2015 z06??
07-17-2013, 01:24 PM
#61
Burning Brakes
I think the C7 Z06 will be lightened chassis (fixed roof, more use of carbon fiber, etc) and use a non-AFM version of the LT1 that will give more power and lighter weight (drivetrain). The AFM system alone adds at least 50 lbs to car and limits power. Also, they may revise 7sp gear ratios for more performance.
07-17-2013, 01:38 PM
#62
I think the C7 Z06 will be lightened chassis (fixed roof, more use of carbon fiber, etc) and use a non-AFM version of the LT1 that will give more power and lighter weight (drivetrain). The AFM system alone adds at least 50 lbs to car and limits power. Also, they may revise 7sp gear ratios for more performance.
07-17-2013, 04:20 PM
#63
Le Mans Master
Member Since: Jul 2009
Location: Los Angeles California
Posts: 9,526
Likes: 0
Received 10 Likes
on
10 Posts
The ZR1 has greater output and different gearing. As I said I would love to see a high output NA variant, but I doubt it will happen. I don't disagree that a mildly tweaked 7.0L LTx variant would return decent economy. But the 575-600hp figures people keep throwing around will necessitate a much bigger cam. better heads and very efficient exhaust. That will make it much harder to hit the driveability and efficiency targets.
With equal gearing a blown motor will return better efficiency. When it's not making boost, it's essentially a NA motor with a lot smaller cam. Blower motors generally have a more conservative (rich) fuel map, so consumption goes up slightly. But it's not close to what a larger cam in the NA motor would consume. My friends A&A C5 making 720hp gets comparable mileage to my ~500hp LS1 with a H/C combo. It's much easier to drive (almost stock like).
You would probably have more than just output differentiating 2 blown models. But even so, people would still buy the top model. Sure the output wouldn't be enough to justify the cost to a DIY type. But that's always been the case. A Z06 with a blower and the right options would outrun a ZR1, but the audience that goes for the ZR1 wants the warranty and polish that goes along with the factory package.
Again I am not against a high output NA motor. I would love it if they did it. I'm just saying that the FI motor route seems to fit GM's current trend with the C7.
With equal gearing a blown motor will return better efficiency. When it's not making boost, it's essentially a NA motor with a lot smaller cam. Blower motors generally have a more conservative (rich) fuel map, so consumption goes up slightly. But it's not close to what a larger cam in the NA motor would consume. My friends A&A C5 making 720hp gets comparable mileage to my ~500hp LS1 with a H/C combo. It's much easier to drive (almost stock like).
You would probably have more than just output differentiating 2 blown models. But even so, people would still buy the top model. Sure the output wouldn't be enough to justify the cost to a DIY type. But that's always been the case. A Z06 with a blower and the right options would outrun a ZR1, but the audience that goes for the ZR1 wants the warranty and polish that goes along with the factory package.
Again I am not against a high output NA motor. I would love it if they did it. I'm just saying that the FI motor route seems to fit GM's current trend with the C7.
I think the C7 Z06 will be lightened chassis (fixed roof, more use of carbon fiber, etc) and use a non-AFM version of the LT1 that will give more power and lighter weight (drivetrain). The AFM system alone adds at least 50 lbs to car and limits power. Also, they may revise 7sp gear ratios for more performance.
07-17-2013, 07:21 PM
#64
4th Gear
Member Since: Dec 2006
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
07 z06
What are the valve Issues you all refer to? I've got 49+k on mine, seems to run as hard or hard than brand new. Now is does sound like valve to rocker arm noise a little at times.
07-17-2013, 07:25 PM
#65
Burning Brakes
35.2 pounds — direct injection, VVT, AFM
15.4 pounds — steel torque tube part of AFM
5.5 pounds — AFM exhaust valves
Adds up to 56 lbs. I know DI and VVT is part of it so said 50lbs in my post.
07-17-2013, 10:10 PM
#66
07-18-2013, 03:36 AM
#67
Le Mans Master
Member Since: Jul 2009
Location: Los Angeles California
Posts: 9,526
Likes: 0
Received 10 Likes
on
10 Posts
VVT and DI have nothing to do with AFM. They'd be there with or without AFM. VVT is probably more weight than you give it credit for. Same with DI injectors and the pump.
07-18-2013, 10:37 AM
#69
Drifting
The ZR1 has greater output and different gearing. As I said I would love to see a high output NA variant, but I doubt it will happen. I don't disagree that a mildly tweaked 7.0L LTx variant would return decent economy. But the 575-600hp figures people keep throwing around will necessitate a much bigger cam. better heads and very efficient exhaust. That will make it much harder to hit the driveability and efficiency targets.
