jhmek4 dohc vtec

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VTEC was initially designed to increase the power output of an engine to 100 HP/litre or more while maintaining practicality for use in mass production vehicles. Some later variations of the system were designed solely to provide improvements in fuel efficiency.

Japan levies a tax based on engine displacement, and Japanese auto manufacturers have correspondingly focused their research and development efforts toward improving the performance of smaller engine designs through means other than displacement increases. One method for increasing performance into a static displacement includes forced induction, as with models such as the Toyota Supra and Nissan 300ZX which used turbocharger applications and the Toyota MR2 which used a supercharger for some model years. Another approach is the rotary engine used in the Mazda RX-7 and RX-8. A third option is to change the cam timing profile, of which Honda VTEC was the first successful commercial design for altering the profile in real-time.

The VTEC system provides the engine with multiple cam lobe profiles optimized for both low and high RPM operations. In basic form, the single barring shaft-lock of a conventional engine is replaced with two profiles: one optimized for low-RPM stability and fuel efficiency, and the other designed to maximize high-RPM power output. The switching operation between the two cam lobes is controlled by the ECU which takes account of engine oil pressure, engine temperature, vehicle speed, engine speed and throttle position. Using these inputs, the ECU is programmed to switch from the low lift to the high lift cam lobes when the conditions mean that engine output will be improved. At the switch point a solenoid is actuated which allows oil pressure from a spool valve to operate a locking pin which binds the high RPM cam follower to the low RPM ones. From this point on, the valves open and close according to the high-lift profile, which opens the valve further and for a longer time. The switch-over point is variable, between a minimum and maximum point, and is determined by engine load. The switch-down back from high to low RPM cams is set to occur at a lower engine speed than the switch-up (representing a hysteresis cycle) to avoid a situation in which the engine is asked to operate continuously at or around the switch-over point.

The older approach to timing adjustments is to produce a camshaft with a valve timing profile that is better suited to high-RPM operation. The improvements in high-RPM performance occur in trade for a power and efficiency loss at lower RPM ranges, which is where most street-driven automobiles operate a majority of the time. Correspondingly, VTEC attempts to combine high-RPM performance with low-RPM stability.

VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC. In the regular four-stroke automobile engine, the intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes determines the timing, lift and duration of each valve. Timing refers to an angle measurement of when a valve is opened or closed with respect to the piston position (BTDC or ATDC). Lift refers to how much the valve is opened. Duration refers to how long the valve is kept open. Due to the behavior of the working fluid (air and fuel mixture) before and after combustion, which have physical limitations on their flow, as well as their interaction with the ignition spark, the optimal valve timing, lift and duration settings under low RPM engine operations are very different from those under high RPM. Optimal low RPM valve timing, lift and duration settings would result in insufficient filling of the cylinder with fuel and air at high RPM, thus greatly limiting engine power output. Conversely, optimal high RPM valve timing, lift and duration settings would result in very rough low RPM operation and difficult idling. The ideal engine would have fully variable valve timing, lift and duration, in which the valves would always open at exactly the right point, lift high enough and stay open just the right amount of time for the engine speed in use.

DOHC VTEC

Introduced as a DOHC (Double overhead camshaft) system in Japan in the 1989 Honda Integra[1] XSi which used the 160 bhp (120 kW) B16A engine. The same year, Europe saw the arrival of VTEC in the Honda CRX 1.6i-VT, using a 150 bhp variant (B16A1). The United States market saw the first VTEC system with the introduction of the 1991 Acura NSX, which used a 3-litre DOHC VTEC V6 with 270 bhp (200 kW). DOHC VTEC engines soon appeared in other vehicles, such as the 1992 Acura Integra GS-R (B17A1 1.7-litre engine), and later in the 1993 Honda Prelude VTEC (H22A 2.2-litre engine with 195 hp) and Honda Del Sol VTEC (B16A3 1.6-litre engine). The Integra Type R (1995–2000) available in the Japanese market produces 197 bhp (147 kW; 200 PS) using a B18C5 1.8-litre engine, producing more horsepower per liter than most super-cars at the time. Honda has also continued to develop other varieties and today offers several varieties of VTEC, such as i-VTEC and i-VTEC Hybrid.

