haypops

Vauxhall HCCI

9 posts in this topic

43 British mpg = ? US mpg?

where is atabloke when you need him? :AH-HA_wink:

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1 Imperial gallon = 1.20095042 US gallons

so 43/1.2 = almost 36 MPG US

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I'd like to see what the LS line would do with this technology

You'll need to get DI and VVL on the small block first. Those are pre-requisite enabling technologies for HCCI. It may also be a challenge to design the combustion chamber's roof for maximum knock resistance and predictability with a pushrod head. The main problem is that the wedge head with a heart-shaped combustion chamber (2-valve OHV heads) are not symmetrical with a squish deck on one side only. A DOHC 4-valve head is symmetrical about 2 axis can be engineered with squish decks on both sides.

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You'll need to get DI and VVL on the small block first. Those are pre-requisite enabling technologies for HCCI. It may also be a challenge to design the combustion chamber's roof for maximum knock resistance and predictability with a pushrod head. The main problem is that the wedge head with a heart-shaped combustion chamber (2-valve OHV heads) are not symmetrical with a squish deck on one side only. A DOHC 4-valve head is symmetrical about 2 axis can be engineered with squish decks on both sides.

haha.. not at you, but you always seem so technically astute, yet can bring it down to a level most people with a good idea how an engine works, can understand.

:thumbsup: (to bad there isn't a highfive smily) :lol:

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Awesome. I'm assuming this will be cheaper than a diesel engine, as surely that is the whole point of HCCI...?

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Awesome. I'm assuming this will be cheaper than a diesel engine, as surely that is the whole point of HCCI...?

I am not sure if it'll be cheaper than a diesel engine. You have to answer this question... What's cheaper? A stronger block and a stouter set of rods or an array of cam switching hardware and in-cylinder pressure sensors? I am not sure I can answer that question.

HCCI will improve on the efficiency of gasoline engines without sacrificing performance, civility and image.

HCCI however is not a diesel and will not get to be as efficient as a diesel. The reasons are three fold:-

(1) The Calorific Value of each drop of diesel fuel is higher than that of each drop of gasoline.

(2) Diesels still operate at a higher compression ratio than HCCI meaning better combustion and thermal efficiency -- ~ 16:1 for turbodiesels and up to 22:1 on NA diesels.

(3) Lastly, and most importantly, one of the biggest difference between a diesel and a gasoline engine is that the diesel engine DOES NOT have a throttle body or plate. In essence it is running at wide open throttle all the time -- include at light load freeway cruise -- whereas gasoline engines choke the engine's airflow with a throttle plate to control power output at all times except when you put the pedal to the floor. A car spends 99.9% of the time off WOT, meaning 99.9% of the time the gasoline engine is working against the pumping resistance of a partially closed throttle plate choking it of airflow. A diesel engine does not do that. Instead, it always allow as much air as the engine will ingest into the cylinders. It controls power simply by injecting more or less fuel. At part throttle it simply runs lean. This is also part of the source of the diesel engine's emission woes, but it makes it a more fuel efficient engine operating concept. The HCCI engine cannot get rid of all the traditional air metering gear because it cannot run in HCCI mode except at light loads and over a subset of its entire operating speed range.

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