With equal gearing a blown motor will return better efficiency. When it's not making boost, it's essentially a NA motor with a lot smaller cam. Blower motors generally have a more conservative (rich) fuel map, so consumption goes up slightly. But it's not close to what a larger cam in the NA motor would consume. My friends A&A C5 making 720hp gets comparable mileage to my ~500hp LS1 with a H/C combo. It's much easier to drive (almost stock like).
You would probably have more than just output differentiating 2 blown models. But even so, people would still buy the top model. Sure the output wouldn't be enough to justify the cost to a DIY type. But that's always been the case. A Z06 with a blower and the right options would outrun a ZR1, but the audience that goes for the ZR1 wants the warranty and polish that goes along with the factory package.
Again I am not against a high output NA motor. I would love it if they did it. I'm just saying that the FI motor route seems to fit GM's current trend with the C7.
With equal gearing a blown motor will return better efficiency. When it's not making boost, it's essentially a NA motor with a lot smaller cam. Blower motors generally have a more conservative (rich) fuel map, so consumption goes up slightly. But it's not close to what a larger cam in the NA motor would consume. My friends A&A C5 making 720hp gets comparable mileage to my ~500hp LS1 with a H/C combo. It's much easier to drive (almost stock like).
You would probably have more than just output differentiating 2 blown models. But even so, people would still buy the top model. Sure the output wouldn't be enough to justify the cost to a DIY type. But that's always been the case. A Z06 with a blower and the right options would outrun a ZR1, but the audience that goes for the ZR1 wants the warranty and polish that goes along with the factory package.
Again I am not against a high output NA motor. I would love it if they did it. I'm just saying that the FI motor route seems to fit GM's current trend with the C7.
By contrast a blown 6.2 has no chance of achieving those kind of numbers even at the same power level. GM has to have figured this out a long time ago and that is why I expect we will see a DI 7.0 in the next car. Word inside the company is that this is true, but everyone is really, really tight lipped about it right now
07-18-2013, 12:56 PM
#70
Do the math an LS7 should get roughly 12.5% less mileage than an LT1 figuring the ratio of relative difference in displacement. Assuming 7th gear is going to close to the same and the Z06 should be a couple hundred pounds lighter that would put the car in the range 26-27 mpg on the highway with AFM engaged. And the car could stay in DOD mode longer because it would have more 4cyl displacement and less weight to pull along.
By contrast a blown 6.2 has no chance of achieving those kind of numbers even at the same power level. GM has to have figured this out a long time ago and that is why I expect we will see a DI 7.0 in the next car. Word inside the company is that this is true, but everyone is really, really tight lipped about it right now
By contrast a blown 6.2 has no chance of achieving those kind of numbers even at the same power level. GM has to have figured this out a long time ago and that is why I expect we will see a DI 7.0 in the next car. Word inside the company is that this is true, but everyone is really, really tight lipped about it right now
A 7.0L LTx variant could return decent economy with the right gearing and a mild power increase. I'm not saying it couldn't. I am saying that the 575-600hp numbers being thrown about would make that nearly impossible. You're looking at a substantial camshaft to make those numbers on an NA motor and that has a big impact on efficiency.
As far as a 6.2L blown engine not returning those types of numbers, why not? If the ZR1 is your only example then you need to do a fair comparison. Find a 550ish RWHP 7.0L and change out it's gearing to match the ZR1 (the ZR1 is geared lower so it spins higher when cruising down the road). As long as the gearing and tuning is there a blown engine will generally return better numbers than a comparable NA engine when driving normally.
Here's a simple analogy. An engine is moving air and fuel through itself all the time. The more of this it can move through efficiently the more power it makes. Imagine a bucket, a funnel, a tube and a large volume of liquid. You pour liquid into the funnel, which goes into the tube and finally into the bucket. The amount of liquid you can process is limited by the diameter of the funnel output and tubing diameter. This is representing the induction side of things in an engine: cylinder heads, intake and camshaft. For an NA application to get in more liquid in, you increase the diameter of the funnel output and tubing. The problem is that even when you don't need to move that volume of liquid, the tubing and funnel diameter does not change. And where an engine is concerned if you have air coming in, fuel must be mixed with it. Using that same analogy on an FI engine you can use much smaller tubing because you have positive pressure forcing the liquid through the tubing/funnel at a much higher rate than it would otherwise support. However when you remove that pressure you are still left with the smaller flow volume that the system naturally consumes. In other words when not on boost the motor is only ingesting the amount of air it would if it did not have the forced induction component present. Again that's oversimplifying things, but hopefully it helps illustrate the point.
Like I said earlier my friends A&A supercharged C5 is able to put up comparable economy numbers to mine (same gearing/tranny). Despite having about 200hp more on tap. My daily driver is a supercharged Cobalt SS that returns a steady 33-35MPG going back and forth to work (as long as I keep my foot out of it). Blown applications can absolutely return good efficiency numbers.
