Engine and Transmission Tech

What's the scoop?

Jim
It's kinda like a diesel injection system for your gas engine. GM has it in they're Eco-tec and 3.6 L V6 engines. Seems to be working out well. Or at least we havn't had to work on any yet!
It does have a high pressure injection pump, but operates at much lower pressures then a diesel pump. About half the psi if I remember correctly. It can run at lower pressures because of the much lower compression ratio of a gas engine compared to the diesels. Less cylinder pressure, requires less injection pressure to squirt the fuel into the combustion chamber. Because of the lower line pressure, it is MUCH quieter then a diesel engine, although the new Dura-Max's are pretty quiet.
Injectors are controlled by the ECM similiar to conventional injection.
The system allows for VERY percise fuel control for improved fuel economy and reduced emisions. I believe it is the wave of the future and we will see more and more direct injected gas engines.

Bill

Interesting, anybody bought one yet? Is the high pressure pump engine driven? (how?) Does the V6 it's on have any provision for variable cam timing by chance? HP outputs? Mileage? Nothing but questions here.

Jim

Jim
I sent you a PM with info on the direct injected 2.0L turbo charged engine. My mistake on the V6, no info on it yet.
I've driven the 2.0L turbo DI, she rips pretty good!

Bill

This is worth watching, particularly with the new developments in cam phasing. What I've seen so far on that looks kinda klunky but definitely a step in the right direction. I don't think there's any reason other than inertia that would prevent the development of a twin cam pushrod V6 or V8 with the ability to vary the timing of the intake cam and the exhaust cam independently. But perhaps they are thinking beyond that.

The stuff isn't likely to be retrofittable, so that is a strong argument for the newer engine designs such as the LS.

Jim

Quote:
[with the ability to vary the timing of the intake cam and the exhaust cam independently]

Jim, ...are you talking "camless" engine technology here?

No, but does someone have one of those too? Man, I've been out of the loop too long.

Jim
Have you seen the Sept.2009 Hot Rod magazine page 92?
An article about direct injection.

Back from NYC! Whats up!?

I was researching a couple years ago about this very topic. I found a company that was working on a prototype rig using EM servos. I'm pretty sure their name was EVA or something. I went and dug up a couple articles about it:

[www.grandprix.com]
[www.swri.org]

WOW that was a long time ago. (I guess it's been more than a couple years) I wonder why it hasn't gotten much traction... Attrition?

Very likely a different type of valve would be required. Modern valves were developed from poppet valves used in steam engines IIRC, and are descended from flat head valves operated by flat tappet in-block cams. A good design for the application but not necessarily the best for an overhead valve actuator driven application. It seems that something a little less bulky, heavy, and power hungry would be more suitable, and the continued advance of valve design over the last century surely has more to offer than this one antiquated idea. In particular, solenoid actuated valves have made tremendous progress. The trouble comes when you start looking at flow rates verses cycling times. Here's what we're up against.

Take a 10,000 rpm redline just for round numbers. Divide by two for the number of times the valve operates in one minute. Divide by 60 for number per second. Roughly 80. divide one second by that. The valve has to complete it's cycle in less than 12 milliseconds. Even at half the rpm it's only 24 milliseconds, and that is the time the engine takes for two complete revolutions so once you start looking at duration you're well under 10 milliseconds on a 5000 rpm motor.

I've worked with state of the art high speed electric solenoids and getting the cycle rate down into that realm takes some pretty fancy footwork, and that's at much lower flow rates than would be needed for an automobile engine. I'm not saying it can't be done but the point here is that you're really stretching the limits in every possible direction to even get into the ballpark. Playing the game is in another league entirely.

So it's a tremendous technical challenge. Much easier to make a briggs and stratton engine run at moderate speed where you have twice the time and half the flow. You really start to hit a wall below 15 milliseconds and once you are down around 10 it becomes almost impossible to go any lower with good repeatability. Heat is also a tremendous problem with those kind of cycle rates, and anything you do to increase the valve opening to more than the absolute minimum needed immediately stretches out the time, slows the cycle rate, increases the heat buildup and reduces repeatability. About ten years ago we were working with valve openings of only .010" with an air valve in order to get down under 15 milliseconds. That was with a disc valve a little over an inch in diameter and less than 1/8" thick. No doubt things have gotten better since then, and a new approach may be the answer. But it isn't just a matter of bolting on some solenoids and away you go.