SOHC VTEC

As popularity and marketing value of the VTEC system grew, Honda applied the system to SOHC (single overhead camshaft) engines, which share a common camshaft for both intake and exhaust valves. The trade-off was that Honda's SOHC engines benefitted from the VTEC mechanism only on the intake valves. This is because VTEC requires a third center rocker arm and cam lobe (for each intake and exhaust side), and, in the SOHC engine, the spark plugs are situated between the two exhaust rocker arms, leaving no room for the VTEC rocker arm. Additionally, the center lobe on the camshaft cannot be utilized by both the intake and the exhaust, limiting the VTEC feature to one side.

However, beginning with the J37A4 3.7L SOHC V6 engine introduced on all 2009 Acura TL SH-AWD models, SOHC VTEC was incorporated for use with intake and exhaust valves. The intake and exhaust rocker shafts contain primary and secondary intake and exhaust rocker arms, respectively. The primary rocker arm contains the VTEC switching piston, while the secondary rocker arm contains the return spring. The term "primary" does not refer to which rocker arm forces the valve down during low-RPM engine operation. Rather, it refers to the rocker arm which contains the VTEC switching piston and receives oil from the rocker shaft.

The primary exhaust rocker arm contacts a low-profile camshaft lobe during low-RPM engine operation. Once VTEC engagement occurs, the oil pressure flowing from the exhaust rocker shaft into the primary exhaust rocker arm forces the VTEC switching piston into the secondary exhaust rocker arm, thereby locking both exhaust rocker arms together. The high-profile camshaft lobe which normally contacts the secondary exhaust rocker arm alone during low-RPM engine operation is able to move both exhaust rocker arms together which are locked as a unit. The same occurs for the intake rocker shaft, except that the high-profile camshaft lobe operates the primary rocker arm.

The difficulty of incorporating VTEC for both the intake and exhaust valves in a SOHC engine has been removed on the J37A4 by a novel design of the intake rocker arm. Each exhaust valve on the J37A4 corresponds to one primary and one secondary exhaust rocker arm. Therefore, there are a total of twelve primary exhaust rocker arms and twelve secondary exhaust rocker arms. However, each secondary intake rocker arm is shaped similar to a "Y" which allows it to contact two intake valves at once. One primary intake rocker arm corresponds to each secondary intake rocker arm. As a result of this design, there are only six primary intake rocker arms and six secondary intake rocker arms.

K SERIES VTEC ENGINE

The K-Series engines have two different types of i-VTEC systems implemented. The first is for the performance engines like in the RSX Type S or the Civic Si and the other is for economy engines found in the CR-V or Accord. The performance i-VTEC system is basically the same as the DOHC VTEC system of the B16A's; both intake and exhaust have 3 cam lobes per cylinder. However the valvetrain has the added benefit of roller rockers and continuously variable intake cam timing. Performance i-VTEC is a combination of conventional DOHC VTEC with VTC.

The economy i-VTEC is more like the SOHC VTEC-E in that the intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust cam. The two types of engine are easily distinguishable by the factory rated power output: the performance engines make around 200 hp (150 kW) or more in stock form and the economy engines do not make much more than 160 hp (120 kW) from the factory.

NSX Type R
Main article: Honda NSX

NSX Type R
Honda produced a very limited number of NSX Type R in 1992 for Japan. Major changes include a more aggressive suspension and an extensive weight reduction to 1230 kg from the normal NSX weight of 1350 kg. The NSX Type R was track oriented and, to reduce weight, lacked sound deadening, audio, electric windows and air conditioning. The NSX type R's role was fulfilled by the NSX type S Zero in 1997.

