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Project Focus ZX3: Part 1

Introduction, intake, exhaust and header

Dave Coleman
Jul 18, 2002

It's about time! We've been promising a Focus project car since our first driving impression more than 17 months ago, but we have, to say the least, been a little behind schedule. As much as we enjoy the Focus' entertaining chassis dynamics, functional layout and adventuresome styling, we've been even more impressed with Ford's aggressive push for aftermarket support. Ford wants people to be able to modify their Foci, and its efforts to kick start the supply-and-demand spiral that carried Honda to bolt-on nirvana should be a model for every automaker. Impressive as it has been, though, Ford's success has not been absolute--at least not in our eyes.

From that fruitful flow of fiddled-with Foci have come dozens of wedgy show cars filled to the fenderwells with fat rubber, brimming with boost and bedecked in boggling arrays of aftermarked baubles. More than once, we snagged the keys, packed our radar guns and stole off to our concrete hideaway for some special time with one of these queens of the show scene. The result was almost always the same. Show cars perform best on their natural habitat: Carpet.

Frustrated that the show cars weren't living up to the potential we expected the Focus to have, we were finally motivated by those carpet racers to stop talking and start wrenching. We took delivery of an egg yolk yellow 2001 Focus ZX3 in December of last year.

Perhaps the most attractive feature of the Focus is its base price. For only $12,710, you can have a great starting point for a project car. Naturally, though, you are going to want some options. For the performance nut, perhaps the only high-priority option is the ABS, which can be had for $400. But unless you like the high-performance bus driver feeling of the base car's high-mounted steering wheel, you will probably want the tilt/telescoping steering column. This option forces you to buy the premium package for $1,095. In addition to allowing you to move the steering wheel to where it belongs, you get air conditioning, a map light (ooh!), 16-inch wheels and tires (which our car, strangely, does not have) and the most obtrusive, obnoxious armrest ever devised. The armrest was apparently designed for use with an automatic transmission--there is no way the interior designer ever tried shifting a manual with this bulbous obstruction in the way. Even when folded up, the armrest interferes with your elbow any time you reach for second, fourth or reverse. We will be removing it soon.

In addition to these necessities, our car came with the power group (power windows, mirrors and remote keyless entry) for $740 and the quaint, manually operated moonroof ($495). We are, perhaps, the only Focus customers who actually like cranking our moonroof manually. We find it an entertaining throwback to a simpler time, but in the customer complaint files, it apparently ranks second only to the ineffective cupholders. Both complaints, ironically, are artifacts of the European design heritage that makes the car so good in the first place. Ideally, our performance motives would be better served with no moonroof at all--a solid roof is stronger and lighter--but a little luxury never hurt anyone.

In total, our Focus rolled out with an MSRP of $15,440, a pretty big penny compared with the base car, but a much more enjoyable daily driver as well.

Before wrenching on it or even driving it hard, our Focus was treated to a 53-mile factory test drive (a card in the car informed us that ours was one of a handful randomly selected each day for a thorough quality-control inspection) and a 2,200- mile road trip. This relatively gentle break in apparently prepared it for our abuse. We have dyno tested quite a few stock Foci and found power output to be highly variable. Anything from 101 hp to 111 hp is fairly normal. Ours made an unusually strong 115 hp. Moral of the story? Be nice to your Focus when it's new.

There is probably more to the wide baseline variance than just break-in habits, though. As we soon learned, there are some pretty loose cam timing tolerances designed into the Zetec engine and this engine is incredibly sensitive to cam timing.

But now we're getting ahead of ourselves. First thing: planning. What do we want our project car to be? Well, naturally, we want it to be fast. Above all else, we want it to be the polar opposite of the aforementioned show cars. Far too many of the Foci we have seen so far promise more performance with their looks than their engines can deliver. Our car will not look the part until it can play the part.

Making a Focus handle well is relatively easy. In stock form it suffers from tires that have their hard bits and soft bits in the wrong places (hard rubber, soft sidewalls) and springs, shocks and bushings that seem to have had their hard bits removed altogether. But the geometry is right, and the handling balance, even with all the squishy bits, is still surprisingly entertaining. We've tested Foci with excellent handling already--both H&R and Eibach have excellent suspension packages for this car--so we'll save that for later. What we haven't tested yet is a Focus with good, reliable power under the hood. That, then, is where we will start.

We'll give away the ending early. We have pushed peak power up by 13 hp and propped up the very top of the rev range by an astounding 23.9 hp, all for a total price of $1,499.55. How did we do it? Read on.

