[Mr. Wyndham]

Originally Posted by TJay74

Says who, did a GM engineer from the Alpha project actually say this? I have dealt with the head engineer over the 2014+ GM truck line now for the last 3 years, if it wasn't for the fact I would feel out of line I would ask him to forward my info over to the chief engineer over the Camaro team just to pose this very question.

That article was from Hot Rod, not from GM. Until a reputable GM source comes out to say that "XYZ is going to happen if ABC is done" then I am going to take a magazine article with a grain of salt.

Otherwise what is keeping all of the I4 / V6 Camaro's on the road and stable when they get over 60mph???

Says the lead aerodynamic engineer for the car. And says the lead project engineer. Both in discussions I was a part of that were not published.

The car has extensive aerodynamic design implemented. If you doubt that because a magazine parroted the info (that's all they do, nowadays, as the vehicle development teams prepare power point presentations and physical demos to go over vehicle features) - that's your prerogative. But frankly, it's not doing you any favors in terms of understanding this car.

For the record, I'm not in the business of trying to convince anybody of anything. And I certainly don't post for an ego boost...it's all just friendly sharing, because I have the pleasure and honor of a friendly relationship with folks on the Camaro team. I have also found, over time, that have a technical aptitude for these topics, and can often times disseminate the info for forum readers.

So...if/when I have information to share with the community that might be of interest...I do. Simple as that.

But if you've asked - I'd be happy to attempt an answer: As far as the LT and SS models. You're misunderstanding the facts as they've been presented.

Here's the TL/DR version: The statement that the ZL1 is stable at speed...does not mean that the LT cars are not. It IS, however, a difference of intensity, and different speed ranges.

Read on for the full explanation:

Fluid Dynamics is a large field of study, and the engineers and designers that work on these cars deal with more than just "drag" and "downforce" as it is presented in the sound bytes in motorsports. I do not understand the field in a capacity that I can effectively engineer a precision spoiler for F1 or something like that. A good deal of the field is still theory-based. It's possibly more complicated than powertrain engineering in that respect.

All mainstream road-legal cars generate lift. ALL of them. In general, this provides better fuel economy to the multitudes of cars that are on the road. However, it also can create instability at speed. Try taking a Cobalt or early Focus down the road at 90+mph, and you'll feel the steering get light and twitchy as the front end of the car begins to "weigh" less due to the lift generated as it goes through the air. But since those cars are rarely driven at those speeds for extended periods of time, it is inconsequential as a design and engineering consideration.

However, sports cars like Camaro will often reach those speeds. Either illegally on the road, or at a motorsports event, as so often sporty cars are marketed for lately.

The key to high speed stability isn't downforce...it's control: Control over the air as it flows over, along, and underneath a vehicle will allow a vehicle development team to tailor the car's fuel economy, cooling, high speed stability, and of course top speed. The slightest feature change could dramatically affect the overall performance of the vehicle as it moves through the air. So designing the aerodynamic properties of any car becomes a balancing act to achieve its desired purpose.

This is why ALL Camaros have underbelly pans, closeout panels, and even why the mufflers seems so big (they direct air out from under the car).

Now. At 60mph...no car is going to be unstable (unless it's built by a sub-par company in a mossy factory somewhere). The LT cars are going to do fine even up to 120+. That's not the point, though.

The point...is that the faster cars in the Camaro family are more stable because of their spoilers/splitters/aerodynamic features.

You will find that the SS was designed differently from the LT cars to allow it to reach even higher speeds safe and stable. They achieve this stability by reducing lift. It is likely that the LT cars (if modified for power) can reach 175 as well...but the SS will feel more stable at that speed, I'd bet anything. The truth is that the shapes and looks of the cars as they get faster are driven by function, and the design folks ply their trade at making the functional bits look good, too.

The 1LE was modified more, to increase stability at "lower" high speeds over the SS. This is why they added spoilers and splitters. *NOT* just for looks. Essentially the effect is to reduce lift further than the standard SS improvements did at lower speeds than the SS did. So when you're on track and throwing the car around a bend at 80, it'll stick better than the SS would in the same situation.

