Reduced internal friction directly leads to less power loss inside the engine and thus more power (from the combustion of the A/F mixture) delivered to the flywheel.
2. Increased Torque
For improved driveability, Honda has been concentrating on torque on their newer engines. Actually more torque at a specific rpm directly means more power at the same rpm but the common term used by car enthusiasts nowadays in that 'torquey' implies more acceleration (due to more power across the rpm range) while 'powerful' can often mean a 'torqueless' engine with all the power coming in at high rpms. In this case, the objective and achievement of the R18A is more torque throughout the rpm range (as compared to the D17A) or alternately and equally as correct, more power throughout the rpm range (take a look at the power chart above to see what I mean).
Specific technologies used to achieve improved torque are listed as
• a new variable-length intake manifold
• Piston Oil jets (similar to those used in the B-series engines)
Of the two items, the new variable length intake manifold is one of the core components of the R18A that is responsible for its torque/power delivery so we will take a closer look at this.
Variable Length Intake Manifold
While the R18A does not rely on traditional VTEC mechanisms to deliver a broad torque/power band, it instead exploits the principle of intake tract resonance to deliver more or less the same result - that of merging two different though relatively narrow torque curves together to a combined curve that is delivers high torque across a much broader rpm band. This is achieved from the new intake manifold which features two sets of intake runners (from the plenum), effectively a variable length intake manifold.
The principle of variable length intake manifold depends upon the resonance of air inside the intake tract. Intake tract here includes the intake manifold and the air-filter system, i.e. from the air-filter right up to the intake valves. When the intake valves open and close, they create air pulses which flow along the intake tract. These air-pulses or sound waves are responsible for the intake roar (or noise, depending on who makes the engines). The frequency of the sound waves is determined by how fast the intake valves are opening and closing - how fast the engine is spinning or engine RPM. An engine spinning at 3.000rpm will create a sound wave at roughly 50Hz.
All sound waves will have resonance points which depend upon the frequency of the sound (or alternately, its wavelength). These are known as the resonance frequencies. When the wavelength for the resonance frequency coincides with the length of the intake tract, high pressure points will be created at the intake valves, higher than atmospheric pressure. This will help in the filling of the cylinders. More air means more fuel can be injected and this means more power. So all engines will feature a specific peak in torque (or power) which is influenced by this resonance frequency. For many Honda engines with a standard intake manifold (e.g. the B16A), this resonance frequency is usually around 3,000rpm. This is also why when we replace the standard air-filter with an open element system, we can destroy the mid-range torque of the engine if we do not make sure that we place our fancy new air-filter back in the same place as the original air-filter box of the stock intake system. This is because if we place the filter too close to the intake manifold, by using a very short metal pipe for e.g., we will effectively change the length of the intake tract and thus the resonance frequency it supports (a short intake tract will have a higher resonance frequency).
The principle of a variable length intake manifold, usually with dual runners like the one used on the R18A is that they make use of two sets of intake runners. One set is designed to have a resonance at a lower frequency (or engine rpm) while at a higher rpm, a 2nd set of much shorter intake runners will be used. This shorter intake runner will of course feature a resonance frequency which is higher. So the 2 sets of intake runners will deliver more or less two separate torque peak or effectively two slightly different torque/power curves. By using the same technique as with VTEC, by selecting the right point to activate the 2nd set of runners, we will be able to combine the two torque/power curves together to deliver a single curve which delivers torque/power across a much broader rpm.
One limitation is that dual runner intake manifolds do not have the same 'bandwidth' as that delivered via valve timing. Also the actual length of the intake runners are constrained by physical space so the two torque curves won't be spaced too far apart. So there are constraints to how far apart the two torque curves are as well as how 'wide' an rpm range they cover. Thus while in principle we can deliver the same benefits with variable length intake manifolds as with a traditional VTEC mechanism, in practise, we cannot work across the same very wide rpm range as VTEC. This is partially (not totally) why the R18A does not have a very high redline.
3. More compact dimensions
In pursuit of their "Man Max-Machine Min' principle, Honda has been introducing smaller and smaller engines. The new R18A is no exception and features a more compact size than the outgoing D17A, despite delivering an extra 100 c.c. of engine capacity. Honda R&D listed two areas for this achievement:
• narrow cam chain
• chain case with built-in oil pump
4. Quiet Operation
Engine 'noise' at both idle and when operating has been reduced with the R18A which Honda attributes to the use of a new Lower block construction for the engine block.




The new MAF sensors
5. Emissions
Acheiving lower emission levels (ULEV and ZLEV being the target) is the other target Honda has for their new range of engines and to deliver a new level of (low) emissions, Honda has employed the following with the R18A :
• 2-bed catalytic converter located immediately after the mainfold
• "Leading-edge" control systems : DBW and airflow sensors
Similar to the K20Z, the R18A employs MAF (mass air-flow) sensors in the air-filter box as well as the exhaust manifold to supplement the MAP sensor in the throttle body. In the Q&A session, I asked about the rationale in using both types of sensors. Honda R&D says they allow them to meter the air-fuel ratio in the engine a lot more accurately than just using either sensors alone and this is crucial to allowing them to achieve more efficient combustion of the a/f mixture, directly leading to more power, better fuel economy and lower emissions.
6. Reduced Weight
Besides being smaller in physical dimensions, the R18A is also lighter than the D17A which Honda attributes to
1. Aluminium VTEC rocker arms
2. integrated cylinder head and exhaust manifold (meaning they come casted as a single item)
3. Plastic head cover
4. High strength cracked connecting rods. The conrods are now casted as a single piece and then 'cracked' apart at the proper place. This gives a very close contact patch when they are bolted over the crankshaft)
5. plastic intake manifold, a 'trick' borrowed from the L-series engines
Some of the parts above, (such as the aluminium rocker arms) also reduce the weight of the internal working components and help in reducing internal power loss.
Drive-By-Wire
Both the K20Z and this R18A engine feature a new Drive By Wire (DBW) system which Honda says allows them to deliver "Exhilarating (throttle) Response" from the R18A engine. A very enlightening explanation was given when Honda R&D showed in the presentation a comparison of the acceleration versus throttle pedal position for the Civic 1.8S.
Note that the VW Bora is being used as the benchmark. While the 'target' remains the Toyota Altis, Honda is also targeting the 'continental' alternatives with this new Civic, hence the use of the VW Bora when tuning throttle response. Within Asia, it is generally held (whether correctly or not) that the continental marques deliver good 'driving feel' so cars from VW, Peugeot, Audi and so forth have been examined during the R&D of this new Civic.
NVH








