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BEWARE WHEN YOU ORDER THAT CUSTOM TUNE – DYNO OR OTHERWISE! This is an important message to read as it exposes what is likely common practice in the tuning industry – and the consequences could be expensive. Before I begin, a little background: I have a 2012 GT500 that I have modified. Originally the modification was a smaller drive pulley on the supercharger and tune by VMP Performance. The original tune was locked by Justin Starkey of VMP and, although I have SCT’s Advantage software, I was unable to modify the tune (and didn’t need to as the tune seemed to work fine). In November of 2015 I was running the Shelby at Daytona in NASA’s HPDE 3 group. On the first session of the second day, the engine developed a rod knock and I had the car flat-bed towed back to St Petersburg, to the Ford dealer where I bought the car. The dealer did what they could, but in the end, Ford refused to cover the damage, even though the car was still under warranty. Before you immediately dismiss considering that they would even think of covering it since I was running it on the track, they actually initially agreed to cover the damage and then refused based on the fact that I had modified the car. They cited extreme detonation (which was not the case, but was more their way of CYA). What did happen is that the engine oil boiled – vaporized and exited the engine through the PCV system. Only 2 quarts remained in the engine when the dealer tore the engine down. There are many theories as to why the oil boiled (Ford’s theory was that the detonation caused the rings to be forced hard back into the ring lands, allowing the oil to pass and be burned). My theory is that it was a combination of events: The dealership possibly put the wrong oil in the car when I had it changed (they were always pushing the cheaper Penzoil) Ford did a very poor job designing heat extraction from that car, and the back of the engine was exposed to extreme radiant heating in the area proximate to the exhaust down-pipes. The aluminum block afforded great heat transfer resulting in high oil temperatures. Keep in mind the ECT was normal during this entire event. Also, the car was covered in the rear with transmission oil – the transmission had gotten hot enough to also boil its oil, which escaped through the transmission vent hole. The tune was too conservative on timing, resulting in higher EGTs, thereby contributing to the radiant heating Now, fast-forward. After spending $20K to have Livernois repair the block and rebuild it to a short block (Livernois does outstanding work), to have the dealer rebuild it to the long block and re-install it, along with adding a larger oil pan and external oil cooling, I paid a well-known tuner for a custom tune (and this time paid extra to get the SCT source file so I can view how the car was tuned and make adjustments). I also paid the tuner to do a dyno tune so I didn’t have to spend the time tuning-testing-tweaking-tuning the car. The dyno tune lasted about 2 hours and consisted of 3 “pulls” on the dyno. The tune started with a tune from another car as the initial baseline, and some adjustments were made as a result of the 3 pulls. That weekend, I ran the car at Sebring, again in HPDE. The car ran 300+ degree oil temperatures. On one session it threw an engine code (Misfire, cylinder 1). I had complained to the tuner that my AFR gauge was showing a rich condition under WOT, but that was explained away as a faulty AFR gauge and wasn’t addressed properly (in my opinion). The main thing was a significant reduction in power from how the car previously performed – naturally aspirated Mustangs were able to catch me in the straights and the car was at least 15 MPH slower in the back straight than the previous time I had run at Sebring. I lost confidence in the tuner and decided to spend the time tuning the car myself. It took weeks – with up to 12 different tunes tested along with driving/logging – before I finally got the car tuned properly (meaning power has been restored, oil temps are down 20 degrees, detonation is gone, and the fuel curve is correct). I then did a compare, using SCT’s software, between my final tune and the tuner’s “dyno” tune. Below are the salient points: Borderline knock tables (used as a starting point for ignition timing) In the area of low RPM – high engine load the tuner had the timing set to 1 degree advance. This resulted in detonation. My final tune has up to 9 degrees retard at the highest load/lowest-RPM point. In the area of low engine load the tuner was very conservative on timing, resulting in sacrificed power (and increased exhaust temperatures). Up to 10 degrees of timing was added resulting in much better low end torque (with no detonation) Even in the mid-range of RPM/load the tuner left up to 6 degrees of timing off the table, again resulting in increased exhaust temperatures and sacrificing of power. The tuner had set the Y-normalizer table to essentially lock the entire range of operation to just a few rows of the table. This seemed to me to be a quick fix – instead of tuning for various RPM-load points. MBT timing table (used as the reference for the best engine timing as determined by the MFR) Much of the table had been scaled back (timing removed) from stock. This made no sense to me as