Civic Type R
19-07-2005, 01:29 PM
ALL IN THE FAMILY
By Keith Buglewicz
A sense of nervousness has seeped into the Honda performance community. It comes not from new anti-racing laws, or emissions regulations that will weld the hoods of new cars shut. No, this nervousness comes directly from Honda itself.
K. It's just a letter, but in the coming years its significance to Honda enthusiasts will achieve the status that "B" has now. With the introduction of the Integra DC5, the new Honda Civic Type R EP3 and CRV, Honda chucked more than 12 years of engine experience and aftermarket support out the window for a clean sheet of paper design. The new engine family is the K series, and on paper, it makes even the highest performance VTEC B series engine look like yesterday's blue plate special.
Look at the specs. The K20A2 in the Integra churns out a solid 200 hp from its 2.0- liters. That's 100 hp per liter, and you can thank i-VTEC for this specific output. The "VTEC" part of that acronym is already familiar to Honda enthusiasts. When the engine reaches a certain speed, rocker arms are locked together, linking them to a higher-lift cam, and allowing more fuel and air into the engine. In the world of variable valves, this is known as cam shifting right now, only Honda, Toyota, BMW and Porsche sell cam-shifting systems in the United States.
However, that little "i" means a lot. It means the K series engines are also equipped with VTC, or Variable Timing Control. This cam phasing system uses a spool gear, oil pressure and some fancy electronics to change the angle of the intake cam by plus or minus 30 degrees of timing.
The result is an engine with excellent power and especially torque, but one that still manages better fuel efficiency and lower emissions than its predecessor.
Now, this is all fine and good, but what does this mean for an aftermarket that has been centered on the B series engines? What can be done with it? Can it be turbocharged? Can it be swapped? Does it respond to the simplest bolt on mods? These are the questions on the minds of Honda enthusiasts, and we intend to answer as many as we can. First, let's take a close-up look at the engines as they come from the factory.
THE ENGINES
The K series currently consists of four power plants. The K20A3 is found under the hood of the standard Integra. With 160 hp at 6500 rpm and 141 Ib-ft of torque at 4000 rpm, it churns out the same power as the B16A, 10 hp less than the B18C1, but much more torque than either one of them, all at a lower engine speed. The i-VTEC system works only on the intake cam on this engine, and it has a composite two-stage intake manifold.
Similar to the K20A3 is the K20A found under the hood of some foreign Civics in the USA / UK and JDM. K20A-what? Well, we're not sure. The cars we've seen have all been pre-production vehicles, without the requisite engine code stamp on the block. The best information we have so far is that it's a K20A3, same as the Intagra. But that sounds a little off to us. While it has the same i-VTEC system as the Intagra, it boasts the fixed, single-stage aluminum intake manifold of the K20A2 under the hood of the Intagra instead of the dual-stage manifold of the base Intagra. Whatever the final engine code works out to being (we'll just call it a K20A for now), this manifold swap actually works against the Civic, reducing its torque. It weighs in with the same 160 hp, but with only 132 Ib-ft of torque at a higher 5000 rpm than its K20A3 sibling.
Following the logic of Honda's engine codes, the K24A1 is a 2.4-liter version of the K series. Following a philosophy similar to the B20 found in the previous CR-V, it's tuned to be a torque monster with a long, 99 mm stroke. That's a full 13 mm (0.51-in.) longer than any of the K20 engines. The extreme stroke works. With 162 lb-ft available at a low 3600 rpm, the CR-V is a veritable stump puller among small four-cylinder 4WDs. At the top of the enthusiast heap is the K20A2 that powers the Intagra. With a lofty 7900-rpm redline, 200 hp and 142 lb-ft of torque, this engine really is as good as its hype. With the exception of the stroked K24, the engines are all very similar structurally. All three of the 2.0-liter versions share the same 86 mm x 86 mm bore and stroke. This is known as a square design. An oversquare engine has a longer stroke than bore, like the K24. This generally results in more torque, but at the expense of peak power. Conversely an undersquare design (such as the S2000's engine) has a bore larger than stroke, and generally produces more high-end horsepower at the expense of torque. Not surprisingly, a square design like the K20 is a compromise between these two extremes, offering good torque and good horsepower without sacrificing or optimizing either. Aside from the manifold change on the Si's version of the K20, the main difference between these engines is the way they manipulate their valves.