In the case of the C7 and a higher output 7.0L we don't have a lot of options. As far as I'm aware DoD limits the lift and duration of the camshaft, which really is the main component to making power. Plus DoD is one of the few easy areas to drop weight. Again they could make a mildly tweaked (think 530ish hp) 7.0L that would probably fit with the direction they've taken with the C7, but I don't see that making people very happy. They could absolutely say to heck with it and make a monster motor that throws efficiency out the window. However that runs contrary to what they've done with the C7 so far.
Personally I'm a big fan of a high output and large displacement NA motor. If I go further down the mod route with the C5 rather than go to a C7 it will be a stroked LS3. Why? Because of all the reasons others have listed. Heat soak, complexity, weight, etc. That and the numbers an FI setup would put out would result in more traction problems with street tires.
Last edited by 99C5JA1; 07-18-2013 at 12:59 PM.
07-18-2013, 01:34 PM
#71
Team Owner
Well, first getting 200lbs out of the C7 is going to be very difficult. It already has an aluminum frame. Ditching AFM would net maybe a 50lb reduction. Adding more carbon fiber would help a bit, but they've already tweaked the composites used in the normal panels to where the savings would be less than on previous generations. You could start to strip features, but I doubt that would happen. GM could decide to make a stripper model (no air, gutted interior., etc), but that would lessen the appeal and thus sales.
A 7.0L LTx variant could return decent economy with the right gearing and a mild power increase. I'm not saying it couldn't. I am saying that the 575-600hp numbers being thrown about would make that nearly impossible. You're looking at a substantial camshaft to make those numbers on an NA motor and that has a big impact on efficiency.
As far as a 6.2L blown engine not returning those types of numbers, why not? If the ZR1 is your only example then you need to do a fair comparison. Find a 550ish RWHP 7.0L and change out it's gearing to match the ZR1 (the ZR1 is geared lower so it spins higher when cruising down the road). As long as the gearing and tuning is there a blown engine will generally return better numbers than a comparable NA engine when driving normally.
Here's a simple analogy. An engine is moving air and fuel through itself all the time. The more of this it can move through efficiently the more power it makes. Imagine a bucket, a funnel, a tube and a large volume of liquid. You pour liquid into the funnel, which goes into the tube and finally into the bucket. The amount of liquid you can process is limited by the diameter of the funnel output and tubing diameter. This is representing the induction side of things in an engine: cylinder heads, intake and camshaft. For an NA application to get in more liquid in, you increase the diameter of the funnel output and tubing. The problem is that even when you don't need to move that volume of liquid, the tubing and funnel diameter does not change. And where an engine is concerned if you have air coming in, fuel must be mixed with it. Using that same analogy on an FI engine you can use much smaller tubing because you have positive pressure forcing the liquid through the tubing/funnel at a much higher rate than it would otherwise support. However when you remove that pressure you are still left with the smaller flow volume that the system naturally consumes. In other words when not on boost the motor is only ingesting the amount of air it would if it did not have the forced induction component present. Again that's oversimplifying things, but hopefully it helps illustrate the point.
Like I said earlier my friends A&A supercharged C5 is able to put up comparable economy numbers to mine (same gearing/tranny). Despite having about 200hp more on tap. My daily driver is a supercharged Cobalt SS that returns a steady 33-35MPG going back and forth to work (as long as I keep my foot out of it). Blown applications can absolutely return good efficiency numbers.
In the case of the C7 and a higher output 7.0L we don't have a lot of options. As far as I'm aware DoD limits the lift and duration of the camshaft, which really is the main component to making power. Plus DoD is one of the few easy areas to drop weight. Again they could make a mildly tweaked (think 530ish hp) 7.0L that would probably fit with the direction they've taken with the C7, but I don't see that making people very happy. They could absolutely say to heck with it and make a monster motor that throws efficiency out the window. However that runs contrary to what they've done with the C7 so far.
Personally I'm a big fan of a high output and large displacement NA motor. If I go further down the mod route with the C5 rather than go to a C7 it will be a stroked LS3. Why? Because of all the reasons others have listed. Heat soak, complexity, weight, etc. That and the numbers an FI setup would put out would result in more traction problems with street tires.
A 7.0L LTx variant could return decent economy with the right gearing and a mild power increase. I'm not saying it couldn't. I am saying that the 575-600hp numbers being thrown about would make that nearly impossible. You're looking at a substantial camshaft to make those numbers on an NA motor and that has a big impact on efficiency.
As far as a 6.2L blown engine not returning those types of numbers, why not? If the ZR1 is your only example then you need to do a fair comparison. Find a 550ish RWHP 7.0L and change out it's gearing to match the ZR1 (the ZR1 is geared lower so it spins higher when cruising down the road). As long as the gearing and tuning is there a blown engine will generally return better numbers than a comparable NA engine when driving normally.
