Anyone know the diff between the RS4 engine and the S5??
11-26-2007, 05:31 PM
#1
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Anyone know the diff between the RS4 engine and the S5??
Just curious if it will be as simple as intake, chip, exhaust to get back the 50 or so hp that audi detuned from the rs4 setup.
11-26-2007, 06:52 PM
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S5 engine is definitely not a simple detuned RS4 engine. Closer to the Q7 engine than anything.
FSI 4.2 is similar to what the Q7 has with closely related bhp and torque values. The RS4 (and R8) engines are vastly different than any of the standard 4.2 engines in the Q7, S5, A6, S4...
11-26-2007, 08:36 PM
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The engine isn't vastly different, however, the 8200 rpms requires
components that can handle the greater torque. I know cams,chain, and several other components are different, in addition, there are in fact 2 ecu's to do the calculations necessary to manage the engine at 8000+ rpms it get's up to. Atleast that's what somebody posted down lower as some of the differences, or I might have read that on another forum.
It would be fairly expensive to recreate the RS4 engine from the S5 engine, they are essentially the same but the management software, extra cpu, and sturdier components to handle the extra rpms is the differentiator.
With that said, you would likely be able to add close to 50HP through other modifications to the engine. New ECU software plus catback might get you 30-40HP. If they come out with a supercharger, now you would be talking. 30-40HP with an engine that's already close to 360HP is pretty little, though.
It would be fairly expensive to recreate the RS4 engine from the S5 engine, they are essentially the same but the management software, extra cpu, and sturdier components to handle the extra rpms is the differentiator.
With that said, you would likely be able to add close to 50HP through other modifications to the engine. New ECU software plus catback might get you 30-40HP. If they come out with a supercharger, now you would be talking. 30-40HP with an engine that's already close to 360HP is pretty little, though.
11-26-2007, 09:32 PM
#5
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Your right there are many changes required to handle the higher RPMs, but...
the RS4 actually has 8 lb-ft LESS peak torque than the S5.
The peak is shifted to a higher RPM which is what requires those aformentioned changes generally lighter, stronger parts required for high RPM running. Would be nice to see a plot of both motors.
The peak is shifted to a higher RPM which is what requires those aformentioned changes generally lighter, stronger parts required for high RPM running. Would be nice to see a plot of both motors.
11-26-2007, 09:45 PM
#6
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Found the plots...
Any photoshop gurus that can do an overlay? Looks like the S5 motor may be ahead by a bit up to 5000 RPMs.
<img src="http://gallery.audiworld.com/albums/album119/RS4050023.jpg">
<img src="http://gallery.audiworld.com/albums/album302/S5070018_medium.jpg">
<img src="http://gallery.audiworld.com/albums/album119/RS4050023.jpg">
<img src="http://gallery.audiworld.com/albums/album302/S5070018_medium.jpg">
11-27-2007, 04:16 AM
#7
You'll probably be able to do about 380chp and 340-350ctq with easy bolt-ons and 450hp+ with a...
supercharger. MTM very conservatively is getting another 100hp out of the cars with their supercharger. So with just the bolt-ons you should be at the the same 1/4 mile as an RS4...but that will be your modded car to a stock RS4. I'm running similar 1/4 mile times as a US model RS4.
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11-27-2007, 04:34 AM
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Disagree. Major internal components are different, incl rods, lightened pistons, diff rings
in the block as well as different flow parameters for intake manifold and likely exhaust manifold. As you mention, internal cylinder head components are different, including the camshafts, valvesprings, intake/exhaust valves, are upgraded and likely lightened as well.
There is much that goes into with the RS4 4.2 engine internally that the S5 4.2 doesn't come close on - all required to reach 8250 rpms reliably and to satisfy the high-reving nature of the engine in comparison to the more lazy (but torquier) 4.2FSI found in the S5,Q7,A6,A8. Same basic block and heads yes, but that's where it ends.