VALVE DANCING
The K20A2 in the Intagra works the way you expect VTEC to work. The two camshafts are equipped with three cam lobes and rocker arms for each cylinder's pair of intake and exhaust valves. At 5800 rpm, oil pressure activates pins that lock the outer rocker arms to the center arm. This forces both valves to use the higher lift, longer duration center camshaft profile. However, this is augmented by VTC on the intake side, which manipulates the timing of the cam itself. This can be used to augment torque, reduce emissions or a variety of different things depending on what the computer thinks is best at the time. The Intagra's K20A3, the Civic Type R's K20A and the CR-V's K24A1 use i-VTEC differently. First, it only operates on the intake valves. But even then, the philosophy is changed. Until the VTEC threshold is reached, the lesser K engines essentiality only use one intake valve per cylinder. The other is opened just a crack, enough to keep fuel from pooling behind the valve, but that's about it. In addition, the VTC is tuned primarily to keep emissions as low as possible. All this weirdness results in excellent swirl inside the combustion chamber and very efficient combustion. It's great for fuel efficiency and low emissions. However, it isn't so great for driving fun, as the engine inhales less deeply and revs lower.
FRANKENSTEIN RETURNS?
The K24A is more closely related to the K20A3 and K20A. While it uses the same i-VTEC tuning as those engines, it's the long stroke design that's intriguing. The difference is in the block. The K24's deck height is roughly 19 mm higher than its smaller siblings. It's also slightly bored, with 1 mm larger cylinders. The compression ratio is also down slightly from the non-Type-S engines, 9.6.1 vs. 9.8:1. So what? Well, the natural temptation is to throw the K20A2's efficient head onto the K24A1 block, raise the redline and have a torquey, ultra-powerful i-VTEC stroker Frankenstein monster engine.
The actual bolting on part wouldn't be too difficult, as the heads should mount right up. However, you do run into an issue with piston speed. At its 7900-rpm redline, the K20A2 in the Intagra has a piston speed of 4464 feet per minute (fpm). Thanks to its long stroke, the K24A1 comes close to that, running at 4225 fpm at its much lower redline of 6500 rpm. By the time you've spun your K24 up to just 6900 rpm, you're already at 4485 fpm, and at the 7900 rpm redline of the K20A2, you're at a crazy 5135 fpm. For comparison, even the hyperkinetic S2000 with its 9000 rpm redline doesn't exceed 5000 fpm (it maxes out at 49% fpm). And the Integra's B18C1 only reached 4573 fpm. Translation: If you're going to plunk a K20A2 head on a K24A1 block and redline the concoction to 7900 rpm without seriously building up the bottom end.. duck.
The Integra is just for comparison, of course, and we've hit the Intagra and CR-V engines. So what's this im hearing about the S2000? That is the true wild-card in all this. It seems as though despite the different engine code (F20C1) and north-south orientation, the S2000's engine block is a kissing cousin of the K series. In fact, according to engine developer Paulus Lee at Advanced Engine Breathing Systems in San Diego, the head gaskets are the same. This means the S2000's standard VTEC head could, in theory, be put on the K series block.
HEAD GAMES
The head design of the different Ks are intriguing, beyond just valve manipulation. The K20A2 found in the Intagra is a wonderful design, according to just about everybody; Honda nailed it, putting even the very effective B series engines to shame. The valves are huge, noticeably bigger than the B series valves even without the use of a caliper. But measure them and the difference is that much more apparent. The intake valves on the K are 2 mm bigger than the B series intake valves, and the same goes for the exhaust valves. The intake port angle is also excellent, with a straighter shot into the combustion chamber than the B series. On the other side of the head, the improvements continue. While the B series heads force the exhaust gases through a strange humped path through the head, the K sends it straight out to the manifold.
There are other improvements. The K uses roller rocker arms. This not only reduces friction in the valvetrain, making more power possible it also frees up the aftermarket to offer durable billet cams for the Ks. Slipper followers like those in the B series put too much pressure on billet cams, wearing them down prematurely. Forged camshafts are better, but expensive to produce in small numbers. Note the difficulty Crane has gone to in creating roller followers for its new billet B series cams. But with roller followers built in, we expect to see some radical profiles for these engines in coming months.
