I wonder how they will make the C7 Z06 stand out over a base C7 corvette Stingray?

You can see the difference in a base C6 and a C6 Z06 ( If your a car guy or gal) but the C7 base Car is so dramatic with all the scoops and curves and Creases that the C7 Z06 will have to be Very Dramatic to stand out.
I did a search on Cars.com and they dont even call the base C7 a Corvette they call it a Corvette Stingray now.

 

As far as the different size/types of engines for the corvette, take a look at the truck line. A v6 and two v8s with different displacements. I can very easily see a similar transistion in the vette as with the c6 history. Base car is c7, then we get a track type car with more power(na) bigger tires, lighter wt, last they hype the model one more time with a zr1 type car with lots of power from the sc. Note: Please tell scm crash not to post and tell me the truck engines have nothing to do with the vette engine.

 

I didn't specify that GM had to use a roots style blower. You claimed there was no way a blown motor could hit that level of efficiency. They can. A centrifugally supercharged motor qualifies as a blown motor. Also as Joe pointed out the compression ratio also causes a hit to economy on the ZR1 (I should have considered that). The DI motor will likely not have to reduce compression much and therefore won't suffer as much efficiency loss. I'd prefer if they go the FI route that they use low mounted turbos for weight balance.

I don't know if the LS7 valve springs are stiffer than an LS3, but if they are that would generate more load on the lifters. The leverage needed for the higher ratio rockers may as well. If you reduce the ratio, you would have to compensate with lift on the cam lobe. And while the LS7 cam may act similar vs the LS3's due to it's larger displacement, that makes no mechanical difference to the valvetrain. It's still more load. GM may be able to do both DoD and cam as large or larger than a Z06. I guess we may find out. As I'm sure you're aware a blower cam wouldn't need to be as aggressive and therefore have a better chance of using a DoD setup.

I don't see a 7.0L LTx with a larger cam (if you want it to make 550+)than the current Z06 getting the same 4MPG increase that the LT1 sees vs. an LS3. The LT1 is using a smaller cam than the LS3 (200/207 0.551/0.524 vs. 204/211 0.551/0.525). That also assumes that it will be utilizing DoD. I hope they go for it and make a large NA motor with performance the focus. Any efficiency they manage would be icing on the cake.

 

Whether they go NA or FI, I for one hope they leave off AFM and its associated iron exhaust manifold and steel driveshaft.

Given the huge ramp up on CAFE requirements in just the next few years tho, it may be tough for them to do that.

 

It was implied when you said GM would use a "blown" 6.2 that you meant a roots style supercharger like the did on the current ZR1. Therefore it's a given that I'm talking about a roots style blower in my statements because if GM does use a blown motor in the C7 Z06 that's 100% what it would be. Bringing up something irrelevant and pointless like what a centrifugal charger might do and isn't a remotely legitimate part of the current discussion to beat your chest and say "I'm right" is just goofy.

As I've already said earlier all they have to do is use 1.7 rockers and the cam specs in the LS7 are essentially the same as the LS3 displacement wise. And if they went from 204 to 200 duration and increased power in the LT1 there is no reason they can't go from 211 to 207 in the 7.0 engine and do the same. Your argument about load on the lifters and such is a straw man that therefore isn't valid, because it is already clear they can achieve the same lift in a 7.0 with a simple no cost change. And if they want to get better fuel economy they will do it without a thought.

A roots blower on a 6.2L isn't going to get the same mileage as a 7.0 NA. If you had enough seat time driving both of these in the C6 (and I've driven well over a thousand miles in a ZR1 and Z06) then you would know that the roots car just builds way more torque so much faster - therefore it consumes more fuel quite easily even at moderate loads. The 13' LS9 uses the same cam as the LS7 but with 1.7 rockers instead (which mean load on lifters is equal to the LS3), but even with the same gearing in the 13' ZR1 compared to the 13' Z06 there is still a significant difference in fuel economy.

DOD isn't going to work on a roots blower because it builds torque so fast under lighter throttle loads you can't keep it enabled long enough at a time to make a real difference. With a 3.5 V4 on the other hand it could run the car for 100 highway miles at a time at 70mph if they wanted to. The other thing people are overlooking is that GM is likely going to offer an automatic with the next Z06 which means they will sell a ton more of them than the C6 Z06.