Here's a simple analogy. An engine is moving air and fuel through itself all the time. The more of this it can move through efficiently the more power it makes. Imagine a bucket, a funnel, a tube and a large volume of liquid. You pour liquid into the funnel, which goes into the tube and finally into the bucket. The amount of liquid you can process is limited by the diameter of the funnel output and tubing diameter. This is representing the induction side of things in an engine: cylinder heads, intake and camshaft. For an NA application to get in more liquid in, you increase the diameter of the funnel output and tubing. The problem is that even when you don't need to move that volume of liquid, the tubing and funnel diameter does not change. And where an engine is concerned if you have air coming in, fuel must be mixed with it. Using that same analogy on an FI engine you can use much smaller tubing because you have positive pressure forcing the liquid through the tubing/funnel at a much higher rate than it would otherwise support. However when you remove that pressure you are still left with the smaller flow volume that the system naturally consumes. In other words when not on boost the motor is only ingesting the amount of air it would if it did not have the forced induction component present. Again that's oversimplifying things, but hopefully it helps illustrate the point.
Like I said earlier my friends A&A supercharged C5 is able to put up comparable economy numbers to mine (same gearing/tranny). Despite having about 200hp more on tap. My daily driver is a supercharged Cobalt SS that returns a steady 33-35MPG going back and forth to work (as long as I keep my foot out of it). Blown applications can absolutely return good efficiency numbers.
In the case of the C7 and a higher output 7.0L we don't have a lot of options. As far as I'm aware DoD limits the lift and duration of the camshaft, which really is the main component to making power. Plus DoD is one of the few easy areas to drop weight. Again they could make a mildly tweaked (think 530ish hp) 7.0L that would probably fit with the direction they've taken with the C7, but I don't see that making people very happy. They could absolutely say to heck with it and make a monster motor that throws efficiency out the window. However that runs contrary to what they've done with the C7 so far.
Personally I'm a big fan of a high output and large displacement NA motor. If I go further down the mod route with the C5 rather than go to a C7 it will be a stroked LS3. Why? Because of all the reasons others have listed. Heat soak, complexity, weight, etc. That and the numbers an FI setup would put out would result in more traction problems with street tires.
There are two transmissions used in the current C6 ZR1.
base ZR1 has a 5th gear of .72 and a 6th gear of .50.
optional transmission has a 5th gear of .82 and a 5th gear of .68
Base C6 and Z06 has a 5th gear of .74 and a 6th gear of .50.
C6 GS/Z51 has a 5th gear of .71 and a 6th gear of .57.
Base C7 has a 5th gear of .74, 6th gear of .50 and a 7th gear of .42
Z51 C7 has a 5th gear of .71, 6th gear of .57 and a 7th gear of .48
As you can see, a base C6 ZR1 does not run down the highway, in either 5th gear or 6th gear, at a higher RPM then the current C6 Z06, as they both have exactly the same gearing(very minor difference in 5th gear).
With the C7, no reason why a high horsepower variant of the LT1 would not have the same transmission ratios of the base C7 of .74 in 5th gear, .50 in 6th gear and .42 in 7th gear.
07-18-2013, 01:54 PM
#72
Le Mans Master
The LS motors are done, any performance motor now will be based off the LT1, I'm sure GM was very careful in the motor design, I doubt there will be 3 motors this time, I'm guessing a FI LT1, in the 80k-90k range, which will still outperform the ZR1.
Also I don't think it will be called Z06, this whole vette is new and I doubt they will carry the Z06 name over 3 generations, GM has already re-licensed the LT motors names, as well as the grand National/GNX names, there is a reason for that.
Also I don't think it will be called Z06, this whole vette is new and I doubt they will carry the Z06 name over 3 generations, GM has already re-licensed the LT motors names, as well as the grand National/GNX names, there is a reason for that.
07-18-2013, 02:31 PM
#73
Drifting
Well, first getting 200lbs out of the C7 is going to be very difficult. It already has an aluminum frame. Ditching AFM would net maybe a 50lb reduction. Adding more carbon fiber would help a bit, but they've already tweaked the composites used in the normal panels to where the savings would be less than on previous generations. You could start to strip features, but I doubt that would happen. GM could decide to make a stripper model (no air, gutted interior., etc), but that would lessen the appeal and thus sales.
A 7.0L LTx variant could return decent economy with the right gearing and a mild power increase. I'm not saying it couldn't. I am saying that the 575-600hp numbers being thrown about would make that nearly impossible. You're looking at a substantial camshaft to make those numbers on an NA motor and that has a big impact on efficiency.