The other K head is not quite as efficient. While the Intagra head boasts big, smooth, unobstructed ports, the regular head features a strange groove cut into the wall between the intake valves. Undoubtedly there to help improve the single-valve operation of the VTEG system these engines use, any head porter can tell you this kind of weirdness plays havoc with airflow into the engine. The result is pretty clear. The Intagra K20A2 is the engine to have. While the other two K20s are OK in their fuel-miserly, non-polluting way - and the K24 is the undisputed torque champ - they are less ambitious, and offer less potential for improvement compared with the mighty K20A2.
THE BOTTOM OF IT
Under the head is an all-new block. Made of aluminum alloy, it's a beefy unit, heavily ribbed and gusseted for extra strength. However, it's also an open deck design. An open deck means that at the top of the block (the deck), the water jackets around the cylinders are open to the head, and rely on the head gasket for sealing. This limits the amount of boost that an engine block can withstand, because the individual cylinders can actually wobble slightly under high pressures. This is why drag racers will seal the deck on their B series engines before pumping the pressure up to bone-crushing levels.
But for a naturally aspirated engine, this is pretty darn strong. Flip the engine over and you're greeted with a bearing girdle that actually makes up the lower quarter of the block. Known as a split case, this design is much stronger than the internal bearing girdle used in the B engines. About the only drawback to this design is that it only uses two bolt mains, rather than the four bolt mains preferred by racers. No matter, considering the overwhelming beefiness of the design, this is still quite acceptable. Remove the lower part of the case, and you'll see there's a lot of room inside the block. This means that one could go pretty crazy with rod length before the block itself needed modification.
The crank is Honda's typical overbuilt forged unit. The Intagra crank is, again, the better of the two, being fully counterweighted. The rods are similar in both designs, although the Intagra rods are stronger to cope with the higher piston speeds encountered in the engine. The pistons are another matter, however. The Intagra pistons are about what one would expect, and are in fact quite similar in design to the high domed structure that one finds in the B series engines. The piston itself accounts for the higher compression in this engine, as the bore and stroke are identical. On the other hand, the lower end K series piston looks, well, weird. Off center on the top of the piston is an odd, round dish that for all the world looks like a bellybutton. We can only speculate that this is another way the non-Type-S engines achieve good fuel economy and low emissions.
more coming ..
Edited by Civic Type R.
By Keith Buglewicz
A sense of nervousness has seeped into the Honda performance community. It comes not from new anti-racing laws, or emissions regulations that will weld the hoods of new cars shut. No, this nervousness comes directly from Honda itself.
K. It's just a letter, but in the coming years its significance to Honda enthusiasts will achieve the status that "B" has now. With the introduction of the Integra DC5, the new Honda Civic Type R EP3 and CRV, Honda chucked more than 12 years of engine experience and aftermarket support out the window for a clean sheet of paper design. The new engine family is the K series, and on paper, it makes even the highest performance VTEC B series engine look like yesterday's blue plate special.
Look at the specs. The K20A2 in the Integra churns out a solid 200 hp from its 2.0- liters. That's 100 hp per liter, and you can thank i-VTEC for this specific output. The "VTEC" part of that acronym is already familiar to Honda enthusiasts. When the engine reaches a certain speed, rocker arms are locked together, linking them to a higher-lift cam, and allowing more fuel and air into the engine. In the world of variable valves, this is known as cam shifting right now, only Honda, Toyota, BMW and Porsche sell cam-shifting systems in the United States.
However, that little "i" means a lot. It means the K series engines are also equipped with VTC, or Variable Timing Control. This cam phasing system uses a spool gear, oil pressure and some fancy electronics to change the angle of the intake cam by plus or minus 30 degrees of timing.
The result is an engine with excellent power and especially torque, but one that still manages better fuel efficiency and lower emissions than its predecessor.
Now, this is all fine and good, but what does this mean for an aftermarket that has been centered on the B series engines? What can be done with it? Can it be turbocharged? Can it be swapped? Does it respond to the simplest bolt on mods? These are the questions on the minds of Honda enthusiasts, and we intend to answer as many as we can. First, let's take a close-up look at the engines as they come from the factory.
THE ENGINES
The K series currently consists of four power plants. The K20A3 is found under the hood of the standard Integra. With 160 hp at 6500 rpm and 141 Ib-ft of torque at 4000 rpm, it churns out the same power as the B16A, 10 hp less than the B18C1, but much more torque than either one of them, all at a lower engine speed. The i-VTEC system works only on the intake cam on this engine, and it has a composite two-stage intake manifold.
