CIF
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Not to go too off-topic, but this Honda oil issue is becoming a big deal it seems. Can't say I'm surprised though.
Also here's an example to dispel the media and internet myth that Honda is some excellent engineering powerhouse when it comes to consumer vehicles. Honda engines, including the very latest turbo Earth Dreams engines use solid valve lifters. These require periodic valve adjustment (a somewhat expensive and involved process that requires an experienced hand to be done properly) for optimal engine operation. Engines with such valves can also be fairly noisy as valve clearances get more out of spec. The benefit is strong and reliable high RPM operation and suitability for aggressive cam profiles. Also technically part of the valvetrain becomes more simple, but other parts of the valvetrain become a bit more complex to necessitate the ability to adjust the valves. In comparison some other competitors, specifically Toyota use hydraulic lifters (and other similar designs) on almost all their modern engines. These automatically adjust the valves keeping them continually in spec for the life of the engine. These engines run quieter overall, require less maintenance due to never needing valve adjustment and in theory offer longer engine life as the valve clearances are always in spec. In comparison to solid lifters, these do not handle high RPM operation all that well. Also the cylinder head design needs to be more complex and expensive, yet other parts of the valvetrain are simplified due to there being no need for accommodating valve adjustment.
There is another key difference between the two. Engines with solid lifters excel at making really good HP at high RPM, with decent HP at moderate RPM and so-so to poor HP at low RPM. Engines with solid lifters also typically make so-so torque numbers at low and moderate RPM, but pretty good torque numbers at high RPM. So in other words much of the engine power curve occurs at higher RPM. In comparison, engines with hydraulic lifters make decent to good HP and torque at low and moderate RPMs, but not great numbers at high RPMs. Solid lifters originate from high RPM race engines, whereas hydraulic lifters were created for consumer engines. So from the consumer market perspective, one can see the problem here. Honda's approach of using solid lifters requires more maintenance for the consumer, leads to generally a noisier engine and requires more work from any consumer driving a Honda as essentially the driver has to always push the engine to high RPM to extract optimal usable HP and torque out of it. In contrast, Toyota's modern approach for consumer engines ensures less maintenance and less hassle, overall quieter operation, and requires less work from the driver as the engine does not need to be pushed to a high RPM to extract optimal usable HP and torque out of it. Now yes different technologies like direct injection and turbos enhance both types of engines to different extents, but they don't change the fundamental nature of each type of valve design.
So in conclusion, Honda's approach is great for high RPM performance applications or high RPM tuning (like in high RPM motorcycles, Honda's core product strength), but not very practical for real world consumer use. Honda's use of turbos does mitigate some of the real world drawbacks of solid lifters for regular consumers, but brings some new problems. Mainly Honda's modern Earth Dreams turbo engines are fairly high maintenance and as we can see with this on-going oil issue, are not that reliable. Many enthusiasts will say that Honda has excellent engineering because they apply their race technology to consumer vehicles. Very few bother to ask why, and at what cost? The average consumer has zero need for a vehicle with an engine that is designed for high RPM operation and tuned with aggressive cam profiles, especially in modern big cities with lots of stop and go traffic. I can personally attest to this, having previously owned a Honda and having test driven many Hondas in heavy stop and go traffic. Every single one personally was a pain to drive in stop and go traffic. I have not test driven any Honda with a turbo Earth Dreams engine yet, but given all these engines are single conventional turbo running fairly high boost pressure combined with solid valve lifters, I can already imagine they would still be a pain to drive in heavy stop and go city traffic.
Also here's an example to dispel the media and internet myth that Honda is some excellent engineering powerhouse when it comes to consumer vehicles. Honda engines, including the very latest turbo Earth Dreams engines use solid valve lifters. These require periodic valve adjustment (a somewhat expensive and involved process that requires an experienced hand to be done properly) for optimal engine operation. Engines with such valves can also be fairly noisy as valve clearances get more out of spec. The benefit is strong and reliable high RPM operation and suitability for aggressive cam profiles. Also technically part of the valvetrain becomes more simple, but other parts of the valvetrain become a bit more complex to necessitate the ability to adjust the valves. In comparison some other competitors, specifically Toyota use hydraulic lifters (and other similar designs) on almost all their modern engines. These automatically adjust the valves keeping them continually in spec for the life of the engine. These engines run quieter overall, require less maintenance due to never needing valve adjustment and in theory offer longer engine life as the valve clearances are always in spec. In comparison to solid lifters, these do not handle high RPM operation all that well. Also the cylinder head design needs to be more complex and expensive, yet other parts of the valvetrain are simplified due to there being no need for accommodating valve adjustment.
There is another key difference between the two. Engines with solid lifters excel at making really good HP at high RPM, with decent HP at moderate RPM and so-so to poor HP at low RPM. Engines with solid lifters also typically make so-so torque numbers at low and moderate RPM, but pretty good torque numbers at high RPM. So in other words much of the engine power curve occurs at higher RPM. In comparison, engines with hydraulic lifters make decent to good HP and torque at low and moderate RPMs, but not great numbers at high RPMs. Solid lifters originate from high RPM race engines, whereas hydraulic lifters were created for consumer engines. So from the consumer market perspective, one can see the problem here. Honda's approach of using solid lifters requires more maintenance for the consumer, leads to generally a noisier engine and requires more work from any consumer driving a Honda as essentially the driver has to always push the engine to high RPM to extract optimal usable HP and torque out of it. In contrast, Toyota's modern approach for consumer engines ensures less maintenance and less hassle, overall quieter operation, and requires less work from the driver as the engine does not need to be pushed to a high RPM to extract optimal usable HP and torque out of it. Now yes different technologies like direct injection and turbos enhance both types of engines to different extents, but they don't change the fundamental nature of each type of valve design.
So in conclusion, Honda's approach is great for high RPM performance applications or high RPM tuning (like in high RPM motorcycles, Honda's core product strength), but not very practical for real world consumer use. Honda's use of turbos does mitigate some of the real world drawbacks of solid lifters for regular consumers, but brings some new problems. Mainly Honda's modern Earth Dreams turbo engines are fairly high maintenance and as we can see with this on-going oil issue, are not that reliable. Many enthusiasts will say that Honda has excellent engineering because they apply their race technology to consumer vehicles. Very few bother to ask why, and at what cost? The average consumer has zero need for a vehicle with an engine that is designed for high RPM operation and tuned with aggressive cam profiles, especially in modern big cities with lots of stop and go traffic. I can personally attest to this, having previously owned a Honda and having test driven many Hondas in heavy stop and go traffic. Every single one personally was a pain to drive in stop and go traffic. I have not test driven any Honda with a turbo Earth Dreams engine yet, but given all these engines are single conventional turbo running fairly high boost pressure combined with solid valve lifters, I can already imagine they would still be a pain to drive in heavy stop and go city traffic.
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