The ZL1 has the most extensive aerodynamicaly-driven design that we've seen on a Camaro to date. For example:

• They discovered that the thickness of the material in the grill pattern (from front to back) was increasing drag and turbulence on the airflow into the heat exchangers. So they thinned it out, and increased cooling capacity by doing so.
• The entire bumper cover panel was sculpted to be aerodynamically "invisible" so the fact that there is a blunt object in the path of air flow...effectively doesn't matter. You could remove the bumper bar altogether and there wouldn't be as huge of a benefit as you'd think.
• There are two sets of "strakes" under the splitter in front of the rear wheels to forcibly direct air where they want it to go, to reduce turbulence in front of the tires, and evacuate some air before it even gets under the car.
• The closeout panel over the transmission fluid cooler is slanted at an intentional angle, like the nose of a concord jet, and perforated at the back to "draw out" air, similar to the way a NACA duct function, this actually increases air flow through that transmission cooler without increasing drag or lift at all.
• The heat extractor on the hood is the most functional design they've come up with since the first hood vent on the 2012 ZL1, and dramatically helps reduce lift...not just for lower temperatures. (which, by the way, was originally supposed to look like a ram air duct similar to the Dodge Demon)
• The chutes and air dams inside of the front fascia are all precisely controlling the flow of air into the heat exchangers for increased cooling efficiency, and reduced counts of lift.

Now...if they put as much thought and effort into those things (and many, many more) do you think they'd just slap a spoiler on the back if it didn't work with the rest of the body's aerodynamics precisely as they want it to?

Fact is - the ZL1 will further reduce lift, and perhaps generate positive downforce (no numbers have been released to that end)...it will do it better than even a 1LE, and all components of the car are necessary to achieve that.

What will happen if you change part A or B? No idea - they probably haven't testing the combination. But you can bet that AT SPEED (I'm talking about the track)...it will negatively affect the balance of the car as it goes through corners**. One only has to look at the reports of the wicker bill on the 2014-15 Z/28...you're able to put up a measurably faster lap time with just that flat piece of metal bolted to the back of the car...At no point, though, have I suggested that changing the spoiler on the ZL1 will make is spin into a ditch, nor will I be so arrogant as to attempt to tell anyone what to do with their car: it's yours, do what you want!

**The only exception to this rule is modifications that were designed and tested, sold, and installed with the sole purpose of further reducing lift, drag, or increasing downforce. Most aftermarket parts are not; props to those that are.

On the highway? Around town? The car will just not be as good as how it was designed. How much less good will it be? Depends...you'd have to stick it in a wind tunnel and spend several hundred hours figuring it out.

[Sven59]

Originally Posted by Mr. Wyndham

Says the lead aerodynamic engineer for the car. And says the lead project engineer. Both in discussions I was a part of that were not published.

The car has extensive aerodynamic design implemented. If you doubt that because a magazine parroted the info (that's all they do, nowadays, as the vehicle development teams prepare power point presentations and physical demos to go over vehicle features) - that's your prerogative. But frankly, it's not doing you any favors in terms of understanding this car.

For the record, I'm not in the business of trying to convince anybody of anything. And I certainly don't post for an ego boost...it's all just friendly sharing, because I have the pleasure and honor of a friendly relationship with folks on the Camaro team. I have also found, over time, that have a technical aptitude for these topics, and can often times disseminate the info for forum readers.

So...if/when I have information to share with the community that might be of interest...I do. Simple as that.

But if you've asked - I'd be happy to attempt an answer: As far as the LT and SS models. You're misunderstanding the facts as they've been presented.

Here's the TL/DR version: The statement that the ZL1 is stable at speed...does not mean that the LT cars are not. It IS, however, a difference of intensity, and different speed ranges.

Read on for the full explanation:

Fluid Dynamics is a large field of study, and the engineers and designers that work on these cars deal with more than just "drag" and "downforce" as it is presented in the sound bytes in motorsports. I do not understand the field in a capacity that I can effectively engineer a precision spoiler for F1 or something like that. A good deal of the field is still theory-based. It's possibly more complicated than powertrain engineering in that respect.

All mainstream road-legal cars generate lift. ALL of them. In general, this provides better fuel economy to the multitudes of cars that are on the road. However, it also can create instability at speed. Try taking a Cobalt or early Focus down the road at 90+mph, and you'll feel the steering get light and twitchy as the front end of the car begins to "weigh" less due to the lift generated as it goes through the air. But since those cars are rarely driven at those speeds for extended periods of time, it is inconsequential as a design and engineering consideration.

However, sports cars like Camaro will often reach those speeds. Either illegally on the road, or at a motorsports event, as so often sporty cars are marketed for lately.

