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Old 16th October 2012, 11:12 AM   #7441
dvv is offline dvv  Serbia
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As I understand it, the car manufacturing lot are taking hints from the audio industry now.

Remember how we used to have (and still probably do) power amps with two sets of power supply lines? So with low volume, we ran them off the lower rails but more in class A, and switched higher rails only when required? Hitachi's Dynaharmony concept?

The automobile lot are now doing the same. Two cylinders run normally, and when required, the other two are powered up (or three, or four, it even works on V16 engines).

Others have worked out that pure class A operation (all cylinders running) is in fact a waste especially when startiung the car from standstill, so they add electric motors to supply the extra torque for the occasion, thus sparing the main engine from wasting a lot of fuel.

In fact, the whole fuel saving scene very strongly reminds me of the audio scene - many topologies in play, and it's anybody's guess who wins in the end, disregarding for the moment the obvious absolute winner, the electric motor drive - but that's still some way off, until they solve the problem of energy storage (batteries).
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Old 16th October 2012, 11:54 AM   #7442
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Exactly right . I think being able to decouple the engines is best so as not to have frictional losses . I do think a discussion engines is an excellent analogy for what we do .

Some engineers advocated 8 stroke engines ( 4 stroke when in full use ,12 or 16 if required ) . This could use down pushing valves instead of the usual spring clamped valves . This allows extra air induction if the engine is lightly loaded . It also improves emissions . When brakes are used the valves can shut if using full braking . the valves are operated through a variation of hydraulic tappets . Also this type of valve will not smash into a piston if the belt brakes . My old Ford Focus could switch cylinders if the water was lost . Apparent it could survive for some kM's at 50 kPH ( in the handbook ) !
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Old 16th October 2012, 06:40 PM   #7443
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Quote:
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Others have worked out that pure class A operation (all cylinders running) is in fact a waste especially when startiung the car from standstill, so they add electric motors to supply the extra torque for the occasion, thus sparing the main engine from wasting a lot of fuel.
My Nissan Armada used to start much faster than much lighter Toyota Primus, and even Honda Civic Hybrid, both with electric motors, despite it was bigger than behemoth.

I miss it... Fuel is getting more and more expensive, almost $5 per gallon now.
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Old 16th October 2012, 07:08 PM   #7444
dvv is offline dvv  Serbia
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My Nissan Armada used to start much faster than much lighter Toyota Primus, and even Honda Civic Hybrid, both with electric motors, despite it was bigger than behemoth.

I miss it... Fuel is getting more and more expensive, almost $5 per gallon now.
Assuming that 1 gallon is equivalent to 4.6 litres, the European price for 1 gallon or 4.6 litres is about $10.30, although this varies from country to country. DOUBLE your price, and you are moaning ?

That's because governments like to raise extra cash by increasing duties on goods with extremely inflexible prices, these generally being food, petrol and tobacco. Since food is very sensitive socially and politically, that's usually the last resort - when a government levies taxes on food stuffs, then you know they are a step away from benkruptcy.

As an example, locally taxes are just 8% of the value of food stuffs, but in the price of 1 litre of petrol, the government is in for 114% over its manufacturing price.
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Last edited by dvv; 16th October 2012 at 07:13 PM.
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Old 16th October 2012, 07:19 PM   #7445
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The new Volvo diesel hybrid is wild . It has a big engine and yet is twice the economy of most . It does 124 mile per US gallon or > 100 kM 2 L . It is expensive . Someone will get there soon at Prius price .

Volvo V60 diesel hybrid highlighted in video - Autoweek
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Old 16th October 2012, 07:50 PM   #7446
dvv is offline dvv  Serbia
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Nige, my experience is that ALL manufacturers lie like dogs regarding fuel consumption.

100% of their figures are obtained in a wind tunnel, on roller roads, i.e. by simulation. This was necessitated by the fact that traffic conditions vary, you can drive the same route three rimes and get three different results simply because traffic conditions were different. Not to ention the given differences in various locations.

