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Technical Paper

1997 GM 5.7 LITER LS1 V8 ENGINE

1997-02-24
970915
General Motors Powertrain Group (GMPTG) has developed an all new small block V8 engine, designated LS1, for introduction into the 1997 Corvette. This engine was designed to meet both customer requirements and competitive challenges while also meeting the ever increasing legislated requirements of emissions and fuel economy. This 5.7L V8 provides increased power and torque while delivering higher fuel economy. In addition, improvements in both QRD and NVH characteristics were made while meeting packaging constraints and achieving significant mass reductions.
Technical Paper

1996 GM 7.4 Liter Engine Upgrade

1996-02-01
960012
General Motors Powertrain Division has developed the next generation big block V8 engine for introduction in the 1996 model year. In addition to meeting tighter emission and on-board diagnostic legislation, this engine evolved to meet both customer requirements and competitive challenges. Starting with the proven dependability of the time tested big block V8, goals were set to substantially increase the power, torque, fuel economy and overall pleaseability of GM's large load capacity gasoline engine. The need for this new engine to meet packaging requirements in many vehicle platforms, both truck and OEM, as well as a requirement for minimal additional heat rejection over the engine being replaced, placed additional constraints on the design.
Technical Paper

The Effect of Operating Conditions at Idle in the S.I. Engine

1997-10-01
972990
A gasoline engine with an electronically controlled fuel injection system has substantially better fuel economy and lower emissions than a carburetted engine. In general, the stability of engine operation is improved with fuel injector, but the stability of engine operation at idle is not improved compared with a carburetted gasoline engine. In addition, the increase in time that an engine is at idle due to traffic congestion has an effect on the engine stability and vehicle reliability. Therefore, in this research, we will study the influence of fuel injection timing, spark timing, dwell angle, and air-fuel ratio on engine stability at idle.
Technical Paper

Making the Case for a Next Generation Automotive Electrical System

1998-10-19
98C006
Introduction of an array of new electrical and electronic features into future vehicles is generating vehicle electrical power requirements that exceed the capabilities of today's 14 volt electrical systems. In the near term (5 to 10 years), the existing 14V system will be marginally capable of supporting the expected additional loads with escalating costs for the associated charging system. However, significant increases in vehicle functional content are expected as future requirements to meet longer-term (beyond 10 years) needs in the areas of emission control, fuel economy, safety, and passenger comfort. A higher voltage electrical system will be required to meet these future requirements. This paper explores the functional needs that will mandate a higher voltage system and the benefits derivable from its implementation.
Technical Paper

Dual Catalytic Converters

1975-02-01
750176
The stringent 1978 emission standards of 0.41 gm/mi HC, 3.4 gm/mile CO, and 0.4 gm/mi NOx may require the use of a dual catalytic converter system (reducing and oxidizing catalyst). These emission requirements have been achieved at low mileage with such a system, but it is complex and has exhibited poor durability. This system also results in the loss of fuel economy at the 1978 emission levels.
Technical Paper

General Motors Phase II Catalyst System

1978-02-01
780205
Three-way catalysts provide a means of catalytically achieving lower NOx emission levels while maintaining good control of HC and CO emissions. However, very accurate control of air-fuel ratio is necessary. The precise air-fuel ratio control required is accomplished by employing a closed loop fuel metering system in conjunction with an exhaust gas sensor and an electronic control unit. To gain production experience with this type of system, General Motors is introducing it on two 1978 engine families sold in California. One is a 2.5 litre L-4 engine and the other is a 3.8 litre V-6 engine. Closed loop controlled carburetors are used on both systems. This paper discusses these 1978 systems. The components used on both systems are described and emission and fuel economy results are reviewed.
Technical Paper

Real World Performance of an Onboard Gasoline/Ethanol Separation System to Enable Knock Suppression Using an Octane-On-Demand Fuel System

2018-04-03
2018-01-0879
Higher compression ratio and turbocharging, with engine downsizing can enable significant gains in fuel economy but require engine operating conditions that cause engine knock under high load. Engine knock can be avoided by supplying higher-octane fuel under such high load conditions. This study builds on previous MIT papers investigating Octane-On-Demand (OOD) to enable a higher efficiency, higher-boost higher compression-ratio engine. The high-octane fuel for OOD can be obtained through On-Board-Separation (OBS) of alcohol blended gasoline. Fuel from the primary fuel tank filled with commercially available gasoline that contains 10% by volume ethanol (E10) is separated by an organic membrane pervaporation process that produces a 30 to 90% ethanol fuel blend for use when high octane is needed. In addition to previous work, this paper combines modeling of the OBS system with passenger car and medium-duty truck fuel consumption and octane requirements for various driving cycles.
Technical Paper

