Pictures on this project will now be on a time delay.


Offset wrist pins
Wrist pin designed to be in same area as lower oil ring
Smaller wrist pins
Wrist pins DLC coated
Domes coated for Top Fuel and Nitrous
Custom designed skirts
Oil res under domes for additional cooling
Pistons extremely light yet designed for 1800 hp
Valve reliefs on pistons to work with .550 lift cams and valve widths are al la RSR

 

As a comparison ....... our 102.5 mm pistons which we decided not to use. Note how the valve reliefs cut through sides of the piston domes while with the 105.7 mm ...... there is plenty of room.

 

Chad, this is Art and Engineering at its best.

 

Porsche Turbocharged Water-cooled 4V engines and Knock


Having spent the last 20 years building these types of engines made by Porsche, I have become accustomed to their knock behavior and signature. With the recent engines produced by Porsche, 996TT and 997TT, I see the same Knock Signature, the same occurrence and the same causes the earlier water-cooled race engines produced. These same engines, (956, 962C) are similarly based and use the same architecture as the recent engines, but for the bore and stroke sizes and the cam drive systems. The rest is pretty much the same and similar. The one main difference that sets the later engines apart from the newer RSR is hydraulic cam followers which lowers the mechanical noise. Both the 956, 962C and the GT3 RSR all have solid pad style tappets and with the required lash become quite noisy in operation.

Modifying these turbocharged engines to produce higher torque numbers requires maximizing the spark timing and minimizing the A/F number dictated by an acceptable engine knock value. If knock can be detected and controlled, the A/F number limited and the spark advance value advanced to a number where complete or almost complete combustion occurs, maximum torque will be produced as the pressure within the combustion chamber will be at the highest.

To understand knock, you first have to know what causes it and what the effects of knock are. If the A/F mixture is ignited without any pre ignition occurrences and the mixture can be completely ignited or burned evenly all the way out to the sides of the cylinder and combustion chamber, no uncontrolled ignition will occur. This is what we strive for. It does not always happen. In Cylinder pressures often ignite the gases at the sides of the chamber walls (end gases) before the flame front can reach them causing uncontrolled ignition. Temperature can also cause this to happen. This ignition and the collision of this force with the already ignited A/F mixture from the spark plug create huge shock waves and localized pressure points.

However, it does need to be known the differences in knock and the different levels at which damage can occur. It is this I find as the cause of so much damage in the recent engines. Both the lack of knowledge in the different levels of knock and the taking for granted the factory system will save the engine are the two main reasons failures are occurring. The high manifold pressures, fuel type etc are all contributors, but these are the known factors or cause. It’s the unknown factors that are the reason for these failures. In watching videos sent to me of different companies re calibrating these engines, I have yet to see anyone using any sort of knock detection other than relying upon the factory system

Within the combustion chamber, there is a layer or thin area of pressurized air fuel mixture that separates the actual chamber walls and the ignited charge. When this “boundary” is penetrated by the forces of detonation the physical damage occurs. The particular area of damage occurs due to temperature, hot spots in the chamber, shape and pressure points. This is one of the reasons you will see smooth surfaces and no sharp edges or corners in the chambers, piston crowns and valve relief’s. Sharp corners have thin sections that super heat and cause detonation usually in the form of pre ignition detonation. The same reason spark plugs cause pre ignition and the reason spark plug designs are known as “cold” verses “hot”.


