That's equivalent to the hybrids.

A scam.
At "part throttle" the pistons descend "against" the lower pressure above them - thus the so called throttling loss. For the same driving condition (hp output) the PRV engine must have the same air pressure to get the same amount of air/fuel in the cylinder (assuming same temperature of the intake air). Why would it matter if the throttle plate causes turbulence losses or not? You do not want to recover the pressure - if you do, you have full power and full air/fuel flow, not part power.
How do they get better mileage, you ask? Who does the neasuring?
I think I'll stay with those big magnets around the fuel lines - they offer the same improvement at lower cost.

Does anyone out there know how much energy a turbine in the inlet (in place of the throttle) could recover during cruise? (Assuming 15” Hg MAP - which may be quite low for today’s transmissions).
How about radically heating the intake air for part power?

Just go with BMW's valvetronic, no throttle butterfly at all.

It is better to not waste the energy in the 1st place than to try to "recover" it. see above

Heating the air could cause problems. Too much heat and pressure and the gasoline will self ignite.

The civic gets 36 mpg in real world driving.
He is claiming 52 miles per gallon with what amounts to a four barrel carb sectioned to each of the 4-cylinders of the engine, and fuel injected rather than aspirated. The idea seems to incorporate some advantages of a carburetor with those of a fuel injection system, and have the venturi effect to slightly boost airflow and cylinder pressure. This may also be compatible with a supercharger if the engine is slightly redesigned.

The system may have merit, but also has a more complex casting and machining requirement.

Does the aerodynamics in the induction system mater?
It sure maters to the amount of energy it takes to propel a car down the road.
It seems that this system enables a smoother flow of induction air versus the throttle plate and the proximaty to the intake valve may be the reason for the improvements.
The only way to know what they mean by pressure recovery is to actually speak to the company.
I think if it works this would be a great aftermarket kit.

This system isn't about reducing pumping losses by removing the throttle butterfly. Rather, it is about using the low pressure in the venturi to vastly improve fuel atomization, which is followed by improved combustion efficiency.

And please, no turbines nested in the intake path to "recover" energy. That's like driving around with a windmill on top of your roof and expecting a net energy gain.

BMW's Valvetronic works but there are two issues:

1) Valvetronic is hideously expensive to assemble.

2) Valvetronic also cannot run at very high RPM well.

Does anyone out there know how much energy a turbine in the inlet (in place of the throttle) could recover during cruise? (Assuming 15” Hg MAP - which may be quite low for today’s transmissions).

How about radically heating the intake air for part power?

it seems that this incorporates the benefits of valvetronic (near elimination of the throttle butterfly) and direct injection without the expense.

"it is about using the low pressure in the venturi to vastly improve fuel atomization"

Fuel atomization hasn't been an issue in 20 years or more. Most modern cars put out nearly 0% unburned HC, so the efficiency gains to be had are minimal.
Surprisingly, the "EPA" test on their website shows very high HC, which goes against the atomization claims. The test also shows very high NOx, which is a sign of a lean-running engine.
Could it be that they just leaned-out the engine as much as possible? That would explain the poor polution scores as well as the slightly improved mileage.

Any independent third-party tests?

How close does this bring a spark ignition engine to the fuel economy of a diesel?

"How close does this bring a spark ignition engine to the fuel economy of a diesel?"

It can surpass it.
If we pretend it works, we can pretend it is better than the diesel.

scam

Bernard,

Take the catalytic convertor off of all cars and run your unburnt HC tests again. I'd wager even a SULEV car would not pass the unburnt HC test on an exhaust gas analyzer (though the numbers will still be small and probably less than 0.5%)

I had a Ford Escort 1.6GL retrofitted with a Venturi carb in 1988 - these have been around for ages.

Every time the piston pulls downward against a vacuum, engine efficiency is lost. This concept is known as pumping loss. All throttle plate designs have substantial pumping losses. The vintage 80s slide plate incurrs the same pumping losses.

PRV induction recovers pressure regardless of engine load because of the integrated throttle (pintle) and the Venturi effect.

Dyno comparisons have been on the website for a year, showing the substantial gains in torque.

James Meyer, PRV Performance. www.prvperformance.com

Every time the piston pulls downward against a vacuum, engine efficiency is lost. This concept is known as pumping loss. All throttle plate designs have substantial pumping losses. The vintage 80s slide plate incurrs the same pumping losses.

PRV induction recovers pressure regardless of engine load because of the integrated throttle (pintle) and the Venturi effect.

Dyno comparisons have been on the website for a year, showing the substantial gains in torque.

James Meyer, PRV Performance. www.prvperformance.com

OK James Meyer,
"Every time the piston pulls downward against a vacuum, engine efficiency is lost. This concept is known as pumping loss. All throttle plate designs have substantial pumping losses. The vintage 80s slide plate incurrs the same pumping losses."
I agree, and part power (and lower consumption) is achieved by having a lower mass of air-fuel (A-F) mixture in the cylinder. To get lower mass you need to get lower pressure. Less mass of A-F = lower pressure = less fuel consumed = less power = cruise. If the PRV induction is recovering more pressure, you get more mass of A-F and more fuel consumed. Ok so you close the integrated throttle (pintle) a bit more until YOU DO NOT RECOVER MORE PRESSURE than the stocker. You're right where you started. If not , close it more, so that you are. Other wise more pressure is more A-F mass is more consumption.
So if the "stocker", at 65 mph cruise has a manifold air pressure (MAP) of say 15" Hg, do you suppose your PRV "MAP" ("manifold air pressure" after the pintle) is more? or less? If it's not the same you will slow or accelerate. If it is the same, then A-F mass is the same and so is power and torque and consumption.