There is much that goes into with the RS4 4.2 engine internally that the S5 4.2 doesn't come close on - all required to reach 8250 rpms reliably and to satisfy the high-reving nature of the engine in comparison to the more lazy (but torquier) 4.2FSI found in the S5,Q7,A6,A8. Same basic block and heads yes, but that's where it ends.
11-27-2007, 06:40 AM
#9
Base V8 FSI vs. High-Rev V8 FSI differences
Here are the differences for those that might think that the RS4 engine has only a few minor "tuning" differences. These come from the Audi 4.2-liter V8 FSI Engine Self-study Program. My understanding is that the S5 FSI engine is a retuned Q7 engine, with a slightly different torque curve. This would have been done with an intake manifold design change. The high-revving engine referred to in this document is the RS4 engine.
For those that have an ebahn account, the document is here
http://ebahn.bentleypublishers.com/AUDI/B/B6/Training/audi.ssp.921603.pdf
The main technical differences between the base engine and the high-revving engine lie in the following:
* Crankshaft/connecting rods/pistons
* Timing gear
* Cylinder head
* Oil supply
* Engine cooling
* Intake path
* Exhaust system
* Engine management
The cylinder crankcase of the high-revving engine was machined to higher specifications due to the higher stresses in this component. To minimize warping of the cylinder manifolds, the crankcase is honed under stress. For this purpose, a honing template is attached to the crankcase before the honing process in order to simulate the warping of the bolted-on cylinder manifold.
Modifications to High-revving Engine
At very high engine speeds, axial vibration occurs due to the unbalance in the single-mass damper. This can cause the crankshaft to break.
To avoid this vibration, a dual-mass damper without unbalance is employed in the high-revving engine. To compensate for unwanted engine vibration, heavy metal inserts are integrated in the first and eighth crank journals by way of unbalance.
Connecting Rod
Cracked connecting rods made of 36MnVS4 are used in the basic engine, while the conventionally split connecting rods in the RS4 engine are made of 34CrNiMo8, for strength.
In addition, the geometry and tolerances of the
connecting rods were reduced on the high revving version of the 4.2L V8 FSI engine.
Bearing journals diameter: 54 mm
Bearing bushings: 1.4 mm thick, 15.25 mm wide
Length of bushing: 0.20 mm diameter rolled
Connecting rod length: 154 mm
Piston
For strength reasons, forged pistons with a slightly higher weight than conventional pistons, are used. Both engines have the same piston geometry.
Piston weight without rings: approximately 290 g (10 oz)
Piston pin: 0.20 mm x 0.11.5 mm x 40 mm
High-revving Engine
* 3/8" simplex sleeve-type chains are used here. Their advantage is their reduced wear and higher stress resistance at high engine speeds. In this case the idler gears have 38 and 19 teeth. The camshaft sprockets have 25 teeth.
Different Features of the High-revving Engine
* To match the higher engine power output and RPM, the following cylinder head components were modified:
* Intake ports are charge optimized (based on larger cross-sections)
* Intake valves are chrome-plated hollow stem valves (for weight reduction)
* Valve springs are made of a material with higher tensile strength and also have higher spring force
* To meet the higher fuel requirements, the injectors are designed for higher flow rates.
* Roller rocker arms are more robustly designed, with peened rollers for higher strength
* Camshafts have different timings and larger opening lengths
* Intake valve opening angle 230 crank angle degrees
* Exhaust valve opening angle 220 crank angle degrees
* The lifters were adapted from the 3.2L V6 engine found in the TT and A3. They have a larger ball stroke which, in the course of testing, proved advantageous for the high-revving engine (with regard to the inflation of the hydraulic valve clearance compensation element).
* The cylinder head has a modified water jacket which circulates coolant to the area between the intake port and the injector, thereby reducing the temperatures in the cylinder head combustion chamber plate.
* Due to a modified camshaft drive reduction ratio, the camshaft adjuster has 25 teeth for the chain drive, as opposed to 30 teeth in the basic engine.
In the more highly stressed high-revving engine, an additional oil-air heat exchanger is used to minimize the oil temperature even at high engine load. This additional heat exchanger is operated in parallel with the heat exchanger via a thermostat.