AEM Intake
The path to power is a well worn one in the early stages. First, intake and exhaust header. Make the intake cold, try to keep the exhaust from being too loud, look for a header with a CARB number on it. A-B-C, 1-2-3. As predictable as this routine is, no two cars respond the same to this round of modifications, so it's always educational to see what we can find.

When we tested AEM's dealer package for the Focus, it was still working on its cold-air intake. Assuming it was done by now, we called NOPI and tried to order one for our Focus. They were happy to offer AEM's underhood intake, but the cold-air, NOPI informed us, was still not ready. Nobody has ever accused us of being patient, so we went directly to AEM and snagged a "mostly finished" prototype. Our intake is functionally complete, but missing the pretty powdercoating and the splash shield that protects the filter from tire spray. We also haven't installed the air-bypass valve that will save our butts if we inadvertently dunk the filter in a puddle (see "Wrench Report," April. '01), but that will be in place soon.

Installation is a little involved. First, the battery must be removed to snake the 4-ft pipe into place. Then the airflow meter's sensing element must be removed from the airflow meter, and screwed into the AEM pipe. Like the Celica, the Focus' airflow meter consists of a removable sensor element in a calibrated pipe. While the Celica's calibrated pipe is built into the air filter box, the Focus airflow meter still has a separate housing. To simplify the intake, the AEM pipe integrates the airflow meter into the aluminum pipe rather than splicing in the stock airflow meter housing.

Like most modern hot-wire airflow meters, the Focus' measures a small sample of the intake air (say, 10 percent, for example) and just extrapolates actual airflow. Pulling this sensor element out of its carefully calibrated housing and dropping it in an intake pipe can screw up this relationship. If you used a larger pipe, the ECU, which thinks it's reading a 10 percent sample, could only be reading an 8 percent sample, for example. The result would be an airflow measurement that is too low, and consequently, the engine would run lean. Of course, unless you are designing the intake yourself, this is of no concern to you. The AEM intake was designed to keep the airflow meter reading accurately by matching the inside diameter of the pipe to the inside diameter of the stock sensor. A few inches of straight pipe on either end of the sensor also ensures the air near the sensor is as close to a uniformly distributed flow as possible.

Removing the sensor element from the stock intake should be as simple as removing two screws, but unfortunately, Ford uses safety Torx head screws, so you need a special driver to remove them. AEM will probably package a tool with the kit; if they don't, installation will be extremely frustrating.

The air filter now mounts near the ground behind the front bumper. Most cars would have a splash shield here, which would protect the filter from water on a rainy day, but the Focus has nothing (did we mention the $12,710 base price?) so the kit will come with a splash shield. For now, we are doing without. (See dyno chart on page 258.)

With everything back in place, the intake was good for 5 peak hp and 6 peak lb-ft of torque, with a 7-hp gain just past 6000 rpm and 8.5 lb-ft of torque around 3500. Strangely, power and torque losses below 3000 rpm were pretty severe, but we suspect that may have been a fluke. We have already noticed some strange engine management issues with Foci in the past (see "Technobabble," December, '00) and this may be another one. Though it seems conceivable that the intake could be responsible for a low-rpm torque loss, the fact the exhaust we tested next regained most of that torque doesn't seem to make sense. Either way, we spend so little time below 3000 rpm that it seems a moot point.

We also tested intake temperatures at the throttle body before and after installing the AEM intake. Because the stock intake actually pulls cold air from in front of the radiator, we didn't really expect a big difference, and, no surprise, we didn't get one. Temperatures at 40 mph and at 70 mph were in the low 70-degree range, both with and without the intake (when ambient temperatures were in the mid 50-degree range), but the temperature at idle was actually about 25 degrees warmer (about 100 to 110 degrees) with the AEM intake than with the stock one. As with most aluminum cold-air intakes, intake temperature drops to its normal cruise temperature almost immediately when the car starts moving.

Thirteen Twenty Exhaust
Next up is the exhaust. With a few notable exceptions, most modern cars will only get very few horsepower from an exhaust system. The state of the muffler art is pretty well advanced, and OEMs have largely figured out how to make the exhaust silent without severely limiting power output. With relatively little power to gain, sound quality, looks and fitment are our highest priority with an exhaust system. Without trying every exhaust (we're not promising to do that just yet) that means listening to every modified Focus we see and trying to pick a good one.

On a recent visit to Thirteen Twenty Morotsports to plan the Focus rally car (see sidebar), our man Josh Jacquot noticed that it was making an exhaust system that wasn't too loud and had a nice, deep exhaust note. Sign us up!

