Monday, January 02, 2006

Car Craft gets it wrong

You won't hear that from me very often - I think Car Craft , as a print mag, is one of the best car magazines out there. At least for those of us who like working on our own stuff, and have a fondness for older cars.

But in the Feb '06 issue, they talk about camshaft-less engines, and a company called Valeo.

Quote from CC:
Ever heard of Valeo? Most people probably haven't. The automotive supplier has revealed technology that would make the cam a novelty item. The company's new technology for reducing fuel consumption and emissions by 20 percent involves a cylinder-head design that utilizes Smart Valve Actuation rather than the mechanical operation of engine valves by the cam belt, camshaft, and hydraulic-cam followers.

By being camless, each engine valve would operate separately by an actuator that is placed on the upper surface of the cylinder head, above the valveguides. The actuator would be linked to an engine-mounted valve-control unit that is in charge of positioning the valves and power-drive function. The idea is that by being able to control the residual gases, reducing pumping loses (sic), and deactivating cylinders and valves, it's better for the environment and also overall performance (a boost in low-end torque). We might see this as soon as 2009. So we can figure out how to bypass it by 2010. (Emphasis mine)
CC didn't give a byline on this passage, unfortunately. I suspect the writer got to the point about it being good for emissions, and quit thinking.

I actually had this idea a few years ago, but didn't pursue it - reliability was the big hangup in my thought process. I mean, timing chains (or belts), camshafts, lifters, pushrods, and rocker arms are all pretty well-developed technology, and pretty dang reliable. A solenoid pushing the valve open and pulling it closed? Dunno about that, in that harsh environment.

BUT - think back to when Electronic Fuel Injection was becoming mainstream. Yeah, it took a little while before it could match a good carburetor in terms of reliability and performance. Pretty much from the word go, however, EFI beat carbs on emissions and driveability. After a few years, EFI proved it was ready for primetime, and match a carb on reliability and performance, and kick the carb to the curb in terms of emissions and driveability.

Camless engines are next.

A camshaft, and using it to open and close valves, is a major power thief to an engine. Overhead cams are a little better than pushrods, but only a little. You've got pretty large friction losses, but the big baddie is pushing valves open against a heavy-duty spring.

Solenoid-actuated valves would get rid of all that, but that's not the BIG issue.

The BIG issue is control! When building an engine, you choose a cam. That's an art and/or science (or maybe voodoo) all its own. And compromises to be made on every choice. You can have something ready to go 6000+rpm and make power, or you can have an idle that won't shake your fillings loose. That's just one choice, they are myriad (I actually don't know crap about spec'ing a cam, when it comes time, I'll call Comp Cams, tell them what I want from the engine, and buy what they tell me to).

With electronic valve control, you don't choose A cam - you get them ALL. With a mechanical bumpstick, you make your choices, and your sacrifices, when you build the engine. With electronic control, you can map valve timing, duration, and lift to other engine parameters, such as RPM, throttle position, and vacuum signal, just like you can with EFI. You won't have to compromise anymore - you can have it ALL.

I expect we'll go through the same growing pains with electronic valve control (EVC - you saw it here first!) as we did with EFI. There will be reliability issues. An engine is a pretty harsh environment, after all. There will be performance issues, as the first valve maps will be unsophisticated, and designed primarily for fuel economy and emissions performance.

But EVC, as a technology, will mature, just as EFI did. And the aftermarket will provide us with the tools to alter the valve maps. And then, Granny bar the door. We'll have musclecars with new tech that have street manners like a 2012 Lexus, but when you hit the loud pedal, they go like a raped ape.

And at the same time, we'll have even more options - like shutting down cylinders. For example - I drive an '02 Silverado to work every day. I really like the V8 under the hood when I'm trying to match traffic flow, or get around some slow idiot, or hauling a heavy load, or pulling a trailer. But when I'm going back and forth to work, about 16 miles of my 18 mile drive is on the highway - that strong V8 is just loafing, but all 8 cylinders are sucking gas. I wouldn't mind at all if, under those conditions, four of the cylinders kept their intake valves shut, their exhaust valves wide open, and I only actually fed four cylinders. Or however cylinder deactivation works, I'm not really familiar with that technology.

We'll have to wait and see how this all shakes out, but I'm pretty excited about it.

The last sentence of CC's writeup should have been "So we can figure out how to re-map it by 2010".

4 Comments:

Blogger Rivrdog said...

There's no reason that solenoid valve operation shouldn't have been on cars for the last 20 years, as the technology for the long-life solenoids has been around at least that long (they're also used in port fuel injection, where they have to operate against spring pressure as well).

As I understand DDEC, Detroit Diesel's Electronic Control, the solenoids are already in use there, but for injection. For a large diesel, those solenoids have to be fairly moosey.

The problem I see is valve seating and sealing. I think that will be the limiting factor.

The solution to it will be 10-16 cylinder engines with tiny cubes in the cyls and tiny valves. The only limiting factor for building a W-16 is the valvetrain(s), so I think we'll see the power you want to tweak with. Honda got over 1,000 hp out of a 1,500cc W-16 almost 30 years ago, but it was hand-built with watchmaker's precision for F-1.

With EVC, W-16s could become the norm for sporty vehicles, with HP ratings easily topping 500. I've got more computing power in my Pocket PC than would be necessary to run the injection AND the valving, which, BTW, are linkable in a chip with simple algorithms.

11:41 PM  
Blogger Aaron Neal said...

Makes sense... with smaller cylinders, and more of them, the valves would be smaller, and you wouldn't need such a HOSS solenoid to handle them. And more cylinders always equals a smoother engine.

12:14 AM  
Blogger Rivrdog said...

But above all, more cylinders equals a wider powerband, that rpm range where both torque and horsepower are near maximum. The old-style V-8s had a problem with powerband, as the torque in a standard engine came in WAAAAY below the ponies.

You could change that a bit with and "RV" cam, but only certain engines, notably MoPars (the 318 comes to mind), were amenable to much of a change.

A W-16 with what I would call TEC (Total Electronic Control) would give a decent powerband from 2,000 on up, which, in turn, would make it easy to set up an electronically-controlled auto trans for BOTH performance AND economy, switchable with chip input. Want to smoke tires? Just hit the (D) for Drag button. Want to stretch the fuel? Just select (E) for economy.

Best of both worlds, but I DO miss the days when I could tune an engine with a matchbook (.018 feeler gage), screwdriver, small Crescent and timing light.

9:18 AM  
Blogger Aaron Neal said...

Actually, re: transmissions, performance trannys usually are more economical. Most people don't like them, though, because they don't shift "smoothly" - they feel like a kick in the pants when they shift under acceleration. They also invite anybody with a decent engine to be dangerous, because those hard shifts tend to break the tires loose if you don't let off the gas for the shift. The softer-shifting trannies are basically just slipping a lot, and wasting buckets of energy.

Also, the electronically-controlled trannies, with variable shifting characteristics are already here - one is in my pickup, in fact. I have a pushbutton on the end of my shift selector, to turn on "Tow/Haul Mode". As far as I can tell, it moves the shift points up in the RPM range, and makes it shift a little harder.

Oh, and you can still tune with the basics... as long as you're working on your Briggs & Stratton mower :)

10:41 PM  

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