How to make port injection as efficient as direct injection
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I know that, but what if we played with the injection timing? Does K-pro allow us to play with this parameter?
The reason why direct injection is more efficient than port injection is because fuel enter the combustion chamber later therefore less fuel gets evaporated and less fuel goes on the cylinder wall. Also the spray pattern is more optimal creating even smaller droplets of fuel.
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On top of the cylinder head modifications - you also need a 2,500+ psi fuel system and some place to drive a mechanical pump (look at new Mazda's). Due to the emissions benefits - Honda will eventually (like most OEM's) switch over to direct injection.
K-Pro does not allow you to play with injection timing, however, AEM does.
Honda's current fuel strategy is pretty damn good though. You can play around with it and not see any benefit. Their injection event is typically 70 to 90 (crank) degrees before the intake event. Injectors are aimed at the back of the intake valves. Fuel is injected, hits the hot intake valves (and port walls), vaporizes, then the intake valve opens to draw in fuel vapor/ air mixture. Since the fuel is already vaporized before the intake valve opens, it mixes better and takes less energy to draw into the combustion chamber. The staggered intake lobes on the cam generate a swirl going into the combustion chamber which makes the fuel/air mix more dense (except when you're in VTEC riding 1 lobe).
Anyone who's tuned a newer engine in cold weather has dealt with this. When the engine is cold, the fuel doesn't vaporize, and that's part of the reason you need a lot more cranking fuel and after start fuel to get it going, until the engine warms up enough for the valves to get hot, then fuel trims start to drop off. On a "cold" 60* day in California - this process may only take 10 - 15 seconds. When it's 32* below freezing, it may take 50 - 60 seconds.
The only inefficient aspect to this strategy (besides warm-up): the molecules of vaporized fuel that don't make it into the mix (Tau fuel). Direct injection eliminates Tau fuel.
K-Pro does not allow you to play with injection timing, however, AEM does.
Honda's current fuel strategy is pretty damn good though. You can play around with it and not see any benefit. Their injection event is typically 70 to 90 (crank) degrees before the intake event. Injectors are aimed at the back of the intake valves. Fuel is injected, hits the hot intake valves (and port walls), vaporizes, then the intake valve opens to draw in fuel vapor/ air mixture. Since the fuel is already vaporized before the intake valve opens, it mixes better and takes less energy to draw into the combustion chamber. The staggered intake lobes on the cam generate a swirl going into the combustion chamber which makes the fuel/air mix more dense (except when you're in VTEC riding 1 lobe).
Anyone who's tuned a newer engine in cold weather has dealt with this. When the engine is cold, the fuel doesn't vaporize, and that's part of the reason you need a lot more cranking fuel and after start fuel to get it going, until the engine warms up enough for the valves to get hot, then fuel trims start to drop off. On a "cold" 60* day in California - this process may only take 10 - 15 seconds. When it's 32* below freezing, it may take 50 - 60 seconds.
The only inefficient aspect to this strategy (besides warm-up): the molecules of vaporized fuel that don't make it into the mix (Tau fuel). Direct injection eliminates Tau fuel.
Gooid post. :up: Before I read yours, I was wondering and about to ask why Honda didn't use DI in the first place.
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Honda has had direct injection K series motors in Japan for some time now:
http://world.honda.com/news/2003/4031127.html
I love this explanation...engineering style! I'M sure Honda will, and must implement direct ignition in there gasoline engines for next generation cars. Diesel engines also must be in production! Imagine, torque number with small engines! Dragster will be finnally happy!
I don't think fuel against the port wall accounts for 8%. It's more efficient because there is no more unburnt fuel that is trapped between the piston and bore above the top compression ring and the air/fuel blowby now becomes air blowby only, also the fact that you reduce pumping losses because the tb is not used when in di mode which then also gives a higher dynamic cr at "part pedal" aka "lean burn". Thermal efficiency is higher since the unburnt air in the cylinder expands when it heats, in a conventional pi system that heat is wasted. So small improvements here and there and you end up with the 8%.
For retrofitting, ivvt's are a more realistic option to look into for part throttle inefficiency and better performance. Lower pumping losses than di but you still have the wasted crevice volume and blowby issues. But it balances out pretty well.
For retrofitting, ivvt's are a more realistic option to look into for part throttle inefficiency and better performance. Lower pumping losses than di but you still have the wasted crevice volume and blowby issues. But it balances out pretty well.
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http://world.honda.com/Diesel/
about 250 tq at 2000 RPM...
they also use a dual spark setup on some motors.
I know about this, but I hope HOnda will bring those engines to North America. They were supposed to be in production for 2009...and now 2010...
I think gasoline engines have reach there maximum performance (fuel consumption, power, torque, durability). I know they can be optimize more, but money wise the gain result for each dollar spend is not much.
Best regards!
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