Engine Tech: How to improve efficiency?

Use the new hi-tech thermal coatings on the piston, chambers, etc to keep heat in the chamber. Coat the intake to keep the heat out of the air stream, and coat the exhaust system to keep the exhaust gas hot (pumps easier)......

From engineering class the most basic, easiest way to make the internal combustion engine more efficient is by increasing compression. As just like everyone else said, heat and friction is what causes all the losses of power. there are no free lunches.

Im a geology major, we are now discovering ways to turn coal, oil shales, tar sand, and such into petroleum products. But with the current KNOWN oil reserves, we'll have gas for another 50 years. But with the all the research on hybrids, electric, and other resources for power, id say in 25 years gasoline will phasing out. Im sure we'll still be able to purchase it, though.

On a better note! the US has by FAR the largest coal deposts, so hopefully we can give a little payback hiking up the prices for everyone we start selling that to.

we can always swap in some rotary motors... im not a huge import fan but these things are amazing!! my physics teacher was a brit and he had an rx-7 that he always went on and on about

Man - there's a lot of interesting 'stuff' in the thread so far. Diesels are throttle-less - they don't have a throttle. They control engine speed and power output simply by varying how much fuel they inject. That means they have more of a varying a/f ratio. With no throttle there are no 'pumping losses'. Gasoline engines with throttles use a lot of energy creating vacuum. Each time the piston drops pulling against a closed or partially open throttle body it takes lots of force. Try pulling a hyperdermic pluger back when the end of it is plugged. That's one way diesels are more efficient. The fuel has a higher specific density than gas. Higher CR's also contribute to better efficiency -- someone mentioned these earlier in the thread. The rpm range of diesels depends on their size and design. Big truck diesels -- all done by about 1800-2100 rpm; and most of 'em get shifted around 1500 rpm. The smaller diesels in pickups are good up to about 2500-3000 rpm. Smaller diesels such as VW's TDI are good up into the 4500-5000 range. And Mercedes and BMW make some kick-arse turbo diesels in Europe. Maybe we'll get them one day -- 270HP/400 ft-lbs of torque; 5000 rpm capability and about 40% better mileage than similar power-level gasoline engines. You just gear for their rpm capability. Go to the strip and watch some of these 6000 lb. Ford/Chevy/Dodge diesels run 12's and 13's -- who cares if they're all done by 2500 rpm?

While manufacturers are experimenting with solenoids driving the valves, no one has production-ready designs yet. BMW's big V8 in the 7 series has no throttle body -- because they control air flow/engine speed by varying the lift of the valves. So -- they're still limiting air flow - so they still have pumping losses. The jury is out on their 'infinity' ratio power steering (variable ratio) -- most don't like the feel of it, and you can 'beat it' with aggressive driving -- it can't keep up with really quick changes in wheel position. Related to that Mercedes just pulled their Bosch brake-by-wire system off the market in their cars -- too many problems.

Turbines are efficient -- but only a bit more than IC engines -- about 40% compared to 25-33% for IC engines. Besides - they're only that efficient if you can load them at their peak efficiency and let them work at that speed -- like a gas compressor application. They don't like speeding up and down at all -- as they'd need to in a car application as the primary power provider. Now a small turbine for use under extended cruise might have possibilities -- but diesels are equally efficient in that application, and are well adapted for use in vehicles; turbines aren't.

Direct injection for gasoline engines is available in Europe -- Audi have pioneered it in the last year. 3000-3600 psig pressures injected directly into the chamber JUST BEFORE the plug fires. They've been able to run static compression ratios of 12:1-12.5:1 with that, and are seeing power and mileage improvements of 12-16% on similar engines with only the direct injection/compression changes. Part of the efficiency improvement comes from better fuel atomization/distribution in the chamber, and some from the increased CR.

Current improvements in efficiency are focused on reducing friction (bearings, rings), direct injection which allows higher CR's, cylinder deactivation coupled with variable lift/valve timing; reduced pumping losses INSIDE the crankcase. Everytime a piston comes down, it moves air around inside the crankcase -- and allowing that air to move more easily inside the crankcase allows the engine to use less fuel pumping that air around.

Hybrids are a HUGE area for efficiency gain - all the talk about heat doesn't mention the heat that goes into the brakes that gets completely wasted. Hybrids allow that waste heat to be captured as electrical energy stored in batteries to be re-used later via electric motors.

And there's a lot work with HCCI -- homogeneous charge compression ignition; kind of like a diesel running on gasoline. If it sounds like detonation -- there's a crucial difference. HCCI happens uniformly throughout the chamber -- and that improves efficiency. And, it occurs at a lower temperature than spark induced combustion - so there's less NOx emissions. All is not perfect though -- it puts out less power in similar sized engines, and exhaust temps are so low that controlling HC and CO is a problem. Also, it's difficult to maintain the HCCI balance at during warmup, light load and full throttle. But it works great at part load/part throttle.

So -- you use variable valve timing and high pressure direct injection to operate the gas engine in a regular Otto cycle during cold starts, idle, full throttle; and HCCI under extended cruise/part throttle. Combine that with a hybrid drive train -- and you've got the recipe for 60-80 mpg gasoline powered small cars -- similar to diesel hybrids.

