Sunday, January 30, 2011

Turning a gasser to dedicated-ethanol?

Now with all that environmental concernments, ethanol has been considered a good option by some people. I prefer biodiesel or straight vegetable oils, but there are those who prefer something that can be easier to burn in their regular gassers. But to have better results with this alternative fuel a few mods are recommended.

Ignition: since ethanol resists more to the detonation, it requires some advance and a higher-capacity ignition coil is also a good option. Ignition wiring must be in good conditions to avoid electric runaways, so those high-performance silicone-coated copper cables are strongly recommended. Spark plugs with a lower thermal grade usually have better results in ethanol-powered engines.

Compression: it's usual to have higher compressions in engines to work with ethanol. Compression ratios above 12:1 can lead to not need too much variations in the ignition advance. Either a different piston design or a lowered cylinder head can be used. Ethanol has a lesser energy density than gasoline, but higher compressions help to take it more efficiently.

Cold start ability: this is a sensible point to ethanol. In Brazil it's very common to see an auxiliary gasoline tank to be used in cold starts, while in other countries such as Sweden, France and the United States it's more usual to find the ethanol blended with regular gasoline from 15% (E85) to 30% (E70). A few years ago, Robert Bosch Gmbh. released a start system special to the so-called "flexfuel" vehicles, the FlexStart, spotting injector tips with a heater element incorporated to them, allowing the fuel to be heated until 120°C, easing the startup and also stabilizing the idle speed in the first 2 minutes after the start. The device had been used commercially only in a special edition of the Volkswagen Polo for the brazilian market in 2009, but should still be considered a serious option to a dedicated-ethanol engine.

Air intake and fuel injection: in some older dedicated-ethanol engines the intake manifold was made out of metal and could be heated by the water from the cooling system to avoid it to freeze due to the ethanol flowing alongside the intake air, but currently plastic manifolds are found almost in every car. With regular indirect injection or with a carburettor the heating is extremely helpful, but currently there are some engines featuring a direct injection setup, so it would be not so easy to have this problem. Maybe direct injection could also ease the cold starts. By the way, since ethanol has a lower energy density, its consumption is about 30 to 43% higher than gasoline, so more flow would still be required even with some mods intended to increase the efficiency with ethanol.

Cooling system: ethanol usually works better when the engine is allowed to operate in a higher temperature, for this reason a more restrictive thermostatic valve can do miracles in a water-cooled engine. For an air-cooled one it's harder to control the temperature, so idling and startups won't be so smooth, but it's not impossible to overcome this difficulty. In some older Volkswagen boxer engines from the 80s there was an automatic fold-away thermostatically-controlled airflow restrictor to leave the engine reach a temperature more suitable to operate with ethanol. However, currently only Honda motorcycles are offered with air-cooled engines able to run on ethanol and there is no airflow restrictors, mainly because of the current electronic fuel injection system that adjusts itself to operate smoothier.

Another thing that I would recommend is about valve seats lubricity requirements: it's not a bad idea to blend from 2% to 5% 2-stroke engine oil in the ethanol, even when using it in a 4-stroke engine. The oil would reduce the fatigue on valve seats, and also protect fuel lines from the more corrosive effects of the ethanol.

Thursday, January 27, 2011

why ru sucha diesel douche

i like diesel engines because of their advantages for heavy duties and for mudding, and the range of a diesel vehicle compared with a simillar with an otto-cycle engine, either a gasser, ethanol-burner or cng/lpg, and due to diesels usually last longer than other engines... i have driven some cars with cng setups and it takes a cargo space that is preserved in a diesel-powered one...

when there is no guidance the people fall, but in abundance of counselors there is victory

Thursday, January 20, 2011

Is GM ready to play the downsizing game?

Even facing some resistence from the (stereo)typical GM's most loyal customers, the downsizing is a reality that can't be denied. However, even famous for its bigger engines, as a global car manufacturing group, General Motors is ready to face competition in the newer trend in engine development.

A clear example is the 4.3L Vortec V-6 engine still offered in basic versions of the Silverado. Some versions of the 2.0L straight-4 Ecotec fitted with turbo and intercooler can deliver the same 260lb.ft. torque rating in a lower engine speed, as well as more than its current 195hp rating. Then, not just due to the smaller weight and displacement of the engine, also since a lower speed is required to do the same jobs it turns the 4cyl turbocharged more efficient.
Some american customers can still see the downsizing as an european trend, and possibly hard to overcome EPA regulations, but the use of improved smaller engines has been a way to cut greenhouse gas emissions, among other pollutants. The combustion proccess is more efficient due to the higher air flow, then less carbon monoxide is generated, for example. And an old phenomenon widely reported in early turbo setups, the turbo-lag, had its effects reduced with newer engine management systems. GM has been dominating the technology of turbochargers, and ready to face some opponents well-known for their advanced technology, such as BMW. Recently, BMW released a 2.0L twin-turbo straight-4 engine, developing 245hp and 260lb.ft, to replace its 3.0L straight-6 (258hp/230lb.ft.) in some models such as the X1. Considering the manufacturing cost, GM still has an advantage since their engine uses only one turbocharger. Even with the benefits of the smaller engine, a traditional customer would not want to pay too much more for it.
Some people possibly would never wonder something more than 50% smaller in displacement performing the same job of a 4.3L V6, often considered even "too small". For example, it's too hard to see a Chevy ambulance with a 6-cyl engine, or a police vehicle, traditionally powered by large V8's , often even restricted to the so-called "police packages".
Drawing above is only for artistic purposes, Chevrolet Astro was never used by any police department in Brazil

However, a smaller engine is not necessarily a worse engine. Recently, General Motors of Brazil limited the offer of the Blazer to a 2.4L flexfuel 141/148hp engine, but until 6 years ago there was the option for the iconic 4.3L V6 that was imported from the United States, that still have some cult status in police departments due to its performance, and some older versions fitted with this engine remain on duty, including some very specific police departments such as Tobias de Aguiar batallion, better known as ROTA and famous for its former all-Chevy fleet. What is hard to understand is why an option for this very specific application was never offered, while the 2.0L turbocharged engine is still made in GM's São José dos Campos engine plant for export markets. Could be a bolt-in replacement...

In other markets, most notably european countries, GM has been successful with the downsizing. Some of its models are currently offered only with turbocharged engines in Portugal, such as the Opel Insignia, currently offered in the american market as Buick Regal, featuring a 2.4L Ecotec non-turbo (182hp/172lb.ft.) not avaliable in its european counterpart and the turbocharged 2.0L in a 220hp/258lb.ft. version (this setup would already be enought to replace the 193hp/250lb.ft. 4.3L V6 in the Blazer). Surprisingly, in a segment where 4-cyl engines are perceived as "less luxury", GM is not offering the 2.8L turbocharged V6, that with its 325hp/320lb.ft. could beat the 3.6L currently used from the Chevy Camaro to the Cadillac SRX (without any V8 option in the current generation) delivering 300hp/273lb.ft., again, at higher engine speeds. Even the Vortec 4800 V8 with its 295hp/305lb.ft. could be replaced by the 2.8L without any prejudice in the performance. All of that with systems already avaliable in GM's portfolio.

So, seems like GM is ready to play the downsizing game. What about you?