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Was playing with Excel this evening :eek: and threw together a little spreadsheet comparing these two combos. I thought the results were interesting and thought I'd share.

I started here (INVALID LINK), figuring it was as good a source as any other for rough numbers. I used the peak torque (and corresponding RPM) and peak HP (and etc., etc.) and then "fudged" a torque curve for each. This could be updated with real numbers later but look like this for the LS3:
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and like this for the L99:
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The HP numbers are calculated from the fabricated torque numbers. (I also plucked two numbers from the air for drivetrain loss. I plugged in 12% for the manual and 14% for the automatic.)

For those who like visuals:
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and:
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This was just the "make up a working model" part. The interesting part, I thought, was then plotting rear wheel torque in each gear as a function of vehicle speed.

In the following two graphs, ignore the diagnal lines and look at the eyebrow-shaped curves that step down from left to right. This represents gears one through six, respectively. The left vertical axis shows rear wheel torque and the horizontal axis is MPH (note that this is not time!)
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and:
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You'll notice that the automatic has a rather aggressive first gear. It probably just barely touches first in normal driving but I'm betting it'll be a beast at stoplights. :cool:

Another thing to note is that the inevitable question when the cars start getting here of "when to shift" is obvious. Every gear is more powerful through its entire powerband than the gear above it (number-wise.) You should always aim for redline.

If anyone's interested, I can update the power numbers when we start getting dyno baselines from real cars. Doing the same thing for the V6 is a possibility, too...

EDIT: I adjusted the numbers in the "table" sections for both engines, which resulted in minor changes to the graphs, so I have corrected them in this post.
 

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Discussion Starter · #3 ·
While I was making the corrections above, I extended the model to do time-to-speed & time-to-distance calculations, too. Below are some results -- view them as rough predictions more than estimates. I think they are close enough to validate the model, though...



 

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Discussion Starter · #7 ·
As we start getting real world numbers, I'll modify my spreadsheet to more completely reflect reality, improving the model a slice at a time. I'm pretty please to have taken just peak HP & torque numbers, combine them with gearing & weight, mix in a few physics fundamentals, and get reasonable results on the first pass that are within the realm of expectations.
 
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