Once again, as Vengeance Racing explains, there doesn’t appear to be any heat soak issue - such a problem wouldn’t make sense anyway, not after all the testing the Z06 has been through and after GM hit the jackpot with just-as-supercharged ZR1 in the past.

It's already known the new Z06 has a potential heat soak issue which started when Motor Trend did their test & noticed Pobst's best time was his first lap because the times got slower and slower. On the 4th lap, the car overheated. Apparently, C&D had a similar issue of their M7 car getting slower after each lap as well. Then you have owners citing a loss of power after 2-4 runs.

So far, only 1 tuner has discovered that the ECU is the potential culprit for causing the car to overheat.

2015 Corvette Z06 Owners Report Heat Soak Power Loss: Actually a Conservative ECU [Updated]

Now that the 2016 Corvette Z06 has hit the streets, sucking our air through its blower, a few owners have complained about experiencing a power loss after back to back runs on the highway or multiple laps on the track. They rushed to point the heat soak finger at the LT4 motor in the Z06, but this doesn’t seem to be the culprit here.

Sure, as the Z06 uses a top-mounted charging hardware, you could expect it to be prone to heat soak issues. When this issue usually appears, after a few consecutive full throttle runs, the heat builds up in the engine compartment, resulting in the a temperature increase for the air charge. This dramatically reduces supercharging efficiency as hot air has reduced oxygen molecule density, allowing for less fuel to be burned.

Moreover, hot intake air charge also increases the risk of detonation. The computer measures the intake air temperature both before and after the charge and when the latter is too high, it starts pulling timing to protect the engine.

However, like we said, this isn’t an issue with the LT4 supercharged V8 in the 2015 Z06, or at least that’s what the tuning scene is reporting.

Aftermarket world explains this is all a conservative ECU setup

Remember Vengeance Racing, the aftermarket developer that did a 1-minute burnout straight out of the showroom when picking up their Z06 last week? The crew started playing with the supercar and obviously came across the same problem.

So far, the guys only did repeated runs on the dyno, where they recorded a rather impressive 20-degree difference between the two aforementioned intake air temperatures. They also performed highway runs, but so far they’ve had 5 to 7 minute breaks between runs to analyze the resulting data and make changes to the ECU. They promissed to take their Z06 out again this week and perform back to back runs, so we’ll have that information soon.

Once again, as Vengeance Racing explains, there doesn’t appear to be any heat soak issue - such a problem wouldn’t make sense anyway, not after all the testing the Z06 has been through and after GM hit the jackpot with just-as-supercharged ZR1 in the past.

In a post on Corvette Forum, the tuner explains the issue lies with the ECU - “With the OE calibration we did experience the same thing... The timing tables are EXTREMELY conservative and the ECU will pull timing for almost any situation. I am waiting for owners to complain about "tip in" as the ECU pulls a massive amount of timing when slightly touching the gas pedal”

We know it sounds convenient for a tuner to say this, but the company claims “most of the loss of power can be addressed in the ECU.” Of course, this may just solve the problem reported by multiple owners, but it will also void the powertrain warranty, not exactly something you want on a $100,000 car, unless you were going to modify it in the first place.

Besides, many now ask themselves what happens once you remove those ECU boundaries. the only problem here is that certain people behave completely different once they’ve modded their car and subsequently complain about reliability issues - such problems would’ve appeared even without the tune, simply due to the change in the driving style.

The LT4 appears to have plenty of unlocked potential

Since the customizer claims the post-intercooler intake air temp is impressive, nobody is quite sure why GM engineers came up with such a conservative ECU tune, with emission regulations being the most plausible reason.

For the record, Vengeance Racing’s 2015 Corvette Z06, a manual, showed 585 hp and 611 lb-ft (828 Nm) of torque at the wheels in stock condition, which are very good values. The LT4 has already proven to be a very capable engine, since the tuner has achieved a hefty output bump with less-than-serious mods. To be more specific, the V8 was taken to 660 RWHP and 663 RWTQ (899 Nm) using only a cold air intake, a smaller upper pulley and, of course, an ECU remap.

We’ve contacted GM to ask them about the reason behind the shy ECU setup and we’ll be back with an update as soon as we have an answer.

