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germanbird writes: "Jalopnik has an interesting article up about Koenigsegg's Prototype Camless Engine. The engine uses pneumatic actuators rather than a cam to open and close the valves in the engine. The engineers behind this claim that it can provide "30 percent more power and torque, and up to 50 percent better economy" when applied to an existing engine designs. The article and some of the comments also mention that some work has been done with electromagnetic actuators to accomplish the same task. It may be a while before this tech is mature enough for passenger vehicles, but maybe if a racing series or two picked it up, it might give some of the manufacturers the opportunity to work the bugs out?
Not sure this is on topic for SoylentNews, but the article brought me back to my introduction to engineering course in college. One of my classmates was a car nut and I remember a discussion with an EE professor one day about the potential (or actually lack thereof due to performance issues) for using electric actuators to open and close valves."
(Score: 1) by epitaxial on Friday February 28 2014, @09:38AM
You do know that rotary engines need a teardown and rebuild much much sooner than piston engines? Fun fact: if you own an RX-8 they recommend you check your oil level every 3 gas fill ups. The engine burns that much oil.
(Score: 1) by Kromagv0 on Friday February 28 2014, @10:32AM
Well that was suppose to have been fixed with the RX-8 generation of rotary engine but they still couldn't resolve the problem with the carbon tips of the rotors lasting. This was a problem on the old RX-7 rotaries as well. It is an interesting design but it just never seems to deliver.
T-Shirts and bumper stickers [zazzle.com] to offend someone
(Score: 1) by computersareevil on Saturday March 01 2014, @10:11PM
Fact 3: No RX has had "carbon tips" aka apex seals since the early 1970's. The have been a steel alloy since at least the RX-3 introduced in 1972. They still use carbon apex seals in some VERY high-power applications, and yes, they don't last long. They've mostly been supplanted by ceramic apex seals.
Fact 4: The RX-8 engine doesn't die due to apex seal failure. The most common failure appears to be rotor side seal failure caused by excess carbon buildup in the side exhaust ports, which is caused by not revving the shit out of the engine daily. The RENESIS engine is the first Mazda rotary with side exhaust ports instead of peripheral ports.
Fact 5: The RX-7 never had a problem with apex seals. Normally-aspirated RX-7s routinely go hundreds of thousands of miles without problems (so long as they are properly-driven). The third-generation FD RX-7 didn't have problems with apex seals, it had problems with boost and fuel control. A cluster-fuck of vacuum hoses and solenoids controlled the sophisticated sequential twin-turbochargers. The cluster-fuck would spit a hose periodically, which would cause a sudden lean condition under boost, leading to catastrophic detonation and subsequently popping an apex seal. The apex seals are not the cause any more than a burned valve or punctured piston is the problem in a boosted piston engine that goes lean. Securing the cluster-fuck of hose ends to their fittings with cable ties solves that reliability problem.
In summary, pretty much all the reputation problems with the Mazda rotary engines amount to FUD, which makes it all the more painful to read it being spread by (supposedly) fellow geeks on SN.
(Score: 1) by computersareevil on Saturday March 01 2014, @09:53PM
Wrong. I own a road-race-track-driven 2005 RX-8 with 70k miles on it, no rebuild yet. Many are over 100,000 miles without a rebuild.
What happens to the Mazda rotaries that shortens their life is that ignorant people like you don't read the owner's manual or look up basic facts about the engine, abuse and neglect it, then bitch when it dies on them.
Fact 1: "Oh, it burns the oils!" The Mazda rotary burns oil on-purpose. This is how it lubricates the apex seals. This is how it's been since the Mazda Cosmo Sport 110S [wikipedia.org] was introduced in 1967. And yet here we are 46 years later and people still can't get it through their soft skulls that it burns oil on-purpose.
Fact 2: Properly maintained and driven Mazda rotaries will go hundreds of thousands of miles. I also race a 1985 Spec RX-7 with 167,000 miles on the engine. They aren't really "broken-in" until they are over 100,000 miles. The secret is that if you drive it like a piston engine, you will ruin it. Everything in a rotary should be done at least 2X the RPM of a piston engine. It should be redlined at least daily, if not at every shift pulling away from a stop. That doesn't mean drag race it at every light, it just means don't shift until the little buzzer lets you know that 9000 RPM has arrived and you should shift when you get around to it. The buzzer is the only way you'll know this buttery-smooth little engine is turning that fast. People who regularly drive under 2000 RPM and never shift over 6000 will kill the engine in under 50k miles.