Audi RS4 Sump
A reliable supply of oil in all driving situations is critical, especially in a sports car such as the RS4. The oil supply system in the high-revving engine was designed for racing applications in which it is subjected to lateral
acceleration of up to 1.4 g. To ensure this, the sump in the RS4 has an additional system of flaps.
Design
Four flaps, whose axis of rotation is parallel to the longitudinal axis of vehicle, are arranged inside a housing. Each of the flaps opens toward the inside of the intake end of the oil pump.
Function
When the vehicle is cornering, the oil flows inside the sump toward the outside of the corner. The two flaps facing the outside of the corner close and hold the oil in the sump intake. At the same time, the two flaps facing the inside of the
corner open to allow additional oil to flow into the intake. This ensures a sufficient supply of oil to the oil pump.
The intake system of the RS4 engine was designed with emphasis on maximum flow control. Pressure loss is minimized by a large cross-sectional areas in the Mass Air Flow (MAF) Sensor G70 and air intake pipe in combination with a 90 mm diameter throttle valve.
To ensure a sufficient supply of air to the engine at high RPM, the power flap in the air filter is opened at engine speeds higher than 5000 RPM and at road speeds higher than 200 kph.
The power flap is opened and closed by a vacuum
actuator which is map-controlled by the ECM via the Intake Air Switch-Over Valve N335.
The sand cast aluminum (should be magnesium) intake manifold was designed specifically to match the sporty characteristic of the engine. In contrast to the basic engine, maximum torque is produced at higher engine RPM. At this engine speed, the intake manifold changeover valve would be switched to the short path for higher power output.
Engine Management
Engine management in the new 4.2L V8 FSI is by two versions of the Bosch MED 9.1.1.
A single control module is used in the Audi Q7 engine. There are two control modules for the RS4 engine. A master-slave concept is required here due to the requisite processing power at engine speeds up to 8250 RPM.
Further differences between the Audi Q7 and RS4 engines with respect to engine management are as follows:
Engine Speed Sensor G28
An inductive sender is used in the Audi Q7 engine. A Hall effect sensor is used in the RS4 engine with master/slave concept.
The signal from the Hall sensor can, unlike the signal from the inductive sender, be split with the result that it can be utilized by both engine control modules.
Applying the signal directly to both engine control modules ensures that the control modules are absolutely synchronized.
Throttle Valve Module
The Bosch throttle valve module used in the Audi Q7 is the largest in the range with a diameter of 82 mm. The Pierburg system was selected because the air intake system in the RS4 has a diameter of 90 mm. However, both systems work in exactly the same way.
Spark Plugs
In contrast to the Audi Q7, spark plugs with a higher heat rating (colder plugs)* are used because the RS4 engine is subjected to higher thermal stresses.
* applies to NGK spark plugs
Injectors
Due to the higher fuel demand and the shorter window of time available for injection at very high engine speeds, the RS4 engine is fitted with larger injectors than the Audi Q7 engine.
Diagnosis
The RS4 engine is diagnosed via the K-wire. The Audi Q7 is diagnosed via the powertrain CAN bus.
The processor operates at a clock frequency of 56 MHz. The internal memory has a storage capacity of 512 Kilobytes. Each of the two external memories has a storage capacity of two megabytes.
The connection to the vehicle network is made by means of a CAN data bus.In the case of the master-slave concept, data is
additionally exchanged across a private bus.
Control Module Communications in the RS4
The Engine Control Module J623 (ECM, master) computes and controls the signals from the actuators for cylinder bank 1.
Most sensors are connected to the ECM (refer to System Overview, pages 34/35).
Both control modules are connected to the CAN data bus; the slave control module is used as a receiver only.
The load signals required to compute and control
the signals for the actuators of cylinder bank 2 are transmitted via private bus.
The slave control module acts as the misfire detector for each of the eight cylinders. It also processes the signal from the Engine Speed (RPM) Sensor G28.
