TOVA Special : L-Series Engines Photo Gallery

The responses to my recent L-Series Technical Overview have been very good. I was happy to learn that many have since gotten a special appreciation of the technologies that Honda have put into this state of the art design. Since the Formula-1 race have kept me busy last weekend which means a delay in my Jazz VTEC review, given the good response to the L-series technical overview, I thought readers might appreciate me publishing some nice photos of the Lseries engine I have in my collection. These are all exhibit engines, cutaway models made from what looks like real engines all of which Honda used for display in various events. I took them over three separate events.

Except for the photos of the L15A i-DSI, all photos in this article have been resized from an original 3Megapixel resolution to XVGA (1024 X 768) resolution and saved for internet-use using a 'JPEG-High' setting. This is to offer the best balance between photo qualify and file size (and thus download speed). Each photo used in this article itself is 320 X 240 in resolution. For each of them, clicking on it will get to the XVGA photo.

L13A - 2003 Tokyo Motor Show

In the 2003 Tokyo Motor Show that I attended together with Jeff, Honda had a whole line-up of cutaway engines on display at their booth. One of them is a cutway exhibit of the original 1.3l SOHC i-DSI L13A. This is actually a 'moving exhibit' in the sense that the pistons, crankshaft, and valve train actually moves ! To simulate the effect of the dual spark plugs firing, Honda put LEDs inside the 2 spark plugs and light the LEDs up to represent the plugs firing. The WMV video on the right is taken using my Fuji S3800 camera's video capture mode. Somehow the camera captured the 'primary' plug firing as very bright but the 'secondary' is dim but still visible if one looks very carefully. Together they show very clearly the dual sequential firing sequence of the i-DSI system.

L15A i-DSI - Honda City Launch 2003

The set of two photos on the left are of the L15A i-DSI, introduced during the launch of the new Honda City way back in early 2003. This launch holds a rather special place in my memory as it is the first model launch that I was invited to attended by Honda Malaysia. In that event, Honda Malaysia put up an exhibit of a cutaway L15A i-DSI engine complete with the CVT gearbox, also in cutaway form.

Of special note in this photo is how the vertical cut of the cylinder head is placed to show the 2 valve - 2 spark-plug diagonal placement of the i-DSI system. The individual dedicated ignition coil distributor-less ignition system of the Lseries is also clearly shown here. Also note how the intake runners are not straight but curves to the left before they mate into the intake ports. The intake ports are also specially designed, and works in conjunction with the intake manifold to induce a swirl in the intake air-flow, one of the key features of the Lseries which helps deliver the excellent fuel economy.

The photos in this section are taken using my old VGA Fuji digital camera which has only 2Mb internal memory and so uses rather high JPEG compression. Consequently the photos are not of very high quality. The original photos are 640 X 480 (VGA) in resolution and so the downloadable full sized photos here are the original ones, at VGA resolution.

L15A VTEC - Honda City VTEC Launch 2004

This is a set of 6 photos, originally in 3M resolution but resized into XVGA (1024 X 768) resolution. They are of a cutaway exbibit of the L15A VTEC engine that Honda Malaysia put on display during the new Honda City VTEC launch late last year.

The 12V/16V VTEC system used in the L15A VTEC's cylinder head is the focus of most of the photos. But the most prominent and impressive component of the L15A VTEC must surely be its gorgeous stainless steel header. Honda assured me that this is an original item supplied as stock with all L15A VTEC engines.

Of special note is the cutaway section of the intake manifold. As can be seen from the corresponding photo above taken of the L15A i-DSI and the photo here, the Lseries intake manifold plenum features some interesting constructs inside. From the throttle body, an internal partition creates two passages. This partition extends halfway into the plenum, thus creating one passage for each set of 2 adjacent cylinders. What it seems to be designed to do is to prevent the two cylinders nearer the throttle body to interfere with the air-flow into the last two cylinders on the other end. So a dedicated passage is created to route air from the throttle body far into the end of the plenum in order to ensure that the two ending cylinders are able to get sufficient air-flow as well. This helps to ensure that all 4 cylinders will have a similar amount of air. This is important as we don't want some cylinders, typically the cylinders furthest from the throttle body to run slightly richer because of less air-flow into them caused by the earlier cylinders. This is a mild problem with a single throttle body intake system and is why some engines uses individual throttle body systems.

Two photos to note are the last two photos, which shows the cylinder itself. Take a good look at the piston top. The new narrow head design allowed the high 10.1 CR of the L15A VTEC to be achieved without having to resort to domed piston tops like those used in the B-series engines. As a result, Honda is free to design the piston top to promote swirl in the intake air-fuel mixture which helps deliver the excellent fuel economy from the L15A VTEC engine. This is why Honda makes such a big fuss of the new compact combustion chamber design. Also the piston top design on the exhaust side suggests that one of the exhaust valves has a more aggressive lift than the other. The slightly greyish colour of the piston skirts is caused by the layer of molybdenum powder coating.

Conclusion

I hope the photos offered for download in this article are worthwhile and readers enjoyed downloading them. My Jazz 1.5VTEC review is progressing reasonably well and I hope to be completing it by the end of the month.

Wong KN
March 2005
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