Direct injection question
Thread Starter
Instructor
Joined: Oct 2006
Posts: 126
Likes: 24
From: SC
Direct injection question
I have a 2019 Z06, which, of course, has direct injection, like the other C7s.
Having an engineering mind, I wondered how the direct system compares to diesel injection. Since the C7s use spark plugs to ignite the fuel, it must be injected well before TDC (top dead center). That's why there is still discussion on spark advance.. So when is the fuel injected? On the intake stroke or the compression stroke? And can I assume that the amount of fuel injected is only dependent on the duration of each injection and not a pressure change?
It is an amazing system that got me 27.2 mpg on a 1000 mile trip with a 650 hp Corvette that can do about 130 in the 1/4 mile!
Still shaking my head over that.
A lot of engineering went into this and I was just curious.
Having an engineering mind, I wondered how the direct system compares to diesel injection. Since the C7s use spark plugs to ignite the fuel, it must be injected well before TDC (top dead center). That's why there is still discussion on spark advance.. So when is the fuel injected? On the intake stroke or the compression stroke? And can I assume that the amount of fuel injected is only dependent on the duration of each injection and not a pressure change?
It is an amazing system that got me 27.2 mpg on a 1000 mile trip with a 650 hp Corvette that can do about 130 in the 1/4 mile!
Still shaking my head over that.A lot of engineering went into this and I was just curious.
Racer
Joined: Jan 2009
Posts: 395
Likes: 194
From: Goderich, ON
On DI, injection timing varies according to conditions - during higher demand injection happens with the intake stroke, at lean cruise it will inject at the very end of the compression stroke. Fuel pressure is created by a mechanical cam-actuated pump (up to 3000 PSI) and is regulated down to 50 PSI under certain conditions. DI combined with VVT are the main contributors that make modern engines both so powerful yet fuel efficient.