The Thirteen Twenty exhaust is powdercoated mild steel, which means it looks like it's painted black, but when you start it, the paint doesn't burn off. The stock exhaust is one piece from the front crossmember all the way to the rear bumper. This is great for installation at the factory, but replacing the exhaust either means removing the entire rear suspension, or cutting the exhaust in half. Cut, we did.

After hacking through the exhaust just after the first muffler, the front section drops straight out and the rear can be worked free around the suspension. The Thirteen Twenty exhaust is made in three pieces, with two slip joints held together with U-bolts. This means you have to hang the whole exhaust, making sure everything is aligned properly, and then tighten the U-bolts. Once tightened, the slip joints are resistant to any further adjustment, so try not to tweak the alignment while you are tightening. Regardless, this is not an exhaust you would want to install in your driveway, on your back or by yourself. This is one you should have installed by somebody with a lift.

With all the appropriate tweaking, the exhaust fit well. Our only criticism is one of the exhaust hangers just in front of the rear suspension, which is welded to the exhaust with far too small a weld. Since the exhaust is supported by no less than five hangers, it probably won't be a problem, but on most exhausts, we would expect a hanger like this to break off after a few years of heat and vibration. We're hoping that won't be an issue.

The sound quality of the exhaust is good. It seems loudest at a high idle (about 1100 rpm) and around 3200 rpm. Neither loud spot is an annoying, booming resonance; it just seems that every time we notice the exhaust, it is at one of those two points. Strangely, the exhaust seems quieter when you drive hard--and that's really the time when you should be attracting the least attention. Like every Focus with an exhaust, ours now makes lots of little gargling and popping noises on deceleration.

On the dyno, the exhaust was good for a few horsepower above 5000 rpm (where the Zetec needs it most) and a boost of low-rpm torque. As we mentioned earlier, we're not entirely confident in the dyno numbers below 3000 rpm.

JBA Header
Close-coupled cats are the sworn enemy of horsepower. When they stay under the floor where they belong, catalytic converters are your friend. We have proven time and again that, in naturally aspirated applications at least, there is no power loss when running a good catalytic converter vs. running a straight pipe. But when they nuzzle up to the engine, the cat can become your enemy very quickly. The Focus' problem is not the cat itself, which is quite large and probably offers little or no restriction, but the fact that its position so close to the exhaust ports restricts exhaust manifold design and prevents proper exhaust scavenging.

The stock exhaust manifold is actually a tubular header of sorts, but its very short runners slam together in a very strange collector. Though removing the cat is out of the question, we can at least look for some power with a better collector. JBA, a Ford tuner better known for its Mustang work, makes a CARB-legal header that squeezes four almost-equal-length primaries and a conventional collector into the very tight confines between the exhaust manifold and the cat.

With the entire header sitting up front, installation looked like it will be easy. Imagine our surprise, then, when we saw the instructions telling us to remove the catalytic converter. "What a waste of time!" we thought, and immediately proceeded to ignore the instructions. Experience breeds wisdom and wisdom says to follow JBA's directions. You can almost get the header out with the cat in place, but getting that last manifold flange bolt out will take more time than removing the cat. After a prolonged struggle, we finally gave up and did what we were told. The Focus, we are quickly learning, is designed around a very efficient assembly process with little or no attention paid to serviceability after production. Everything is designed to go together in sub-assemblies in one particular order, and if you aren't on the assembly line, you're out of luck.

After a 3-hour struggle that would have been considerably shorter if we followed orders, the header was in place and ready to go. To our surprise, the JBA header made a meaningful improvement in low-rpm power and torque, but did little at high rpm. The exhaust and header, it turns out, complemented each other beautifully.

FocusSport Cam Sprockets
FocusSport's adjustable cam sprockets are the one departure we made from our standard first stab at power. Cam sprockets are usually a fine tuning tool that we reserve for dialing-in aftermarket cams or satisfying bouts of anal retentiveness, but FocusSport assured us the Zetec engine responds unusually well to cam timing adjustments, so we decided to give it a shot. Installing cam sprockets is usually a very straightforward procedure, but as with so many other parts of this car, Ford decided to do things just a little bit differently.

First, the plastic timing belt cover must be removed. This wasn't really designed to be removed with the engine in place, and there is a bit of an interference fit between the plastic cover and the passenger-side engine mount. Removing the cover, warned FocusSport's Randy Robles, usually means breaking it. Ours came out without the telltale sound of shattering plastic. The trick? Our engine was still warm from the drive to the shop. Perhaps, possibly, just maybe if you remove the cover while the engine is still hot, the plastic will be soft enough to come out in one piece. Just don't blame us if you burn yourself trying. With the cover out, there should be a mark left where the engine mount was in the way. We took this opportunity to trim the plastic around the mount to ease installation later.