"Dyno comparisons have been on the website for a year, showing the substantial gains in torque."
Harry Potter has been on web sites for longer but I'll not be riding a broom off a roof soon.

I do understand your frustration with the concept. If it were simple it would have been done long ago.

I just put a pressure gauge on the Venturi discharge while the car is idling. Every time the injector fires, the pressure spikes to +6psig. The tap happens to be near the throat so there was some vacuum fluctuation.

The oratory above overlooks the effect of vaporizing fuel in a confined space downstream of the pintle. There is now question that substantial torque gains are realized from PRV. If seeing is not believing, write me offline and I will put you in touch with the firm that performed to dyno work.

James Meyer,
Fuel vaporization contributes almost NOTHING to reduce pumping loss at partial throttle. Here's why:

At cruise, the Honda engine is at about half of maximum manifold pressure (~7-8 psi from vacuum). Since atmospheric pressure is 14.7 psi, the piston has to fight against ~7 psi of atmospheric pressure on the intake stroke, and this represents pumping loss.
Air contains 21% Oxygen only, and it takes 17 molecules of O2 to combust with 1 molecule of Octane (C8H18) to make CO2 + H2O. So, when the fuel is completely vaporized, the increase in manifold pressure is only 1/17 x 21%=1.23% as the result of complete fuel vaporization very early before the intake stroke.
Not enough to do anything to reduce pumping loss!

It is vital to recognize that the PRV plenum is always at atmospheric pressure -- there is no throttle plate. Consequently, when the intake valve closes on any of the four Venturis, that entire Venturi -- intake, throat and expansions sections relax to atmospheric pressure. As the intake valve opens, the initial charge has full atmospheric pressure to drive the flow. As the piston travels toward the bottom of the cycle, the same pressure is achieved as a conventional manifold so that the same mass of air and fuel is in the cylinder at any given load at the end of the pumping cycle.

It’s how you get to the final cylinder vacuum pressure that makes the difference. Under low load conditions, a conventional manifold is under considerable vacuum, and the pumping losses occur from top to bottom of the piston cycle. With PRV, the pressure at the intake valve always starts high and moves lower with the piston. The summation of the pumping losses are considerably less due to the gradual pressure reduction ahead of the intake valve facilitated be the contoured flow of the Venturi and expansion of the fuel. Consequently, pumping losses are much smaller at the initiation of the airflow into the cylinder and the summation of the losses over the entire piston travel is substantially reduced.

Now you're talking, Mr. Meyer. Exactly the point. A motorcycle engine with Mikunis carburetors one for each cylinder would have similar effect. The bulk of pumping loss reduction lies in the fact that each cylinder has its own carburetor that allows for partial equilibration of the manifold pressure to atmospheric level prior to each intake stroke (oops, there is no intake manifold!, each cylinder has its own indepedent intake runner)

I would guess that one can modified current engines by putting a throttle plate on each intake runner instead of having all 4 cylinders running on one throttle plate, while using port fuel injection, and the effect of pumping loss reduction would be quite dramatic.

But, of course, if PRV can eliminate the currently more expensive electronic port fuel injection system and replace with the much cheaper venturi-effect fine fuel atomization, the achievement would be still quite significant.

On the second thought, the pumping loss reduction may not be that great...due to the fact that less intake runner differential in pressure from atmospheric early in the intake stroke will be made up for by a larger vacuum force later in the intake stroke as the piston travels downward and expanding the cylinder space but is not being filled fast enough with air due to the much more restrictive flow thru the pintle device.

Otherwise, Honda ought to know about this...they've made millions of motorcycles using Mikunis-type of carburetors, besides Civics and Accords...

Here is a simple exercise to illustrate the PRV pumping loss reduction concept:

1. With your thumb and forefinger, partially pinch your nose and inhale deeply. Your diaphragm represents the piston and your lungs represent the cylinder. The sensation on your diaphragm is the pumping loss of a piston pulling on a partial pressure manifold. Your nasal passage represents the intake valve pressure drop

2. Repeat without pinching you nose at first, then a slight pinch at the end of the inhale cycle. This exercise represents PRV draw-down from a Venturi starting from full atmospheric pressure.

3. Note that your lungs pulled the same number of air molecules. It was much easier without the vacuum induced by your fingers. At the bottom of the piston cycle, the same number of molecules are pulled into the cylinder, given the same engine load, whether PRV or conventional throttle. This is because at the end of intake cycle, intake pressure – the pressure just immediately upstream of the intake valve -- must be the same for the same amount of air (and fuel). So, for the last millimeter of piston pull, pumping loss is identical...but PRV facilitates flow at the beginning where full atmospheric intake valve pressure is available. As intake valve pressure draw-down continues, the Venturi effect is applied but diminished until the last molecule of air is ingested. Note that the plenum pressure into the Venturi is always fully atmospheric and pressure reduction occurs only ahead of the intake valve. The overall effect is reduced cumulative pumping loss, and consequently, improved engine efficiency.