Question for ScrapHemi

[ASpHole]

Seeing as how you build racing engines for a living, I was wondering if you could answer a question that has always seemed as if it would be a great idea.

Why is it that nobody has done away with the mechanical camshaft in engines and instead replaced the camshaft valvetrain actuating mechanisms with HID/Fast capacitor activated solenoids to actuate the valves?  -- It appears obvious to me that you would have a gain of at least several HP by ditching the parasitic load caused by the turning the camshaft with the engine crank. Another advantage of this, is that you could could also more precisely control the valve timing through a broader range of engine RPM's. --Why has nobody done this?

[Tesla]

Good question, I'm interested to hear the reply.

One guess could be that if you have an electrical failure the piston would hit the valve and require a rebuild.  Although you could overcome that with a non-interference engine.  Or, having the valves closed by default, and the solenoids open the valves....

[Christopher McCandless]

Seeing as how you build racing engines for a living, I was wondering if you could answer a question that has always seemed as if it would be a great idea.

Why is it that nobody has done away with the mechanical camshaft in engines and instead replaced the camshaft valvetrain actuating mechanisms with HID/Fast capacitor activated solenoids to actuate the valves?  -- It appears obvious to me that you would have a gain of at least several HP by ditching the parasitic load caused by the turning the camshaft with the engine crank. Another advantage of this, is that you could could also more precisely control the valve timing through a broader range of engine RPM's. --Why has nobody done this?

I think there are legal regulations, i know steering wheels have to be attached mechanically etc

[DirtDawg]

Not only could you control each valve stroke more precisely, but you could also design in a control curve that would tailor the valve timing to the rpm, and engine load, air pressure, etc.

I just wonder if it would actuate fast enough for a high RPM engine. Excellent question.

[ASpHole]

Good question, I'm interested to hear the reply.

One guess could be that if you have an electrical failure the piston would hit the valve and require a rebuild.

The Valves would be held in the closed position via spring loaded retainer in the manner that they are held closed in a conventional engine with cam actuated valves.

Also, to further MarkingDawgs reply, you could also have variable cylinder control in the manner that Cadillac had breifly in the early 80's, in the fact that you could also turn cylinders off for increased fuel efficiency in city driving and stop and go traffic without anywhere near the parasitic load that would be exhibited with a traditional engine with a camshaft.

[Scrapheap]

In a nutshell, you have reliability problems due to heat soaking of the solenoids. I've heard this idea before being tried in F1 and I think it was abandoned not just because of the reliability issue, but because of added weight, EMI other teething issues.

[Tesla]

Good question, I'm interested to hear the reply.

One guess could be that if you have an electrical failure the piston would hit the valve and require a rebuild.

The Valves would be held in the closed position via spring loaded retainer in the manner that they are held closed in a conventional engine with cam actuated valves.

Also, to further MarkingDawgs reply, you could also have variable cylinder control in the manner that Cadillac had breifly in the early 80's, in the fact that you could also turn cylinders off for increased fuel efficiency in city driving and stop and go traffic without anywhere near the parasitic load that would be exhibited with a traditional engine with a camshaft.

I read recently of an six stroke engine... Here it is:  http://www.damninteresting.com/?p=467

[Scrapheap]

Good question, I'm interested to hear the reply.

One guess could be that if you have an electrical failure the piston would hit the valve and require a rebuild.

The Valves would be held in the closed position via spring loaded retainer in the manner that they are held closed in a conventional engine with cam actuated valves.

Also, to further MarkingDawgs reply, you could also have variable cylinder control in the manner that Cadillac had breifly in the early 80's, in the fact that you could also turn cylinders off for increased fuel efficiency in city driving and stop and go traffic without anywhere near the parasitic load that would be exhibited with a traditional engine with a camshaft.

I read recently of an six stroke engine... Here it is:  http://www.damninteresting.com/?p=467

I've actually met Bruce Crower (he's a friend of Austin Coil) who designed that. He's had someinteresting designs in the past including a same-side port Chevy small block. Like most uncoventional designs, it likely has several engineering problems  that are damn near impossible to overcome. Like- how do you keep blow-by gasses from contaminating the engine oil??