Similar to the K20A3 is the K20A found under the hood of some foreign Civics in the USA / UK and JDM. K20A-what? Well, we're not sure. The cars we've seen have all been pre-production vehicles, without the requisite engine code stamp on the block. The best information we have so far is that it's a K20A3, same as the Intagra. But that sounds a little off to us. While it has the same i-VTEC system as the Intagra, it boasts the fixed, single-stage aluminum intake manifold of the K20A2 under the hood of the Intagra instead of the dual-stage manifold of the base Intagra. Whatever the final engine code works out to being (we'll just call it a K20A for now), this manifold swap actually works against the Civic, reducing its torque. It weighs in with the same 160 hp, but with only 132 Ib-ft of torque at a higher 5000 rpm than its K20A3 sibling.
Following the logic of Honda's engine codes, the K24A1 is a 2.4-liter version of the K series. Following a philosophy similar to the B20 found in the previous CR-V, it's tuned to be a torque monster with a long, 99 mm stroke. That's a full 13 mm (0.51-in.) longer than any of the K20 engines. The extreme stroke works. With 162 lb-ft available at a low 3600 rpm, the CR-V is a veritable stump puller among small four-cylinder 4WDs. At the top of the enthusiast heap is the K20A2 that powers the Intagra. With a lofty 7900-rpm redline, 200 hp and 142 lb-ft of torque, this engine really is as good as its hype. With the exception of the stroked K24, the engines are all very similar structurally. All three of the 2.0-liter versions share the same 86 mm x 86 mm bore and stroke. This is known as a square design. An oversquare engine has a longer stroke than bore, like the K24. This generally results in more torque, but at the expense of peak power. Conversely an undersquare design (such as the S2000's engine) has a bore larger than stroke, and generally produces more high-end horsepower at the expense of torque. Not surprisingly, a square design like the K20 is a compromise between these two extremes, offering good torque and good horsepower without sacrificing or optimizing either. Aside from the manifold change on the Si's version of the K20, the main difference between these engines is the way they manipulate their valves.
VALVE DANCING
The K20A2 in the Intagra works the way you expect VTEC to work. The two camshafts are equipped with three cam lobes and rocker arms for each cylinder's pair of intake and exhaust valves. At 5800 rpm, oil pressure activates pins that lock the outer rocker arms to the center arm. This forces both valves to use the higher lift, longer duration center camshaft profile. However, this is augmented by VTC on the intake side, which manipulates the timing of the cam itself. This can be used to augment torque, reduce emissions or a variety of different things depending on what the computer thinks is best at the time. The Intagra's K20A3, the Civic Type R's K20A and the CR-V's K24A1 use i-VTEC differently. First, it only operates on the intake valves. But even then, the philosophy is changed. Until the VTEC threshold is reached, the lesser K engines essentiality only use one intake valve per cylinder. The other is opened just a crack, enough to keep fuel from pooling behind the valve, but that's about it. In addition, the VTC is tuned primarily to keep emissions as low as possible. All this weirdness results in excellent swirl inside the combustion chamber and very efficient combustion. It's great for fuel efficiency and low emissions. However, it isn't so great for driving fun, as the engine inhales less deeply and revs lower.
FRANKENSTEIN RETURNS?
The K24A is more closely related to the K20A3 and K20A. While it uses the same i-VTEC tuning as those engines, it's the long stroke design that's intriguing. The difference is in the block. The K24's deck height is roughly 19 mm higher than its smaller siblings. It's also slightly bored, with 1 mm larger cylinders. The compression ratio is also down slightly from the non-Type-S engines, 9.6.1 vs. 9.8:1. So what? Well, the natural temptation is to throw the K20A2's efficient head onto the K24A1 block, raise the redline and have a torquey, ultra-powerful i-VTEC stroker Frankenstein monster engine.
