i've always preferred this one

 

Why would anyone believe GM has overstated the 0-60 times? Tadge Juechter hinted at some surprises to come from what's already been released about the C7 and he did so with obvious pleasure. The sub 4 second 1/4 mile announced without giving an exact figure gives credence to the idea that it might be lower than 3.9. From a marketing standpoint it makes a lot more sense for a surprise to be a positive than a negative.

 

Reading skills are nice to have. Maybe you should ask Santa to bring you a Dick and Jane first grade reader next Christmas.

Is the best you can debate with is that the chart(dyno graph) I showed is not of for a "car" but for a "truck".

Look at the Graph. It was made by GM, not me. It says in plain English..."2014 Corvette 6.2L LT1 lbs-ft, and GM even placed a C7 crossflags in the lower right hand corner.

 

The weight is where they want it give or take a couple pounds.. They will probably add some more HP to the motor. In last interview with Tadge he said 450 right now but its not set in stone.

 

I'm betting on 470hp/3250lb as the final numbers. I think they'll get the number up to leave some room for the Chevy SS sedan which should have the LT1 as well.

 

Did he giggle when you asked if the horsepower is going to be 450?

one giggle=460 HP
two giggles=470 HP
three giggles=490 HP
four giggles=500 HP.

I'm letting you in on this secret code that is only known to engineers, so don't be spilling the beans, Okay?

 

Still, we are having to go by the numbers that the chief engineer himself said, and what GM published. Weight, " slightly more than the C6", 0-60 times "less than 4 seconds", 1/4 mile not improved over the C6, power output 450/450 (15 hp more than C6).
With a minimal increase in power (at least as far as we now know), increased weight and smaller tires, what do we expect?
We can only use the info we have now. And, what we know now suggests that all the vaunted weight saving work hasn't paid off.
I hope all the specs will be much improved before they are on sale.

 

I find there is way too much talk about the cars weight, and I think most people fail to realize that the 1953 C1 Corvette weighed 2840 lbs.

60 years later with all of the crash regulations and then some, the new C7 will weigh around 3200 lbs according to some people in this forum who consider that heavy.

So in 60 years the Corvette has gained 360 lbs (if the C7 does weigh 3200 lbs) with all of the crash protection and extra equipment that were not even available 60 years ago.

Extra equipment being a V8 (compared to the original inline 6), bigger transmission, anti lock brakes, a/c, power seats etc etc, thats todays Corvette has.

That being said, the engineers at Corvette have done an outstanding job.

 

I'm sure GM knows how to operate a dyno but it's obvious you don't know how to read dyno graphs. Contrary to what you say, dyno graphs can and do lie...your LS7 dyno graph is a lie, the HP and torque curves don't cross at 5252 RPM. No where close in fact. How did you make your list above without noticing the LT1 was making more HP than the LS7 at 4000 RPM where torque was equal and 5000 RPM when the LS7 was making more torque? Maybe you need the Dick and Jane equivalent for math...

 

I don't know what the deal was with the original LS7 dyno graph I showed but here is what it should have been.



The cam in the LT1 looks to be almost identical to the LS3 cam. Please explain why, with the same cam, the LT1 has so much greater torque at lower RPMs vs the LS3.

 

Joe, doesn't the LT1 include a variable cam timing? Also DI at play?

 

Yep. And what effect does the VVT have on torque, and it's range?

 

We'll, degreeing cams, moving the lobe centers always had a pretty profound effect on the breadth, location and rake of the powerband on my racebikes. Just saying, it doesn't seem surprising that vvt + di would be spreading the torque band around, moving the curve in a way that is different than a fixed cam with otherwise the same lift and duration.

 

Where is the video or written statement where the engineers said the c7 would be slightly heavier?

 

That dyno graph is wrong also and in so many ways...where are you finding these bogus graphs??? The HP and torque curves still don't cross at 5252 RPM although it is closer. The torque curve peaks at too high of an RPM and goes flat for over 1000 RPM which is not the way a real LS7 is. The overlay with the LT1 dyno graph has the LS7 at 450 lb-ft while the one above has it at 420 lb-ft...I bet I can tell you which one is wrong. Show me a Z06 from the factory with an LS7 turning 8000 RPM not to mention the HP wouldn't be anywhere near what the graph shows at 8000 RPM. And finally, not all of the inflections on the torque curve match the inflections on the HP curve...mathematically impossible.

