Twitter headlines« Saudi Aramco and Total Create Refinery Joint Venture | Main | Ford, Brunel Studying CAI Combustion with Methanol and Ethanol in Direct Injection Engine »
Pintle-Regulated Venturi Induction Prototype Achieves 52 mpg at 65 mph
23 June 2008
On-going improvements to the pintle-regulated Venturi (PRV) induction system developed by PRV Performance (earlier post) have led to improved performance results.
Most recently, a 203-mile highway test loop was completed with 3.9 gallons of fuel (10% ethanol) at 65 miles per hour, yielding 52 miles per gallon (4.5 L/100km). Prior testing in December 2007 at Environmental Testing Corporation in Aurora, Colorado delivered 48.1 mpg and 106 g CO2/km in the EPA highway test. (Earlier post.)
The most recent testing kept the car—a Honda Civic with a JDM D15B single overhead cam engine—at 65 mph on a 203-mile highway loop up and down hills. A short urban drive was used to get onto the road, according to James Meyer at PRV Performance.
The fueling is done with careful diligence. The tires are placed within an inch of the some position before and after the test and fuel is filled exactly to the same position on the filler neck. I have found the results to be reproducible to within 1 mpg...It’s quite clear that PRV has a profound effect on fuel economy, probably due primarily to the reduction of pumping losses.
—James Meyer
Running the car with a stock manifold on the same loop delivered results of 41.7 mpg. (The stock results are better than reported on the website because of recent changes to the exhaust and suspension. All those changes were completed before both tests, so 41.7 mpg vs 52 mpg is a fair head-to-head comparison, says Meyer.)
The company has developed nine PRV induction prototypes and driven them for a total of 20,000 miles so far.
Recent modifications for PRV-9 include improved closed loop tuning at the stoichiometric air/fuel ratio, lighter weight aluminum throttle components and micro-adjustment of the pintles to ensure uniform air distribution to each cylinder.
PRV induction improves fuel economy 20+% and torque 15% by recovering intake air pressure. In contrast to a conventional throttle plate that creates a vacuum, the Venturi effect allows pressure recovery immediately upstream of the intake valve.
Expansion of fuel in the confined space downstream of the Venturi throat enhances pressure recovery. Consequently, efficiency loss caused by drawing air from a vacuum (as with a throttle plate) is eliminated. Concurrently, fuel is nebulized and vaporized at the Venturi throat, precluding cylinder wall stratification.
Certified EPA testing of emissions, fuel economy and dynamometer results for the ninth prototype will be released later this summer on the company’s website.
June 23, 2008 in Engines, Fuel Efficiency | Permalink | Comments (29) | TrackBack (0)
Comments
Posted by: Roger Pham | July 03, 2008 at 01:13 PM
I am for increasing hybrid mileage on the highway. Hybrids are great for city driving gains, so now if we can increase mileage for them on the highways, the commuters could benefit as well.
Posted by: sjc | July 10, 2008 at 09:56 PM
I am for increasing hybrid mileage on the highway. Hybrids are great for city driving gains, so now if we can increase mileage for them on the highways, the commuters could benefit as well.
Posted by: sjc | July 10, 2008 at 09:57 PM
I could not relocate this thread until I recently got your emails.
What I THINK you (James) and Roger are now describing is:
1. a. Intake throttling so configured as to result in low pressure drop into the cylinder (high pressure in the cylinder above the piston) during the early part of the intake stroke. b. During the later part of the intake stroke; high pressure drop into the cylinder (low pressure in the cylinder).
Plus:
2. The use of a critical flow venturi (a sonic choke) acting as a flow limiter to increase the effective of item 1. The low flow at the beginning of the stroke encounters minimal resistance (so called good recovery) through the venturi. Later (probably just before mid stroke, as the crank geometry causes the piston to approach maximum speed) the resistance increases dramatically; all without moving any valves.
When, exactly, these low and high resistance phases actually occur can, to some degree I am sure, be controlled by the volume between the pintel and the piston.
A “critical flow venturi” has low pressure drop up to the critical flow, (near a 2 to 1 pressure ratio; 15 psi upstream and 8 psi down stream) after which even lower downstream pressure does not effect the flow rate.
I think this would be more convincing on your website.
Posted by: ToppaTom | July 19, 2008 at 11:05 PM
TrackBack
TrackBack URL for this entry:
http://www.typepad.com/services/trackback/6a00d8341c4fbe53ef00e55368f0d78833
Listed below are links to weblogs that reference Pintle-Regulated Venturi Induction Prototype Achieves 52 mpg at 65 mph:
I have a more graphic idea:
How about graphing pressure vs. piston travel for 3 cases at 50% intake charge density:
--normal engine with a single throttle plate
--engine with BMW Valtronic early closure of intake valve, and,
--PVR modified engine with pintle-venturis
You will find that BMW Valtronic will have practically no pumping loss, while normal engine will have highest degree of pumping loss, and PVR mod engine will have pumping loss somewhere in between, probably closer to the curve of BMW Valtronic, with much less cost and complication.
PVR is still a great idea!
You're welcomed to use the graphic illustration of the 3 scenarios in your presentation of the PVR's mod concept to potential investors in order to dissuade potential skeptics.