The factory system as with most modern knock control systems offer the engine a safety system that will retard the ignition timing if knock is sensed above a pre set threshold and knock count within a prescribed crank angle window. Most knock systems look for knock anywhere between 10° BTDC and 40° ATDC. This “windowing” can change based upon a systems control. Typically the base engine mapping has been done after many tuning sessions both statically and dynamically. The knock frequency has been measured and the placement of the sensors based upon a series of tests. This is all based upon the engines basic dimensions. The bore of an engine is critical in the frequency count an engine will produce. The use of “listening” devices is a common and inexpensive way to monitor engine knock. It is not a way to safely control knock if one of many parameters are changed. If the engines dimensions and components are not changed, and the engine calibration is not changed from the factory settings, it is a very good inexpensive way to control any detonation that could occur due to temperature, fuel condition, and any other issues that can be introduced to the engine during operation. The actual knock threshold (noise level) the ECU will accept as normal engine component noise, the number of knock counts above this level the ECU will accept and some other factors are all set based upon what is seen on more precise measuring devices. Commonly used are pressure sensing devices within the cylinder, spectral analyzers and some very sophisticated monitoring devices. As soon as any of the engines calibration, dimensions etc are changed, all of the factory knock control parameters are questionable. They will retard the most severe knock counts, but the actual knock noise levels and knock counts can all be erroneous. Engine bore size and in cylinder temperatures have the biggest effect on the Knock frequency. Change this and the engines primary frequency is completely different. In many cases bore sizes are not changed, but the in cylinder temperatures are exponentially changed due to higher manifold pressures and greater air mass numbers. I hear all too often the air mass sensor has been changed due to the stock OEM sensor been max’ed out and the turbocharger boost pressures increased. Both contribute to huge increases in cylinder temperatures.

The typical knock sensing device used in OEM applications are “listening" types known as piezoelectric sensors. These are broad band width sensors typically. Some sort of signal conditioning is used to modify and enhance the signals received. As the whole system is used as a safety system, the same sensor is often used on different engines to help lower the cost to the manufacturer. Different engines produce different primary knock signals or frequencies, but using a sensor that has a broad sensing window allows a common sensor. The down side to this cost savings is a detection system that has a lower level of detection and performance. In a safety system, this lower level is not really an issue, until you change something.

When there is any uncontrolled ignition or Knock, the shock wave that is generated has a certain frequency. This is around 6 KHz in many cases. Usually a system that can measure frequencies between 5 and 7 KHz will catch most primary frequencies generated by knock. Unfortunately the primary frequency includes all of the engines mechanical noises. So changing any of the engines components has a huge effect on the level of mechanical noise. Without the ability to separate the actual mechanical noise from knock, (threshold level number), this can then can limit an engines performance or increase the probability of undetected detonation.

This is somewhat of a basic overview of Knock, but it is hoped that it gives you some sort of idea of how important it is to be aware of the forces involved, the cause and the reason to do whatever is necessary to detect knock when recalibrating these engines. I do not intend to go any deeper as it gets really deep into signatures, signal conditioning requirements, and all of the different strategies. Suffice to say, make sure your tuner understands the basics and listens for knock or has some sort of pressure sensing system for detecting the sudden rise in cylinder pressures when knock occurs. Failure to do so will more often result in engine damage.

What I have seen and can deduce from engine inspections and looking at data supplied, is the level of the knock is what is creating the damage. The factory system is picking up the severe knocks and retarding the timing as required. The factory system can retard the timing per individual cylinders. Here lies another problem. I will go into this a little later.

It is my opinion that the small continual knock levels or amplitudes are casing the damage. As the damage never seems to happen during calibration but over time, the inability to adjust the threshold and count numbers in the factory system create an environment where un detected knock is happening and over time continued detonations are causing huge in cylinder temperatures, head gasket failures and erosion of cylinder walls and chambers at the parting lines. The common failure points are exacerbated by coolant temperature inconsistencies and differences in cylinder head clamping values. I have seen many engines where torque values are used to secure the cylinder heads to the engine block. Often re torquing is done in an effort to make sure there is no settlement in the head and gasket. We have carried out many tests and found that the actual clamping values are very inconsistent due to friction and other factors. Repeating the torque procedures has little or no difference in the clamping forces.

The sealing system used on your motor has been very successful along with your head stud/design. The change in your stud is all about the anchoring in the block and has nothing really to do with stud deflection or stretch. Making sure the head does not deflect under clamping loads is another factor we consider. Our head washers solve this problem. Heads should be checked for hardness when repaired and any head that has gone “soft” should be re heat treated or replaced.