The key to high speed stability isn't downforce...it's control: Control over the air as it flows over, along, and underneath a vehicle will allow a vehicle development team to tailor the car's fuel economy, cooling, high speed stability, and of course top speed. The slightest feature change could dramatically affect the overall performance of the vehicle as it moves through the air. So designing the aerodynamic properties of any car becomes a balancing act to achieve its desired purpose.

This is why ALL Camaros have underbelly pans, closeout panels, and even why the mufflers seems so big (they direct air out from under the car).

Now. At 60mph...no car is going to be unstable (unless it's built by a sub-par company in a mossy factory somewhere). The LT cars are going to do fine even up to 120+. That's not the point, though.

The point...is that the faster cars in the Camaro family are more stable because of their spoilers/splitters/aerodynamic features.

You will find that the SS was designed differently from the LT cars to allow it to reach even higher speeds safe and stable. They achieve this stability by reducing lift. It is likely that the LT cars (if modified for power) can reach 175 as well...but the SS will feel more stable at that speed, I'd bet anything. The truth is that the shapes and looks of the cars as they get faster are driven by function, and the design folks ply their trade at making the functional bits look good, too.

The 1LE was modified more, to increase stability at "lower" high speeds over the SS. This is why they added spoilers and splitters. *NOT* just for looks. Essentially the effect is to reduce lift further than the standard SS improvements did at lower speeds than the SS did. So when you're on track and throwing the car around a bend at 80, it'll stick better than the SS would in the same situation.

The ZL1 has the most extensive aerodynamicaly-driven design that we've seen on a Camaro to date. For example:

• They discovered that the thickness of the material in the grill pattern (from front to back) was increasing drag and turbulence on the airflow into the heat exchangers. So they thinned it out, and increased cooling capacity by doing so.
• The entire bumper cover panel was sculpted to be aerodynamically "invisible" so the fact that there is a blunt object in the path of air flow...effectively doesn't matter. You could remove the bumper bar altogether and there wouldn't be as huge of a benefit as you'd think.
• There are two sets of "strakes" under the splitter in front of the rear wheels to forcibly direct air where they want it to go, to reduce turbulence in front of the tires, and evacuate some air before it even gets under the car.
• The closeout panel over the transmission fluid cooler is slanted at an intentional angle, like the nose of a concord jet, and perforated at the back to "draw out" air, similar to the way a NACA duct function, this actually increases air flow through that transmission cooler without increasing drag or lift at all.
• The heat extractor on the hood is the most functional design they've come up with since the first hood vent on the 2012 ZL1, and dramatically helps reduce lift...not just for lower temperatures. (which, by the way, was originally supposed to look like a ram air duct similar to the Dodge Demon)
• The chutes and air dams inside of the front fascia are all precisely controlling the flow of air into the heat exchangers for increased cooling efficiency, and reduced counts of lift.

Now...if they put as much thought and effort into those things (and many, many more) do you think they'd just slap a spoiler on the back if it didn't work with the rest of the body's aerodynamics precisely as they want it to?

Fact is - the ZL1 will further reduce lift, and perhaps generate positive downforce (no numbers have been released to that end)...it will do it better than even a 1LE, and all components of the car are necessary to achieve that.

What will happen if you change part A or B? No idea - they probably haven't testing the combination. But you can bet that AT SPEED (I'm talking about the track)...it will negatively affect the balance of the car as it goes through corners**. One only has to look at the reports of the wicker bill on the 2014-15 Z/28...you're able to put up a measurably faster lap time with just that flat piece of metal bolted to the back of the car...At no point, though, have I suggested that changing the spoiler on the ZL1 will make is spin into a ditch, nor will I be so arrogant as to attempt to tell anyone what to do with their car: it's yours, do what you want!

**The only exception to this rule is modifications that were designed and tested, sold, and installed with the sole purpose of further reducing lift, drag, or increasing downforce. Most aftermarket parts are not; props to those that are.

On the highway? Around town? The car will just not be as good as how it was designed. How much less good will it be? Depends...you'd have to stick it in a wind tunnel and spend several hundred hours figuring it out.

[17CamaroZL1]

Originally Posted by Squatch

I still have my doubts this wing on the '17 ZL1 does anything at any speed, (I never believe a magazine either, they just market stuff) its just too low to the car, and its in the turbulent air from the downslope of the rear window. Looking at the wing on the GT4, that is a truly functional appliance, (although bit exaggerated for a DD car), its in clean unmolested air.
Just my 2 cents, Ill leave the stock wing on the car when I buy one in 2019, but might change it to a black or carbon fiber one for looks.