NVH is another area which Honda R&D focussed on in the development of the R18A. Specifically they looked the 'High frequency range', i.e. how much 'noise' the R18A delivers in the higher frequencies.
The graph on the left shows their achievement in this area. Honda R&D itemized the following areas as being the main focus during development:
• Intake Sound
• A New "Torque Rod Mount" system
In addition, to reduce intrusion of outside noise into the cabin, Honda also employed sound insulation techniques.
A new 'torque rod mount' system was designed to supplement the standard engine mount system. This system consists of an upper and a lower torque rod added to the engine-gearbox package and helps to reduce vibration and twisting of the engine during application of throttle. The net result is the reduction of 'booming noise' from the engine in the high frequency range.




For sound absorption, this was done through a new "soundproof package" which helped in 'Improved Quietness' via the reduction of outside noise intrusion. These was done using double door seals and a special 'Sound absorbing door hole seal' which is a special hole opened up inside each door which serves to cancel out outside noise through resonance (see diagram).
There is also use of sound absorbing materials for improved sound insulation, specifically in the roof lining and the use of insulating floor carpets.
When Honda launched the new 8G Civic, they made a lot of reference to how much attention was paid to details - to regain back as much of the 'Civic DNA' of old as they can. One of the most important areas in this case was the sound of the engine, or rather how the engine sounds when pushed hard. Honda made lots of reference to how they actually tuned the engine sound when designing this new Civic.
In the area of engine sound, the target was to generate a 'Linear Engine Sound Output'. The D17A's sonic 'signature' was severely lacking (to be frank) in this area. So the new R18A was literally designed to 'make all the right noises at the right place' ! Honda characterized it as 'Sporty Intake Sound Tuning' (to improve the 'sonic quality' of the intake roar) and one of the places they paid a lot of attention to was in the specific tuning in the intake system (air filter system) by the use of 'optimized intake parts'. This comprises 4 main areas, identified in the diagram above on the left and which are :
1. A 'silencing device' for frequency change in the air-filter box
2. optimized Air cleaner SHAPE
3. Optimized duct length - note how the intake duct is twisted
4. A 'silencing device (for) frequency change' put in the middle of the intake duct, specifically for the tuning of the engine sound !
The sonic tuning involves the reduction of engine sound during low-rpm operation and an increase of the "High rpm intake sound", i.e. roar of the intake at high rpms was increased. The overall target was to produce a more linear engine sound during WOT runs. The achievements in this area are identified in the graph on the left.
So the idea is that the engine should be quiet when baby'ed but be suitably 'noisy' when pushed hard - clearly catering to the wishes of Honda enthusiasts ! After years of being told by us (enthusiasts), it looks like Honda R&D finally understood that the sound of an accelerating (Honda) engine is an extremely important and integral part of the Honda driving experience.
The careful attention paid to the engine sound during WOT runs for both the K20Z and R18A are explained by the term 'Linear Engine sound output' and is highlighted in the graph below.



Interior sound level at WOT for Civic 1.8S Engine sound achieved level for front seat middle sound
Like the K20Z, the R18A is now designed to work in conjunction with the new 5AT gearbox as a 'package'. The specific areas of improvement for the new 5AT have already been covered in the K20Z technical review so we will not be going through it again here.
Conclusions
During the launch of the new Civic, it was clear that Honda is quite proud of what they have managed to achieve with the new R18A engine for the new 8G Civic. What should now be clear from this article? Remember that 140ps max power output from a 1.8l engine can rightfully be considered 'very high spec', ignoring the standards set by Honda themselves with the original B18C engines. This can be supported if we compare the R18A output with those from competitors including 'high specification' twin-cam engines of similar size. For e.g. the 1.8l DOHC Twin-Spark engine used in the Alfa Romeos are delivering 140ps as are the 1.8l DOHC EFi engines used in the local (Malaysian made) hot-hatches like the Proton Satria GTi and Proton Putra. This is also comparable to the 1.8l Toyota Altis (138ps) and superior to the 1.8l Nissan Sentra (130ps).
Coupled with potentially exceptional fuel economy (for a 1.8l engine) and specific characteristics targeted to please long time Honda enthusiasts, it is clear how technically advanced the new R18A engine is.
I was truly impressed by how much technology was in the new R18A when I sat through the presentation. Ignore common misconceptions that 'SOHC means low tech while DOHC means high tech'. Owners of the new 8G Civic 1.8S should be proud and reassured that their new 1.8l SOHC i-VTEC engine is truly 'state of the art' !

I hope that explains everything about the FD1