The first thing you'll notice is the cam sprockets are held to the cams with a #55 Torx bolt. You might as well buy a whole Torx socket set; the Focus is covered with Torx bolts. Go ahead and get them now, we'll wait...

OK. Now that the cam sprockets are in view, you need to remove the valve cover and the plastic shield over the crank pulley so you can rotate the engine. If you look at the back of the camshafts, there is a groove cut in each shaft. When the engine is at top dead center, a special tool (also known as a steel bar which is, thankfully, included in FocusSports sprocket set) fits in these slots and keeps the cams from moving.

Now, I know what you're thinking: "The bar will hold the cams in place, so I'll bust out my shiny, new Torx socket and break those bolts loose!" Don't. Though he hasn't broken one himself, Robels warns that the camshaft is likely to break if that much torque is put through those slots. The best thing to do is hold the camshaft near the sprocket end of the shaft. Of course, Ford didn't bother to cast in any flat areas to allow you to grab the camshaft with a wrench. We were able to grab the cam with a specially modified crescent wrench that looked like it spend too much time next to the belt sander. Be forewarned, this part may require some ingenuity.

Once you loosen the belt tensioner and remove the cam sprockets, you're in for another Focus surprise. The cam sprockets are not indexed to the cams with any dowel pins, woodruff keys or even any marks. You could, if you were really careless, bolt the cams in with the timing so far off, the engine wouldn't even run. That's not really our concern, though. The real problem is the fact the cam sprockets cannot be installed precisely without hours of work. It had been our hope that we could spend hours on the dyno finding the best setting, tell you where to set your cams and save you the hassle of hitting the dyno yourself. That simply isn't possible. If we tell you to retard your intake cam 4 degrees, for example, that will only mean four degrees from where we bolted our sprocket on. You might very well bolt your sprocket on four degrees more advanced than we did, requiring 8 degrees of retard on your cam. The sprocket doesn't have to move much during the torquing process to make a huge difference in performance. This goes a long way toward explaining why we see anything from 101 to 115 hp from stock Foci. The factory cam timing probably varies as well.

OK, so do your best to get everything back together right, put it all back together and head straight to the dyno. We set our cams at -4 degrees on the intake and -7 degrees on the exhaust, because that is where FocusSport made the most power on its car. Imagine our surprise, then, when we were all the way back down to 115 hp at the wheels! Our 0-degree mark was apparently very different from its mark. Retuning to 0 degrees on both cams, we found that we had already gained about 8 hp around 6500 rpm. Obviously, 0 degrees now was far from 0 degrees before. Most engines respond well to a few degrees of advance on the ignition cam, so we set the intake cam at +2 and did another dyno pull.

We lost power.

Backtracking, we set the intake cam at -2 degrees and showed huge gains at high rpm and a slight loss below 4000 rpm. If some works, more must be better, so we set the intake at -4 degrees and tried again. We got more high rpm power than ever, but were starting to see significant torque loss all the way to 4700 rpm. Not wanting to ruin drivability, we backtracked to -3 degrees on the intake cam and maintained all our high-rpm power while gaining back a few of the lost lb-ft at low rpm. Not really eager to sacrifice any of our newfound power, we next turned to the exhaust cam.

Making incremental changes with the exhaust cam yielded nothing but slight losses in both directions, so we went back to 0 degrees and called it good. Very, very good. We gained an almost unbelievable 15.7 hp just before the rev limiter kicked in, bumped peak power by 6 hp, managed not to lower our torque peak at all, and lost only 4 to 5 lb-ft of torque below the torque peak. Since the Zetec was already a very torque-biased engine, this made a huge improvement in the way the car drives.

Performance, after this first round of modifications, is drastically improved. Power delivery now feels like a stock Nissan SR20DE, but without the SR20's close-ratio gearbox and instant throttle response. It's a start.

While we're thrilled with what we have achieved so far, we've barely scratched the surface. Our call to NOPI may not have yielded a finished intake, but we did manage to pick up an Unorthodox Racing underdrive pulley. In addition to that, a FocusSport aluminum flywheel is in the cards. This may seem minor, but the stock flywheel is a massive 22 lbs; the FocusSport part shaves more than 10 lbs from that weight. We are also looking at ways to use FocusSport's full-length race header with an under-floor, high-flow cat. Space is tight, but we're optomistic. Then there's the cylinder head, the cams, the intake, the gearbox. Boy, do we have plans!

By Dave Coleman
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