As for shale oil and coal -- unless the infrastructure in our country changes, look for them to be converted to liquid fuels we can still drive cars/trucks with. It's a simple matter of economics to make that work -- how high does gas have to get to make it work? If it gets up to $3-$4/gallon and stays there -- we'll see all sorts of other technologies start to make economic sense. But they can't compete when gas is $2 and available.

We live in interesting times guys.

Stangjunkie - ask those RX8 owners what kind of mileage they're getting --- it's the downside; the things DRINK fuel. Not very efficient compared to other cars of similar size and performance.

Michael Yount said:

We live interesting times guys.

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That is so true that I just had to quote you.

Think about this: The Automobile has only been around for 100 years. Think about all the advancments that have happened between now and then. Now try to think about the next 100 years... In 15 years, things are going to get very interstesting indeed.

MYount coming strong . Good info on the direct injection and HCCI. What about the BMW "infinitely variable intake length or something?" Is it true and if so how come nobody made a polymer (plastic) intake with variable intake length runners for Mustangs??? There may be a few lb-ft of torque and few mpgs there.....food for thought.

sunil6784 said:

Hmmm....that might be a practical way tmoss. How long does the coating last for ? Is it expensive ?

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wow - catch your breath Mike

The coating lasts a long time, but it is not cheap. Jet-Hot or other coating companies can do the ceramic coatings on the intake and exhaust. The engine parts take special coatings meant for each part.

srothfuss said:

In 15 years, things are going to get very interstesting indeed.

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I'll probably be dead.......or close to it.........

Let's hope not.

The only problem with rotary engines, is that in most cases seen. They make very little torque.

bomber -- a BUNCH of different companies have had variable length intakes for a long time -- my wife's 1985 Toyota MR2 had one. For your Ford types -- the Taurus SHO has what I consider to be the most wicked looking variable length intake of all time.

The reason you don't see them on pushrod V8's is because their big benefit comes in helping smaller displacment engines that make good HP at high rpm, also make decent torque at low rpm. Most V8's make enough torque at low rpm already. Porsche's V8 in the Cayenne SUV has variable length runners -- and it's composite. Almost all of the better, contemporary V6's and 4's have it. Variable valve timing is available on most engines too - even Ford's newer V8's, and GM has fitted it to many of their new LS architecture pushrod V8's. BMW calls it VANOS, Honda - VTEC, the list goes on and on.

MYount - I guess there is no replacement for displacement Although it would be nice to have low end torque of stocker and top end Edelbrock Victor or a box intake

Yeah - there's a replacement for displacement -- it's called money....

Michael Yount said:

bomber -- a BUNCH of different companies have had variable length intakes for a long time -- my wife's 1985 Toyota MR2 had one. For your Ford types -- the Taurus SHO has what I consider to be the most wicked looking variable length intake of all time.

The reason you don't see them on pushrod V8's is because their big benefit comes in helping smaller displacment engines that make good HP at high rpm, also make decent torque at low rpm. Most V8's make enough torque at low rpm already. Porsche's V8 in the Cayenne SUV has variable length runners -- and it's composite. Almost all of the better, contemporary V6's and 4's have it. Variable valve timing is available on most engines too - even Ford's newer V8's, and GM has fitted it to many of their new LS architecture pushrod V8's. BMW calls it VANOS, Honda - VTEC, the list goes on and on.

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V-6 SHO Taurus is all Yamaha,not Ford.

Both the V6 AND THE V8 SHO's were engineered and built by Yamaha -- but Ford paid LOTS of money to put their name on it --- so it's a Ford. The Chrysler Crossfire has a Mercedes engine and tranny in it. Some of Saturn's vans have Honda engines. Ford's new hi/po Focus line in Europe will be powered by Volvo-derived engines; Lincoln LS V8 shares architecture with Jaguar/Aston Martin V8's (both owned by Ford); the new Toyota Nascar trucks and (soon) Camry's run pushrod V8's developed by Toyota Racing Development (TRD) -- Toyota doesn't have a pushrod V8 of their own; Bugatti's new Veyron has (basically) a VW motor in it; the Corvette 4-valve ZL-1 from years back had it's engine design/developed by Mercury of boat fame --- the list could go one forever. The manufacturers do what they have to do to put out product they think they can sell at a price that keeps them profitable.

If you really want to get convoluted -- take a look at Volvo's new 4.4L 60 DEGREE V8 - sound familiar? The folks at Yamaha were involved in that one too via Ford's ownership of Volvo...it's a bigger/bolder SHO III.

Roterys are really poor on gas mileage. They have really poor torque ratings too. I think my friend's rx7 is pushing 330HP to the rear wheels and sub 100ft lbs(believe its 65 ft. lbs...) of torque. The heat from the combustion and exhaust is absolutely the worse because you are getting 3 power cycles per rotor which they typically have 2 of.
Kevin

Oh, of course it makes more torque than that......

The new RX8's have 1308 cc's of displacement (1.3L) -- they make 250HP at 8500 rpm; 159 lb-ft of torque at 5500 rpm. That's actually a lot of torque for a naturally aspirated 1.3L (that would be about 480 lb-ft for a proportional 5.0L) --- it's just you have to rev them to get to it.

I gotta check out my friend's dyno sheet again. Maybe i missed a 1 somewhere but it was pretty disappointing.
Kevin