Tonight if I have time between packing to head out of town I'll gather a list of post where you have fought with every tuner that actually sponsors this forum... Trust me I know finding 10-15 won't be a problem at all...

One thing to remember with cars is that "S*** happens...", and I am guessing you are a engineer possibly? I know that is not a good enough answer for any kind of engineer (and I say that in a non-disrespectful way). Every friend I know that has a degree in it will argue points to try and pin-point the exact reason why everything happens with car stuff. Sometimes stuff breaks... I lost a transmission in 2 weeks back in 2000 in a 98 Cobra (fresh T-45), previous had 20k miles on it (since 98) and I beat the crap out of it the same way. The following lasted till I sold the car a year and a half later. All three were taken to the track and all three were powershifted... So why did one take awhile to break and the other basically instantly, and the third last another year and a half?

That or you are a lawyer hence your nature to argue every point!

 

Again....

TTdude...I respect the fact that you want answers, and I love being able to give them, but I don't know what else I can say.

Keep one thing in mind though. The engine that these rods came out of didn't fail completely. It still ran. It still made GREAT power, and it still felt VERY fast. And there were no blatant signs that anything was wrong. We could have *maybe* kept driving it to this day and it would have held together just fine. We're extremely critical of the way the car drives, and because we were so critical, that's why we noticed that the performance seemed to have decreased a little. Don't get me wrong, it still drove like an animal. Going out on a limb, I'd venture to say that the average person may not have even noticed that it wasn't 100%. Down here, luckily our weather is pretty consistently hot from day to day (and even night), so we can easily notice when something doesn't feel right from one day to the next. But in other places that have 20-40º changes in temperature from day to day, someone might just attribute it to a hot day. Just a thought...

Purely for my own curiosity's sake, can I ask what power package you have on your car?

 

It's good to know that I don't discriminate and while you're at it, please don't forget to count all the positive things I've said too.

It doesn't really matter what I do for a living, that's irrelevant. I can agree with everything but that's boring. But I do agree with your comment about "S*** happens...

 

Thanks for sharing that extra bit of info. I wouldn't have imagined the car still running almost the same with rods looking like that. Mine power package is fairly modest. I have 63.5 mm vtgs, upgraded ICs, clutch, and tune. I can consistently run 6.9s 60-130 (4th gear pull) on race tune at 1100 ft elevation (~3% less O2). So my awhp is well below 700 but I still worry about it and know that there are risks. You have to trust the tuning/tuner if one decides to go down this route for more power.

 

You have a pretty similar kit to milou....who, according to his dynos above, is running high 600's (almost 700) to the wheels. What I'm wondering though (and I ask this question entirely with the best intentions)....how come the 60-130's aren't faster? It's similar power to KerCar's car, so it should be getting the same result, or at least pretty close. Maybe because his car is a tip and yours is 6 speed? I haven't followed the whole 60-130 thing long enough so I'm a little naive about that whole concept to be honest.

I'm sure getting a fast 60-130 time has a bit of technique involved, and I know KerCar had the help of Whiteknight when he was running them. His runs were pretty consistent though...5.5, 5.6, 5.5...all right in the same range. But since there's human error involved, just like running a fast 1/4 mile, the whole concept loses a little credibility for me.

 

this thread is becoming less constructive and more antagonistic with each page. It would be a shame if it derailed to the point of being locked

 

+1.

2 Questions:

- Is anyone certain that the rods weren't bent before CMS did anything?
- Could it have been a bad batch of rods? Any metallurgy done to compare the bent rods with another specimen?

 

I'm not sure what Milou has these days. If I'm not mistaken, I believe he has the newer version of upgraded vtgs, 65mm wheel, extrude honed. It's a significant improvement over mine. My time is similar to Eclou's, who has AWE's package. I don't brake boost either which I know people do to get faster times. Kercar's time is very very impressive for vtgs, no doubt about it.

PS I should add that there are APR tunes with stock turbos running ~6.5 (tip) and ~6.7 s (6speed with two shifts, 3-4 & 4-5!) that are faster than upgraded vtgs. I could probably lean out my tune and get a faster time but not willing to risk it.

 

well said mike

 

This thread is starting to go in a direction I really don't like. First, let me summarize the discussion thus far:

-Champion was professional and responsible enough to post a thread, explaining their concern that the stock 996/997.1 rods may not be able to deal with greater than 700whp. Tom states that he feels the cylinder pressures at this level are too high, greatly increasing the chance that the rods will bend, possibly causing catastrophic engine damage. He also makes some very good points regarding the fact that Champion warranties their kits, so they are drawing the line in the sand at 700whp, which I think is completely fair.

