Conservative ECU Tuning Causing Power Loss On 2015 Chevrolet Corvette Z06

[LTC8K6]

Interesting info about GM ecu tuning...

Some Z06 owners have reported that they’re experiencing a power loss in their cars after running multiple laps on a track or back-to-back acceleration runs on the highway. This led many to believe that the Z06’s 6.2-liter LT4 V-8 may be losing power due to supercharger heat soak, but it turns out that the culprit is actually conservative ECU tuning.

the conservative ECU tuning is necessary to ensure emissions targets are met as well as the preservation of the powertrain over the life of the car

https://autos.yahoo.com/news/conser...sing-power-loss-2015-chevrolet-135005851.html

 

[Fenixgoon]

preservation of the powertrain over the life of the car

emissions be damned, i'd be more worried about powertrain life.

 

[thescreensavers]

a GM spokesman said in a statement. “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.”

Emissions is a bitch to any performance car...

Like my stock WRX runs lean well into boost almost at peak torque which can cause knock which = eek

 

[Wuzup101]

Emissions is a bitch to any performance car...

Like my stock WRX runs lean well into boost almost at peak torque which can cause knock which = eek

They could be trying to increase EGT a bit during spool to speed up the gas flow (via thermal expansion). Still looks pretty lean though lol...

 

[JCH13]

Emissions is a bitch to any performance car...

Like my stock WRX runs lean well into boost almost at peak torque which can cause knock which = eek

They could be trying to increase EGT a bit during spool to speed up the gas flow (via thermal expansion). Still looks pretty lean though lol...

Uh... it starts at 14.7:1 and goes down... assuming you're running normal gasoline you're at stoich and then rich. It might be leaner than you think it should be... but it's not a 'lean' burn. I'm sure Subaru knows how to tune a turbo engine.

 

[Wuzup101]

Uh... it starts at 14.7:1 and goes down... assuming you're running normal gasoline you're at stoich and then rich. It might be leaner than you think it should be... but it's not a 'lean' burn. I'm sure Subaru knows how to tune a turbo engine.

Sorry - I mean "lean" in the relative sense as compared to the plot done by Cobb (just stated poorly). My point was that they do know how to tune the engine from the factory and you don't need to be running an AFR of 11:1 on any factory engine during spool. I'm just used to seeing a richer fuel mixture than 14:1 during spool. I've never seen that on a factory graph before.

 

[Elganja]

aftermarket tuning will solve all of this

 

[Ferzerp]

That asserts that there is something to "solve"

What you have is a ton of internet hype from a single youtube video of two idiots trying to make a name for themselves. I say they are idiots because they are both street racing, and also because they are straight line racing cars built for cornering. For a race that, at best, can be considered a driver's race, there sure has been an awful lot of unfounded speculation. With the sheer amount of marketing these guys are doing over their little video, I begin to wonder what their real motivation is.

 

[darkswordsman17]

That asserts that there is something to "solve"

What you have is a ton of internet hype from a single youtube video of two idiots trying to make a name for themselves. I say they are idiots because they are both street racing, and also because they are straight line racing cars built for cornering. For a race that, at best, can be considered a driver's race, there sure has been an awful lot of unfounded speculation. With the sheer amount of marketing these guys are doing over their little video, I begin to wonder what their real motivation is.

GM's response seems to be validating this though.

What? You're right, no one ever drag races Corvettes and Vipers. 😵 At least I'm assuming that's what you're talking about.

I certainly wouldn't put it past GM to be putting versions with less restrictive ECU tunes in journalists hands, whereas they'd have to sell a certain version. With the rumors about the Hellcat having trouble with emissions I wouldn't be shocked to find Dodge is doing the same thing. Actually I wouldn't be surprised if this is very common (thinking of the GTR launch control for instance, and I know there's been a lot of complaints about the lengths Ferrari goes to with their media testing).

If you're buying a performance car and they have to limit its performance after a short period of hard running then they should have to disclose that openly.

 

[Ferzerp]

GM's response seems to be validating this though.

Not really. There is nothing to indicate that any protection in place on this engine is any more than any other engine. Nor does the little GM blurb indicate this. The same stories were present on my last FI car as well. Never managed to replicate it at the track (did manage to boil the stock brake fluid, but that was easy to take care of).

People look for drama. People manufacture drama. That from one youtube video people managed to manufacture this particular drama is pretty good evidence that I am right.

 

[Wuzup101]

Not really. There is nothing to indicate that any protection in place on this engine is any more than any other engine. Nor does the little GM blurb indicate this. The same stories were present on my last FI car as well. Never managed to replicate it at the track (did manage to boil the stock brake fluid, but that was easy to take care of).

People look for drama. People manufacture drama. That from one youtube video people managed to manufacture this particular drama is pretty good evidence that I am right.

This is what I don't get. You could replace "corvette Z06" with nearly any other performance car built in the last 20+ years in that linked article and it would fit.

This just in: automakers don't tune their performance cars for 100% performance and instead have to balance emissions, fuel economy, and reliability.... more at 11.

 

[LTC8K6]

Well, the power loss seems to be fairly widely reported, so I don't think it's a fluke.

Vengeance Racing took delivery of a Z06 last week and says it doesn’t believe the problem is a heat soak issue. In fact, in a post on Corvette Forum, the tuner says it experienced the same power loss with the OE calibration.