The actual bolting on part wouldn't be too difficult, as the heads should mount right up. However, you do run into an issue with piston speed. At its 7900-rpm redline, the K20A2 in the Intagra has a piston speed of 4464 feet per minute (fpm). Thanks to its long stroke, the K24A1 comes close to that, running at 4225 fpm at its much lower redline of 6500 rpm. By the time you've spun your K24 up to just 6900 rpm, you're already at 4485 fpm, and at the 7900 rpm redline of the K20A2, you're at a crazy 5135 fpm. For comparison, even the hyperkinetic S2000 with its 9000 rpm redline doesn't exceed 5000 fpm (it maxes out at 49% fpm). And the Integra's B18C1 only reached 4573 fpm. Translation: If you're going to plunk a K20A2 head on a K24A1 block and redline the concoction to 7900 rpm without seriously building up the bottom end.. duck.
The Integra is just for comparison, of course, and we've hit the Intagra and CR-V engines. So what's this im hearing about the S2000? That is the true wild-card in all this. It seems as though despite the different engine code (F20C1) and north-south orientation, the S2000's engine block is a kissing cousin of the K series. In fact, according to engine developer Paulus Lee at Advanced Engine Breathing Systems in San Diego, the head gaskets are the same. This means the S2000's standard VTEC head could, in theory, be put on the K series block.
HEAD GAMES
The head design of the different Ks are intriguing, beyond just valve manipulation. The K20A2 found in the Intagra is a wonderful design, according to just about everybody; Honda nailed it, putting even the very effective B series engines to shame. The valves are huge, noticeably bigger than the B series valves even without the use of a caliper. But measure them and the difference is that much more apparent. The intake valves on the K are 2 mm bigger than the B series intake valves, and the same goes for the exhaust valves. The intake port angle is also excellent, with a straighter shot into the combustion chamber than the B series. On the other side of the head, the improvements continue. While the B series heads force the exhaust gases through a strange humped path through the head, the K sends it straight out to the manifold.
There are other improvements. The K uses roller rocker arms. This not only reduces friction in the valvetrain, making more power possible it also frees up the aftermarket to offer durable billet cams for the Ks. Slipper followers like those in the B series put too much pressure on billet cams, wearing them down prematurely. Forged camshafts are better, but expensive to produce in small numbers. Note the difficulty Crane has gone to in creating roller followers for its new billet B series cams. But with roller followers built in, we expect to see some radical profiles for these engines in coming months.
The other K head is not quite as efficient. While the Intagra head boasts big, smooth, unobstructed ports, the regular head features a strange groove cut into the wall between the intake valves. Undoubtedly there to help improve the single-valve operation of the VTEG system these engines use, any head porter can tell you this kind of weirdness plays havoc with airflow into the engine. The result is pretty clear. The Intagra K20A2 is the engine to have. While the other two K20s are OK in their fuel-miserly, non-polluting way - and the K24 is the undisputed torque champ - they are less ambitious, and offer less potential for improvement compared with the mighty K20A2.
THE BOTTOM OF IT
Under the head is an all-new block. Made of aluminum alloy, it's a beefy unit, heavily ribbed and gusseted for extra strength. However, it's also an open deck design. An open deck means that at the top of the block (the deck), the water jackets around the cylinders are open to the head, and rely on the head gasket for sealing. This limits the amount of boost that an engine block can withstand, because the individual cylinders can actually wobble slightly under high pressures. This is why drag racers will seal the deck on their B series engines before pumping the pressure up to bone-crushing levels.
But for a naturally aspirated engine, this is pretty darn strong. Flip the engine over and you're greeted with a bearing girdle that actually makes up the lower quarter of the block. Known as a split case, this design is much stronger than the internal bearing girdle used in the B engines. About the only drawback to this design is that it only uses two bolt mains, rather than the four bolt mains preferred by racers. No matter, considering the overwhelming beefiness of the design, this is still quite acceptable. Remove the lower part of the case, and you'll see there's a lot of room inside the block. This means that one could go pretty crazy with rod length before the block itself needed modification.
The crank is Honda's typical overbuilt forged unit. The Intagra crank is, again, the better of the two, being fully counterweighted. The rods are similar in both designs, although the Intagra rods are stronger to cope with the higher piston speeds encountered in the engine. The pistons are another matter, however. The Intagra pistons are about what one would expect, and are in fact quite similar in design to the high domed structure that one finds in the B series engines. The piston itself accounts for the higher compression in this engine, as the bore and stroke are identical. On the other hand, the lower end K series piston looks, well, weird. Off center on the top of the piston is an odd, round dish that for all the world looks like a bellybutton. We can only speculate that this is another way the non-Type-S engines achieve good fuel economy and low emissions.
more coming ..
Edited by Civic Type R.