LOOP SCAVENGING versus THROUGH SCAVENGING of TWO-STROKE ENGINES

1958-01-01
580044
THIS paper reports the latest investigation of the relative merits of loop scavenging versus through scavenging. The authors hope that the conditions of the work permitted an objective evaluation of the two types of engines. The results of the study may be summarized as follows: 1. With symmetrical timing, neither cylinder shows significant advantage in trapping efficiency. 2. With symmetrical timing, the best ratio of exhaust-port to inlet-port effective area seems to be about 0.6. 3. Unsymmetrical timing is an effective method of improving trapping efficiency. 4. The value of net indicated fuel economy shows no significant difference between the two cylinders. The authors point out that because the areas were equal it is unlikely that the optimum port design of each type was used in comparing the cylinders. If optimum porting had been used, the two types might have shown more difference.
Technical Paper

Emission and Fuel Economy Measurement Improvements

1979-02-01
790233
A program was initiated to improve the emission and fuel economy measurement accuracy and test cell to test cell correlation. Improvements were made to the Constant Volume Sampling System, electric dynamometer, instrument calibration ranges and system checks were initiated to improve the accuracy of the bag emissions, modal emissions, calculated and measured fuel economy. Unique emission and fuel economy problems associated with gasoline and diesel testing were studied and resolutions effected when possible.
Technical Paper

Concept and Implementation of a Robust HCCI Engine Controller

2009-04-20
2009-01-1131
General Motors recently demonstrated two driveable test vehicles powered by a Homogeneous Charge Compression Ignition (HCCI) engine. HCCI combustion has the potential of a significant fuel economy benefit with reduced after-treatment cost. However, the biggest challenge of realizing HCCI in vehicle applications is controlling the combustion process. Without a direct trigger mechanism for HCCI's flameless combustion, the in-cylinder mixture composition and temperature must be tightly controlled in order to achieve robust HCCI combustion. The control architecture and strategy that was implemented in the demo vehicles is presented in this paper. Both demo vehicles, one with automatic transmission and the other one with manual transmission, are powered by a 2.2-liter HCCI engine that features a central direct-injection system, variable valve lift on both intake and exhaust valves, dual electric camshaft phasers and individual cylinder pressure transducers.
Technical Paper

Observer Design for Fuel Reforming in HCCI Engines Using a UEGO Sensor

2009-04-20
2009-01-1132
Homogeneous Charge Compression Ignition (HCCI) combustion shows a high potential of reducing both fuel consumption and exhaust gas emissions. Many works have been devoted to extend the HCCI operation range in order to maximize its fuel economy benefit. Among them, fuel injection strategies that use fuel reforming to increase the cylinder charge temperature to facilitate HCCI combustion at low engine loads have been proposed. However, to estimate and control an optimal amount of fuel reforming in the cylinder of an HCCI engine proves to be challenging because the fuel reforming process depends on many engine variables. It is conceivable that the amount of fuel reforming can be estimated since it correlates with the combustion phasing which in turn can be measured using a cylinder pressure sensor.
Technical Paper

Opportunities and Challenges for Blended 2-Way SCR/DPF Aftertreatment Technologies

2009-04-20
2009-01-0274
Diesel engines offer better fuel economy compared to their gasoline counterpart, but simultaneous control of NOx and particulates is very challenging. The blended 2-way SCR/DPF is recently emerging as a compact and cost-effective technology to reduce NOx and particulates from diesel exhaust using a single aftertreatment device. By coating SCR catalysts on and inside the walls of the conventional wall-flow filter, the 2-way SCR/DPF eliminates the volume and mass of the conventional SCR device. Compared with the conventional diesel aftertreatment system with a SCR and a DPF, the 2-way SCR/DPF technology offers the potential of significant cost saving and packaging flexibility. In this study, an engine dynamometer test cell was set up to repeatedly load and regenerate the SCR/DPF devices to mimic catalyst aging experienced during periodic high-temperature soot regenerations in the real world.
Technical Paper

Switching Roller Finger Follower Meets Lifetime Passenger Car Durability Requirements

2012-09-10
2012-01-1640
An advanced variable valve actuation (VVA) system is characterized following end-of-life testing to enable fuel economy solutions for passenger car applications. The system consists of a switching roller finger follower (SRFF) combined with a dual feed hydraulic lash adjuster and an oil control valve that are integrated into a four cylinder gasoline engine. The SRFF provides discrete valve lift capability on the intake valves. The motivation for designing this type of VVA system is targeted to improve fuel economy by reducing the air pumping losses during part load engine operation. This paper addresses the durability of a SRFF for meeting passenger car durability requirements. Extensive durability tests were conducted for high speed, low speed, switching, and cold start operation. High engine speed test results show stable valvetrain dynamics above 7000 engine rpm. System wear requirements met end-of-life criteria for the switching, sliding, rolling and torsion spring interfaces.
Technical Paper

Optimizing Base Oil Viscosity Temperature Dependence For Power Cylinder Friction Reduction

