going uphill. PTE solved this problem by adding an electric scavenge pump. They mounted the pump very low, however, exposing it to road hazards. Last time we reported, our theory was it was mounted so low because oil needed to flow downhill from the turbo to the pump.

Turns out we were wrong about that, too. The pump can actually pull suction on the intake side, so it will pull the oil uphill. Upon discovering this, GT Fabrications moved it to the driver's frame rail where it's much less likely to get hit by a dead raccoon.

Intercooler plumbing
The ZX3 Focus has a vertical throttle body in the middle of the intake manifold. To accommodate this clumsy arrangement, PTE has a cast-aluminum pipe that incorporates the sharp, 90-degree bend you need to reach the throttle body without hitting the hood. Though this bend is no longer needed to reach the SVT's more conventional side-mounted throttle body, the casting incorporates the Mass Airflow Sensor (MAF), so we have to use it. GT Fabrications made a short adaptor pipe to connect the casting, in its new location, to the existing intercooler plumbing. The result looks a bit crude, but it turns out it's a temporary solution anyway, so we can live with it.

Going the extra mile to keep the wastegate's exhaust from screwing with the turbine's, GT Fabrications added a divider wall that slides between the two and ensures each goes down its own pipe.

Going the extra mile to keep the wastegate's exhaust from screwing with the turbine's, GT

The MAF works by diverting a small portion of the engine's airflow through a small tube. Inside the tube, the air flows in a nice, uniform, laminar way, so it's easy to measure. This sample tube hangs in a cylindrical plastic housing and whoever calibrated this whole thing knows exactly what percentage of the air flowing through the housing is actually going through the sampling tube. If, say, 10 percent of the air gets sampled, you just multiply the mass of air sampled by 10 and you get total airflow. Problem is, we're eventually going to more than double the airflow into this engine, and the sensor isn't calibrated to read that high. We can squeeze all that air through the MAF, that's not a problem, but eventually the sample tube will reach its maximum, 5-volt reading and the ECU won't know what's happening anymore.

The PTE kit addresses this by increasing the size of the MAF. The SVT MAF is 2.775 inches in diameter, while the cast-aluminum tube the MAF now sits in is 3 inches in diameter. This increases the cross-sectional area of the sensor by about 17 percent, which increases the maximum flow the same amount. If it really did read 10 percent before, the sensor would now read about 8.5 percent of the total flow.

Aftermarket flex joints are seldom as reliable as stock ones, and the SVT joint is as big as our 2.5-inch downpipe, so we decided to stick with it. We had planned to replace the stock SVT exhaust, but now that we've tried it, we like its sound quality and high flow.

Aftermarket flex joints are seldom as reliable as stock ones, and the SVT joint is as big

Tuning
We'd been faithfully following the turbo kit's instructions when we got to the last step: take your car to a dyno and get it tuned.

Huh? How exactly are we supposed to do that?

Luckily, the guys at FocusSport, who had been holding our hands through the very confusing process of working on a non-Japanese car, had a solution. Superchips Custom Tuning has cracked the SVT ECU. In fact, it has cracked every Ford ECU. This means we can tune the car simply by using its software to reflash the stock ECU. Better yet, we used Superchips' president to reflash the stock ECU. We had had Jerry Wroblewski, president of SCT, tune our car, but you can also have one of its distributors, like FocusSport, do it, or you can buy the software (about $800) and do it yourself. Not a single wire has to be cut. SCT simply plugs into the diagnostic port and lets you datalog and tune to your heart's content.

Wroblewski first loaded a base SVT program that cures many of the SVT Focus quirks. The rough idle after cold start, for example, or the erratic power delivery at the extreme low and high ends of the tach. Below 1800 rpm or so, the airflow meter signal is spastic. The high-overlap cams in the SVT cause pulsation in the intake tract that makes air flow back and forth across the MAF sensor element. The sensor doesn't know the difference between forward and backward, so when the same air flows back and forth across the sensor, it sees more air than there really is. Wroblewski tells the ECU to ignore the MAF under certain conditions, fixing the glitch.

The oil scavenge pump, which once hung perilously below the A/C compressor, is now tucked up on the driver's side frame rail. The line from the pump to the oil separator had to be lengthened, as did the one from the turbo to the pump.

The oil scavenge pump, which once hung perilously below the A/C compressor, is now tucked

At high rpm, the knock sensor gets overactive and timing gets erratic. Wroblewski turns down the knock sensor sensitivity a bit and smooths out some strange lumps in the timing curve.

He also makes some changes to the variable cam timing maps that he says make significant power improvements on naturally aspirated cars. How well they work on a turbo depends on how much backpressure the turbo causes.

Next, he told the ECU how big our injectors were and loaded fuel and timing maps he's used on turbocharged base Zetec engines. With these basics set, tuning could begin.

The SCT software data logs everything going in or out of the ECU and this, combined with the wideband O2 sensor hooked to the Dynojet he was tuning on, gives him enough information to make the right tuning decisions.

Fuel delivery had to be adjusted slightly because our modified MAF reads differently from the base Focus the fuel map was designed on. Timing also had to be retarded, even off boost, to cope with the SVT's higher compression (10.3:1 vs. 9.6 on the base Zetec). A few dyno pulls into the tuning session, we were putting down 265 hp, but that was dangerously lean and tended to knock at high rpm. Aiming for a conservative air/fuel ratio of 11:1 and pulling timing back until all the scary noises stopped dropped power to 245 at the wheels is still far more than we expected to see on the 8.5 psi the PTE wastegate actuator was giving us.

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