Acura RSX Type S

Get your head around this: The car on these pages is, to car nuts like us, the new Integra. To Japan, Europe, Australia and the rest of the world, this is the new Integra. To the rest of the American public and our friends in Canada, this is the all-new Acura RSX. Got that?

The reason for the confusion is simple. In Europe and Japan, the Integra has always been a Honda, and everyone has been happy. Here in Acura-land, however, the Integra has seemed a little out of place in the Acura line. While the TL, RL and CL oozed calm, comforting luxury from every stitch of their leather-lined cabins, the Integra has been a screaming, pavement clawing terror. Like a wild child in a retirement home, it just seemed like it belonged somewhere else. Naturally, that's exactly why we liked it.

Getting the Integra, or its successor, more in line with the rest of Acura's cars meant changes from both sides. The introduction of the CL Type S and, more recently, the TL Type S, has shot some adrenaline into the sedate end of the Acura line; now it's time for the wild child to grow up.

Grown up, mature and refined are the standard euphemisms for big, heavy and boring, so it was with some trepidation that I first settled into the driver's seat of the new RSX. The PR spin is that the RSX is both more luxurious and a better performer than the Integra, but that sounds suspiciously too good to be true. Luxury means heavy, performance means light; luxury means quiet, performance means loud; you get the picture. But then again, this is Honda Motor Company, the same company that made a 9000 rpm, 120-hp/liter Low Emissions Vehicle. Compared with the S2000, an all-around better Integra should be a cakewalk.

Sure enough, by the fourth turn of Honda's spectacular Twin Ring Motegi road course, it was pretty obvious Honda had done it again. Turn four is a slightly deceiving off-camber right, the third of an exhilarating four-turn series that you must string together just right to come out fast. I didn't, of course, and by turn four, I was headed toward the grass at 8000 rpm. This is where a driver's car shows its stuff. I dropped off the throttle momentarily and gave the wheel the tiniest jab to the right. At this point, your mom's car would hold its line and simply slow down and squeal. The less sorted performance car might tuck in and go right, then snap back to the left when you try to get back on the right line. The RSX, on the other hand, responded perfectly. With a quick bark from all four tires, the nose tucked in, the tail slid wide just a bit and the car went right where I wanted. Very few cars seem so predictable and so balanced the first time you drive them, but the RSX was obviously developed with the wild child in mind.

Let's get the name thing out of the way first. The 160-hp RSX effectively takes the place of the Integra RS, LS and GS, while the GS-R is succeeded by the 200-hp RSX Type S. The Integra Type R has no replacement--for now. The official word on the Type R is that there is no official word, but several engineers admitted they are already working on it. Specs have just started being released in Japan as we go to press. Expect 220 hp, a limited slip diff, and Brembo brakes. We'll say more when we know it.

On paper, the RSX is an inch wider and 2.5 inches taller than the Integra, but it's about the same length and sits on exactly the same wheelbase. The wheelbase dimension, though, may be the only thing that was carried over from the old car. The suspension, as usual, shares its basic geometry with the Civic, which now means MacPherson struts up front and a new double-wishbone-style suspension in the rear. The layout seems a step backward from the four-wheel double wishbones of the GS-R, but you would never know it by driving the cars back to back. The RSX has less body roll and is more balanced and precise at the limit than the stock GS-R we had for comparison. How the two suspensions will compare once the aftermarket gets its hands on them is anybody's guess.

The new chassis is significantly reinforced around the suspension mounting points and the rear hatch area, both critical regions for handling response. A strut tower bar on the Type S also ties the strut towers to the firewall. The net result is a much-needed 116-percent improvement in torsional rigidity and a 35-percent improvement in bending rigidity. Total vehicle weight is up about 100 lbs, to 2,775, which isn't bad considering the stiffer chassis, larger engine, larger brakes and extra cog in the gearbox. The engine and front suspension mount to a rigid, fully boxed subframe made up of hydroformed steel tubing. This ensures a stable, flex-free mounting point for the lower control arms.

The steering rack is mounted high on the firewall, as it is in the new Civic, with the steering arms almost meeting in the middle of the rack. The high-mounted rack is one of the many tricks needed to keep the hood short and the interior roomy, and the center-mounted steering arms are needed to keep the high-mounted rack from causing nasty bump steer problems. The steering rack is quicker than the Integra's (15:1 vs. 16:1 for the Integra), and the steering has a meaty, well-weighted feel to it, but initial turn-in is surprisingly sluggish. Softer turn-in was actually a design goal--something to help the RSX tow the luxury line--and while it doesn't really hurt during aggressive driving, the soft turn-in does take some of the zing out of zipping around town at moderate speeds.

