FChampOH
02-17-2010, 01:05 AM
For those of you who enjoying reading stories about the IS-F and how we ended up with such an enthusiasts dream I thought I would share some stories about various aspects of the IS-F that not everyone knows.
Enjoy!
The Lexus IS F Engine:
Power with a Purpose
The new Lexus IS F has 416 horsepower and 371 lb.-ft. of torque. Let those numbers wash over you
for a minute.
The oft-quoted horsepower number is where the “glamour” is and the new Lexus IS F clearly has it in
abundance. High horsepower is often felt as a late rpm rush to redline partially because engine
speed is such an important factor in creating horsepower.
But take a closer look at the second number, because it’s the less frequently-mentioned torque that
can make you feel like you’ve been shot from a cannon when you bury the throttle coming off a
corner, or when passing a big rig on a narrow two-lane. Big torque always quickens the pulse.
Now imagine a perfect marriage of great torque with a strong mid-to-high rpm surge as the
horsepower is building to a crescendo. The upshot is an addictive acceleration rush (with a sound to
match) that feels effortless, like it will never end—all very much intentional.
Of course, racetrack-scorching performance is only part of the story because this new Lexus engine
oozes smart technology to help produce its abundant power with great efficiency, durability, low noise
and minimal emissions.
Welcome to the IS F 5.0-liter V8 engine.
A Few Fast Facts
Basic specifications:
Engine designation 2UR-GSE
Engine type 90° DOHC V8
Engine block and cylinder head construction Die cast aluminum alloy with steel cylinder liners
Valvetrain
32-valves
Intake camshaft - Electric VVT-iE
Exhaust camshaft - Hydraulic VVT-i
Chain drive
Combustion chamber type Pent roof
Induction system Normally aspirated
Displacement (cc) 4968 (303.2 cu. In.)
Bore x stroke (mm) 94.0 x 89.5 (3.70 x 3.52 in.)
Compression ratio 11.8:1
Maximum horsepower (SAE) 416 @ 6600 rpm
Maximum torque (lb.-ft.) 371 @ 5200 rpm
A Head Full of Good Ideas
The IS F twin-cam aluminum 4-valve cylinder heads employ low-friction roller rocker arms that pivot
on fixed points (no hydraulic lifters). The fixed pivot design helps ensure accurate valve operation.
Due to their minimal weight, titanium intake valves are large in diameter. The camshafts are hollow
for further weight reduction and mirror polished to minimize friction. The combination of low friction
and light weight allows a high-lift, high speed valvetrain designed for performance and efficiency. To
cap everything off (so to speak), the heads wear lightweight magnesium cam covers.
The intake and exhaust ports are optimized for performance as well. Intake pressure losses have
been reduced and air intake volume maximized via careful port cross section and shape tuning.
Emissions are reduced by careful shaping of the branch area to make it difficult for non-combusted
gas to adhere.
More Variable VVT
Lexus engines have used hydraulic-type variable valve timing for a number of years. The IS F uses a
system recently introduced on the LS that provides important gains in the ability to precisely control
camshaft timing. Known as VVT-iE, the system now uses electric motors to vary intake cam timing.
The use of electric motors expands the operation control range, especially at low rpm where hydraulic
pressure may be insufficient to control cam timing by itself. The result is improved engine startup,
performance and fuel efficiency with reduced emissions. Exhaust cams continue to use hydraulic
actuation to vary timing.
The Cylinder Block – Horsepower Holding Cell
The robust, yet lightweight cylinder block is die cast in aluminum and uses thin-wall steel cylinder
liners with careful attention to heat transfer and cooling which is enhanced by a liquid cooled oil cooler.
Stiffening ribs are strategically positioned on the exterior of the block for rigidity. Four knock control
sensors are installed in the V-bank to improve engine controllability.
A high-strength forged steel crankshaft is used with counterweights and a double torsional damper to
minimize vibration. Pistons are specially coated to reduce friction and their shape is optimized to
enhance combustion and reduce noise. Compression ratio is 11.8:1. Connecting rods are forged
from high-strength sintered iron alloy.
When Oil in a Corner is a Good Thing
Keeping an ultra-high performance engine properly lubricated is crucial to engine durability. This can
be especially difficult when the vehicle is driven on racetracks with frequent high-G cornering loads.
To ensure consistent oil supply in these conditions, the IS F uses a dedicated pump to scavenge oil
that could otherwise accumulate in the cylinder heads during hard cornering and return it to the oil
pan.
Dual Air Intake (and Exhaust) System = Dual Personality
A remarkable air intake system was developed for the IS F that gives the engine a bit of a dual
personality. The first is responsive and relatively quiet until about 3,600 rpm; then the beast seems to
break its chains, unleashing all of its power with a menacing growl. You can of course throttle the
beast but what fun is that?
The system works by employing primary and secondary inlets in two locations: The primary pulls air
from just above the grille while the secondary inlet draws air from inside the right front wheel well.
At low speeds, air is taken only from the primary inlet, which promotes responsive yet smooth and
relatively quiet operation. This makes the IS F more relaxing to drive in traffic, for example. The
secondary inlet opens at 3,600 rpm, allowing substantially more air into the intake system and with it,
all the rest of the IS F’s considerable power--modulated by your right foot, of course. A low-restriction
semi-dual exhaust system does its share in promoting engine airflow and adds a distinctive
soundtrack as well.
Lexus engineers also spent considerable time tuning both intake and exhaust systems for throttle
smoothness and sound quality. Their goals were to create a highly responsive, yet drivable car with a
powerful, captivating sound devoid of uncomfortable peaks. The payoff is an engine with a
charismatic split personality that always entertains when asked and never annoys.
