In the April/May issue of Honda Tuning, we took an up-close look at Honda's new K series engine, the motivational power behind the RSX, new Civic Si and CR-V sport utility. We compared it to the B series powerplants, far and away the mainstay of the Honda tuning market, and discovered Honda really did its homework on this engine. With robust construction, bigger ports, extremely trick valvetrain, and a number of other goodies, we were positively giddy with excitement.
However, we're just a bunch of magazine schlubs, so we talked to some of the top tuners to discover what they thought of the K, what they have planned, and what obstacles they've had to overcome to achieve their goals. Although we said we'd have this for you in the last issue, we wanted to give the tuners a little more time to develop their various K series projects.
The K20A2 found under the hood of the RSX Type-S obviously king of the hill. While the A3 in the standard RSX and new Civic Si, and the A1 in the CRV, have been tuned with an eye toward fuel efficiency and low emissions, the A2 has been tuned for power.
The big difference between the A2 and the other K series engines is how the cam-switching part of iVTEC works. The A2 uses a cam-switching technique familiar to most Honda fans. Extra rocker arms are slaved to one of two cams, increasing lift and duration at higher revs for better high-end power. The other engines use a version tuned for fuel efficiency. One intake valve is essentially closed when "off cam," and when the switch happens, the closed valve is just slaved to the same cam the opening one does. No higher lift or duration, but some pretty good fuel economy and emissions figures.
The K20A2 is a gem of a powerplant, and is already making serious power in the Type R versions of the Integra (Yes, it's still called that in Japan.) and Civic. It's clear it has plenty of potential for performance, but how will it react to intake and exhaust modifications? What about nitrous oxide and forced induction? Can the engine be turbocharged or supercharged with all that cam-phasing wackiness?
If you're looking for basic, bolt-on power, you're in luck. The K20A2 responds beautifully to intake systems, some systems making a solid 10 hp at the wheels. Manufacturers, such as AEM and Injen, are coming up with short ram and cold-air systems. Short ram systems bolt right in, while the location of the windshield washer bottle requires a bit more work from cold-air systems. The bottle must be relocated or removed, and a small portion of the fender liner needs to be trimmed, as well.
For the skinny on exhaust systems, we turned to DC Sports of Corona, Calif. These guys have been in the Honda exhaust market longer than just about anyone in the United States and are the first to have both an effective cat-back system and header for the Type-S.
The engineer in charge of the K series engines, Jehan Tetangco, told us the RSX proved to be a tricky customer. Naturally, DC fell back on its prior knowledge of Honda engines, fitting a 2.25-inch B-pipe to the car. It promptly lost power. A 2-3/8-inch pipe lost even more power. After going backwards and fitting a 2-inch pipe, which pushed power back up to just less than stock levels, he finally reached for the B series power handbook and threw it away. Clearly, this K was a completely different animal.
After much experimentation, Tetangco finally discovered a combination that worked. According to DC Sports, its Twin Canister System axle-back system and a 2.5-inch B-pipe resulted in a solid 6 hp gain and an average 3 hp gain from 3000 rpm to redline.
Headers are an even more difficult proposition. The good news is the catalytic converter is still separate from the exhaust manifold. However, it is shoved so close to the head that there is very little room for long exhaust runners. In fact, Tetangco discovered Honda's engineers did such a good job on runner size that he, instead, focused attention on the collector. After trying numerous designs, he discovered one that worked, again adding a nice 6 hp and 3 hp, average. Together, the header and cat back are good for 8.6 hp, according to DC Sports. However, add DC's cold-air intake system and the power gain shoots up to over 22 horses, with almost a 10 hp average gain from 3000 to redline. Clearly, intake, not exhaust, is the K20A2's biggest shortcoming from the factory.
Nitrous Oxide and Forced Induction
Traditionally, one of the quickest and easiest ways to get power from an engine is a shot of good ol' nitrous oxide. With more power just the push of a button (and a few hundred dollars) away, many vehicles find themselves with nitrous bottles in the trunk for a little added oomph. Simple, single-fogger systems are commonplace, but multiple fogger systems with ports drilled directly into the intake manifold are not unusual.
We spoke to Eric Vargas of Advanced Engine Management in Torrance, Calif. Eric is the brain behind AEM's burgundy, nitrous-charged RSX you might have seen in our sister publication, "Sport Compact Car." The car has been through a lot, including a blown engine caused by an unforeseen problem with the fuel delivery system.
The Integra (and previous Hondas) used a fairly conventional fuel and ignition system. The fuel routed to the rail where a regulator controlled pressure, and excess fuel was returned to the fuel tank. Even in the high-tech Integra, a mechanically activated distributor controlled the ignition.
The K series has a "headless" fuel system, meaning the regulator and return line are actually in the tank. There is no fuel return from under the hood. This gives Honda the advantage of building the pump, regulator, return and fuel level sensor all in one unit. It also helps reduce evaporative emissions.
