Mods for the 5.7 Hemi

Using a tuner will get you a noticeable number of additional ponies. With the tuner you won’t need the Pedal Commander.

 

Since long-tube headers scavenge so well, I am curious if some of the gasoline injected is being discarded out the exhaust valves, unburnt.

If it is not the case that the gasoline is injected early enough to do that, I think you could run a leaner (detected) air-fuel ratio without affecting just what the air-fuel ratio is in the combustion chambers much. You would be allowing un-fueled fresh air to exit the exhaust valve, then injecting fuel at a point (which varies by RPM and throttle opening) that the fuel is preferably all going to wind up in the combustion chamber.

While high-overlap cams are designed to add duration without discarding low-RPM driveability, with a set of really free-flowing equal-length headers, you could use a longer duration with less overlap and achieve similar scavenging as the stock cam with more restrictive manifolds, especially if those manifolds were the cheap log-type.

It would be interesting to see someone do super-scavenging with an exhaust supercharger (superevacuator?) There is no better exhaust backpressure than deep-space vacuum. It would be interesting to see a heat-proofed centrifugal supercharger of a larger size than that of the intake supercharger if there was one, to study exhaust dynamics with extremely low backpressure. Would the engine gain more power than the exhaust supercharger/superevacuator cost?

With a heat-proof Roots unit, the energy cost would not be too high, I think, because it is taking air from a high-pressure zone and transferring it to a low-pressure zone.

 

^^^. If one does the math, at 6000 rpm there isn’t enough time to spray 12 ms of injector pulse width upon valve opening. Some of the fuel shot is sprayed onto the closed valve. Of course, all this is dependent on fuel pressure, injector specifics, and injection strategy.

If the scavenging tuning is matched to the cam timing it shouldn’t be a concern.

 

At 6000 RPM, the intake valve, if open for 220 degrees, takes 220/360X60/6000seconds).
A mere 0.00611 seconds of intake valve opening.
.012 seconds of pulse width, about 1.96 times as long as the valve open event.

IF the Hellcat uses 70.7 pounds of air per minute for combustion, then at 11.5:1 a/f ratio, it would use 6.1478 pounds of fuel per minute.
0.7684 pounds of fuel per cylinder per minute.
0.01280 pounds of fuel per cylinder per second.

intake valve open average time 0.00305555 seconds per rotation. 100 rotation per second. Intake open 0.305555 of each second.

0.01280 pounds of fuel per second/0.305555 seconds is rate of fuel per second:0.04189 pounds per second maximum flow rate per cylinder, which is 150 pounds per hour flow rate, so the injector has to be open longer than the intake valve is open, because at 57 pounds per hour at 0.01280 pound of fuel per cylinder per second, there is no way the injector can open only during valve opening time. An injector that could flow about 150 pounds per hour could get it close, but it would have to be timed exceedingly accurately. A 200 lb/hour injector would have an easy time of it, but how would you verify your timing? With a high-speed camera available at all RPM and loads?

I would rather have much larger injectors that could bracket the injection event neatly between the valve opening and closing times, but, oh boy, the science involved in just neatly squirting the fuel in so it is in the intake air flow when the valve is open, at the exact moment when that particular intake air is entering the cylinders is an art in itself.

Direct injection would be optimal, as used by Ferrari on it F140 and other engines, because NONE of it will end up on the back of the intake valve, one would hope.

If you were bold and persistent, an 850 pound/ hr injector could work, IF you could slam it open and shut fast enough to accurately place the accurately-matching amount of fuel.

But, even with a short 0.1ms pulse width, would it be little enough fuel for idle? It's only 6.5ms of valve open time to slot in the injection, so 0.1ms would work if it was even possible to accurately do.