| strat61caster |
02-03-2016 02:41 PM |
Quote:
Originally Posted by MrDinkleman
(Post 2533433)
Well, don't need much power and I don't think economy is improved much at idle.
Why does DI kick in at idle, anyway? While sitting at a signal, the engine will be idling fairly quietly then all of a sudden the clattering starts.
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Direct injection is more precise than port injection, you can get a better air-fuel mixture more precisely straddling the line between rich and lean and minimizing exhaust emissions. You both avoid over-fueling the cylinder (wasting fuel) and leaning it out (not maximizing power) as well as running ultra-lean to save fuel and running rich to advance timing and increase power depending on the needs at that time. While the DI is squirting just the precise amount of fuel into the cylinder to nail the air-fuel ratio a port injection system is spraying more fuel than is needed as some of the fuel sticks to the walls of the intake and head and valves as it travels into the engine.
Comparing direct injection to port injection is like comparing port injection to carburetors. The differences are small today (i.e. early port injection in the 70's and 80's) but will be big tomorrow (today's port injection vs. pretty much any production carburetor).
Early stories on the 86 had claims that without Toyota's D4-S system the FA20 would peak at about 120 horsepower in order to meet emissions requirements. I'll take a little noise and a bump in price tag for 80hp.
http://blog.toyota.co.uk/tada-how-to...eated-the-gt86
https://en.wikipedia.org/wiki/Gasoline_direct_injection
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