When the factory system or any system that can retard the Ignition timing per cylinder, actually detects knock and retards the ignition advance in that cylinder, the whole system is supposed to do so until no knock is detected. Although systems are very fast, so is the actual engine cycle. The more cylinders and the higher the engine speed is, the more this function becomes self destructing. It does retard the timing but as soon as the next cylinder in the firing order comes up to fire, the engine has already become in balanced. Think of a 4 cylinder engine firing every 180°. Now we add another 2 Cylinders and the firing angle becomes smaller by 60°. Increase the RPM and this becomes even smaller but in time not crank degrees. There is a certain amount of “bleed over” occurring. The system is often limited by 1 or 2 sensors. As soon as knock is detected, the ECU knows which cylinder is firing and so retards that cylinder. But very soon after the next cylinder to fire is at the set ignition point and so that cylinder is retarded some. This is typically not an issue when a stock engine is safely retarded as performance is not the parameter the user is worried about. The engine safety is.

Now we need to look at the "hot rodding” of these engines. The knock system is compromised as the performance levels are increase often by large factors. If the stock system could be re calibrated and the stock knock thresholds increased and the knock counts re evaluated, then the whole knock system would be re configured to allow for this higher level of performance. The fact that it isn’t in my opinion is giving me real cause to be concerned. The low level detonation that is going undetected and the in balance of the ignition system due to the knock system retarding when it senses hard knocks all make for a precarious situation.

 

Nice shape, but I will verified something about it and the air flow.

 

m42racer,

The knock information was from Neil Harvey. The ECU currently being designed will address all the above issues.

Regarding the intake, I am talking to a couple of friends to see if I can find two other people interested in this same specially designed intake, it would lower the per unit cost by 25% if three were to be made.

The plenums and X over manifolds would all be double O ringed together giving a cleaner outside appearance, polished and anodized to any color of choice or clear to give a matt finish that is easy to clean.

It would be made up of the following:

1) Dual Injector Lower Manifold left hand side.
2) Dual Injector Lower manifold right hand side
3) Includes design, material, machining with CNC porting to match Cylinder heads
4) Fuel Rail (for dual injectors per cylinder) left hand side and mounting brackets
5) Fuel Rail (for dual injectors per cylinder) right hand side and mounting brackets
6) Butterfly housings (six throttle bodies)
7) Plenum left hand side
8) Plenum right hand side
9) X Over Manifold with Dual Inlets
10) Linkage .... Includes the Oldham couplers between throttle housings, and linkage arms and links between LHS and RHS manifolds.
The accelerator by wire would use the cars existing servo motor.

All the design work would not be charged for as it has already been taken care of.

If you know of anyone who has the money (expensive but whole lot better pricing with three) and would be interested in this set up let me know.

 

Simon,

After the intake we have to pair the dual injectors, fit the CD Ignition/coils and tune the Link system on the engine dyno.

 

I will try to design the new carbon part.

But I need some information,

The camshaft shape, and the graphic of pressure of the turbo.

Thank

 

i dont,please do tell. I have always wondered about this. Thanks again

 

QTC,

I appreciate the offer. Neil @ PD is already working on this.

 

bimmer,

The following is part of the explanation that Neil Harvey had come up with earlier:

Modifying these turbocharged engines to produce higher torque numbers requires maximizing the spark timing and minimizing the A/F number dictated by an acceptable engine knock value. If knock can be detected and controlled, the A/F number limited and the spark advance value advanced to a number where complete or almost complete combustion occurs, maximum torque will be produced as the pressure within the combustion chamber will be at the highest.

To understand knock, you first have to know what causes it and what the effects of knock are. If the A/F mixture is ignited without any pre ignition occurrences and the mixture can be completely ignited or burned evenly all the way out to the sides of the cylinder and combustion chamber, no uncontrolled ignition will occur. This is what we strive for. It does not always happen. In Cylinder pressures often ignite the gases at the sides of the chamber walls (end gases) before the flame front can reach them causing uncontrolled ignition. Temperature can also cause this to happen. This ignition and the collision of this force with the already ignited A/F mixture from the spark plug create huge shock waves and localized pressure points.

