Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

Error 404--Not Found

Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

Tech Briefs

March 2002
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Chevy revs for 2002 IRL season


Side view of the 2002 Chevrolet IRL engine.

A more powerful small block engine has erupted from a significantly revamped Indy Racing League (IRL) V8. The new 2002 engine maintains its predecessor's base architecture while increasing power, reducing engine weight, lowering its center of gravity, and improving reliability.

From 1997 through the 2001 IRL racing season, the Oldsmobile Aurora V8 notched 49 of 51 race wins, grabbed 51 of 51 pole positions, nailed five of five Indianapolis 500 wins, won five of five championships, and logged the fastest lap in 31 consecutive IRL events.

"That's a tough act to follow," admitted Roger Allen, General Motors Racing's Lead Design Engineer for the 2002 Chevrolet IRL V8 engine, which is based on the Oldsmobile powerplant. (Allen also was the lead design engineer on the Aurora V8 IRL engine.)

The 1997 engine—a 90° 4.0-L powerplant producing 503 kW (675 hp)—essentially has been modified twice. For the 2001 race season, changes were made to produce a 180° 3.5-L engine producing 481 kW (645 hp) via revising the intake ports, retuning the induction system, as well as making adjustments for a higher compression ratio and shorter duration intake and exhaust cams. The 2002 race season brings additional engine alterations.

"With Chevy returning to IRL, it gave us an opportunity to take the basic architecture and evolve that into an engine that fit the rules better," said Allen during a press event showcasing the Chevrolet 2002 V8 race engine at Katech Inc., the Clinton Township, MI-based company handling the engine's development and durability testing.

The IRL's opening race at Homestead-Miami Speedway in Homestead, FL, on March 2 marked the competition debut of the second-generation Chevy Indy V8 to open-wheel racing after the first-generation Chevy V8 departed in 1993. Unlike the 1997 Aurora engine's development, which used only 2-D CAD, engineers confirmed the performance and robustness of the Chevrolet Indy V8 via 3-D solid modeling, computer simulations, CFD, and FEA. The 2002 Chevrolet engine carries over only the oil- and water-pump assemblies of the Aurora engine. "Both assemblies worked well—very robust, very reliable," said Allen. The primary components that underwent alteration were the cylinder heads, valvetrain, crankshaft, connecting rods, pistons, cam covers, and front cover.

A left-front view of the Chevrolet V8 during engine dynamometer testing.

Members of the GM Racing team increased the 481 kW (645 hp) of the 2001 engine to 500 kW (670 hp) by reducing the frictional losses and reciprocating weight inside the engine, increasing engine airflow, and improving intake-port and combustion-chamber shapes as well as valve-timing events.

Relative to reducing frictional losses, rod bearings went from a 62.7- to 53.3-mm (2.47- to 2.10-in) main journal, while the 47-mm (1.85-in) rod journal diameter was trimmed to 43 mm (1.70 in). To reduce reciprocating weight, piston mass went from 355 to 330 g (12.5 to 11.6 oz). Increased engine airflow was accomplished by reducing the bore shrouding of the valve positions within the chamber.

Improved intake-port shape resulted from increasing the cross-sectional area to 1774 mm2 (2.75 in2) at the port opening. Combustion-chamber shape alterations improved the airflow into the engine, while valve-timing events were improved through lower inertia valvetrain components as well as mass reductions: the intake valve mass went from 44 to 37 g (1.55 to 1.31 oz), the exhaust valve from 42 to 33 g (1.48 to 1.16 oz), the intake bucket from 43 to 35 g (1.52 to 1.23 oz), and the exhaust bucket from 40 to 31 g (1.41 to 1.09 oz).

Mass reduction also transpired relative to the crankshaft, the cylinder head assembly, the left-hand cam cover, and the right-hand cam cover, resulting in a total engine mass reduction of 5 kg (11 lb). "That's a significant amount of weight to be carrying around the track, and with the Chevy engine that extra weight won't be there," said Allen. A great deal of the weight reduction came from high center-of-gravity components, which correlated to reducing the engine's center of gravity.

In redesigning the cylinder head water jacket, the team improved the engine's cooling efficiency and increased the lifespan of cylinder heads. "We had a problem with the heads at high mileage," said Allen. "At 2414 km (1500 mi) on the Aurora engine, the heads were (at end of life) because of cracking at stress points. We reduced the overall stress concentrations by increasing fillet and radiuses and optimizing the wall thickness in those high stress areas. We expect the Chevy engine heads to last 4828 km (3000 mi)."

Computer simulations enabled the team to relocate valve pockets in the pistons to increase the section between pocket and top ring lip. The change virtually eliminates thin areas, which can overheat or pinch a piston ring, according to Allen. Through FEA, the design team was able to make a material substitution without changing the 13 g (0.46 oz) of the valve retainer. The Aurora engine used a titanium component covered in chrome plating. The chrome plating "wore and chipped off, then that chrome material would get transferred through the engine (becoming) embedded in pistons and bearings," said Allen. The Chevy engine uses steel valve retainers.

The oil-pump assembly is one of only two engine carryovers.

Engine improvements also targeted the intake manifold assembly. Alterations included a new throttle cable location as well as an upgrade to the fuel-line routing. "It takes about 1 lb (0.45 kg) out of the manifold and reduces the center of gravity," said Allen.