Over the last year, while I was selecting my next motor vehicle (Chevy Cruze), I did a lot of research and discovered that despite all the electronics and whatnot in modern cars, any given engine size will have a rather narrow window of difference. VW's claims regarding fuel consuption were aggrivatingly deflated, absolutely impossible to attain in real life. A real life 2 litre engine will require 10-11 litres per 100 km in city driving no matter what they publish, and more if it has been turboed and has over 200 bhp.

Fortunately for me, a local car magazine hit on the same idea and did a big test on some 12 cars of different categories. They compared declared consumption with actually achieved consumption. I remember just two figures: 1) Honda Civic with a 1.8 litre, 140 bhp engine was the least offenderm being off by just under 10%, and 2) the AVERAGE off percentage was 27% (i.e. in real life they drank on average 27% more).

So, our own audio theme here seems to ge much more general and widespread than just audio. Measurements there are just as unrelated to reality as in audio.

As for the Volvo you mentioned, I will bet my life that in actual driving it will literally NEVER get that low, unless it has a low power, low displacement engine and generally drives like a wet blanket. Like most Volvos. They are safe, they are well made, but they are made to stand still and show off.
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Old 16th October 2012, 08:12 PM   #7447
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Currently I drive Nissan Sentra SE, with 2 liter DOHC engine. The real result is 32 miles per gallon, while Honda Civic Hybrid in similar conditions averaged at 36 miles per gallon. I can compare now "Class A" Armada, 8 pots 5.6 liters (14 miles per gallon), with optimal class AB Sentra, and class D Civic Hybrid. Class AB wins in day-to-day life, while class A I would prefer for special occasions.
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Old 17th October 2012, 06:35 AM   #7448
dvv is offline dvv  Serbia
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Currently I drive Nissan Sentra SE, with 2 liter DOHC engine. The real result is 32 miles per gallon, while Honda Civic Hybrid in similar conditions averaged at 36 miles per gallon. I can compare now "Class A" Armada, 8 pots 5.6 liters (14 miles per gallon), with optimal class AB Sentra, and class D Civic Hybrid. Class AB wins in day-to-day life, while class A I would prefer for special occasions.
Yep, that sounds about right, that's what I was referring to. A 2 litre engine will use up about that, although another variable is the quality of fuel. I find that my current Cruze is able to adjust its electronics to better quality fuel (my favorite is Shell VPower+100, 101 octanes nominally) and it does a bit better on mileage with it. But I think its adjustment range only goes up from Euro Super (95 octanes) to Euro Super Plus (98 octanes), 101 is above its range, more of my ego trip than anything.

But people like VW declrate their 2 litre, turbocharged engines at something like 6.3 litres per 100 km/h, or about 54 miles/gallon - which is ridiculous and can be achieved only by very special modes of driving. Like driving 50 mph on a highway where 75 mph is the speed limit, on a dry day with lots of sun and zero wind, with high efficiency Michelin low roll resistance tyres - which they do not supply with their cars.
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Old 17th October 2012, 06:52 AM   #7449
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They recently gave my license back ( not banned , medical ) . A lot of the time writing here was because for 7 months I have been having tests . On returning I treated myself as a new driver . This I retain unless pushed . Keeping to our national speed limits I do about 61 MPG imperial in my Golf TDi ( 90 BHP ) . That is better than 50 US MPG or about 4.7 L /100 kM . This degrades slightly if using motorways and cold weather . This agrees well with the book figures . I cleaned the sensor device recently to diagnose a fault . The fault was in a vacuum tube which I suspect the garage damaged . The upshot was I am fairly certain the consumption improved after that ( over night in iso alcohol ) . I also notice diesel cars work better after 100 000 kM and continue to improve . The iso and I suspect computer self resetting was worth about 3% .