As far as a 6.2L blown engine not returning those types of numbers, why not? If the ZR1 is your only example then you need to do a fair comparison. Find a 550ish RWHP 7.0L and change out it's gearing to match the ZR1 (the ZR1 is geared lower so it spins higher when cruising down the road). As long as the gearing and tuning is there a blown engine will generally return better numbers than a comparable NA engine when driving normally.
Here's a simple analogy. An engine is moving air and fuel through itself all the time. The more of this it can move through efficiently the more power it makes. Imagine a bucket, a funnel, a tube and a large volume of liquid. You pour liquid into the funnel, which goes into the tube and finally into the bucket. The amount of liquid you can process is limited by the diameter of the funnel output and tubing diameter. This is representing the induction side of things in an engine: cylinder heads, intake and camshaft. For an NA application to get in more liquid in, you increase the diameter of the funnel output and tubing. The problem is that even when you don't need to move that volume of liquid, the tubing and funnel diameter does not change. And where an engine is concerned if you have air coming in, fuel must be mixed with it. Using that same analogy on an FI engine you can use much smaller tubing because you have positive pressure forcing the liquid through the tubing/funnel at a much higher rate than it would otherwise support. However when you remove that pressure you are still left with the smaller flow volume that the system naturally consumes. In other words when not on boost the motor is only ingesting the amount of air it would if it did not have the forced induction component present. Again that's oversimplifying things, but hopefully it helps illustrate the point.
Like I said earlier my friends A&A supercharged C5 is able to put up comparable economy numbers to mine (same gearing/tranny). Despite having about 200hp more on tap. My daily driver is a supercharged Cobalt SS that returns a steady 33-35MPG going back and forth to work (as long as I keep my foot out of it). Blown applications can absolutely return good efficiency numbers.
In the case of the C7 and a higher output 7.0L we don't have a lot of options. As far as I'm aware DoD limits the lift and duration of the camshaft, which really is the main component to making power. Plus DoD is one of the few easy areas to drop weight. Again they could make a mildly tweaked (think 530ish hp) 7.0L that would probably fit with the direction they've taken with the C7, but I don't see that making people very happy. They could absolutely say to heck with it and make a monster motor that throws efficiency out the window. However that runs contrary to what they've done with the C7 so far.
Personally I'm a big fan of a high output and large displacement NA motor. If I go further down the mod route with the C5 rather than go to a C7 it will be a stroked LS3. Why? Because of all the reasons others have listed. Heat soak, complexity, weight, etc. That and the numbers an FI setup would put out would result in more traction problems with street tires.
A 7.0L LTx variant could return decent economy with the right gearing and a mild power increase. I'm not saying it couldn't. I am saying that the 575-600hp numbers being thrown about would make that nearly impossible. You're looking at a substantial camshaft to make those numbers on an NA motor and that has a big impact on efficiency.
As far as a 6.2L blown engine not returning those types of numbers, why not? If the ZR1 is your only example then you need to do a fair comparison. Find a 550ish RWHP 7.0L and change out it's gearing to match the ZR1 (the ZR1 is geared lower so it spins higher when cruising down the road). As long as the gearing and tuning is there a blown engine will generally return better numbers than a comparable NA engine when driving normally.
Here's a simple analogy. An engine is moving air and fuel through itself all the time. The more of this it can move through efficiently the more power it makes. Imagine a bucket, a funnel, a tube and a large volume of liquid. You pour liquid into the funnel, which goes into the tube and finally into the bucket. The amount of liquid you can process is limited by the diameter of the funnel output and tubing diameter. This is representing the induction side of things in an engine: cylinder heads, intake and camshaft. For an NA application to get in more liquid in, you increase the diameter of the funnel output and tubing. The problem is that even when you don't need to move that volume of liquid, the tubing and funnel diameter does not change. And where an engine is concerned if you have air coming in, fuel must be mixed with it. Using that same analogy on an FI engine you can use much smaller tubing because you have positive pressure forcing the liquid through the tubing/funnel at a much higher rate than it would otherwise support. However when you remove that pressure you are still left with the smaller flow volume that the system naturally consumes. In other words when not on boost the motor is only ingesting the amount of air it would if it did not have the forced induction component present. Again that's oversimplifying things, but hopefully it helps illustrate the point.
Like I said earlier my friends A&A supercharged C5 is able to put up comparable economy numbers to mine (same gearing/tranny). Despite having about 200hp more on tap. My daily driver is a supercharged Cobalt SS that returns a steady 33-35MPG going back and forth to work (as long as I keep my foot out of it). Blown applications can absolutely return good efficiency numbers.
In the case of the C7 and a higher output 7.0L we don't have a lot of options. As far as I'm aware DoD limits the lift and duration of the camshaft, which really is the main component to making power. Plus DoD is one of the few easy areas to drop weight. Again they could make a mildly tweaked (think 530ish hp) 7.0L that would probably fit with the direction they've taken with the C7, but I don't see that making people very happy. They could absolutely say to heck with it and make a monster motor that throws efficiency out the window. However that runs contrary to what they've done with the C7 so far.
