OVERVIEW
The Integra Type R features an advanced 1.8-liter, 195-horsepower,
dual overhead cam, 16-valve inline 4-cylinder engine equipped with
the Variable Valve Timing and Lift Electronic Control (VTEC) system
pioneered in the Acura NSX.
Its additional horsepower, which is 25 more than the 170-horsepower Acura Integra
GS-R, is the result of key technological achievements such as:
- High-compression, low-friction pistons
- High-performance camshafts and valve gear
- Larger throttle body and single-port intake manifold
- Hand-polished intake and exhaust ports
- High-volume induction and exhaust system
The engine also features Programmed Fuel Injection (PGM-FI), a highly rigid crankshaft with eight full balance weights, a crankshaft reinforcing bridge, an oil cooling system and oil jet piston cooling, dual-spring intake and exhaust valves, a highly rigid integrated aluminum die-cast engine stiffener, and a number of other technologies to increase performance while maintaining reliability and durability, along with smooth operation.
To get the most out of the engine's added horsepower, the Type R also features a close-ratio, 5-speed manual transmission and a limited slip differential. The development emphasis was placed on dramatically increasing performance at high rpm. This emphasis resulted in an engine with a significantly different character than the Integra GS-R, further reinforcing the Type R's image of a limited production, ultra-high-performance sports coupe.
Putting out 195 horsepower at 8000 rpm, and 130 lbs-ft of torque at 7300 rpm, the Type R engine is one of the most powerful normally aspirated mass-produced automobile engines per liter ever produced (108 horsepower per liter).
ENGINE BLOCK AND CRANKSHAFT
The Type R utilizes a pressure die cast aluminum alloy block with
cast-iron cylinder liners for light weight and maximum rigidity. Its
highly rigid crankshaft is made of forged, high-strength steel with
eight full balance weights to reduce vibration at high rpm by 20
percent. The journals of the crankshaft also feature a special
micro-polished surface finish for reduced friction and increased
durability.
SURFACE-ORIENTED CRYSTAL BEARING MATERIAL
The use of a surface-oriented crystal bearing material was pioneered
in Formula One racing and has been adapted for use in the Type R
engine. Unlike the surface of conventional bearing material, the
crystal bearing surface has molecules oriented into a pyramid shape.
This surface traps a layer of oil and holds it far better than
conventional bearing surfaces, reducing friction and enhancing
reliability.
PISTONS AND CONNECTING RODS
Exclusive pistons and connecting rods have been developed for the
Type R. The high-pressure die cast piston crown has been reshaped to
increase the compression ratio to 10.6:1 and valve pockets deepened
to accommodate the increased valve lift and duration of the Type R.
The piston skirt is coated with molybdenum to minimize friction and
allow it to withstand high-rpm operation, while specially designed
oil paths have been machined into the underside of the piston to
provide additional lubrication to the piston pin.
Extreme care is taken in the forging and machining of the connecting rods to ensure each engine has a precisely matched set of connecting rods. As in the GS-R, the rods are constructed of special high-strength steel for a rigid yet lightweight component. Extremely accurate machining of the Type R connecting rod minimizes variation between parts. Connecting rod bolt elongation is strictly controlled for uniform fastening force. This is achieved through manual assembly of each and every connecting rod for the Type R, and the result is a significant reduction of fastening force variance.
The combination of lightweight pistons and connecting rods helps to reduce reciprocating inertia and enhances throttle response significantly.
OIL JET PISTON COOLING
To help ensure long-term durability and reliability, the Type R
engine uses an oil jet cooling system. A jet of pressurized engine
oil is directed to the underside of the piston to help dissipate the
extreme heat generated during sustained high rpm operation. This
technology has proven itself in Formula One and other top-level
racing engines.
CYLINDER HEAD, VALVES AND CAMSHAFTS
Cylinder head design for the Type R is a double overhead camshaft,
four-valves-per-cylinder configuration, which incorporates the
exclusive VTEC system. The Type R engine utilizes the latest
combustion technology to provide a combination of fuel efficiency and
power. Because of the low surface-to-volume area of the chamber,
minimal surface area is exposed to the heat of combustion and more
heat is retained in the expanding gases, resulting in increased
thermal efficiency. And the generous "squish" area around the
combustion chamber yields increased gas turbulence for faster flame
propagation, and even better efficiency.
Extensive modifications of the cylinder head were undertaken to improve performance. This also involves hand-polishing of the intake and exhaust ports near the valve seat area. In addition to hand polishing the ports to improve flow, special lightweight intake valves are also fitted. These valves feature a thinner shaft to reduce weight and increase flow. The head of the valve is also lightened to further reduce valvetrain weight. These modifications net a 12 percent weight reduction of the intake valves, allowing the engine to rev higher. These lighter intake valves help extend the rpm range of the Type R engine by an additional 200 rpm.
Special high-performance dual intake valve springs with an oval-shaped cross section are utilized to allow the use of high-performance camshafts for increased flow at high rpm. The unique oval shape allows a stronger valve spring to be fitted in the same area as a conventional spring. Conventional dual high-performance valve springs are used on the exhaust valves. Camshafts fitted to the Integra Type R are longer duration with higher lift to help increase engine breathing and top-end horsepower. At high engine speeds, valve lift on the intake side is increased by 0.9 mm, and on the exhaust side by 1.1 mm, compared to the GS-R. The valve timing is extended an additional 10 degrees on the intake side and 8 degrees on the exhaust side.