-However, some other posters have mentioned that 700whp does not sound accurate due to the fact that there are many other cars, built by other tuners, that currently have or have made more than 700 whp (in some cases, MUCH more) without ever having any problems. This includes some members who actually have personal experience with their own Porsche engines, and who have seen and held in their own hands, their stock rods after they have been exposed to greater than 700rwhp...with no ill-effects. These members have questioned if 'something else' could have gone wrong; namely a tuning issue, bad fuel, or excessive torque.

-Tom claims that it's none of the above because their tunes are essentially above reproach with many safety features left intact, that would prevent any possibility of detonation (I'm paraphrasing).

-Certain fans of Champion, the majority of whom have never even seen the inside of their engine, or dealt with any other tuners other than Champion, take extreme offense to any questions or comments implying that Champion's tune may be the reason the rods were bent, and begin attacking those that dare to disagree with Tom's assessment that this issue was in no way caused by a tuning issue or running too much torque.

The facts are this:

-Champion makes very, very good kits. They are meticulous, professional, and have a high degree of candor. They are a top-notch shop.

-There are other tuners on this forum who also run top-notch shops. They are also professional and meticulous, and have the results to prove it.

-Something happened to this Champion motor, but no one knows with 100% certainty what it was. Tom says it has nothing to do with the tune. That may be true. What also may be true is that it made too much peak torque, or a detonation event occurred that bent the rods. It's really all speculation at this point.

-There are many, many dozens of cars built by other tuners that are running well over 700, 800 whp that are having no problems with their engines.

-There are quite a few cars that have previously made over 700whp that have had their motors taken apart only to find that the rods were/are still in perfect condition.

-No one can prove that 700rwhp is totally safe, but on the flip-side no one can prove that it's not. The evidence of multiple cars running that much or greater power without issue seems to suggest that it is at least somewhat safe, assuming proper tuning and fuel....but as has been said, "**** can happen" with a high powered car.

-Just because people ask hard questions to Tom, doesn't mean that all the 'supporters' need to remove their swords from their sheaths, and jump in and defend him. No one is calling Champion names. No one is trying to "knock them off" some invisible pedestal. No one is saying Champion is a bad tuner. I actually commend Champion greatly for creating this thread, and I would personally be confident in allowing them to work on any Porsche that I own. But...for the benefit of the community, hard questions should be asked, and people should stop taking those questions so personally. We are simply trying to get to the bottom of what happened, knowing full well that it could happen to anyone...not just Champion.

At any rate, I want to leave this thread open, so here are the rules: If I see any further attacks on people simply for asking questions (from either side), or attacking people who make counter-points to Tom's, the post will be edited, the offender given an infraction, and the thread may be closed. If you're found to be a shill for a particular vendor, you'll be banned.

 

Excellent summary!

Damn, I almost produced wood when I thought that the 68mm vtgs ran a 5.5s 60-130 on pump gas!!!! It's still impressive even though it's on race gas (or equivalent).

I think Milou has 63.5mm vtg with extrude and meth kit but of course he could answer for himself if he chooses.

I think many of us are still in shock that a sub-6 sec 60-130 is possible with vtgs b/c no-one else has done it afaik.

Great thread, please keep the hard questions coming, and not the personal attacks...

 

I posted a link to an old post (in another thread) in post #44 of this thread. I could hear the crickets as there was not a single comment one way or another.

Below I have posted the post in it's full context ...... any comments?


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.

 

Outstanding summary. If the knock sensors are just listening for certain frequencies, then other modification in the engine compartment could cause them to tell the ECU to retard timing. Could any of the following cause this situation to occur: stiffer/solid suspension components, louder exhaust systems, semi solid engine mount (wevo's for example). Can the ECU be reprogramed to listen to more specific frequencies that are cause by knock rather than other factors? Are other more precise peizoelectric sensors available?

 

A better question you need to answer is ......... what is the frequency being generated by the modified parts?

Don't lose sight of the fact, while the knock system is part of the equation. You might also want to look at the ignition system. I have said enough now. Let's see if some of the tuners/engine builders out there want to further the discussion?

 

great tech here ^^. Sometimes in road racing folks have found that solid motor mounts can lead to erroneous triggering of the engine knock protection, which can quietly cost power