Downforce would likely increase if the wing was raised higher like you said, but a wing or spoiler doesn't have to be high up in the air to create downforce. Nascar spoilers are a perfect example of that. They are down on the deck lid and slight changes in rake, height, or width can make or break the handling of the car at the limit. GM increased the front to rear size and the width of the wing to increase downforce for better balance after adding the front splitter.

Originally Posted by TJay74

Says who, did a GM engineer from the Alpha project actually say this? I have dealt with the head engineer over the 2014+ GM truck line now for the last 3 years, if it wasn't for the fact I would feel out of line I would ask him to forward my info over to the chief engineer over the Camaro team just to pose this very question.

That article was from Hot Rod, not from GM. Until a reputable GM source comes out to say that "XYZ is going to happen if ABC is done" then I am going to take a magazine article with a grain of salt.

Otherwise what is keeping all of the I4 / V6 Camaro's on the road and stable when they get over 60mph???

I do remember a video somewhere along the way where someone from GM made mention of widening the wing to increase rear downforce. Widening the wing put more of its surface area out in clean air over top of the rear quarter panels.

I don't think anyone said the car would be out of control over 60. Just that at 60 and above, downforce on the wing counters the lift being produced by the body, therefore keeping the rear planted. This is mainly going to show benefits when driving at or near the limit around curves or very high speeds on straights, especially over humps and bumps.

[G Fo12ce]

Originally Posted by Mr. Wyndham

[*]There are two sets of "strakes" under the splitter in front of the rear wheels to forcibly direct air where they want it to go, to reduce turbulence in front of the tires, and evacuate some air before it even gets under the car.

It would be cool if these companies like C7 Carbon who are copying the ZL1 sides incorporated these. Probably wishful thinking.

[TJay74]

Well we will maybe have an in depth answer soon then. I went ahead and spoke with my contact and he put me in contact with the Chief engineer over the Camaro program.

Point is, for the average driver they can change the spoiler out and be just fine.

More so since the article just came out in regards to the ZL1 / 1LE that will be release in limited numbers that is faster than the current ZL1 around the GM proving grounds track.

[Sven59]

Originally Posted by TJay74

Well we will maybe have an in depth answer soon then. I went ahead and spoke with my contact and he put me in contact with the Chief engineer over the Camaro program.

Point is, for the average driver they can change the spoiler out and be just fine.

More so since the article just came out in regards to the ZL1 / 1LE that will be release in limited numbers that is faster than the current ZL1 around the GM proving grounds track.

So, Mr. Wyndham's answer wasn't in-depth enough for you. Why don't you just get a hold of the President of GM.

[LT4Greg]

If a person that buys a ZL1 wants to change the spoiler out for a different one then it would be a personal preference IMO. But if I was fortunate to afford one I damn sure wouldn't change it!!

[Blown67]

Originally Posted by Squatch

I still have my doubts this wing on the '17 ZL1 does anything at any speed, (I never believe a magazine either, they just market stuff) its just too low to the car, and its in the turbulent air from the downslope of the rear window. Looking at the wing on the GT4, that is a truly functional appliance, (although bit exaggerated for a DD car), its in clean unmolested air.
Just my 2 cents, Ill leave the stock wing on the car when I buy one in 2019, but might change it to a black or carbon fiber one for looks.

There's not much turbulent air behind a rear window like that. Should be mostly a laminar flow. The turbulent air would be right behind the rear bumper if not diffused correctly, that's where the low pressure will be. Bernoulli's principle, and I'd be willing to bet that this particular spoiler is more effective close to the decklid than raised up.

[TJay74]

Originally Posted by Sven59

So, Mr. Wyndham's answer wasn't in-depth enough for you. Why don't you just get a hold of the President of GM.

While Wyndham's response was detailed and very technical and I am not doubting the source, the concensus he and others are making is that the ZL1 based on the Hot Rod info and info from his GM sources sounds like it will become a un-driveable vehicle. While that is not the exact words, that is the push that comes out to a person who wants to change the spoiler out.

In his defense though the same thing comes out in the 1LE forum of the owners who want to make changes and or add a supercharger to a SS 1LE, people act like the vehicle will be reduced to a un-driveable vehicle at that point.

I mean I know that I am young, but 42 isn't that young these days and I have been modifying cars since 1990 following along in the foot steps of my father just like many of us.

The whole thing still flows back to the OP and any other ZL1 owner who wants to change that spoiler out to the 1LE spoiler. If used for daily driving I can bet the car will be just fine, if anything else a person really needs to worry more about tire temps and waiting for the tires to warm up before they have fun in their car.