the MBT table is the reference for the maximum timing to demand (theoretically, since MBT represents the best timing in an otherwise perfect world, there should be no reason to change these tables from stock). The MFR most likely spent hundreds hours of test in determining these values. I put the table back to stock values. The tuner disabled clutch protection. This may be desirable for launching hard in drag races, but I had told him I road race the car so launching hard is not an issue. I re-enabled it and put the settings back to stock. I suspect the settings were from a previous tune that was used as the basis for this tune, and were overlooked. The tuner turned off 16 different code switches, essentially disabling the PCM from reporting those diagnostic codes. Such codes as P0175 and 74 (reporting rich conditions). This is, in my mind, one of the most egregious and unprofessional (by engineering standards) things done. I can think of no reason to do this other than to prevent the tune recipient from subsequently calling up and asking for the tune to be fixed because the car is now throwing a check-engine code. This eliminates that from happening but leaves the unsuspecting customer open for possible engine-damaging scenarios that now go unreported. Knock sensor When I was with the tuner during dyno tuning, he said he didn’t trust the knock sensors on my car and, although he did not disable them, he severely limited their operation by entering the maximum retard as 1 degree. I experienced detonation almost immediately upon running the car and changed the max retard to 10 degrees (stock is 6). I also confirmed, through running the car on the street while data logging (1 driver, 1 logger) that the knock sensors work well – that they do indeed show knock when there is audible detonation. Spark retard for ACT and ECT The tuner was conservative in these tables as well – pulling out up to 10 degrees for ACT values of 160 degrees. I did a calculation of expected ACT using Corky Bell’s book called Supercharged (I highly recommend it) and pulled out less timing. While this is a bit of a nit, I point this out as the final timing number is a function of borderline knock, MBT, ACT, and ECT tables (as well as anything the knock sensors might be doing) Anyway, what I feel was done is whatever was necessary to get me off that dyno quickly. The tuner assumed I did not know anything. I did not witness any dialing in of the MAF transfer function – especially in the high load range (at the tuner’s suggestion, I put an ATI 10% overdrive pulley on the engine which brought the boost up to 15 lbs, and I suspect the MAF transfer function was not correct in that range of boost and resulted in higher reading of air ingested than was really entering the engine, resulting in over-fueling.) I also did not witness tuning at various load points – just three full throttle pulls (with data logging). As an engineer, I can’t see how you can properly tune a car without studying it’s performance at various RPM/load points. This may be isolated or it may be standard operating procedure in the tuning industry. Beware if it’s the latter! As I mentioned, this tuner is well known and you will find his advertising in all major car magazines. About me – I have a BS and MS in electrical engineering and I have designed hardware and software for control systems (like a PCM) – so I find the PCM’s operation and the control tables to be intuitive. I have also worked on cars for over 40 years. I am also a member of Mensa. What I don’t have – and what I thought I was paying for – is the “tribal knowledge” that comes from doing this for a living. What I got instead, in my mind, is a quickly thrown together tune that did not result from proper engineering discipline – one that caused the car to run poorly and possibly contribute to the high oil temperatures that caused the original failure. If anyone is interested, I will be happy to share the SCT comparison file between the two tunes. Oh, and by the way, while I’m on the subject of superchargers (again I highly recommend Corky Bell’s book), I see much on the forums about Eaton’s TVS-style roots blowers – comparing them to other blowers and claiming superiority due to flow rate. The real thing that should be compared is thermal efficiency – how much heat will it produce meaning how much intercooling will be required and/or how much timing will have to be pulled out to stop detonation. Roots style blowers – or any blower that does not have an internal compression ratio (meaning they just move air from one side to the other) – have the worst thermal efficiencies. That’s because the compression of the air happens on the output side of the supercharger – so that’s where the heat is added – with limited chance to dissipate prior to the intercooler. Twin screws are superior for thermal efficiency because the compression happens between the screws, allowing the body of the supercharger to help in dissipating the heat before it reaches the intercooler. More expensive but they will allow higher levels of boost without detonation. PV=nRT – pressure goes up and volume and air mass stay the same means the temperature has to go up. Could be TVS has better thermal efficiency than previous roots designs, but it is still a roots-style blower (meaning no internal compression ratio).