Yes, the LT1 cam has a little less duration than the LS3 cam. The LT1 makes more torque at low RPM because it can...that's the Reader's Digest condensed version, not trying to be a smart azz. The VVT allows them to optimize dynamic compression ratio while direct injection allows higher BMEP at the lower RPMS without incurring knock. There is also less negative work with the more efficient combustion which is like "free" HP/torque. And of course the higher static compression helps too. However, you already know this, you're just trying to deflect from your bogus dyno graphs. It's really no big deal, I just have fun messing with you.

 

Advancing the cam will shift the torque curve down and retarding the cam will shift the torque upwards. At low RPM, the advanced cam of the VVT will give greater low end torque vs a non VVT cam straight up. As the RPM moves upward and the cam retards, the torque also moves upward, but there is a limitation. You still need the bigger cam(more duration, faster ramps and higher lifts), bigger TB, bigger runners, bigger ports and bigger valves to enable the engine to make the upper RPM torque and horsepower.

The LT1 does not have the LS7's larger TB, nor the LS7's larger intake manifold, nor the LS7's larger ports, not the LS7's larger valves or the LS7's bigger cam. Also the LT1 doesn't have the LS7's displacement. All those items are necessary for an engine to breathe and make horsepower. That's why the LT1 makes good torque at low RPMs, but doesn't make the LS7's horsepower at upper RPMs. The LT1 can't pass enough air to equal a LS7, so why does everyone think(wish) that the LT1 will equal the LS7 in torque and horsepower.

 

I get your point, but from a stoplight you gotta go between 2K and 4K EVERY time -- and the LT1 will equal the Z06 every time that happens. Plus, not everybody downshifts to the correct gear every time. Plenty of accelleration occurs between 3K and 5K unless you are maxing out every time. My car is a DD so it sees all kinds of driving styles. And, I enjoy it at 2K, 4K and every other point on the tach

 

You cannot win an argument with logic so you resort to insults?

I am quite confident of grasping your point -- interestingly, your own data (which may not be 100% correct based on good analysis by other thoughtful posters, but let's assume it is) illustrates MY point which is correct -- but you clearly did not get. Look at the data in bold red. Is it not obvious from that that as the LT1 sweeps from 4K to 5K that the average HP for the LT1 is very close? (Given that the LT1 is, apparently, 40HP GREATER @ 4K RPM and only 10 HP less @ 5K RPM). Accordingly, it would be very surprising if the LT1 would not stay with the LS7 thru 5K RPM. Further, the 365 HP for the LT1 @ 6500RPM is meaningless in your example becuase by then the LT1 driver would have shifted and put the engine in a more favorable part of the torque curve where the horsepower delta would have been reduced a bit.

So let's state this in a clear way as illustrated by your own data:

1K => 4K RPM LT1 > LS7
4K => 5K RPM LT1 ~ LS7
5K => 7K RPM LS7 >> LT1

So, your LS7 will own the 5K to 7K range, but if the C7 LT1 driver knows when and how to shift they will reduce the advantage somewhat. Meanwhile, they may even own you a bit in the very common street range of 3K => 5K RPM. And none of your bluster or insults means a thing becuase neither of us has seen the final stats on this yet -- when we do, I guarantee you I will know exactly the point at which the LS7 is superior.

Seriously -- what % of the time do you run your Z over 5K RPM? I mean, except for your Talladega triumph...

 

Jawnathin -- my point was not about PEAK HP for the LS6 @ 6300 RPM, nor the 55 ft/lb extra torque the LS7 delivers. It was the way JoesC5's initial post made it seem as though the LT1 simply dies after 4K RPM (it does not, with fairly flat torque through at least 4500 RPM and peak HP @ 5900 RPM) and that the LS7's 55 ft/lb torque advantage is constant from 6300 RPM => 4K RPM (it is not; it grows more gradually). Simply meaning that peak numbers do not tell the whole story.

Lost in all this is that we all agree with what the Chevy folks are suggesting -- that the performance numbers for the C7 base should fall neatly between the C6 GS and the Z06. My provocative thought is: don't be shocked if the C7 winds up VERY close to the Z06 (especially if they were a bit conservative with the 450/450 estimate). Then again, if the C7 really does weigh 3300 lb, the Z06 should remain significantly superior

 

No matter the final weight, we know that it is 136 lbs less than it would have been with a steel frame and old body weight. To my thinking that pays off to the tune of 136 lbs.