A first prototype engine completed a simulation test in October 2001 when a computer-controlled engine dynamometer duplicated the 354-km/h (220-mph) race pace of the Indianapolis 500. Computerized controls accelerated and decelerated the engine under load to reproduce aerodynamic and mechanical forces. After the simulation played-out for 129 km (80 mi) (or 32 laps on the 4-km (2.5-mi) Indianapolis Motor Speedway oval track), the program paused for a virtual pit stop while the test cell engine was refueled.

"The dynamometer simulation is extremely demanding because there are no caution periods that allow the engine to rest," said Joe Negri, GM Racing IRL/Road Racing Group Manager. "Our experience has shown that when an engine is developed to the point that it can endure this validation test, it is usually very reliable on the track as well. In addition to achieving our durability and reliability goals, we have also met our initial performance targets for power and torque." Engine-in-vehicle testing was scheduled at tracks in Phoenix, AZ, and Indianapolis, IN.

Technical specifications of the 2002 Chevy Indy engine include a 93-mm (3.66-in) bore, a 205.75-mm (8.10-in) minimum deck height, bore center line spacing of 102 mm (4 in), a 180° crankshaft, a 10,700 rpm limit, and a torque of 468 N•m (345 lb•ft) at 8500 rpm. The maximum parts kit cost is $89,000. Eight different engine builders will assemble 100 of the new Chevrolet IRL V8s.

Because of IRL rule changes, GM Racing is designing and developing an all-new Chevrolet engine, which will be lighter and smaller than the 2002 engine. "The 2003 engine will have no interchangeability with the existing Chevrolet IRL engine for 2002," said Allen, who is also the lead design engineer on the 2003 engine. The product-development timetable calls for "running" engines of the 2003 powerplant in the summer of 2002.

- Kami Buchholz


Toyota MR-2 Spyder SMT


Drivers of the Toyota MR-2 Spyder can choose from neutral, forward, and reverse gears, with the shift lever allowing traditionalists to execute upshifts and downshifts. The steering wheel-mounted shift buttons only work once underway.

If necessity is the mother of invention, it might well also qualify as the mother of adaptation. Toyota did not invent the computer-shifted manual transmission in its MR-2 Spyder with sequential manual transmission (SMT). But it did adapt the existing five-speed manual gearbox for automatic applications when it found demand among U.S. customers for an automatic transmission in its little roadster. The problem was that Toyota designed the MR-2 only for its manual transmission, with the company's automatics not substituted easily. However, the incorporation of automation hardware from LuK allows the manual transmission to work at the press of a button.

Beneficial side effects of using a manual in an automatic role include better fuel economy than a traditional automatic and sporty, racecar-like shift operation. Toyota's Electronic Throttle Control System-intelligent (ETCS-i) throttle-by-wire system (already seen in Toyota's newest models) gives the engine-management computer the ability to match engine revs to road speed on downshifts, without input from the driver. Shift action and clutch control are provided by a hydraulic pump that generates pressure and by actuators that execute these functions. A gas-filled accumulator maintains constant pressure in the system and a three-port linear spool-type solenoid valve distributes the pressurized hydraulic fluid. Shifts are activated either by buttons mounted on the steering wheel or by a shift lever on the floor. Buttons on the back of the steering wheel spokes activate upshifts, while buttons on the face of the steering wheel activate downshifts.

Because it can be difficult to reach the buttons when turning, and because some people may prefer the feel of a more traditional shift lever, shifts may also be made using the lever. Drivers pull back for upshifts and press forward for downshifts. The shifter has a dogleg arrangement similar to that used by some manually shifted automatics.

The shifter pictographic embedded in the MR-2 Spyder's speedometer indicates the position of the shift lever. When in drive, the LCD panel shows the gear currently engaged.

The car starts from the neutral position only, and, for safety, only with the brake applied. Reverse is forward of neutral and the forward gears are down and to the right. Once the forward gate is engaged the transmission moves into first gear. Without any throttle applied, however, the clutch is disengaged and the car rolls freely. When the accelerator is pressed, the clutch is automatically engaged for a smooth start. Once underway, shifting is a matter of toggling up and down through the gears. The computer doesn't execute excessively mismatched shifts that might damage the engine, and it automatically returns to first gear when the car stops.

The shift lever is designed to provide tactile feedback through the use of moderation pins, moderation crests, and springs that give the feel of moving linkage, even though the system is electronic. When the engine computer receives a signal to shift, it disengages the clutch, determining disengagement through a signal from the clutch stroke sensor. It then orders the shift solenoid and the select solenoid to change gears, again determining completion through signals from stroke sensors on both solenoids. Once the shift is completed, the computer re-engages the clutch, controlling the speed and stroke.

During the shift process, the computer automatically closes the throttle using the ETCS-i so that the engine doesn't rev while the clutch is disengaged. Throttle operation returns to manual control once the clutch has re-engaged. While a Ferrari 360 Modena can change gears in less than 200 ms, the MR-2 system takes about 1 s to execute gear changes. Toyota hasn't released exact shift times for the system.

- Dan Carney


More 1 2 3

Error 404--Not Found

Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.