The driving position is higher and more upright than the Integra, giving a somewhat less sporty feel just cruising around, but paying off with better visibility. The shifter has also been moved higher and closer to the driver--a good thing, as some around these offices have been known to complain that the Integra's shifter was too far away. Though the interior is fairly conservative, it's the seats that give away the sporting intent of the Type S. Leather seats and performance cars usually don't mix, the leather surface being too slippery for hard driving, but the RSX seats are a different story. They are, quite frankly, a work of art. They are very aggressively bolstered, with firmer foam being used in the areas needed for lateral support. Once you sit in them, you'll never notice them again. That is high praise indeed when driving at the limit on a racetrack. The GS-R's softer leather seats, on the other hand, made themselves obvious on the first turn, as I scrambled around to support myself during high-g cornering.

As with most high-performance Hondas, it's the drivetrain that shines brightest when you're behind the wheel. All the gory details about this all-new powerplant are in the "Nerd's Eye View" elsewhere in this story, but if the details don't interest you, here's the short version: It's a screamer! Power delivery is fantanstic, with healthy torque and a gearbox that lets you stay up in the meat of the powerband the whole time.

The stronger torque band of the larger engine is especially obvious from a standing start. Launching at just 2400 rpm has the tires complaining all the way through first gear. We had the time to pull off a few preliminary acceleration and braking runs in our brief time with the car. Though there was no room for a full quarter mile, and our tests were run on a very slight slope, the average of the best uphill and the best downhill run netted a 0-60 time of 7.1 seconds. Faster than the 7.6 of the last GS-R we tested, but still short of the best times we've run with a Type R (as good as 6.1 seconds, but usually around 6.5). Traction did seem to be very limited, however, and this may have had a serious effect on times. Our measured 60 to 0 braking distance, for example, was a very long 145 feet, despite the fact that the brakes felt unusually strong on the track. We are looking forward to more extensive testing on more familiar ground.

More luxurious and sportier? You bet. In the end, the RSX ends up bigger and more comfortable on the inside and faster on the outside. But will it be the aftermarket king its predecessor has been? The competition is certainly stiffer this time around, but I'd put money on the RSX doing just fine.

On The Inside
The B18C is the undisputed king of the four cylinders. There are more parts, more options and more ways to make power with Honda's B-series engines than any other four cylinder on the market. As packed as it is with high-tech goodies, it's easy to forget that the B-series is more than 10 years old and, with the new RSX, it's now out of production. In its place is the new K20C, a wonder in its own right and a worthy successor to the mighty B-series.

Don't count on using any B-series knowledge on the new K20; it is a different beast in every way. First, it rotates clockwise, where the B18 rotates counterclockwise. Honda engines have traditionally rotated the opposite direction from virtually every other production engine, but beginning with the most recent V6 powerplants, all new Honda engines will roll with the crowd. The change is part of a grand plan to cash in on Honda's enviable base of engineering knowledge by supplying engines to other manufacturers or, at least, to have that option available. As a result of rotating the other way, the engines now sit on the passenger's side of the engine compartment.

Next, where the B18 was undersquare, with a relatively small bore and long stroke (81mm x 87.2mm, for the record), the K20 is square, with an 86 mm bore and stroke. Interestingly, this is the same bore and stroke as the other aging darling of the aftermarket,

Nissan's SR20. The K20 again uses an open-deck, die-cast aluminum block with cast-in iron cylinder liners, but at the bottom of the crankcase, where the B18 used a sturdy main bearing girdle for bottom-end strength, the K20 does one better, integrating the main bearing caps into a crankcase extension. This "split crankcase" design is becoming the standard for new engines, as it delivers noise, vibration and harshness benefits as well as improved strength.

As expected, the crankshaft is a high-strength forging with micro-polished journals. The connecting rods are 139mm long, giving the engine a 1.62:1 rod/stroke ratio. This is slightly better than the B18's 1.58:1, but still relatively small compared with most high-performance non-Honda engines. The K20C in the Type S and the K20A in the standard RSX use different connecting rods (those in the Type S are stronger) and different pistons. The Type S piston is domed for an 11.0:1 compression ratio (the base RSX is 9.8:1) and has low-friction coatings on the piston skirts. The bottom of the Type S pistons are cooled with high-pressure oil squirters as well.

A common trend in modern engines is to move the top compression ring closer to the top of the piston. This reduces the volume of end gasses trapped in the small crevice between the piston and the cylinder wall--a popular hangout for unburned hydrocarbons. The side effect of this strategy, though, is a thinner ring land, and probably a less detonation-resistant piston. Honda, notably, did not take this step with the K20. The piston rings appear to be in the normal location, leaving a big, meaty ring land capable of surviving some really bad aftermarket tuning. In an effort to minimize internal friction, the rings themselves, however, are some of the thinnest we've seen.