Personally I'm a big fan of a high output and large displacement NA motor. If I go further down the mod route with the C5 rather than go to a C7 it will be a stroked LS3. Why? Because of all the reasons others have listed. Heat soak, complexity, weight, etc. That and the numbers an FI setup would put out would result in more traction problems with street tires.
Current C6 Z06 7.0L mpg is 24 hwy
We know the LT1 went to 30mpg hwy from 26mpg in the LS3 - a 4mpg gain. With an equal weight car (C7 Z06 to Stingray coupe) and a similar AFM DOD system using DI why couldn't GM get the same 4mpg gain with adding AFM to the new 7.0L engine on a C7 Z06? You cannot legitimately dispute that the increased displacement would allow as much or even more use in 4cyl mode thus increasing the potential fuel economy gains to be even higher than those achieved on the LT1. A 7.0L would also be lighter and taking up less space than a blown 6.2L engine to boot. Cost to produce should also be less than a supercharged version.
So really GM could debut a 550-560hp 7.0L engine achieving close to or right at 28mpg highway. There is absolutely no way that a blown car has any chance of returning this kind of economy, and GM certainly seems to be really concerned about that right now
07-18-2013, 03:04 PM
#74
Slight correction to your post regarding the ZR1's gearing.
There are two transmissions used in the current C6 ZR1.
base ZR1 has a 5th gear of .72 and a 6th gear of .50.
optional transmission has a 5th gear of .82 and a 5th gear of .68
Base C6 and Z06 has a 5th gear of .74 and a 6th gear of .50.
C6 GS/Z51 has a 5th gear of .71 and a 6th gear of .57.
Base C7 has a 5th gear of .74, 6th gear of .50 and a 7th gear of .42
Z51 C7 has a 5th gear of .71, 6th gear of .57 and a 7th gear of .48
As you can see, a base C6 ZR1 does not run down the highway, in either 5th gear or 6th gear, at a higher RPM then the current C6 Z06, as they both have exactly the same gearing(very minor difference in 5th gear).
With the C7, no reason why a high horsepower variant of the LT1 would not have the same transmission ratios of the base C7 of .74 in 5th gear, .50 in 6th gear and .42 in 7th gear.
There are two transmissions used in the current C6 ZR1.
base ZR1 has a 5th gear of .72 and a 6th gear of .50.
optional transmission has a 5th gear of .82 and a 5th gear of .68
Base C6 and Z06 has a 5th gear of .74 and a 6th gear of .50.
C6 GS/Z51 has a 5th gear of .71 and a 6th gear of .57.
Base C7 has a 5th gear of .74, 6th gear of .50 and a 7th gear of .42
Z51 C7 has a 5th gear of .71, 6th gear of .57 and a 7th gear of .48
As you can see, a base C6 ZR1 does not run down the highway, in either 5th gear or 6th gear, at a higher RPM then the current C6 Z06, as they both have exactly the same gearing(very minor difference in 5th gear).
With the C7, no reason why a high horsepower variant of the LT1 would not have the same transmission ratios of the base C7 of .74 in 5th gear, .50 in 6th gear and .42 in 7th gear.
ZR1 looks to get 14/21 and the Z06 15/24. So about 26% more power for about 13% less mileage. I'm sure part of it has to do with the induction inefficiencies and parasitic load with the roots blower. I've never looked at the tune on a ZR1, but if it's typical of other blown GM motors it's probably quite rich compared to what it needs to be. Needless to say the cam (along with the supporting modifications) needed to get another 130hp out of a Z06 would probably decrease mileage by at least that much. I'd guess mid to upper teens on the highway. I did a quick search to see if I could find any discussions of mileage on big LS motors in the 550rwhp range. I found one mention of a 402 making close to that getting 19 MPG. Not really a good sample range.
07-18-2013, 03:40 PM
#75
My analysis at 26-27mpg assumes no weight savings
Current C6 Z06 7.0L mpg is 24 hwy
We know the LT1 went to 30mpg hwy from 26mpg in the LS3 - a 4mpg gain. With an equal weight car (C7 Z06 to Stingray coupe) and a similar AFM DOD system using DI why couldn't GM get the same 4mpg gain with adding AFM to the new 7.0L engine on a C7 Z06? You cannot legitimately dispute that the increased displacement would allow as much or even more use in 4cyl mode thus increasing the potential fuel economy gains to be even higher than those achieved on the LT1. A 7.0L would also be lighter and taking up less space than a blown 6.2L engine to boot. Cost to produce should also be less than a supercharged version.