A second iteration of the Type R, dubbed NSX-R, was released in 2002, again exclusively in Japan. The NSX-R had a more aggressive rear spoiler and hood vent, along with various refinements to reduce weight to 1270 kg. Under the body, panels and air fences in the front, along with a small rear diffuser, produced balanced downforce. These subtle changes along with its renowned handling kept the NSX-R competitive on the track against considerably higher-powered cars.

Integra Type R
Main article: Honda Integra

1998 Honda Integra for the European market
The DC2 Type R came standard with a 200 PS (figure may vary in different countries, 195 hp USDM) 1.8-litre DOHC VTEC engine, known as the B18C5 (US) or B18CR (Japan), and other versions depending on the country where it was sold. Equipped with a close ratio 5-speed manual transmission and a Helical LSD, the DC2 Integra Type R had significantly improved performance and handling relative to the base model GS-RSiSiR Integra. Type R had the minor change long headlights that remained only for the JDM models while the world market version had the pre-facelift double round lights.

In 1995, Honda introduced their first Integra Type R to the Japanese domestic market.

The world market ITR feature virtually the same power train and engine controls as the JDM 1996 ITR. Noted differences in the exhaust manifold with the JDM ITR manifold (identical to JDM GS-R being the largest), UKDM ITR has the smallest with a unique 4 to 2 twin wall tube manifold. World ITR have a 2" ID cat, JDM ITR has a "2.5" OD cat, all ITR have 2 and 1/4 exhaust systems with 2.0" chock points. JDM ITR +100 RPM fuel cut to 8500 RPM. USDM ITR has a .4 reduction in CR to 10.6:1.

Quarter-mile times for USDM ITR best test: 14.5@96 mph (sports compact car 2000). Most test show the ITR to be in the high 14s at 94 mph. JDM ITR 1996 and 1998 are identical for base model ITR at 14.2@98 mph in the 400 meter (unknown roll-out, speed estimated).

1998 JDM ITR have a 4 to 1 twin wall header. 1998 JDM and AuDM ITR feature a different gear (4.7) and fifth gear ratio, yielding near the same overall final gear ratio but much steeper 1 to 4th gear ratios for better take-off and response. All ITR 1998+ have a slightly larger intake cam.

The base model went through extensive changes, including a strengthened chassis with extra spot welds and thicker metal around the rear shock towers and lower subframe, weight reduction (reduced sound insulation, 10% thinner windscreen, no sunroof, lighter wheels), more power, stratospheric 8400 RPM red line, hand built engine featuring hand-polished and ported intake ports, high compression pistons with low friction coating, undercut valves and revised intake and exhaust systems, and suspension upgrades. The result was a capable[clarification needed] sports coupe which was acclaimed by motoring journalists worldwide.[who?]

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Listed weights
curb weight ITR 1997 US no A/C at 2560 lb (Car and Drive), 2633 lb for 2000 USDM ITR which includes: A/C, rear wiper, assume side impact crush beam AuDM 2001 ITR 2397 lbs Motor January 2001, JDM 1996 ITR listed as 2325 lb JDM 1998 ITR 2420 lbs. The 1997 USDM ITR is the lightest USDM version with a curb weight (full fluids) of 2560 lbs (Car and Driver 1997). USDM added structural material for safety estimate: front and rear bumpers and associated crumple zones +25 lb, door safety brace and dense foam padding approximately +15 lb,rear seat crush brace and welded in B pillar support boxes +25 lb => total 65 lb to the car. Different safety features added to world ITR at different times.

1998 AuDM ITR weight gain (compared to VTi-R) test weight listed by Wheels 1994 at 1176 kg, 2593 lbs, similar to USDM GS-R but without spoiler and CC, test car included A/C.

Using actual Wheels Magazine test weight of 1176 kg for VTi-R -40 kg listed AuDM Type R weight reduction yields at approximately a 1136 kg (2504 lb) AuDM ITR test weight.