[DirtDawg]

Good question, I'm interested to hear the reply.

One guess could be that if you have an electrical failure the piston would hit the valve and require a rebuild.

The Valves would be held in the closed position via spring loaded retainer in the manner that they are held closed in a conventional engine with cam actuated valves.

Also, to further MarkingDawgs reply, you could also have variable cylinder control in the manner that Cadillac had breifly in the early 80's, in the fact that you could also turn cylinders off for increased fuel efficiency in city driving and stop and go traffic without anywhere near the parasitic load that would be exhibited with a traditional engine with a camshaft.

I read recently of an six stroke engine... Here it is:  http://www.damninteresting.com/?p=467

I've actually met Bruce Crower (he's a friend of Austin Coil) who designed that. He's had someinteresting designs in the past including a same-side port Chevy small block. Like most uncoventional designs, it likely has several engineering problems  that are damn near impossible to overcome. Like- how do you keep blow-by gasses from contaminating the engine oil??

"Damn near impossible", I would say. I would also expect it to contaminate the oil very quickly, considering the internal temperatures that he claims the engine maintains. At least if your oil is really hot, much of the water that might enter the crankcase would evaporate and be vented before it was homogenized into the oil. I guess it would need to run water and oil distillation equipment onboard.

Doesn't a turbo present a near-perfect way to re-capture some of that wasted heat?

[DirtDawg]

In a nutshell, you have reliability problems due to heat soaking of the solenoids. I've heard this idea before being tried in F1 and I think it was abandoned not just because of the reliability issue, but because of added weight, EMI other teething issues.

I vaguely remember reading something similar in use for helicopter engines, before the turbines became so highly perfected, but my inefficiency at googling  hasn't turned up anything.

[Scrapheap]

"Damn near impossible", I would say. I would also expect it to contaminate the oil very quickly, considering the internal temperatures that he claims the engine maintains. At least if your oil is really hot, much of the water that might enter the crankcase would evaporate and be vented before it was homogenized into the oil. I guess it would need to run water and oil distillation equipment onboard.

Another problem would be how to get even power out of it. I doubt you could use it to power a car, it could only likely be used in a stationary role like running a generator or pump or something.

Doesn't a turbo present a near-perfect way to re-capture some of that wasted heat?

A turbo is perhaps the best thing to happen to the internal combustion engine. It does recover some lost energy going out through the exhaust, but only when the engine is under a heavy enough load to develop boost.

[Scrapheap]

Also, to further MarkingDawgs reply, you could also have variable cylinder control in the manner that Cadillac had breifly in the early 80's, in the fact that you could also turn cylinders off for increased fuel efficiency in city driving and stop and go traffic without anywhere near the parasitic load that would be exhibited with a traditional engine with a camshaft.

The system that Cadillac used in the early 80's was ignition and not valve-train  based.

I think you're overestimating the parasitic power loss of traditional cam systems. Even pushrod engines with their heavy lifters and pushrods can come close to the specific output of overhead cam designs.

Really, if you're looking to improve the mechanical eficiency of an engine, there's other places to look.

[TheoK]

The Wankel engine was brilliant. It could be run on almost any fuel without any convertion. Though it wasn't "the right time" for it, when it was invented.

[Christopher McCandless]

The Wankel engine was brilliant. It could be run on almost any fuel without any convertion. Though it wasn't "the right time" for it, when it was invented.

Mazda use them

[matthe]

very interesting. theo thanks for the bump.

i read recently of someone(cant remember but ill try and find it) doing solenoid controlled valves, but the system i read about still had a camshaft and the solenoids were used to change the timing of the valves. ill dig it up and post the click


6-stroke? sounds cool except for the putting water in the cilindars part 

The  engine was brilliant. It could be run on almost any fuel without any convertion. Though it wasn't "the right time" for it, when it was invented.

fixed (sorry im not a mazda fan)


anyone heard of this axial vector thing? it has alot less rotating mass than traditional ice's.

http://www.axialvectorengine.com/