Master and slave control modules are identical in design and have the same part number. A voltage code in the control module determines whether the control module in the master or the slave.
If battery positive is applied to the encoding pin, the control module is the master.
For those that have an ebahn account, the document is here
http://ebahn.bentleypublishers.com/AUDI/B/B6/Training/audi.ssp.921603.pdf
The main technical differences between the base engine and the high-revving engine lie in the following:
* Crankshaft/connecting rods/pistons
* Timing gear
* Cylinder head
* Oil supply
* Engine cooling
* Intake path
* Exhaust system
* Engine management
The cylinder crankcase of the high-revving engine was machined to higher specifications due to the higher stresses in this component. To minimize warping of the cylinder manifolds, the crankcase is honed under stress. For this purpose, a honing template is attached to the crankcase before the honing process in order to simulate the warping of the bolted-on cylinder manifold.
Modifications to High-revving Engine
At very high engine speeds, axial vibration occurs due to the unbalance in the single-mass damper. This can cause the crankshaft to break.
To avoid this vibration, a dual-mass damper without unbalance is employed in the high-revving engine. To compensate for unwanted engine vibration, heavy metal inserts are integrated in the first and eighth crank journals by way of unbalance.
Connecting Rod
Cracked connecting rods made of 36MnVS4 are used in the basic engine, while the conventionally split connecting rods in the RS4 engine are made of 34CrNiMo8, for strength.
In addition, the geometry and tolerances of the
connecting rods were reduced on the high revving version of the 4.2L V8 FSI engine.
Bearing journals diameter: 54 mm
Bearing bushings: 1.4 mm thick, 15.25 mm wide
Length of bushing: 0.20 mm diameter rolled
Connecting rod length: 154 mm
Piston
For strength reasons, forged pistons with a slightly higher weight than conventional pistons, are used. Both engines have the same piston geometry.
Piston weight without rings: approximately 290 g (10 oz)
Piston pin: 0.20 mm x 0.11.5 mm x 40 mm
High-revving Engine
* 3/8" simplex sleeve-type chains are used here. Their advantage is their reduced wear and higher stress resistance at high engine speeds. In this case the idler gears have 38 and 19 teeth. The camshaft sprockets have 25 teeth.
Different Features of the High-revving Engine
* To match the higher engine power output and RPM, the following cylinder head components were modified:
* Intake ports are charge optimized (based on larger cross-sections)
* Intake valves are chrome-plated hollow stem valves (for weight reduction)
* Valve springs are made of a material with higher tensile strength and also have higher spring force
* To meet the higher fuel requirements, the injectors are designed for higher flow rates.
* Roller rocker arms are more robustly designed, with peened rollers for higher strength
* Camshafts have different timings and larger opening lengths
* Intake valve opening angle 230 crank angle degrees
* Exhaust valve opening angle 220 crank angle degrees
* The lifters were adapted from the 3.2L V6 engine found in the TT and A3. They have a larger ball stroke which, in the course of testing, proved advantageous for the high-revving engine (with regard to the inflation of the hydraulic valve clearance compensation element).
* The cylinder head has a modified water jacket which circulates coolant to the area between the intake port and the injector, thereby reducing the temperatures in the cylinder head combustion chamber plate.
* Due to a modified camshaft drive reduction ratio, the camshaft adjuster has 25 teeth for the chain drive, as opposed to 30 teeth in the basic engine.
In the more highly stressed high-revving engine, an additional oil-air heat exchanger is used to minimize the oil temperature even at high engine load. This additional heat exchanger is operated in parallel with the heat exchanger via a thermostat.
Audi RS4 Sump
A reliable supply of oil in all driving situations is critical, especially in a sports car such as the RS4. The oil supply system in the high-revving engine was designed for racing applications in which it is subjected to lateral
acceleration of up to 1.4 g. To ensure this, the sump in the RS4 has an additional system of flaps.
Design
Four flaps, whose axis of rotation is parallel to the longitudinal axis of vehicle, are arranged inside a housing. Each of the flaps opens toward the inside of the intake end of the oil pump.