At the end of the day I am a enthusiast, I enjoy the cars and love the leaps and bounds that the new tech is proving us each year.

[Sven59]

I don't remember anyone saying it would be undriveable. Just that at about 60 mph it does have some effect on the cars aero, at that speed I am sure it would be minor but start to feel the effects as you go over 100 mph.

[Mr. Wyndham]

Originally Posted by TJay74

While Wyndham's response was detailed and very technical and I am not doubting the source, the concensus he and others are making is that the ZL1 based on the Hot Rod info and info from his GM sources sounds like it will become a un-driveable vehicle. While that is not the exact words, that is the push that comes out to a person who wants to change the spoiler out.

I never said, nor insinuated that. There's a fine line, here, I think is being misread.

I read the rest of your post, can I ask - have you ever been to a road course with any of the cars you've worked on? Any of the late model "track ready" Camaros? My intention is not to patronize or be critical...perhaps I can restate things.

[tbrennyZL1]

I'm sure they just found the ZL1 wing to be more optimal then a blade style. They were able to create more downforce, so more speed into and out of corners without sacrificing straight line speed. And now they have the new ZL1 1LE which has an even higher wing for more downforce creating faster corning speeds, and for the majority of tracks leads to faster laps. I bet in straight line though a standard ZL1 will be faster due to less drag, very similarly the stage 1 Z06 is faster in straight then the Z06 w/Z07 package. In the real world I doubt changing to a blade spoiler would affect 0-60, 1/4 and straight line stuff, but it would become slower on a track and when lateral G kicks in. I think soon enough active aero (specifically spoilers) will be introduced on many of these cars to provide the best combination possible.

[TJay74]

Originally Posted by Mr. Wyndham

I never said, nor insinuated that. There's a fine line, here, I think is being misread.

I read the rest of your post, can I ask - have you ever been to a road course with any of the cars you've worked on? Any of the late model "track ready" Camaros? My intention is not to patronize or be critical...perhaps I can restate things.

My time on a road course was limited to a 1000cc sportbike, though the plan is to eventually get the 1LE out there this year.

That is where we stray though from the OP request and where I chimed in on the fact that for most of the 80% of the owners who will only daily drive their ZL1's that they wont notice the change in the spoilers.

I am not disputing or doubting the track benefit of the data. I know GM all to well, I know their engineering group spent the time making sure the car is thoroughly sorted out as they are out to prove a point and a very bold one. That GM can make a car (several actually) that can and will hang will anything domestic and up to and including some exotics and make them work to not see the tail lights of the new Camaro's.

[Infern0]

Originally Posted by TJay74

That is where we stray though from the OP request and where I chimed in on the fact that for most of the 80% of the owners who will only daily drive their ZL1's that they wont notice the change in the spoilers.

I am not disputing or doubting the track benefit of the data.

If you change ANY part on ANY car, you are modifying some aspect of the reason it was put there in the first place. Sometimes for the better, sometimes to the detriment. That doesn't always matter.

This can be summed up in video game terms. I'm sure you've played racers, or shooters, where changing parts will sometimes have positive and negative affects to multiple attribute categories. Better suspension may increase cornering, but will be heavier and reduce top speed...for example.

As far as 80% not noticing, I don't think anyone disagrees with that point. I think you're right. The point that is being made is with this specific car and spoiler, it was designed, and proven to begin having a benefit, whether perceivable or otherwise, or whether it was even needed at that point, at around the 60MPH and above, on or off the track (it starts doing spoiler things at this speed because of science - not opinions). Changing the spoiler will reduce/remove that benefit and those that weren't aware of it before will not likely be aware that it's gone - as you said, because they aren't in a performance competition.

What hasn't been said is that while the aftermarket spoiler some will add for looks may actually have improved downforce capabilities (by accident or design), but may not reduce the drag coefficient as much as the stock spoiler did. Doesn't mean the car is un-driveable or that it will be noticed. It's just a fact.

Let's put it in different terms for analogous purposes only. Assume the tires were specifically chosen to perform better at higher speeds. Assume this was also proven by scientific research and supporting data. If someone decides to change their tires and rims to something that wasn't designed for the same purposes, they've lost that benefit. Doesn't mean their car is now un-drivable, or can't handle 60MPH+ speeds. Though, at 60MPH they MAY have also had more grip just by virtue of how they were designed.

I think people are overthinking this a little too much.