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Appreciated, thought you'd say 24, 48 or 64 - 2000 is remarkable for any DAU; not knowing what the onboard memory is, you are most likely correct that it will not sample 2mhz over all channels.
But still, very neat toy.
I read a little more - 100k samples per second across all enabled channels is the max the device can do. Max of 2000 channels, max of 1000hz per channel if below the 100k across all channels.
So, it'll run a solid 500hz across all 2000 channels - that is damn impressive, one should be able to capture just about any failure or condition with that.
Wow, John. I see that's all on the stock intake manifolds; are you running stock heads/valves/cams or have those been changed? That is huge power at relatively low boost, especially on 91oct! What are the uncorrected numbers?
Wow, John. I see that's all on the stock intake manifolds; are you running stock heads/valves/cams or have those been changed? That is huge power at relatively low boost, especially on 91oct! What are the uncorrected numbers?
Hi Sam,
I'm glad to hear you're doing well. I’ve never looked at the uncorrected numbers. The dyno we use locally is legit being used to certify all cars for just about every active racing organization. We've been using this dyno for years along with just about everyone in the Porsche world in our area. Flashed 996TT Mezgers typically dyno in the mid 400s which is an accurate benchmark.
There are a number or reasons we are able to get significant numbers on 91 octane. First of all, We’ve gone to great pains to eliminate just about all exhaust restrictions with headers, free flowing turbines, and a 3.5" straight pipe exhaust which allows the engine to expel heat efficiently. On the intake side, we have thoroughly tested and evaluated everything and have opened it up to the greatest extent possible. Probably the greatest gains, in excess of 150whp, have been through the optimization of the Variocam system on this engine. The OEM variocam profile is completely wrong for a 4.0L engine with the mods we are running. It's actually completely wrong for even relatively mildly modded cars with larger turbos. Chris spend quite a bit of time on the dyno mapping the variocam profile to maximize performance throughout, especially on the midrange and top end where the OEM profile is most out of optimal spec. Unlike the 2-step variocam on a 996TT/GT2 engine, Chris has figured out how to make the Variocam infinitely controllable throughout the whole rpm range. The gains as a result of this are significant. Finally, the amount of performance that can be extracted with a modern ECU like the M150 is night and day compared to the 25 year old Bosch ECU. We have a tremendous amount of data on the car and can take advantage of it when it comes to tuning. Finally, the engine runs lower compression that stock and that combined with the high efficiency on the exhaust side makes the engine very much resistant to knock and allows us to be more aggressive with the timing on pump fuel. Chris has spent a lot of time making sure the mapping of the knock sensors is very precise because the harmonics of the engine are substantially different from the typical engine mainly due to the 106mm pistons and also due to the fact the the whole drivetrain is mounted to the chassis via solid mounts.
With that said, we currently have OEM Todd McKenzie ported heads and valve train along with Schrick Motorsport intake and exhaust cams. The intake distributor is stock and shockingly we have found it reasonably good. We have 997Cup heads and a 997Cup dual resonance intake on hand along with 997.1GT3 cams and variocam. The cup heads are being sent to Todd McKenzie as we speak. We are going to install this next year and that will allow a significant improvement in the intake side. We anticipate being able to get 1000whp at 8500 on less than 1 bar boost on 91 pump. The ultimate goal is to run 900whp @ 8200 on 0.7 bar with no more than 600ft.lbs.
Here are the detail of the engine as it stands right now:
It's actually completely wrong for even relatively mildly modded cars with larger turbos. Chris spend quite a bit of time on the dyno mapping the variocam profile to maximize performance throughout, especially on the midrange and top end where the OEM profile is most out of optimal spec. Unlike the 2-step variocam on a 996TT/GT2 engine, Chris has figured out how to make the Variocam infinitely controllable throughout the whole rpm range.
This is interesting - how does one address this when one's 980s go on and one doesn't have a MOTEC?
It's actually completely wrong for even relatively mildly modded cars with larger turbos. Chris spend quite a bit of time on the dyno mapping the variocam profile to maximize performance throughout, especially on the midrange and top end where the OEM profile is most out of optimal spec. Unlike the 2-step variocam on a 996TT/GT2 engine, Chris has figured out how to make the Variocam infinitely controllable throughout the whole rpm range.