Note about car weight: USDM curb weight is a car with all fluids topped off, curb weight is really shipping weight for AuDM, JDM, and UKDM (assume shipping weight fluid levels of 2.2 gallons of fuel, a full tank would add 67 lb).

Honda lost money on every single vehicle sold, even though extra dealer markups sometimes made for excessive dealer profit.[citation needed] Honda produced the DC2 Type R for homologation purposes to meet FIA certification of the motor and the chassis changes to make the car more competitive in N-series and World Cup racing. The details required hand tooling in early versions and finishing the product through the use of various small fabrication shops in Japan made for increased costs in manufacture that could not be made up in the list price of the vehicles. Honda (and Acura in the US) deemed the car important for the marque's image and important for the racing programmes of the era, and the parent company therefore accepted a financial net loss on each vehicle sold.[citation needed]

It has been acclaimed by motoring journalists world-wide, including Evo magazine, who named the Type R "the greatest front-wheel-drive performance car ever"[1] and TheAutoChannel.com, who also named it 'the best handling front-wheel drive car ever.'[2]

The DC5 Type R (Japanese market only) comes standard with a K20A 220 hp (164 kW) 2.0-litre DOHC i-VTEC four-cylinder engine. The "i" in i-VTEC stands for intelligent VTEC, which employs VTC (Variable Timing Control) to advance or retard the timing up to 50 degrees. The DC5 comes equipped with Recaro seats, four-piston Brembo front brakes, a close-ratio six-speed manual transmission, a limited-slip differential, and a stiffer suspension.

Accord Type R/ Euro-R
Main article: Honda Accord

EDM 'CH1' Face-lifted 2002 Accord Type-R

JDM 'CL1' Accord Euro-R
The Honda Accord Type-R (ATR) was produced from 1998 to 2003 using the CH1 Accord chassis and sold in UK/EU markets, the JDM Accord Euro-R uses the CL1 chassis, Using a naturally aspirated 2.2-litre four-cylinder DOHC H22A7 "Red Top" VTEC motor which produces 217 bhp (220ps, 161.8Kw)and the EDM produces 210 bhp (212ps, 155.9Kw) @ 7,200 rpm and 164 lb·ft (222 N·m) @ 6,700 rpm. The Type-R Accord model is differentiated by a number of sporting features including, but not limited to, stiffer suspension and chassis, Torsen limited-slip-differential, twin-piston brakes, dual exhaust system, 17-inch alloy wheels, Xenon headlights, Recaro seats and a leather-trimmed Momo steering wheel. As an option, there was a distinctive tall and functional rear spoiler wing that most customers opted for.

Not so demanded among the crowd presently due to its family four-door configuration, it is the most international awarded basic version of the Type-R's, since it (the Accord) was battling with great success in the 2000 European Super Touring Cup season.

Its successor is the CL7 Accord Euro-R, produced 2004–2007 built in Sayama, Japan for the JDM market, it came with a K20AI-VTEC motor {Displacement: 1998 cc, Compression: 11.5:1, power: 220 bhp (220 PS,162 kW) @ 8000 rpm, torque: 152 ft·lbf (206 N•m) @ 7000 rpm and a Redline of 8800 rpm} same as the '02–'06 Integra Type R. It has the standard Type R modifications – including Recaro seats, a limited-slip-differential and independent double-wishbone suspension.

Civic Type R
Main article: Honda Civic Type R
The 1997 EK9 Civic was the first to be given the Type R badge. Based on the EK4 SiR chassis it featured a Type R prepared B16B engine producing 185 PS (182 hp), stiffer chassis, upgraded sway bars and strut bars, Recaro alcantara seats, 15-inch alloy wheels and a large boot spoiler. Since then, most generations have offered a Type R variant. The Type R version of the Civic has never been sold outside of Japan until the introduction of the 2nd generation chassis.