So really GM could debut a 550-560hp 7.0L engine achieving close to or right at 28mpg highway. There is absolutely no way that a blown car has any chance of returning this kind of economy, and GM certainly seems to be really concerned about that right now
Current C6 Z06 7.0L mpg is 24 hwy
We know the LT1 went to 30mpg hwy from 26mpg in the LS3 - a 4mpg gain. With an equal weight car (C7 Z06 to Stingray coupe) and a similar AFM DOD system using DI why couldn't GM get the same 4mpg gain with adding AFM to the new 7.0L engine on a C7 Z06? You cannot legitimately dispute that the increased displacement would allow as much or even more use in 4cyl mode thus increasing the potential fuel economy gains to be even higher than those achieved on the LT1. A 7.0L would also be lighter and taking up less space than a blown 6.2L engine to boot. Cost to produce should also be less than a supercharged version.
So really GM could debut a 550-560hp 7.0L engine achieving close to or right at 28mpg highway. There is absolutely no way that a blown car has any chance of returning this kind of economy, and GM certainly seems to be really concerned about that right now
If you were able to use both AFM and DI on a cam sized around the Z06 cam you still wouldn't see the same 4 MPG bump. The bigger cam has to eat into that. The 6.2L LT1 has almost identical torque down low vs. the LS7, so I don't think it would be in 4cyl mode appreciably longer. If you used the same cam, you'd only see about 20-30HP gain from DI putting it at about 530HP. To hit the 550-560 range you would need another cam increase and would again take an efficiency hit. Still I could see a 540-550hp variant in the 25-26MPG range.
There is absolutely a way a blown engine can hit that efficiency level. I've driven a 700+hp A&A supercharged C5 that returned an indicated 28 MPG in steady state driving. The DIC is always optimistic, so doing the math put it around 26. I was curious to see what the mileage was on a stroker LSx and didn't find much, but did see a couple of Procharged cars reporting better mileage than the A&A car I experienced. The way the EPA rates things these days, these cars would probably be in the 23-26 range to put it in perspective to the numbers we're talking about.
07-18-2013, 03:45 PM
#76
Instructor
Member Since: Dec 2009
Location: London Ontario
Posts: 120
Likes: 0
Received 0 Likes
on
0 Posts
My blown 2004 z06 /w 500rwhp hit 30mpg on the highway.
A blown LT1 /w 7 speed should be able to hit 30mpg.
At the end of the day even though I would brag about 25-30mpg in 6th.... I was always using 3rd/4th/5th to make highway driving "more spirited"
A blown LT1 /w 7 speed should be able to hit 30mpg.
At the end of the day even though I would brag about 25-30mpg in 6th.... I was always using 3rd/4th/5th to make highway driving "more spirited"
07-18-2013, 04:20 PM
#77
My personal opinion is that the Z06 should and more than likely does have ONE objective. Beat the new Viper in all performance aspects, be more affordable, and look better doing it.
Mag ride, great tires, and 600hp will be utilized to achieve these goals. The ZR1 though, will be used to crush all exotic super-cars beyond the viper. Chevy is going to turn heads in the coming years.
I'm just blessed to have the chance to own the Stingray C7
'MERICA!
Mag ride, great tires, and 600hp will be utilized to achieve these goals. The ZR1 though, will be used to crush all exotic super-cars beyond the viper. Chevy is going to turn heads in the coming years.
I'm just blessed to have the chance to own the Stingray C7
'MERICA!
07-18-2013, 04:38 PM
#78
Drifting
Your post read like weight savings were a factor, my apologies for misreading it. I'm not disputing that 7.0L LTx couldn't spend more time in 4cyl mode than the current motor. What is questionable is whether DoD/AFM would work with a cam with the lift specs of the current Z06 cam or one even larger to make the power you're stating. We have a G8 and I did a little research on DoD and evidently the lifters can only take so much. It may have improved. If it can't support the cam needed now your efficiency gain is purely from DI. Which is about 1-2 MPG I believe.
If you were able to use both AFM and DI on a cam sized around the Z06 cam you still wouldn't see the same 4 MPG bump. The bigger cam has to eat into that. The 6.2L LT1 has almost identical torque down low vs. the LS7, so I don't think it would be in 4cyl mode appreciably longer. If you used the same cam, you'd only see about 20-30HP gain from DI putting it at about 530HP. To hit the 550-560 range you would need another cam increase and would again take an efficiency hit. Still I could see a 540-550hp variant in the 25-26MPG range.
There is absolutely a way a blown engine can hit that efficiency level. I've driven a 700+hp A&A supercharged C5 that returned an indicated 28 MPG in steady state driving. The DIC is always optimistic, so doing the math put it around 26. I was curious to see what the mileage was on a stroker LSx and didn't find much, but did see a couple of Procharged cars reporting better mileage than the A&A car I experienced. The way the EPA rates things these days, these cars would probably be in the 23-26 range to put it in perspective to the numbers we're talking about.