This is interesting - how does one address this when one's 980s go on and one doesn't have a MOTEC?
You’ll do just fine and make great power. With the basic intake and exhaust mods you’ll likely see 650whp on pump with a torque peak right at 4000. It’s just going to take 0.5bar more boost to make up for the Variocam inefficiencies that you can’t do anything about with the stock ECU. You’ll end up running 1.2 to 1.3 bar to hit those #s with pump. You’ll love it.
It's actually completely wrong for even relatively mildly modded cars with larger turbos. Chris spend quite a bit of time on the dyno mapping the variocam profile to maximize performance throughout, especially on the midrange and top end where the OEM profile is most out of optimal spec. Unlike the 2-step variocam on a 996TT/GT2 engine, Chris has figured out how to make the Variocam infinitely controllable throughout the whole rpm range.
This is interesting - how does one address this when one's 980s go on and one doesn't have a MOTEC?
If no Motec, then Syvecs can do it!
In reality, I don't think there is an easy way to do it on stock ECU to the level that his car is doing currently. John will correct me if I am wrong, but prior to Motec when was running Cobb he had a Motec C125 dash logger with a custom table that was controlling the variocam solenoid's on/off timing in a way that was still modified over stock operation, but not full PWM and constantly variable like he has currently. I am not sure if the C125 can PWM the variocam like the full standalone ECUs can without doing some digging.
I'll go a step further and say the stock variocam operation isn't even optimized for modified stock turbo cars and may even leave some on the table on a completely stock car too. I picked up over 30 whp by modifying the variocam tables when I was on unmodified K16s. My stock turbo car was making power closer to what you'd expect from a car with K16 billets.
I do agree with John that you'll be fine either way you go. You will still make the power, just will take more boost.
In reality, I don't think there is an easy way to do it on stock ECU to the level that his car is doing currently. John will correct me if I am wrong, but prior to Motec when was running Cobb he had a Motec C125 dash logger with a custom table that was controlling the variocam solenoid's on/off timing in a way that was still modified over stock operation, but not full PWM and constantly variable like he has currently. I am not sure if the C125 can PWM the variocam like the full standalone ECUs can without doing some digging.
I'll go a step further and say the stock variocam operation isn't even optimized for modified stock turbo cars and may even leave some on the table on a completely stock car too. I picked up over 30 whp by modifying the variocam tables when I was on unmodified K16s. My stock turbo car was making power closer to what you'd expect from a car with K16 billets.
I do agree with John that you'll be fine either way you go. You will still make the power, just will take more boost.
To expand on what T10Chris said above, and he's 100% correct, both Motec and Syvecs can do it. As he mentioned, it may be possible to fully control the variocam with the C125 but the ECU mapping would need to be optimized for the cam changes. I would have to check with Cervelli. I'm my opinion, 20+ years ago Porsche hit their 400hp target with the engine and saw no need to optimize it any further especially in light of the fact that the K16s that came on the car were out of their efficiency range much past 5000. Putting more than 400hp into a car with the relatively horrendous 996TT suspension would probably not have been good idea. They also wanted to have room to grow performance wise with the 997 turbo Mezgers. I do not know how the variocam operates on the 997 turbo cars but it was certainly no breakthrough as even the 997GT2RS only manages just shy of 600whp on 1.6bar. I do know that all GT3s starting with the 996.2 received fully variable Variocam, the 996.2 with 45º on the intake and the 997.1 with 55º. The 7.2GT3 also received variocam on the exhaust.
With that said, for a little background on the Variocam stuff, we started playing around with it back 3 years ago when we discovered a potential for 120+ hp and tq gains with it on a stock ECU. There was just no way for us to seamlessly integrate it as we were not doing the ECU engine tuning ourselves at the time. Here is a thread on it from 2019:
You’ll do just fine and make great power. With the basic intake and exhaust mods you’ll likely see 650whp on pump with a torque peak right at 4000. It’s just going to take 0.5bar more boost to make up for the Variocam inefficiencies that you can’t do anything about with the stock ECU. You’ll end up running 1.2 to 1.3 bar to hit those #s with pump. You’ll love it.
