4 ms·

Just look at the cars they currently make. Highly tuned supercars not economical commuter vehicles. skeptical tech from one will transfer to the other. I used

Just look at the cars they currently make. Highly tuned supercars not economical commuter vehicles. skeptical tech from one will transfer to the other. I used to work for a supercar company, our unit price made certain tech possible, not even thinkable for mass-auto.

ehnto 7y ago
You're right, I wouldn't expect this level of performance from a commuter car with similar displacement. That said, Hyundai recently developed their Continuously Variable Valve Duration system, which looks to solve changing valve duration more affordably in an all mechanical system.
- ska 7y ago
  There are a few of these valve systems around (if i recall correctly they've been around for decades, really). BMW started putting them in motorcycles recently.
  - ehnto 7y ago
    You might be thinking of VVT or variable valve timing, which changes when the valve opens. Variable valve duration changes for how long it opens for and I think is a recent innovation. The latter allows for more efficiency as the engine at different speeds and loads requires more or less lift duration. It's also continuously variable across the RPM/load table, wheras most VVT systems just swap between two different activation timings and as such are always a compromise somewhere in the range. I have also seen a system that swaps between two different cam lobes entirely, offering two different cam profiles which can also vary valve duration and not just timing, but you're limited to two settings again, where these newer systems offer complete variability.
    - ska 7y ago
      No, these are not VVT. I might be misremembering, but I thought the new bmw system was dual cam - so exactly what you are suggesting, a trade off in the middle, but not vvt. At any rate, variable cam systems in bikes have certainly been around since the early 80s with one of the 400c cbrs. They never really caught on but there are a bunch of variations.
  - Grazester 7y ago
    Not with variable duration. Hyundai is the only car company doing that now.
    - kelchm 7y ago
      Worth noting that Rover apparently had a VVC system [1] that allowed the duration of intake valves to be continuously varied all the way back in 1995. [1]: https://www.autozine.org/technical_school/engine/vvt_4.htm https://www.autozine.org/technical_school/engine/vvt_4.htm
    - ska 7y ago
      Like I noted, not the same as they hyundai system, but not VVT either. And bikes, not cars.
  - ska 7y ago
    I should have been more explicit, but above is not incorrect. Honda had VTEC engines even back in the 80s, they physically choose between (three, if I recall correctly) cams. These are not pure VVT systems, although they are not continuous like the Hyundai.

ehnto 7y ago

You're right, I wouldn't expect this level of performance from a commuter car with similar displacement. That said, Hyundai recently developed their Continuously Variable Valve Duration system, which looks to solve changing valve duration more affordably in an all mechanical system.

ska 7y ago
There are a few of these valve systems around (if i recall correctly they've been around for decades, really). BMW started putting them in motorcycles recently.
- ehnto 7y ago
  You might be thinking of VVT or variable valve timing, which changes when the valve opens. Variable valve duration changes for how long it opens for and I think is a recent innovation. The latter allows for more efficiency as the engine at different speeds and loads requires more or less lift duration. It's also continuously variable across the RPM/load table, wheras most VVT systems just swap between two different activation timings and as such are always a compromise somewhere in the range. I have also seen a system that swaps between two different cam lobes entirely, offering two different cam profiles which can also vary valve duration and not just timing, but you're limited to two settings again, where these newer systems offer complete variability.
  - ska 7y ago
    No, these are not VVT. I might be misremembering, but I thought the new bmw system was dual cam - so exactly what you are suggesting, a trade off in the middle, but not vvt. At any rate, variable cam systems in bikes have certainly been around since the early 80s with one of the 400c cbrs. They never really caught on but there are a bunch of variations.
- Grazester 7y ago
  Not with variable duration. Hyundai is the only car company doing that now.
  - kelchm 7y ago
    Worth noting that Rover apparently had a VVC system [1] that allowed the duration of intake valves to be continuously varied all the way back in 1995. [1]: https://www.autozine.org/technical_school/engine/vvt_4.htm https://www.autozine.org/technical_school/engine/vvt_4.htm
  - ska 7y ago
    Like I noted, not the same as they hyundai system, but not VVT either. And bikes, not cars.
- ska 7y ago
  I should have been more explicit, but above is not incorrect. Honda had VTEC engines even back in the 80s, they physically choose between (three, if I recall correctly) cams. These are not pure VVT systems, although they are not continuous like the Hyundai.