here is an on-line version of one the projects I work on for my job. I spend about 15 to 20 % on my time on this project. The engineers I do work for are the 3 controls guys in the white lab coats, these guys are very smart (PHD's) when it comes to engine controls. I did some of the mechnical/ Fab work and some running of the dyno. this is from popular mechanics magazine. HCCI engine pictures, video and write up with GM Researchers http://www.popularmechanics.com/automotive/new_cars/4270120.html?page=1 http://www.popularmechanics.com/automotive/new_cars/4270120.html?page=2 http://www.popularmechanics.com/automotive/new_cars/4261288.html?series=19 Make sure you click on side pics, and video and read some of the comments from the public on the bottom of the page
I look at all of this thinking of my uncle Moe telling me he put one of them things under the carb and picked up 20 MPG, telling me if them car companies wern't in bed with the oil companies they could make an engine get 100 MPG. I looked at him telling myself, Moe you're a *****! This just reinforces my thoughts. Will we ever get 50+ MPG from a gas engine on a regular basis?, maybe, but not without a huge price and a lot more computers, which I hate!... Thanks for the post!
I hope someone builds a car capable of 100 + mpg real soon and sells millions of them. Then there will be more gas left for hot rods.
Well, this goal of 50 mpg or 100 mpg will never happen simply due to the physics of how the internal combustion engine operates. It is at best 33% efficient, with the typical range being 25-30%. This low efficiency is due to two things, the fact that it has to reject all of the heat from combustion into the cooling system (wasted heat energy) and the high amount friction inside the engine such as piston rings, the camshaft working against the valve springs and against the friction of rocker arm or valve bucks on OHC's and the friction of the valves in the valve guides. Now another source of low mpg is that people want all of these fancy comforts in cars so that adds so much additional weight to cars and reduces the mileage. All this additional weight (or comforts) is what has caused the small cars that used to get 40+ mpg back in the mid 90's to disappear.
I'm not sure if I'd say 100 mpg will never happen.................look at the high-zoot scientists and engineers a few years (decades? ago) that said a trap speed in the quarter mile in excess of 200 mph was physically impossible.
Yeah, for the IC engine as we know it. I was looking at a web site yesterday that mentioned minimizing waste heat. And, did you look at the web site posted? " HCCI Invented in 1978 by engineers at the nippon Clean Engine Research Ins***ute in Japan trying to perfect a cleaner burning, more efficient two-stroke engine, HCCI was originally seen as impractical because computers weren't up to the task of controlling it properly. But advances in microprocessors, sensors and control systems have made it easier to manage, sending carmakers into overdrive to perfect it. <BLINK><BLINK>HCCI employs exhaust trapped from one combustion cycle to achieve the desired ignition temperature for the next cycle</BLINK></BLINK>, helping to vaporize the incoming fuel and raising the homogeneous charge to a higher-than-normal temperature. As the piston moves upward, the temperature of the fuel, air and exhaust ****tail rises to the point of spontaneous ignition, just before the piston reaches top dead center. The result is a more efficient burn at temperatures under 2000 degrees K (about 3140 F), too low to form harmful nitrogen oxides (NOx). Though HCCI might seem like a cross between gasoline and diesel processes, mechanically it's very different, with sophisticated sensors and actuators, a variable valve train, pressure transducers to keep tabs on the combustion chamber and a powerful computer to harness it all together." Thanks, Kurt
Most HAMBER's know how to make an engine get better MPG. But what US auto companies have to worry about is meeting California emissions regs. while getting better MPG. the Chevy Chevette and the VW rabit had diesels that got great MPG,,, but no car maker could build those cars today because of strick emissions regs. VW still has not been able to meet the new Cali Emission laws with its New Diesel car. Put a small 3 or 4 cyl turbo diesel in a light, aero Hot rod ( belly tanker) and you would get 50+ MPG. but it would not meet the new Cali. emissions laws.
It was also once believed that a lap around the Brickyard in excess of 150 was impossible too. I don't know what the most limiting factor in 4 cycle IC engines is as they are, but I might guess the valves. If there were a more efficient way of introducing and extracting the mix, compared to valves as we know them, a large leap might be possible, IMO. But I'm no engineer, just something I've thought about. Variable valve timing is a step in the right direction but not the end all. Even the best valve trains are still a tremendous parasitic drag on the engine, as well as being a major compromise for an engine that sees a wide range of RPM, loading, etc.
<BLINK><BLINK> What would happen if you ran gasoline heated to the point of vaporization right into a carb?
First off, the fuel pressure needs to be bumped up to around 300 psi. Then you need a direct injector with an exhaust temp controller. Just look at how much engine management is required to deal with unburned fuel. You need to atomize it completely, and keep things on the lean edge of the rich edge, so you make the most power without wasting anything. To do that you need way better atomization than anything out there now. Adding a fifth cycle of steam vapor could reclaim much of the lost heat energy, and using part of the exhaust heat to warm up the fuel system could get you another inch closer...
happens all the time with old cars with carbs,,,vapor lock. A carburetor is really a fantastic hydraulic fuel computer. It meters liquid fuel to get 14 to 1 fuel ratios and then goes rich for hard acceleration. but carbs do not work ( meter fuel) on vapors. You would need something like a LPG or natural gas carb. but any carb is not as good as electronic fuel injection. </BLINK></BLINK>
There was some little bitty Honda.. CRX maybe? In the late 80s That had a super-econo version, it deleted sway bars and things to save weight... that could get 57 MPG. Of course, it was made of tinfoil and didn't even have crash bars in the doors, if you survived the collision you wouldn't survive the secondary impact when the car landed from flying through the air like a baseball from the primary impact; you could get out and walk faster going up hills, and if it broke down 4 guys could carry it to the garage... but the only point is 50 MPG is possible from a small enough, light enough gas engined vehicle.
Aero drag in the old cars we drive is the biggest obstacle to high mileage at highway speeds, regardless of what kind of mpg you could get with a fuel-stingy engine. Which is why I get a chuckle every time I see a Duvall (sp?) windshield on a deuce. It's like wings on a brick - serves no purpose at all - just a stylsh face shield. Gary
The average American car today has 100 more hp, and 1000 lbs more weight than the average car from the 80's. That's why fuel economy hasn't improved with the advances in technology.
I was going to mention the same. I remember Smokey building a 2.5 Pontiac, highly insulated with exhaust excessively wrapped and operating around 400 deg. As I recall, it was very efficient. Just found a an article about Smokey's engine in a Fiero. Take a look. http://legendarycollectorcars.com/?page_id=901
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