Ohhhhhh, yes indeedy, I am looking forward to this.
Here is little more tuning info that some of you guys may find interesting. Since we had already optimized the tune for various torque levels, one would think we were done. As most guys that have had their engines tuned already know, pretty much all "custom" tunes that are done are based on a datalog of a full throttle pull in 3rd or 4th gear upon which the tuner than optimizes the file. This is usually repeated a couple of times to get it perfect. This is typically the end of the tuning process.
While the file may be optimized for full throttle operation, it is likely not going to be optimized during part throttle operation. Since we don't always drive at full throttle, optimizing a particular tune at part throttle operation pays off in getting an engine to behave in a very linear, smooth, and progressive fashion. One way to look at it is to say that in a perfect world, 50% throttle should result in 50% hp, 70% throttle in 70% hp, 100% throttle in 100% hp, etc, etc. Every tune I have had lacked in this department because the engine simply did not have the behavior I just described. In most cases, the ECU was commanding / giving full boost at less than full throttle. As such, we wanted to get the part throttle transition optimized to get as close to a normally aspirated throttle linearity as possible. Essentially, we are optimizing the whole throttle range within a single tune, not just the very top.
We used our 600 wtq 1.0 bar max boost map to tailor first as this is the everyday file for normal operation. Chris electronically limited the throttle in the I2 tuning software to predetermined limits which would then be tuned individually. We started with 50% throttle and then progressed with 55, 60, 70, 80, 90 and finally 100% (which was the optimized starter file). I2 can then extrapolate between the various levels to make the transition seamless. By having the throttle electronically limited, the throttle pedal was fully depressed and the throttle body would then be commanded to a perfect and rock steady 50% or whatever % was selected. We could then do perfectly repeatable pulls to optimize each part-throttle operation threshold.
The result of this was that at 50% throttle, we would get a max of 0.5 bar boost and 407whp. This is pretty close half of the 1.0 bar and 832 whp at 100% throttle. All the other points in between the 50 and 100% are evenly spaced providing excellent linearity which makes precise throttle modulation a snap.
Another advantage of having the engine tuned this way is the simple fact that I can have perfectly tuned "low power" files to be used during rain or other condition of low traction. Trying to tune an engine for significanlty reduced output can be very tricky cause you get into an area where the boost control is simply not in its sweet spot and thus can be difficult to control. On our set up, mapping files below 500 wtq is not optimal with the TB at 100% but since the engine is precisely mapped for part throttle operation, using the throttle plate as a "restrictor" within a particular tune allows us to easily have precisely selectable low HP/tq level limits. The operation is completely seamless as the full travel of the throttle pedal simply reduces the travel of the throttle body plate in a linear fashion. The other advantage of having the engine tuned this way is the I can select any of 10 preloaded hp/tq maps by simply toggling a switch in the cockpit. This allows me to easily run the car in several different classes by simply selecting the appropriate map for a particular class HP/weight limit.
Finally, as had been touched on in another thread here regarding turbocharger lag, when the part throttle operation of the tune is optimized, lag can pretty much be eliminated or at least largely minimized. As you can see below, the curves pretty much show what the engine pulls freely from just about any point on the chart without hesitation in a smooth linear fashion.
The last thing we did was to make sure the timing retard for thermal loading with increasing IATs was programmed correctly. If it is not aggressive enough, the engine will be subject to knock with potential catastrophic results. If the retard is too agressive, you are then leaving power on the table. The way we went about precisely tailoring this was by first removing the cooling fans from the intercoolers. We advanced the timing by 4 degrees on the two "noisier" cylinders in order to induce knock during the pulls. We then did consecutive dyno pulls while carefully watching knock displayed live on I2. With each pull we could see the IATs rise by roughly 10F. We started at 100F IAT (our default dyno pull temperature) and ended up near 170F. During the course of each pull we could adjust timing retard to make sure all cylinders stayed under the predetermined threshold at the particular knock frequency that this particular engine produces predominantly. Doing it this way we could made sure the ECU is correctly programmed to keep the engine safe from knock with increasing IATs while at the same time not leaving power on the table.
XR1000 / M150 50-100% throttle map of the 600wtq tune:
10-27-2022, 05:13 PM