However, it does need to be known the differences in knock and the different levels at which damage can occur. It is this I find as the cause of so much damage in the recent engines. Both the lack of knowledge in the different levels of knock and the taking for granted the factory system will save the engine are the two main reasons failures are occurring. The high manifold pressures, fuel type etc are all contributors, but these are the known factors or cause. It’s the unknown factors that are the reason for these failures. In watching videos sent to me of different companies re calibrating these engines, I have yet to see anyone using any sort of knock detection other than relying upon the factory system

Within the combustion chamber, there is a layer or thin area of pressurized air fuel mixture that separates the actual chamber walls and the ignited charge. When this “boundary” is penetrated by the forces of detonation the physical damage occurs. The particular area of damage occurs due to temperature, hot spots in the chamber, shape and pressure points. This is one of the reasons you will see smooth surfaces and no sharp edges or corners in the chambers, piston crowns and valve relief’s. Sharp corners have thin sections that super heat and cause detonation usually in the form of pre ignition detonation. The same reason spark plugs cause pre ignition and the reason spark plug designs are known as “cold” verses “hot”.


The factory system as with most modern knock control systems offer the engine a safety system that will retard the ignition timing if knock is sensed above a pre set threshold and knock count within a prescribed crank angle window. Most knock systems look for knock anywhere between 10° BTDC and 40° ATDC. This “windowing” can change based upon a systems control. Typically the base engine mapping has been done after many tuning sessions both statically and dynamically. The knock frequency has been measured and the placement of the sensors based upon a series of tests. This is all based upon the engines basic dimensions. The bore of an engine is critical in the frequency count an engine will produce. The use of “listening” devices is a common and inexpensive way to monitor engine knock. It is not a way to safely control knock if one of many parameters are changed. If the engines dimensions and components are not changed, and the engine calibration is not changed from the factory settings, it is a very good inexpensive way to control any detonation that could occur due to temperature, fuel condition, and any other issues that can be introduced to the engine during operation. The actual knock threshold (noise level) the ECU will accept as normal engine component noise, the number of knock counts above this level the ECU will accept and some other factors are all set based upon what is seen on more precise measuring devices. Commonly used are pressure sensing devices within the cylinder, spectral analyzers and some very sophisticated monitoring devices. As soon as any of the engines calibration, dimensions etc are changed, all of the factory knock control parameters are questionable. They will retard the most severe knock counts, but the actual knock noise levels and knock counts can all be erroneous. Engine bore size and in cylinder temperatures have the biggest effect on the Knock frequency. Change this and the engines primary frequency is completely different. In many cases bore sizes are not changed, but the in cylinder temperatures are exponentially changed due to higher manifold pressures and greater air mass numbers. I hear all too often the air mass sensor has been changed due to the stock OEM sensor been max’ed out and the turbocharger boost pressures increased. Both contribute to huge increases in cylinder temperatures.

The typical knock sensing device used in OEM applications are “listening" types known as piezoelectric sensors. These are broad band width sensors typically. Some sort of signal conditioning is used to modify and enhance the signals received. As the whole system is used as a safety system, the same sensor is often used on different engines to help lower the cost to the manufacturer. Different engines produce different primary knock signals or frequencies, but using a sensor that has a broad sensing window allows a common sensor. The down side to this cost savings is a detection system that has a lower level of detection and performance. In a safety system, this lower level is not really an issue, until you change something.

When there is any uncontrolled ignition or Knock, the shock wave that is generated has a certain frequency. This is around 6 KHz in many cases. Usually a system that can measure frequencies between 5 and 7 KHz will catch most primary frequencies generated by knock. Unfortunately the primary frequency includes all of the engines mechanical noises. So changing any of the engines components has a huge effect on the level of mechanical noise. Without the ability to separate the actual mechanical noise from knock, (threshold level number), this can then can limit an engines performance or increase the probability of undetected detonation.

This is somewhat of a basic overview of Knock, but it is hoped that it gives you some sort of idea of how important it is to be aware of the forces involved, the cause and the reason to do whatever is necessary to detect knock when recalibrating these engines. I do not intend to go any deeper as it gets really deep into signatures, signal conditioning requirements, and all of the different strategies. Suffice to say, make sure your tuner understands the basics and listens for knock or has some sort of pressure sensing system for detecting the sudden rise in cylinder pressures when knock occurs. Failure to do so will more often result in engine damage.