Jim

OK that makes sense. I guess it would be cool to build one of those rotory valve things to work. Like maybe have it slide laterally with a servo as the RPM goes up so you could open the ports bigger. Or have them actuate based on demand. Maybe eliminate the throttle plate with it.

OK so maybe you isolate the rotors intake and exhaust and have them actuate laterally to change the port size based on demand. Eliminate the throttle plate, just use a hole or forced induction, and direct injection for the fuel delivery.

[www.coatesengine.com]

Yes, that could be a very significant improvement. The ability to use a rotating valve means much lower energy requirements to open and close the port. Running at engine speed it would be fairly simple to advance or retard the valve timing on either intake or exhaust, and with no heavy springs to overpower the hydraulics, the advance mechanism could be small and light. All very significant advantages. How you would best control the volume of gasses passing the valve is another question and one that I did not see an immediate remedy for but it's certainly a big step in the right direction. Possibly even retrofittable to some engines. Good find Nick! (What are the disadvantages?)

Jim

Anybody build one yet ? Headless, slide valve with direct injection...that's what I'm talkin ! One bore surrounding two-opposed pistons with multiple/small int. and exh. ports on opposite sides of cylinder,interposed between pistons. Perhaps 3/8" of slide travel required ? Since volume increase is doubled,(2 pistons), would tend to favor fast burning fuel like, hydrogen ? Headless horsepower. What if ? roverman.

Hi Guys,

Your on my pet project now, I came up with the idea originally about 20 years ago but the electronic development at that time would not have supported the operation of running the valves.

I picked it up again about 5 years ago after a discussion with a young friend who's at Brookes Oxford College of technology and we married my original thinking with what is potentially available now in the way of high speed stepper motors to operate the barrel valves, with the benefit of constantly variable valve timing and potentialy volume of delivery by splitting the valve into two ports for high and low speed running.

Haven't done any more work on it for about a year do to my health and the limitations on the time of my young associate who is tied up with college projects including their Formula student car.

As it is unlikely to get done by me i don't mind sharing my thoughts if anyone wants to pursue it further,

Heres a shot of the basic head design showing the barrel valves, the actuators would be attached to the end of each barrel valve and could even be geared to limit the amount of work that the electronics had to do and also speed up the operation without overstressing the stepper motor.



Kevin.

Get ready for the spark plugs being replaced by laser ignition. Ford is presently experimenting with laser technology to ignite the mixture. It's not only about igniting but also having the laser beam read and feedback combustion data to the computer. Each cylinder will get analyzed and re-adjusted to perfection (A/F). All of a sudden, I feel real ancient (LOL)

Jacques, I've felt ancient for soo-long...I can't remember. Let's move-on, shall we ? "Laser ignition", I like the concept for a headless engine ? Not being a skilled aerodynamicist, I suspect "barrel valves"/Coates, will generate unfavorable turbulences at less than full open ? I think slide valve, with 3/8" traverse and "cleaner" open/close cycle, should have less ? I've heard, "Ising-glass" motors,(combustion research), use slide valves. Anybody? roverman.

Art,

The coates Barrel valves do have a somewhat torturous path to the cylinder, the slotted rotator I showed would be more efficient and have much greater flow from initial opening than a standard poppet type valve at low lift.

Kevin.

Art, is this link what you're referring to? This one has been out for awhile now and I just don't understand why it hasn't taken off. The beauty about the design is its simplicity. Originally, the heads were adapted to Ford's popular 5 Liters engine. I hope the link comes through ok.

[www.coatesengine.com]

I know this thread has evolved far from the original question but this new engine from Alfa Romeo is interesting and I suspect borrows a lot from current F1 technology.

Click on Multiair.

[www.alfaromeo.co.uk]

Kevin.



Edited 1 time(s). Last edit at 02/18/2010 03:44PM by castlesid.

Kevin, In your picture, front is combustion chamber, with spark plug hole in middle ? If so, SV ratio looks big. Dirty chamber ? Burn speed ? Thanks for sharing, roverman.