Vargas tells us the down side to this type of system is it becomes very difficult to build extra fuel pressure. It used to be that adding a fuel pressure regulator would build enough additional pressure from the stock pump to make forced induction or big nitrous applications relatively simple. The way the K series' fuel is supplied makes building adequate pressure much more difficult.
Unfortunately, there is no simple workaround for this problem. The stock fuel pump is capable of about 55 lbs of pressure, adequate for a low-horsepower (40 hp or so) nitrous system or very low-pressure turbo or supercharger. Any higher and the system will run very lean-`a dangerous condition that could result in a blown engine.
For higher horsepower applications, a return line will have to be run, meaning the single-piece fuel pump/regulator/return/level sender assembly in the tank will have to be separated into individual components. This is an expensive and time-consuming process that would make a bolt-in kit a more difficult proposition. Of course, that hasn't kept HKS, GReddy and Jackson Racing from continuing to develop kits. Racing applications that need more than just a few pounds of boost are still in the future.
The ignition system is also very different. The B and H series engines use distributors, despite all the high-tech valve gizmos. The K uses a computer-controlled ignition without a distributor. While this is great for precisely retarding and advancing spark to meet different conditions, it makes it very difficult to alter the spark curve using external devices. Simply put, the engine freaks out and switches into limp mode until the computer itself is allowed to manipulate spark again.
It's easy to see the K's computer is the dominant force in the engine, and nobody knows Honda computers better than Doug Macmillan of Hondata in Torrance, Calif. After digging into the stock computer, his excavations have unearthed some surprising--and hopeful--answers.
First, the programming is extensive. The fuel maps alone take up more memory than all of the programming for the B series put together. Macmillan told us there are six non-VTEC and six high-lift cam tables. There are also another 24 that, as of press time, he was still working on. He also discovered the ignition tables and the tables governing VTC cam advance.
Additionally, he discovered something tuners are going to love about the stock ECU: Flash programmability. Unlike the previous car, this would make reprogramming of the computer far simpler. And with the hurdles surrounding ignition and cam timing for forced-induction engines, being able to directly manipulate these factors is crucial.
Macmillan also told us a possible trouble spot doesn't seem to affect the engine's performance potential. The RSX's computer is multi-plexed, meaning it sends multiple signals to different systems down the same line. This would have the potential to play havoc with aftermarket tuning but it seems the multi-plexing is confined to systems outside the engine compartment.
Frankensteins and Swaps
One of the greatest performance features of the B series engines is the interchangeability of the parts. With some modification, you can put a VTEC head with a Type R intake manifold on a B20 block and make yourself a monster of an engine.
Is the same true for the K? Skunk2 thinks so. It's in the process of building a naturally aspirated race engine based on the Frankenstein concept. With the K20A2's high-powered VTEC head mated to the CR-V's long-stroke K24A1, Michael Choi of Skunk2 told us he hopes to create a high-revving, high-power, high-torque monster that will rip the wheels off the shop's racecar. The biggest obstacle will be the lack of off-the-shelf, high-performance parts. Anybody wishing to build up the internals of their K engine will simply have to wait for those parts to fill the pipeline.
Engine swaps are a different story. We spoke to Brian Gillespie of Hasport, based in Phoenix, Ariz. Known throughout the tuning industry for its engine mount kits, Hasport has already been working on stuffing the K into its chassis mates.
The easy part is swapping K series engines between cars that were originally equipped with them. So, if you want more bang out of your Civic Si, it's relatively simple to drop in an RSX Type-S engine and be on your way. The only snag might be with swapping a K24 engine into the RSX or Civic, owing to its slightly taller block.
The non-Si Civics are a different matter. The current-model EM Civics are built on the same basic chassis as the RSX and CR-V. This means that, theoretically, the K series engines should fit in the Civic chassis. However, the engines mount differently in their respective bays--the D series engines used in the Civics on the driver's side, the K on the passenger side. This is a more complicated proposition for potential swappers.
According to Gillespie, the trick is using the RSX subframe. This subframe simply bolts in place of the standard Civic subframe, and has the rear engine and transmission mounts in the proper place for the K series engine. After that, it's a matter of developing the proper engine mounts on the sides of the engine. Gillespie is confident the swap will be complete soon, and that before long he'll have a K20A2-powered Civic coupe up and running. This is great news for owners of current-model Civics who have been stymied by the D17's lack of tuning options.
The future is bright for the K series but, compared to what the aftermarket is used to, the K series is a whole new ball game. From the most basic tuning to the most advanced, it's going to take time for the RSX and its counterparts to get up to speed. But it will. Whether you like it or not, Honda is not making the B anymore. Smart tuners are going to get cracking on the new K as soon as they can. Those that don't, will undoubtedly be left behind.
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