What I have seen and can deduce from engine inspections and looking at data supplied, is the level of the knock is what is creating the damage. The factory system is picking up the severe knocks and retarding the timing as required. The factory system can retard the timing per individual cylinders. Here lies another problem. I will go into this a little later.

It is my opinion that the small continual knock levels or amplitudes are casing the damage. As the damage never seems to happen during calibration but over time, the inability to adjust the threshold and count numbers in the factory system create an environment where un detected knock is happening and over time continued detonations are causing huge in cylinder temperatures, head gasket failures and erosion of cylinder walls and chambers at the parting lines. The common failure points are exacerbated by coolant temperature inconsistencies and differences in cylinder head clamping values. I have seen many engines where torque values are used to secure the cylinder heads to the engine block. Often re torquing is done in an effort to make sure there is no settlement in the head and gasket. We have carried out many tests and found that the actual clamping values are very inconsistent due to friction and other factors. Repeating the torque procedures has little or no difference in the clamping forces.

The sealing system used on your motor has been very successful along with your head stud/design. The change in your stud is all about the anchoring in the block and has nothing really to do with stud deflection or stretch. Making sure the head does not deflect under clamping loads is another factor we consider. Our head washers solve this problem. Heads should be checked for hardness when repaired and any head that has gone “soft” should be re heat treated or replaced.

When the factory system or any system that can retard the Ignition timing per cylinder, actually detects knock and retards the ignition advance in that cylinder, the whole system is supposed to do so until no knock is detected. Although systems are very fast, so is the actual engine cycle. The more cylinders and the higher the engine speed is, the more this function becomes self destructing. It does retard the timing but as soon as the next cylinder in the firing order comes up to fire, the engine has already become in balanced. Think of a 4 cylinder engine firing every 180°. Now we add another 2 Cylinders and the firing angle becomes smaller by 60°. Increase the RPM and this becomes even smaller but in time not crank degrees. There is a certain amount of “bleed over” occurring. The system is often limited by 1 or 2 sensors. As soon as knock is detected, the ECU knows which cylinder is firing and so retards that cylinder. But very soon after the next cylinder to fire is at the set ignition point and so that cylinder is retarded some. This is typically not an issue when a stock engine is safely retarded as performance is not the parameter the user is worried about. The engine safety is.

Now we need to look at the "hot rodding” of these engines. The knock system is compromised as the performance levels are increase often by large factors. If the stock system could be re calibrated and the stock knock thresholds increased and the knock counts re evaluated, then the whole knock system would be re configured to allow for this higher level of performance. The fact that it isn’t in my opinion is giving me real cause to be concerned. The low level detonation that is going undetected and the in balance of the ignition system due to the knock system retarding when it senses hard knocks all make for a precarious situation.



bimmer, in simple terms, we believe Porsche has improved both the window (where knock is being listened to) and the frequency and therefore has looked at insipid knock (areas where knock was not prior detected or listened to so as to take preventative actions). This is why the 9967tt when modified (to a point) and still using stock rods will not be exposed to the same detonation issues.

We believe the 997tt knock system is better, however, we also believe it is not up to the standards required in the power areas some of these motors are now entering.

 

Chad, Thank you for the response and explanation, i alway appreciate the knowledge you share.

 

bimmer,

Keep in mind this is our opinion based on our research. It may not be correct. However, we are building our own knock system which will directly read the cylinder pressures along with listen to certain windows and frequencies. It will be adjustable over a wide range.

If it works then I will say we were correct in our assumptions. We should know very soon.

 

We are going ahead with the complete redesigned intake system. I could not find anyone else with an interest that I knew. Neil found one from his side that was interested.

Here is the update:

Ok, we are moving forward and will do all of the design etc. I will keep you informed of the progress. There may be some down time on the engine as we are using it as a moch up for all of the design work. The system will use 2 E Throttle motors one on each bank with a link between. This way we can drive both sides but keep them sync’ed.

nh

 

Chad. What's the target road date now. Hopefully this coming spring/summer.