One trait that was true in the past was a flat battery would force the car into the " get you home mode " . This would be about 20% worse consumption if petrol . This would result in an expensive reprogramming at the dealer . I am told if allowed to work for a few weeks ( days , 20 operations and can be done in 1 hour , something about temperature which I forget needs to be correct if so ) the engine will reprogram itself . The process is gradual and is the one that samples the fuel and adjusts timing minute by minute . Default assumes 87 octane or whatever . That is sampled by a small microphone type device I am told which listens for knock ? I found in the past if you do not know the timing of an engine 5 degrees before TDC static seems always to work . I set a Suzuki 4x4 recently when a new distributor was handed to me by a young lady in the middle of nowhere . I put it in and guessed 5 degrees ( Before TDC - 1 mm with a lolly stick down the plug hole is one way if all else fails ) . It worked fine . The garage said I got it more or less exactly right . The point is the lady removed the old unit to seek a new one . It wasn't the distributor . The AA man was wrong . It was her anti theft device . The order of firing I got with my finger on the plug hole ( compression ) . I had to rock the car in gear to be certain it was the right side of TDC . Turning the engine is not a sure thing . Some rotate opposite to what you might think . 5 deg after will work .... badly . By 8 deg before TDC it already gets critical for some engines . 40 deg advanced is about maximum if that is the only way to know . That can be checked by rotating the rotor arm if an old car . If that one is not correct the car will struggle after 2000 RPM . That can be worn out parts . 4 degrees variation between cylinders is not unknown at advanced ( cam and / or bearing problems ) . The vacuum advance is usually checked by disconnecting and listen for the revs to change . Makes you want an old car ? One that can be understood without a PHD . The old Mini was good. The carburetor a work of art . 6L/100 kM . Always carry a radiator bi pass tube for those , the spring type not the original . That required the head to be removed , the other a 10 minute job . I guess the old MGB was not so bad if not expecting a modern car . Peugeot 404 Estate is top dog . The car that survived Africa . Citroen Light 15 , perfection .

Another tip . If you need to replace a valve spring on the road string down the plug hole will retain the valve ( bring piston up to compress the string ). If a tool can be improvised the spring can be changed !!!! Saw a guy wiring his valve spring on a BSA 650 A10 once . Was dubious , he thought it would get him home if revs were keep low !! He was so sure I suspect he knew what he was doing ? A friend said he made a Norton kick start return spring from piano wire to get him home . He was in Edinburgh and found a piano shop that did have it ! It worked and was not replaced . The favourite for that was a piece of bicycle inner tube to strap it up when started . If not the noise it makes would wake the dead .
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Old 17th October 2012, 01:53 PM   #7450
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MPGe seems like a lot of BS as well since the EPA uses the storage capacity of the battery pack without accounting for the efficiency of the power generating facility that produced the electricity.



The Chevrolet Vega got a bad name for two reasons. (1) bad valve seals that failed at 55-65K miles, (2) no overflow tank on radiator with a habit of blowing water out the overflow when hot.

The first is solved by knocking the ceramic insulator out of a spark plug, and welding a quick disconnect for an air hose to it. Screw it in in place of a plug and hit it with 100psi air. It holds the valve in position while removing the keepers, and valve spring to replace the seal.

The second problem was simply solved by installing an aftermarket overflow kit.

The three Vegas in our family all went over 150K miles without problems before being sold.

Cheve was stupid for not fixing both problems.

They fixed it in the Sunbird, which used the same engine as the Vega. The Vega got a bad name, the Sunbird did not.


The higher the octane rating, the lower the fuel mileage as the energy content of high octane gas is lower than lower octane gas.



I dual-plugged my 1975 Harley Davidson XLCH Sportster to eliminate knock and allow me to run low grade gas.

It has a 10.5:1 compression ratio with a Hemi chambers and gets 45mpg on regular gas with no ping even in the hottest weather (104F in Columbia SC one summer).
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