Jan 10, 2007 1:56:38 PM
Quote:
RR4 said:
In short direct injection means on average an extra 30-40 hp.
Currently most, if not all (except for the RSR Cup Car) motors that Porsche use, only have one throttle control valve for ALL 6 cylinders. It controls the amount of fuel sprayed into each cylinder depending on that particular cylinders cycle. The problem is that each cylinder is in a diffent position of their cycle at any one time and ONE throttle control valve does not take that into consideration - instead it averages the amount fo fuel required by each cylinder and sprays it in, some cylinders get more fuel than they need, and some get less. In efficient and power robbing.
What direct injection does is it controls each cylinder separatly and injects the exact amount of fuel that that specific cylinder requires depending on where it is on its cycle.
So basically a direct injection engine has 6 control valves ONE for each cylinder and non-direct injection only has ONE that controls all 6 cylinders.
Tuners have been selling mechanical direct injection-like systems for the 993 motor, which gives on average 35hp.
The RSR also uses a mechanical system which is responsible in part for the 485hp that engine makes.
Jan 10, 2007 2:20:30 PM
Jan 10, 2007 2:32:55 PM
Jan 10, 2007 2:44:20 PM
Jan 10, 2007 3:24:13 PM
Quote:
mcdelaug said:
Let me take a stab at it...as much of what is said above is correct, but not quite as succinct as it might be.
Here's the simple way to think about fuel delivery with gasoline engines.
Carburetion: one or more carburetors sits atop the intake manifold, constantly mixing fuel into the intake path's airstream at a rate controlled by how hard you're pressing the accelerator pedal.
Throttle body fuel injection: replace the carburetor(s) with a one or two large fuel injectors that sit on the intale manifold, providing more precise fuel delivery, but still not cylinder specific delivery.
Multi-point fuel injection: each cylinder has its own injector that sprays gasoline into the intake manifold just above the intake valve, not into the cylinder itself.
Direct Injection: each cylinder has its own fuel injector that sprays directly into the cylinder, (as opposed to the intake manifold just above the intake valve in MPFI) using the more sophisticated mulitple pulses of varying sizes and with a particular "spray" pattern alluded to above.
I hope this clarifies things a little.
mcdelaug
Jan 11, 2007 4:09:44 AM
Jan 11, 2007 4:32:05 AM