VARIABLE VALVE TIMING AND LIFT ELECTRONIC CONTROL (VTEC)
SYSTEM
The Variable Valve Timing and Lift Electronic Control (VTEC)
system, first pioneered in the Acura NSX, works similar performance
magic in the Integra Type R. As the performance of the NSX has
already aptly demonstrated, VTEC is an innovative solution to an
age-old automotive engineering problem. It elegantly solves the
trade-off between tuning an engine for either high-end horsepower or
low-end torque. With VTEC, Acura engineers no longer have to
compromise between the two. VTEC-equipped engines can have the best
of both.
The VTEC system uses three cam lobes and three corresponding rocker arms for each pair of valves. The VTEC system operates on both the intake and exhaust valves. The two outer cam lobes have a profile that optimizes low-speed torque and response. The middle lobe has a high-lift, longer-duration profile that is designed to optimize high-end horsepower.
The changeover point between low lift and high lift in the Type R is 5700 rpm (compared to 4400 rpm on the GS-R) for excellent midrange torque. This makes the Type R engine responsive under all operating conditions, especially when going from part-throttle, steady-state cruising to full throttle.
THROTTLE BODY/ INTAKE MANIFOLD/ AIR INTAKE
In the interests of high rpm, high output and weight reduction, the
Type R utilizes a large-diameter throttle body and exclusive
single-port intake manifold. Compared to the GS-R, the throttle bore
has been increased by 2 mm to 62 mm and the intake runners have
increased 7 mm in diameter from 35 mm to 42 mm to dramatically
increase intake flow, especially at high rpm.
The cast aluminum intake manifold features a large-diameter, single intake runner for each cylinder with a short, direct path to the cylinder head for maximum high-rpm efficiency. The single-port design also results in a 3.2 kg weight savings. Also, the fuel injectors point almost directly toward the center of the intake valves, helping to reduce fuel condensation on the intake port walls and improving driveability and engine response. To ensure a large amount of cool, fresh intake air, the air inlet has been moved from the engine compartment to an area behind the left-front fender.
EXHAUST SYSTEM
A major contributor to the Type R's ability to generate 195
horsepower from only 1.8 liters displacement is its highly efficient
exhaust system. The exhaust flow rate has been increased by 30
percent over the Integra GS-R model thanks to a number of
improvements. Starting with a large-diameter Tri-Y header system, the
individual head pipes gently converge into a tapered collector to
provide smooth flow with minimum obstruction. The stainless steel
header connects to a free-flowing exhaust system with significantly
increased pipe diameters, the addition of a third exhaust chamber,
and a performance-oriented muffler with a large NSX-style exhaust
tip.
ENGINE OIL COOLER
To maintain optimum engine oil temperature, the Type R features an
aluminum oil cooler for maximum heat dissipation and thermal
efficiency. The aluminum cooler is mounted on the engine block.
5-SPEED MANUAL TRANSMISSION
The main design goals of the Type R close-ratio transmission were to
take full advantage of the additional high-rpm power and provide
smooth, seamless shifting.
The close-ratio transmission used in the Type R model features different ratios, bearing design, and clutch than the GS-R. The changes were necessary to handle the higher output of the Type R engine and to extract maximum acceleration and performance from the 195 horsepower engine.
Like other Integra models, the Type R features a short-stroke shift linkage of exceptional rigidity. The system approaches the quality feel and short stroke of the Acura NSX shift linkage system.
For improved throttle response, the Type R utilizes a special lightweight flywheel coupled with a heavy-duty, hydraulically actuated clutch.
The Type R also employs a uniquely integrated aluminum die-cast engine stiffener for improved engine-to-transmission fastening rigidity to cope with additional engine output and high rpm. Vibration is reduced 22% compared to the traditional separate fore and aft fastening systems.
The Type R, like all Integra models, features equal-length halfshafts, which virtually eliminate torque steer.
HELICAL LIMITED-SLIP DIFFERENTIAL
Working in combination with a suspension setting designed to further
improve front-wheel grip, the Type R adopts a torque-sensitive
helical type limited slip differential for both improved traction and
reduced understeer in high-cornering load situations. The helical
gear generates repelling force in proportion to driving torque. This
repelling force, in turn, pushes the pinion gear toward the
differential gear casing, thus limiting the differential effect.
Compared to viscous coupling-type limited slip differentials, helical
limited slip differentials offer a more responsive, proactive torque
transfer. This allows improved traction not only when exiting tight
corners, but also when on slippery or uneven (undulated) road
surfaces.
100,000 MILE TUNE-UP INTERVAL
The Type R's first scheduled tune-up is required at 105,000 miles;
during that time only routine inspections and fluid changes are
required. Long-wearing, platinum-tipped spark plugs makes this
longevity possible. Careful design and engineering of the VTEC
valvetrain allows the 1.8-liter in-line four engine to reliably
maintain proper valve tappet clearances without inspection until the
scheduled first tune-up.
ON-BOARD VAPOR RECOVERY SYSTEM
The On-board Vapor Recovery System is standard -- two years earlier
than required by regulation.