The two models have completely different cylinder heads, sharing only the basic layout. Even that basic layout has changed from the B18, with the intake now on the front of the engine, and the exhaust out back. The rear-mounted exhaust allows the catalytic converter to be moved slightly closer to the exhaust ports without requiring a true-close coupled layout (with a front-mounted exhaust, the catalyst at this distance would end up under the oil pan, where it would heat the oil and cause ground clearance issues). The exhaust routing is similar to the new Civic and to Toyota's 2ZZ-GE Celica GT-S engine, with a short, low-mass tubular stainless-steel four-into-two manifold followed by an "e-pipe"--basically a large single pipe with a divider wall down the middle--in place of traditional secondary pipes. The e-pipe design reduces surface area so less heat is dissipated to the outside air. Heat loss is further reduced by making the outside of the e-pipe double-walled. All these low-mass, double-walled, low-heat-loss games are efforts to speed catalytic converter light-off. It obviously works, as both models meet strict Low Emissions Vehicle Level II standards.

The RSX uses a short-runner aluminum intake manifold, with velocity stacks cast into the ends of the runners. To make this complex shape, the manifold has to be cast with a large opening in the bottom of the plenum, which is capped off with a bolt-on plate. I don't know how, but somebody is going to figure out something clever to do with this plate, trust me.

The valvetrain is, as usual for Honda, quite complex and clever. The new i-VTEC system combines Honda's traditional VTEC with continuously variable intake cam timing, or VTC. The two systems are essentially independent of each other. VTC advances or retards the intake cam over a 50-degree range, depending on operating conditions. Retarding the intake cam at idle virtually eliminates valve overlap for optimum idle stability. At cruise, the intake cam is advanced, and the high overlap condition results in the dilution of the intake charge with exhaust gasses. This internal exhaust gas recirculation actually reduces NOx emissions and eliminates the need for an EGR valve. At wide-open throttle, the valve timing varies, depending on rpm. If you've ever played with adjustable cam sprockets, you've seen how some cam timing settings give you better power at low rpm and others benefit high rpm. VTC simply keeps the timing optimized at all times.

In addition to the VTC, the familiar VTEC system is still at work on the Type S engine. Three cam lobes and three rocker arms are used.

The outer rocker arms push directly on the valves and follow relatively mild cam lobes.

The center rocker arm, which follows a far more aggressive cam lobe, just floats between the other two, pushing on nothing. At the changeover rpm, a pin is pushed through all three rocker arms, linking them together. Since the center lobe opens earlier and farther and closes later, new newly united rocker arms have to follow the big lobe. This is essentially the same system that was used on the B18, but the rocker arms now follow the cam lobes with big rollers to reduce friction. Roller rockers were used on the S2000 as well. The S2000 also used a rifle drilled VTEC engagement pin to reduce valvetrain mass slightly and though we couldn't see it on the K20, a similar design is probably being used here.

The base RSX engine uses a similar VTC system, but the VTEC system operates differently. First, there is no VTEC on the exhaust cam at all. On the intake cam, there are only two cam lobes instead of three for each pair of valves and there is one rocker arm for each valve. The difference here is that one cam lobe is fairly normal, while the other is a pathetically small little bump. At low rpm, each valve follows its own cam lobe. One opens normally and one barely cracks open--just enough to prevent fuel from pooling behind the valve. This creates a strong swirling effect in the cylinder, which tends to concentrate fuel near the center of the swirl where the spark plug happens to be. High-swirl engines like this tend to have a faster burn speed and a slightly stratified charge, with more fuel being concentrated near the spark plug for easier ignition. At high rpm, where the single intake valve would be too restrictive, a pin locks both rocker arms together, forcing them both to follow the larger cam lobe.

The base RSX engine also uses a plastic dual-path intake manifold, with long intake runners for low-rpm operation and shorter runners for high rpm. Earlier dual-runner Honda manifolds used a set of butterfly valves in the short runners to keep them closed at low rpm. This left the butterfly valve shaft in the middle of the intake runner when they were open, restricting flow slightly. The new design uses a rotary valve that has no obstructions when it's open.

About the only shortcoming to be found anywhere in the drivetrain is the lack of a limited-slip differential. The Type R, whenever it finally gets here, will have one, but the current Type R limited slip, unfortunately, will not fit this transmission.

Thanks to a more compact chain drive for the cams (vs. a wider belt on the B18) and a chain-driven oil pump located in the oil pan (the B18 pump was located on the nose of the crankshaft), the K20 is actually smaller than the B18. This is despite the larger bore and larger bore spacing (94mm on the K20 vs. 90mm on the B18). Overall length of the engine and transmission has been reduced by 2 inches and the weight has been reduced by 22 lbs.

Because the engines have changed rotation, all new transmissions were needed as well. The base RSX is available with a five-speed manual or a five-speed automatic, while the Type S comes with a six-speed manual. Both new manuals use cable shift mechanisms in place of the more direct-acting rod shifters Honda has traditionally used. We were not able to try the five speed, but with the six speed, Honda has set a new standard for shift feel on a cable-actuated transmission. Shifts have the same light, crisp feel of the old Type R transmission. This is partially due to attention to detail in the shift mechanism and partially to the triple cone synchros on first and second gears and the double cone sychros on third through sixth. The six speed is remarkably compact. It is actually almost an inch shorter than the five speed, and weighs the same amount. Despite this, its torque capacity is supposedly 10-percent higher.