Update: GM has responded, explaining the reasons behind the ECU setup reigning over the LT4 V8. To put it shortly, Chevy wants to make sure the Z06 meets emission targets and keeps placing those 650 ponies at the mercy of your right foot for at least 10 years or 100,000 miles (160,000 km), which are the intervals covered by the warranty.

To use the automaker's words: "We are confident that the vast majority of customers are going to be more than satisfied with the performance the Z06 offers in stock form. For those that want more power, they can visit an aftermarket tuner – who are not held to the same standards [emissions and warranty] as an OEM. However, this presents significant risk to the customer. An aftermarket tune voids the vehicle warranty as Chevrolet cannot possibly test or confirm the durability of their calibration; and aftermarket calibrations could cause drivability issues that are not present in the factory setting."

When asked about a possible track tune, that would unlock some extra potential for limited amounts of time, GM said they are not planning such a move.

Basically, GM acts like a father who's giving you a car - it hands you the keys and whether you want to enjoy the supercharged thrills in marathon or sprint mode, the choice is yours. It's just that you must remember to cover your dad's 100 grand pension fund in return, on the spot.

Update: GM has responded, explaining the reasons behind the ECU setup reigning over the LT4 V8. To put it shortly, Chevy wants to make sure the Z06 meets emission targets and keeps placing those 650 ponies at the mercy of your right foot for at least 10 years or 100,000 miles (160,000 km), which are the intervals covered by the warranty.

To use the automaker's words: "We are confident that the vast majority of customers are going to be more than satisfied with the performance the Z06 offers in stock form. For those that want more power, they can visit an aftermarket tuner – who are not held to the same standards [emissions and warranty] as an OEM. However, this presents significant risk to the customer. An aftermarket tune voids the vehicle warranty as Chevrolet cannot possibly test or confirm the durability of their calibration; and aftermarket calibrations could cause drivability issues that are not present in the factory setting."

2015 Corvette C7 Z06 gutless? Heat soak versus "conservative OEM tuning" bullshit

The reports are coming in, the "fastest Corvette ever and most track capable Corvette ever" craps out under high speed acceleration and decreases its power and track performance after literally a few minutes of track duty, IN THE MIDDLE OF WINTER.

So what is going on here? If one listened to aftermarket tuners like LMR and Vengeance Racing (the same idiots who posted a burn out in a car with 5 miles on it, only to be followed with the dyno run to continue with the stupidity), +General Motors decided to be "overly conservative" when setting up tuning for the latest Z06. Furthermore, the same idiots report a "proof" of this conspiracy theory by bringing up the intake air temperature being low during testing, without even realizing how the air temperature monitoring is handled in the Z06.

Of course, since there is no heat soak and apparently ECM and TQM decide to retard the timing and limit available purely as a protective measure that can be easily defeated by already available custom tuning software.

So is there heat soak and is it the heat soak the culprit of gutless Z06? YES, THERE IS HEAT SOAK and considerably more so than with the previous ZR1. Furthermore, the available power reduction is the EFFECT not the cause of the car being so gutless.

Why there is such a drastic difference between LT4 and LS9? Direct injection is the main reason actually. Specifically, the fact that DI maintains very lean a/f ratio due to its efficiency. When heat soak happens, air temperature raises and even though the volume remains the same, the density and oxygen content go down. When this happens, engine becomes very prone to detonation, something that is already well documented on the normally aspirated LT1 engine receiving a "custom tune". Direct injection sets very specific constraints on A/F ratios and it is very easy to introduce detonations in the engine cycle.

When a supercharger is added in the mix (pun intended), things become considerably worse, especially with a small and fast spinning supercharger used on LT4.

Is the +General Motors OEM tune overly conservative? Not at all, it is actually a very optimistic one, attempting to extract maximum performance WITHIN EMISSION and HEAT limits. The simple fact that the ignition timing pulls is a textbook example of GM attempting to save the engine from self destruction, like it already happened with LT1.
+Tadge Juechter should be given a big credit here, creating engine capable of high power output but only after its ECM and TQM are altered to remove safety limits. Should a rod seek daylight through the wall of the block, it is not a GM problem, unless tuner decides to warrant the engine, it will be strictly on the owner of the car stupid enough to rely on aftermarket short term power gain bait. Certainly, a very expensive lesson that is coming soon.