“The timing tables are EXTREMELY conservative and the ECU will pull timing for almost any situation,” Vengeance wrote in the post. “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.”

While that explanation sounds good on paper, if I had just handed out $100 grand for a powerful Z06, I think I’d want to be able to drive it as much on the track as I wanted – without having to worry about any such power loss.

http://www.corvetteblogger.com/2014...ible-for-power-loss-on-the-2015-corvette-z06/

 

[Wuzup101]

Well, the power loss seems to be fairly widely reported, so I don't think it's a fluke.



http://www.corvetteblogger.com/2014...ible-for-power-loss-on-the-2015-corvette-z06/

A quote from Ron @ Vengeance:

ANYONE who cancels/declines their order over one video on the internet is a FOOL.... There is no DATA/no FACTUAL information other than a 3524lb C7 Z06 lost to a 3390lb Naturally aspirated Gen V Viper....

Naturally aspirated power is always faster... The C7Z is heavier... These aren't excuses, they are facts. That does not change the fact the C7 Z06 is amazing in every aspect.

I owned and loved a 2013 Grand Sport, but I am here to tell you the C7 Z06 is an entirely different level supercar...

http://www.corvetteforum.com/forums...ok-so-who-s-going-to-decline-their-order.html

Still haven't actually seen any data showing that the car is pulling an absurd amount of power to protect the engine. I'd love to see some hot dyno tests showing that it's dropping 100rwhp or something absurd. Please link if you do find anything.

Vengeance themselves seemed to be surprised how much power the car put out on the dyno. The only thing that seems to be widely reported is copies of that story you linked and that it lost to a viper during some roll racing... which wasn't entirely surprising given the weight/power of the cars.

Edit: hot dyno test:

This Z06 produced power figures of 572 horsepower and 589 pound-feet of torque at the rear wheels. According to High Tech Corvette, their dyno was calibrated based on a number of factors including weight and weather. Additionally, the engine was running hot to account for real-world driving conditions. Per their YouTube video, this method of testing produces the truest results to what a driver can actually expect.

Going with that standard 15% powertrain loss, this would put the High Tech Corvette numbers at 658 horsepower and 677 pound-feet of torque at the crank. That's closer to the General's numbers but still greater than advertised... and that's a wonderful thing.

https://autos.yahoo.com/news/another-c7-corvette-z06-hits-dyno-posts-strong-171720515.html

 

[LTC8K6]

Disregard the video.

People have been noticing a loss of power. They have been blaming it on heat soak. But testing shows that it can't be heat soak, as temps are not that high. So it has to be something else.

 

[LTC8K6]

People are comparing it to the Hellcat, which apparently never quits making all it's power.

I wouldn't know whether it's normal or not to lose power after a couple of hot laps.

Car and Driver did write this about the Hellcat:

Pushing just a tad harder reveals plenty of power in reserve and a competent chassis to handle it, so somewhere north of 150 we do the only sensible thing and switch on the A/C and ventilated seat. Four laps later, the temperature gauge hasn’t budged.

 

[Ferzerp]

People have been noticing a loss of power

The "people" you refer to are all relaying what they have "heard". If you can find this rash of primary sources that you claim exist, by all means do so, but as someone who follows information on this car closely, I will say again, it all traces back to the single source.

It's the old repeat the same thing often enough and people accept it as fact thing.

 

[Wuzup101]

Yeah - I'm trying to find the primary source of the info which is surprisingly hard. I expect that there is someone somewhere that tortured it on the dyno or what not and kept seeing the output drop... or did the same thing over repeated passes at a rented out drag strip where they could run back to back. All I've found thus far is viper video, and people rehashing the article you linked (which just says that the tune is conservative - which is no surprise).

I'm not trying to be argumentative. But as a c7 owner and someone that has some interest in getting a Z sooner or later... I'd love some good reading.

 

[Ferzerp]

Yeah - I'm trying to find the primary source of the info which is surprisingly hard. I expect that there is someone somewhere that tortured it on the dyno or what not and kept seeing the output drop... or did the same thing over repeated passes at a rented out drag strip where they could run back to back. All I've found thus far is viper video, and people rehashing the article you linked (which just says that the tune is conservative - which is no surprise).

I'm not trying to be argumentative. But as a c7 owner and someone that has some interest in getting a Z sooner or later... I'd love some good reading.

None of the dyno folk ever mentioned power loss. It all goes back to the silly idiots and their street racing. That said, the same "people" will tell you it loses massive amounts of power on repeated dyno measurements. No one actually can produce a reference though 😉

 

[LTC8K6]

The "people" you refer to are all relaying what they have "heard". If you can find this rash of primary sources that you claim exist, by all means do so, but as someone who follows information on this car closely, I will say again, it all traces back to the single source.

It's the old repeat the same thing often enough and people accept it as fact thing.

I don't get that impression, but I guess we will see.

 

[Ferzerp]

I don't get that impression, but I guess we will see.

Then obviously you will be able to provide us with some primary sources that aren't a youtube video of some people street racing. 😉

Otherwise you're just repeating what someone else heard someone repeat, etc, etc.

 

[LTC8K6]

Then obviously you will be able to provide us with some primary sources that aren't a youtube video of some people street racing. 😉

Otherwise you're just repeating what someone else heard someone repeat, etc, etc.

If it's a real problem on some Corvettes, I won't need to provide anything. 😀