A huge percentage of C6 Grand Sport buyers were just like me in that they wanted a Z06 but felt they had to have an automatic transmission for daily driving. There are a lot of people who can well afford to buy the higher hp Z06 model but demand an auto, so if GM can offer a 7.0 that gets 27-28mpg on the highway with that available then they will sell them as fast as they can build them for 2-3 years. That is what people are really missing here when they analyze this. As much as I hate the rear of the C7 if the build a 7.0 Z06 with an auto trans I will be in line to buy it once a great deal is available.

In the meantime I am just going to put an A&A kit on my cammed C6 GS coupe to get me by for 3 years or so

 

There will be a Z06. It is an iconic name that represents the performance end of the Corvette line. I don't think they would let it go.

 

No the discussion has run the whole "what if" gamut. I didn't intentionally imply it.

No chest beating here. That wouldn't be constructive and it's somewhat insulting to imply it. If you feel I haven't been civil in the discussion, then I apologize as it was certainly not my intention. You made a broad statement, I didn't read it the way you thought it would be read. We're just discussing the possibilities. GM can do any type of FI, they certainly may be more likely to do a roots type blower based on past experience.

Dropping the rocker ratio will decrease lift and as a result power. That will not help get you to 550+hp. If we're discussing a more modest increase, sure.

I honestly don't know what the DoD system can handle. I'd be very interested to know where the limits lie. It's certainly a concern. Especially if you want to increase the cam specs beyond where they are now.

I agree they would have to do something about the low rpm boost. Even with a roots blower, an LTx variant would pick up efficiency due to being able to run a lot more compression. The real question on efficiency depends on your target output? 530hp, the 7.0L would be an easy fit. 600? Even a roots blower will be a better choice.

Like I said earlier, the LT1 is already making the same torque as the LS7. So I don't think there would be as large of difference in time spent in 4cyl mode. An auto is a great idea. I talk to a lot of owners that would love that. The CTS-V can do it, why not the C7.

That will be a great combo.

 

Lift doesn't make much extra power past a certain point it is duration that controls the powerband and hp. Lowering the lift from .590 to .560 in the 7.0 isn't going to cost more than 1-1.5% of the power the car is making now if that, and ask me how I know having tuned well over 500 LSx cam swaps personally. And it's already clear that GM prizes fuel economy to a far greater extent than peak hp numbers, so there is zero reason to think they will be shooting for anywhere near 600 in a Z06 version.

They will offer a 700hp blown version without DOD for $125k or more that is a no compromise all out race car just like the ZR1. It will sell in very limited numbers thanks to the ultra high price. Because they know people that buy it are going to run it either hard or with a lot more boost they will certainly offer a low compression motor - not good for fuel economy.

The Z06 will be geared for track use with the manual and as the top performance model for those wanting an automatic. An NA motor is simply far better for these applications than a roots-style supercharger and will certainly yield better economy. The real question is wondering if GM will be smart enough to go twin turbo on the new ZR1, because that will give buyers the opportunity to test the limits of 1000 flywheel hp by dialing up the boost and upgrading the fuel system

 

The LT1 is making almost, but not the same, torque as the LS7 but it is reached at a lower RPM. That's why the LT1 is 45 horses short of the LS7's 505.

My 300 HP 1964 Vette makes 360 lb-ft of torque but is 75 horses short of the fuel injected engine that makes 10 lb-ft less torque than mine.

 

Joe, I was referencing the low RPM 4cyl mode as far as time spent in that mode (I was replying to an earlier point about this). Not the overall curve which is certainly not the same. I didn't mean for it to be taken out of context.

 

I agree. I seriously doubt we'll see a 575-600hp large displacement LTx variant. The C7 shows how much focus they have put into meeting Government mandates. I think we're on a similar page about what they could do if they go this route. Modest changes and a modest power bump. I'm a little less optimistic about the economy aspect, but I think it would be doable.

Even though some would be disappointed with that, it would be nice to have a large displacement, non-FI version, for all the reasons folks have listed (heatsoak, weight, etc). It would also be an excellent starting point for mods.

Yes, low mounted twin turbos really seem ideal for the FI route. I really hope they get away from the roots type setup. It puts weight where you don't want it and has more problems with heat. I'm very curious to see where they end up with on compression with the next FI setup. DI will help quite a bit. Will they compromise output to keep compression high and thus increase economy? It will be interesting to see.