If you were able to use both AFM and DI on a cam sized around the Z06 cam you still wouldn't see the same 4 MPG bump. The bigger cam has to eat into that. The 6.2L LT1 has almost identical torque down low vs. the LS7, so I don't think it would be in 4cyl mode appreciably longer. If you used the same cam, you'd only see about 20-30HP gain from DI putting it at about 530HP. To hit the 550-560 range you would need another cam increase and would again take an efficiency hit. Still I could see a 540-550hp variant in the 25-26MPG range.
There is absolutely a way a blown engine can hit that efficiency level. I've driven a 700+hp A&A supercharged C5 that returned an indicated 28 MPG in steady state driving. The DIC is always optimistic, so doing the math put it around 26. I was curious to see what the mileage was on a stroker LSx and didn't find much, but did see a couple of Procharged cars reporting better mileage than the A&A car I experienced. The way the EPA rates things these days, these cars would probably be in the 23-26 range to put it in perspective to the numbers we're talking about.
So while the equal geared (to the C6 Z06) ZR1 gets 21hwy mpg you think somehow they will introduce a blown LT1 that gets the same 27-28mpg a 7.0L very well should hit? Ain't happening brother
I have tuned over 600 LSx cars and many of them have been forced induction. I can tell you that there is a significant drop in economy on any car with a roots style blower on it because they get into boost (and therefore fuel consumption) really fast. They also heat soak during extended hard use worse than any other kind of setup out there
07-18-2013, 05:39 PM
#79
Team Owner
I'll take your word for it. I read some auto rag complaining about the ZR1 economy being worse due to gearing. The ZR1 hasn't been on my radar of something I would buy, so I haven't read up much on it past the usual magazine comparisons. I'm not going to change the original post, so your correction doesn't look out of place.
ZR1 looks to get 14/21 and the Z06 15/24. So about 26% more power for about 13% less mileage. I'm sure part of it has to do with the induction inefficiencies and parasitic load with the roots blower. I've never looked at the tune on a ZR1, but if it's typical of other blown GM motors it's probably quite rich compared to what it needs to be. Needless to say the cam (along with the supporting modifications) needed to get another 130hp out of a Z06 would probably decrease mileage by at least that much. I'd guess mid to upper teens on the highway. I did a quick search to see if I could find any discussions of mileage on big LS motors in the 550rwhp range. I found one mention of a 402 making close to that getting 19 MPG. Not really a good sample range.
ZR1 looks to get 14/21 and the Z06 15/24. So about 26% more power for about 13% less mileage. I'm sure part of it has to do with the induction inefficiencies and parasitic load with the roots blower. I've never looked at the tune on a ZR1, but if it's typical of other blown GM motors it's probably quite rich compared to what it needs to be. Needless to say the cam (along with the supporting modifications) needed to get another 130hp out of a Z06 would probably decrease mileage by at least that much. I'd guess mid to upper teens on the highway. I did a quick search to see if I could find any discussions of mileage on big LS motors in the 550rwhp range. I found one mention of a 402 making close to that getting 19 MPG. Not really a good sample range.
With the LT1 and it's Direct Injection, I see no reason why they can't keep it's 11.5:1 CR with a blower on top. The LT1 is way overbuilt(forged crank, nodular iron main bearing caps, possible forged pistons, pistons squirters, etc.) for a NA 455 HP engine. It appears they have designed the base engine for adding a puffer to get more horsepower.
GM spent way too much time and money on the 6.2L LT1's design to just add a stroker and enlarge the bore to get 7L and design new heads, with higher flow rates. Not enough demand to redesign(ie: $$$$$$$$$) the LT1 to make it 7L to keep it NA.
The LS series(Gen IV) is history now, so the LS7 will never be installed in the Corvette again, IMHO.
07-18-2013, 05:57 PM
#80
The Consigliere
Member Since: May 2006
Location: 2023 Z06 & 2010 ZR1
Posts: 22,243
Received 5,430 Likes
on
2,268 Posts
Joe is absolutely correct re the reason for the fuel efficiency diff b/n LS9 and LS7. It's the compression ratio (and a minor contribution from the perf gear option). And when loafing down the highway, you're not in boost at all, and you're reaping the lower efficiency of the lower compression ratio. Which is why comparing LS motors that were designed/built for NA, but which somebody slapped a huffer on, doesn't explain the difference b/n the LS9 and LS7. The NA LS engine started with a higher compression ratio to begin with.
And if they put the guts in the LTx to run a higher compression with its DI and FI, then it should pull a higher mpg than the LS9.
And if they put the guts in the LTx to run a higher compression with its DI and FI, then it should pull a higher mpg than the LS9.
Last edited by OnPoint; 07-18-2013 at 06:02 PM.