Function
When the vehicle is cornering, the oil flows inside the sump toward the outside of the corner. The two flaps facing the outside of the corner close and hold the oil in the sump intake. At the same time, the two flaps facing the inside of the
corner open to allow additional oil to flow into the intake. This ensures a sufficient supply of oil to the oil pump.
The intake system of the RS4 engine was designed with emphasis on maximum flow control. Pressure loss is minimized by a large cross-sectional areas in the Mass Air Flow (MAF) Sensor G70 and air intake pipe in combination with a 90 mm diameter throttle valve.
To ensure a sufficient supply of air to the engine at high RPM, the power flap in the air filter is opened at engine speeds higher than 5000 RPM and at road speeds higher than 200 kph.
The power flap is opened and closed by a vacuum
actuator which is map-controlled by the ECM via the Intake Air Switch-Over Valve N335.
The sand cast aluminum (should be magnesium) intake manifold was designed specifically to match the sporty characteristic of the engine. In contrast to the basic engine, maximum torque is produced at higher engine RPM. At this engine speed, the intake manifold changeover valve would be switched to the short path for higher power output.
Engine Management
Engine management in the new 4.2L V8 FSI is by two versions of the Bosch MED 9.1.1.
A single control module is used in the Audi Q7 engine. There are two control modules for the RS4 engine. A master-slave concept is required here due to the requisite processing power at engine speeds up to 8250 RPM.
Further differences between the Audi Q7 and RS4 engines with respect to engine management are as follows:
Engine Speed Sensor G28
An inductive sender is used in the Audi Q7 engine. A Hall effect sensor is used in the RS4 engine with master/slave concept.
The signal from the Hall sensor can, unlike the signal from the inductive sender, be split with the result that it can be utilized by both engine control modules.
Applying the signal directly to both engine control modules ensures that the control modules are absolutely synchronized.
Throttle Valve Module
The Bosch throttle valve module used in the Audi Q7 is the largest in the range with a diameter of 82 mm. The Pierburg system was selected because the air intake system in the RS4 has a diameter of 90 mm. However, both systems work in exactly the same way.
Spark Plugs
In contrast to the Audi Q7, spark plugs with a higher heat rating (colder plugs)* are used because the RS4 engine is subjected to higher thermal stresses.
* applies to NGK spark plugs
Injectors
Due to the higher fuel demand and the shorter window of time available for injection at very high engine speeds, the RS4 engine is fitted with larger injectors than the Audi Q7 engine.
Diagnosis
The RS4 engine is diagnosed via the K-wire. The Audi Q7 is diagnosed via the powertrain CAN bus.
The processor operates at a clock frequency of 56 MHz. The internal memory has a storage capacity of 512 Kilobytes. Each of the two external memories has a storage capacity of two megabytes.
The connection to the vehicle network is made by means of a CAN data bus.In the case of the master-slave concept, data is
additionally exchanged across a private bus.
Control Module Communications in the RS4
The Engine Control Module J623 (ECM, master) computes and controls the signals from the actuators for cylinder bank 1.
Most sensors are connected to the ECM (refer to System Overview, pages 34/35).
Both control modules are connected to the CAN data bus; the slave control module is used as a receiver only.
The load signals required to compute and control
the signals for the actuators of cylinder bank 2 are transmitted via private bus.
The slave control module acts as the misfire detector for each of the eight cylinders. It also processes the signal from the Engine Speed (RPM) Sensor G28.
Master and slave control modules are identical in design and have the same part number. A voltage code in the control module determines whether the control module in the master or the slave.
If battery positive is applied to the encoding pin, the control module is the master.
11-27-2007, 06:53 AM
#10
S/RS Audi brochure I picked up Sat. says RS4 has V-10. I did a double-take on that.
Thats not right is it? Brochure also had a section on S5 but, unlike sections on S4, RS4, S6 and S8, there were no specs listed. Audi may need new marketing/publications dept.