Well, if you made it this far I guess you read the whole story. I have more stories on other aspects of the IS-F to share. If you would like to read them as well, just show your response on this thread! :D
Thanks, Doug
Enjoy!
The Lexus IS F Engine:
Power with a Purpose
The new Lexus IS F has 416 horsepower and 371 lb.-ft. of torque. Let those numbers wash over you
for a minute.
The oft-quoted horsepower number is where the “glamour” is and the new Lexus IS F clearly has it in
abundance. High horsepower is often felt as a late rpm rush to redline partially because engine
speed is such an important factor in creating horsepower.
But take a closer look at the second number, because it’s the less frequently-mentioned torque that
can make you feel like you’ve been shot from a cannon when you bury the throttle coming off a
corner, or when passing a big rig on a narrow two-lane. Big torque always quickens the pulse.
Now imagine a perfect marriage of great torque with a strong mid-to-high rpm surge as the
horsepower is building to a crescendo. The upshot is an addictive acceleration rush (with a sound to
match) that feels effortless, like it will never end—all very much intentional.
Of course, racetrack-scorching performance is only part of the story because this new Lexus engine
oozes smart technology to help produce its abundant power with great efficiency, durability, low noise
and minimal emissions.
Welcome to the IS F 5.0-liter V8 engine.
A Few Fast Facts
Basic specifications:
Engine designation 2UR-GSE
Engine type 90° DOHC V8
Engine block and cylinder head construction Die cast aluminum alloy with steel cylinder liners
Valvetrain
32-valves
Intake camshaft - Electric VVT-iE
Exhaust camshaft - Hydraulic VVT-i
Chain drive
Combustion chamber type Pent roof
Induction system Normally aspirated
Displacement (cc) 4968 (303.2 cu. In.)
Bore x stroke (mm) 94.0 x 89.5 (3.70 x 3.52 in.)
Compression ratio 11.8:1
Maximum horsepower (SAE) 416 @ 6600 rpm
Maximum torque (lb.-ft.) 371 @ 5200 rpm
A Head Full of Good Ideas
The IS F twin-cam aluminum 4-valve cylinder heads employ low-friction roller rocker arms that pivot
on fixed points (no hydraulic lifters). The fixed pivot design helps ensure accurate valve operation.
Due to their minimal weight, titanium intake valves are large in diameter. The camshafts are hollow
for further weight reduction and mirror polished to minimize friction. The combination of low friction
and light weight allows a high-lift, high speed valvetrain designed for performance and efficiency. To
cap everything off (so to speak), the heads wear lightweight magnesium cam covers.
The intake and exhaust ports are optimized for performance as well. Intake pressure losses have
been reduced and air intake volume maximized via careful port cross section and shape tuning.
Emissions are reduced by careful shaping of the branch area to make it difficult for non-combusted
gas to adhere.
More Variable VVT
Lexus engines have used hydraulic-type variable valve timing for a number of years. The IS F uses a
system recently introduced on the LS that provides important gains in the ability to precisely control
camshaft timing. Known as VVT-iE, the system now uses electric motors to vary intake cam timing.
The use of electric motors expands the operation control range, especially at low rpm where hydraulic
pressure may be insufficient to control cam timing by itself. The result is improved engine startup,
performance and fuel efficiency with reduced emissions. Exhaust cams continue to use hydraulic
actuation to vary timing.
The Cylinder Block – Horsepower Holding Cell
The robust, yet lightweight cylinder block is die cast in aluminum and uses thin-wall steel cylinder
liners with careful attention to heat transfer and cooling which is enhanced by a liquid cooled oil cooler.
Stiffening ribs are strategically positioned on the exterior of the block for rigidity. Four knock control
sensors are installed in the V-bank to improve engine controllability.
A high-strength forged steel crankshaft is used with counterweights and a double torsional damper to
minimize vibration. Pistons are specially coated to reduce friction and their shape is optimized to
enhance combustion and reduce noise. Compression ratio is 11.8:1. Connecting rods are forged
from high-strength sintered iron alloy.
When Oil in a Corner is a Good Thing
Keeping an ultra-high performance engine properly lubricated is crucial to engine durability. This can
be especially difficult when the vehicle is driven on racetracks with frequent high-G cornering loads.
To ensure consistent oil supply in these conditions, the IS F uses a dedicated pump to scavenge oil
that could otherwise accumulate in the cylinder heads during hard cornering and return it to the oil
pan.
Dual Air Intake (and Exhaust) System = Dual Personality
A remarkable air intake system was developed for the IS F that gives the engine a bit of a dual
personality. The first is responsive and relatively quiet until about 3,600 rpm; then the beast seems to
break its chains, unleashing all of its power with a menacing growl. You can of course throttle the
beast but what fun is that?
The system works by employing primary and secondary inlets in two locations: The primary pulls air
from just above the grille while the secondary inlet draws air from inside the right front wheel well.
At low speeds, air is taken only from the primary inlet, which promotes responsive yet smooth and
relatively quiet operation. This makes the IS F more relaxing to drive in traffic, for example. The
secondary inlet opens at 3,600 rpm, allowing substantially more air into the intake system and with it,
all the rest of the IS F’s considerable power--modulated by your right foot, of course. A low-restriction
semi-dual exhaust system does its share in promoting engine airflow and adds a distinctive
soundtrack as well.
Lexus engineers also spent considerable time tuning both intake and exhaust systems for throttle
smoothness and sound quality. Their goals were to create a highly responsive, yet drivable car with a
powerful, captivating sound devoid of uncomfortable peaks. The payoff is an engine with a
charismatic split personality that always entertains when asked and never annoys.
Well, if you made it this far I guess you read the whole story. I have more stories on other aspects of the IS-F to share. If you would like to read them as well, just show your response on this thread! :D
Thanks, Doug