Comment by toxik

5 years ago

This was excellent, but should perhaps be clarified that this is a gasoline engine - diesels don’t ignite by spark, but by immense pressure in the chamber. This also invalidates the “you cannot add fuel to increase power” of gasoline engines. Diesels can (and should!) run at lower rpm; they don’t stall because the ECU can add fuel to increase power output.

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toxik

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keanebean86  5 years ago

What I want to try is replacing valves with electric iris mechanisms. The computer would signal the iris to open or close depending on the situation.

No more complicated variable valve stuff. Just hold the iris open longer. Also no more interference engines and timing chain/belt changes.

Iris: https://commons.m.wikimedia.org/wiki/File:Iris_Diaphragm.gif

Edit: fixed typo, added link to iris gif

  • addison-lee  5 years ago

    I don’t think an iris like that would last very long with the immense pressures in the cylinders. It makes way more sense to electronically control the valves themselves, like Koenigsegg is doing with their Freevalve tech, so you get the mechanical seal of the valve with the control of electronics.

  • toxik  5 years ago

    It’s a good question, why is only fuel injection and ignition computer controlled? The intake and exhaust valves must also be solenoid controllable.

    • LeonM  5 years ago

      Swedish hypercar builder Koenigsegg has made a system like this, they call it FreeValve.

      Their upcoming car called the Gemera will feature FreeValve, its 2.0L 4-cylinder is said to generate over 600HP. Though it must be said that this is a 1.5 million dollar car, so don't expect this kind of performance per displacement from other brands.

      A guy on Youtube made his own version of freevalve, and got it to work on a Mazda Miata: https://www.youtube.com/watch?v=E9KJ_f7REGw

    • golemiprague  5 years ago

      Because of reliability and the potential damage, not injecting fuel is not such a big deal but a stucked valve can cause serious damage with all the pressure inside the cylinder. There are some cars now with no camshaft, but they are very high end experimental sport cars like Koenigsegg