2014-04-01
2014-01-1658
Lubricant viscosity along the engine cylinder liner varies by an order of magnitude due to local temperature variation and vaporization effects. Tremendous potential exists for fuel economy improvement by optimizing local viscosity variations for specific operating conditions. Methods for analytical estimation of friction and wear in the power-cylinder system are reviewed and used to quantify opportunities for improving mechanical efficiency and fuel economy through lubricant formulation tailored specifically to liner temperature distributions. Temperature dependent variations in kinematic viscosity, density, shear thinning, and lubricant composition are investigated. Models incorporating the modified Reynolds equation were used to estimate friction and wear under the top ring and piston skirt of a typical 11.0 liter diesel engine.
Technical Paper

Least-Enthalpy Based Control of Cabin Air Recirculation

2015-04-14
2015-01-0372
The vehicle air-conditioning system has significant impact on fuel economy and range of electric vehicles. Improving the fuel economy of vehicles therefore demand for energy efficient climate control systems. Also the emissions regulations motivate the reduced use of fuel for vehicle's cabin climate control. Solar heat gain of the passenger compartment by greenhouse effect is generally treated as the peak thermal load of the climate control system. Although the use of advanced glazing is considered first to reduce solar heat gain other means such as ventilation of parked car and recirculation of cabin air also have impetus for reducing the climate control loads.
Technical Paper

Investigating the Effect of Intake Manifold Size on the Transient Response of Single Cylinder Turbocharged Engines

2017-09-04
2017-24-0170
This paper evaluates the lag time in a turbocharged single cylinder engine in order to determine its viability in transient applications. The overall goal of this research is to increase the power output, reduce the fuel economy, and improve emissions of single cylinder engines through turbocharging. Due to the timing mismatch between the exhaust stroke, when the turbocharger is powered, and the intake stroke, when the engine intakes air, turbocharging is not conventionally used in commercial single cylinder engines. Our previous work has shown that it is possible to turbocharge a four stroke, single cylinder, internal combustion engine using an air capacitor, a large volume intake manifold in between the turbocharger compressor and engine intake. The air capacitor stores compressed air from the turbocharger during the exhaust stroke and delivers it during the intake stroke.
Technical Paper

Measurements of Cycle to Cycle Variability of the Inlet Flow of Fuel Injectors Using LDA

2006-10-16
2006-01-3314
The focus of this research effort was to develop a technique to measure the cyclic variability of the mass injected by fuel injectors. Successful implementation of the measurement technique introduced in this paper can be used to evaluate injectors and improve their designs. More consistent and precise fuel injectors have the potential to improve fuel efficiency, engine performance, and reduce emissions. The experiments for this study were conducted at the Michigan State University Automotive Research Experiment Station. The setup consists of a fuel supply vessel pressurized by compressed nitrogen, a Dantec laser Doppler anemometry (LDA) system to measure the centerline velocity of fuel, a quartz tube for optical access, and a Cosworth IC 5460 to control the injector. The detector on the LDA system is capable of resolving Doppler bursts as short as 6μs, depending on the level of seeding, thus giving a detailed time/velocity profile.
Technical Paper

Anti-Shudder Property of Automatic Transmission Fluids - A Study by the International Lubricants Standardization and Approval Committee (ILSAC) ATF Subcommittee

2000-06-19
2000-01-1870
In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).
Technical Paper

Factors Affecting Axle Lubricant Stability

2005-10-24
2005-01-3892
There are many factors that can affect the service lifetime of a lubricant. In automobiles, one lubricant that has been heavily tested in recent years for fuel efficiency improvement and durability is axle lubricant. While a substantial amount of testing has been performed toward developing new axle lubricants to aid original equipment manufacturers to reduce warranty costs, improve Corporate Average Fuel Economy, and provide extended drain intervals, not as much testing has been documented to show some of the effects that different operating conditions have on these lubricants. The scope of this work is to bring to light some of the different parameters that affect axle lubricant.
Technical Paper

Rationale for Technology Selections in GM's PNGV Precept Concept Car Based on Systems Analysis

2000-04-02
2000-01-1567
The CY2000 cornerstone goal of the Partnership for a New Generation of Vehicles (PNGV) is the demonstration in CY 2000 of a 5-passenger vehicle with fuel economy of up 80 mpg (3 l/100km). As a PNGV partner, GM will demonstrate a technology-demonstration concept vehicle, the Precept, having a lightweight aluminum-intensive body, hybrid-electric propulsion system and a portfolio of efficient vehicle technologies. This paper describes: 1) the strategy for the vehicle design including mass requirements, 2) the selection of dual axle application of regenerative braking and electric traction, and 3) the complementary perspective on energy management strategy. This paper outlines information developed through systems analysis that drove technology selections. The systems analyses relied on vehicle simulation models to estimate fuel economy associated with technology selections. Modeling analyses included consideration of both federal test requirements and more severe driving situations.
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