Honda S2000
F20C
Displacement: 1,997 cc (121.9 cu in)
Compression: 11.7:1 (Japan), 11.0:1 (North America, Europe)
Bore: 87 mm (3.4 in)
Stroke: 84 mm (3.3 in)
Rod Length: 153 mm
Rod/stroke ratio: 1.82
Power:
JDM 250 PS (183.88 kW) @ 9,200rpm & 22.2kgm (217.71 Nm) @ 7,500 rpm
USDM 240 HP @ 8,300 rpm; 153 ft lb, 207 Nm @ 7,500 rpm
Redline: 8900 rpm
VTEC: "around 6000 rpm" [3]
The F20C was designed with high maximum rpm capability in mind, for increased power output; redline is at 8900 rpm, with VTEC engagement at 6000 rpm. Its relatively long stroke of 84mm results in a mean piston speed of 4965 ft/m, or 25 m/s, second highest than any other production car to date.[4] It is only beaten by the B7 Audi RS4 (2006-2008). Power output is 240 bhp (179 kW) at 8300 rpm in North America and Europe. The Japanese version, which has a higher compression ratio, is capable of 250 PS (247 bhp) at 8600 rpm. Honda's F20C Engine won a spot on Wards' 10 Best Engines List four times, in 2000, 2001, 2002 and 2003.

The engine displaces 1,997 cc (121.9 cu in), lending to the Honda S2000's name. This method of naming follows suit with the rest of the Honda S roadsters (i.e. Honda S500, S600, and S800).

Applications:

1999-2005 Honda S2000 (Japan)
2000-2003 Honda S2000 (F20C1) (North America)
1999–2009 Honda S2000 (United Kingdom, Europe, Australia)
The F20C produces the highest specific power output for any naturally aspirated 2.0L piston engine in a car priced under US$100,000, at 123.5 hp (92.1 kW) per liter, ahead of the SR16VE N1 found in the homologation version of JDM Nissan Pulsar producing 197 bhp (147 kW) for a specific power of 123.45 bhp (92.06 kW) per liter. The F20C held the record for producing the highest specific power output for any mass production naturally aspirated piston engine until Ferrari released the 458 Italia and Porsche the GT3 RS 4.0 in 2010/2011, which produce 124.5 HP/L / 125 HP/L, respectively.

F22C1

F22C1
Displacement: 2,157 cc (131.6 cu in)
Compression: 11.1:1 (North America, Europe)
Bore: 87 mm (3.4 in)
Stroke: 90.7 mm (3.57 in)
Power:
USDM 240 HP @ 7,800 rpm; 162 ft lb @ 6,500 rpm[5] (revised to 237 hp (177 kW) @7800 rpm in 2005 per SAE Certified Power standard)[6]
Redline: 8200 rpm
VTEC: "around 6000 rpm" [7]
In 2004, Honda produced a stroked 90.7 mm (3.57 in) version of the F20C, increasing displacement by 160 cc (9.8 cu in) to 2,157 cc (131.6 cu in). Dubbed the F22C1, it was originally designed for the North American market being introduced for the 2004 model year. Maximum power output was maintained at 240 hp (180 kW) @7800 rpm. Rated torque increased from 153 lb·ft (207 N·m) at 7500 rpm for the F20C to 162 lb·ft (220 N·m) at 6500 rpm for the F22C. The redline was reduced from 8900 rpm to 8200 rpm, mandated by the longer travel distance of the pistons. Peak horsepower output was originally rated identical to the F20C, with "overall powerband characteristics strengthened 4% to 10% between 1000 -8000 rpm".[8]

The F22C1 was used exclusively in the North American market for 2004 and 2005 with the F20C being used in all other markets. In 2006, the engine fully replaced F20C engines in the Japanese market as well which resulted in a drop in rated power output from 250 PS (247 bhp) to 242 PS (239 bhp). Outside of Japan and the United States, the F20C continued to be the only available engine.

Applications:

2004–2009 Honda S2000 (F22C1)(North America)
2006–2009 Honda S2000 (Japan)