Wnts2Go10O

iTrader: (12)

the bold is why i think theres more to it than what is traditionally known. its a fairly simple change in position but the changes that happen because of it are more complicated.

concerning the rest: the SAE paper points out how badly the 'DI LS7' ran compared to the final design we have now. part of it being the lack of mixing airflow (swirl) at the point of injection in the cylinder. it also seemed to point out that DI engines are very sensitive to port design and can become sensitive to timing changes if the air/fuel doesnt mix well enough. more sensitive than what the community is used to.

the advantage that PFI has on DI is that the air and fuel has more time to mix inside the port (fuel spraying the back of a closed valve at lower RPM) and because of that, swirl isnt all that important.

arghx7

I think the main factors will be whether changing other aspects of the system, such as the amount of exhaust backpressure, valve timing events, etc can overcome possible degradation of combustion performance. Only time will tell though; modding for power has a different set of conditions and constraints than developing heads for mass production. I'm excited to see what our vendors learn.

I can also say that on PFI, high swirl and tumble flow are mostly for cold start emissions. That's why you'll see swirl or tumble control valves on overhead cam PFI engines that only operate when the engine is cold. The emissions aspect applies to DI as well. The fundamental difference as we've pointed out is that you've only got about 1/3 the time in actual seconds (~5 milliseconds on DI vs ~15 on PFI) and in crank angle degrees (~150 degrees on DI vs ~600, maybe even full 720 at max duty cycle) for the mixture to form.

FSAE_Junkie

To answer the question on the discharge coefficient:

Late Model Racecraft

Thanks for posting this up, i hadn't had time to do it.

Wnts2Go10O

iTrader: (12)

well thats certainly a telling graph.

ringram

Not bad, now for the dyno results.. and tuning info.

With DI perhaps AFR can be closer to stoich? Maybe even some lean burn at part throttle.

Surely compression can also rise. 11.5 seems very low when ferrari run 12.5:1 in the 458.

Looks to be plenty of additional variables to play with.

Thanks for sharing your development info guys.

Late Model Racecraft

We plan on milling these heads some, but its hard to see how much we can mill off without having an injector to mock up. We want to make sure it has plenty of material around it.

Late Model Racecraft

Here is our proprietary LT1 porting program is finally on the machine being digitized and make some fine adjustments before we cut the first set.

NW-99SS

iTrader: (6)

In for results...looking forward to see what the curve looks like after porting!

Late Model Racecraft

Here is a video of our Proprietary CNC porting program being run on a fresh set of 2014 Gen V LT1 cylinder head. Our porting program picks up the airflow of this cylinder head by 45cfm over stock at .650 lift on the intake and 42cfm at .650 lift over the factory exhaust port at 28" of water when flowed on a 4.060" bore.

oakley6575

iTrader: (3)

Good work boys! Can't wait to see dyno results