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Is it true the M7 version of a z51 has slightly steeper gears than a base non z51? Thus making the z51 slightly quicker than a base car with all things being equal ?
Is it true the M7 version of a z51 has slightly steeper gears than a base non z51? Thus making the z51 slightly quicker than a base car with all things being equal ?
The gear ratios are optimized for track work on the Z51, whereas the non Z51 gear ratios are a bit more street friendly. As for being faster that will be up to the driver.
The gear ratios are optimized for track work on the Z51, whereas the non Z51 gear ratios are a bit more street friendly. As for being faster that will be up to the driver.
On the street say I am in 3rd at 45 mph and I give it some gas- can you feel the difference between the base and the z51 in the acceleration? I have the base and always wondered what effect the performance gears had on acceleration.
On the street say I am in 3rd at 45 mph and I give it some gas- can you feel the difference between the base and the z51 in the acceleration? I have the base and always wondered what effect the performance gears had on acceleration.
At a drag strip....IF there are 0 traction issues the z51 will run to the 60 & 300 ft quicker and untimely be a lower ET than a base car with taller gears 1-4.
that being said i also believe the base car "might" run 1-2 mph faster at the strip.
It technically a hair faster but I believe the main reason is to the gearing optimized for the tracks so that you are in the optimized gears coming into and existing the turns. I had the same thing on a 1LE Camaro, they use the Z51 gearing. I have a base C7 M7 now, I can't really tell the difference. It is just flat out fast in all gears...
As a guy who has owned both, if you are going to daily-drive it at all, I'd recommend the base. I feel like I'm shifting less in traffic with the base.
ist, 2nd and 3rd gear are a little shorter in a z51 car. 0 - 60 should be a tenth quicker and 1/4 mile et a tenth or 2 quicker. 4th gear is 1 to 1 in both trans and shouldn't effect MPH in a 1/4mile race. MPH isn't important anyway in the 1/4, ET wins.
Pole to pole or light to light street racing the Z51 should be quicker if all is the same.
At a drag strip....IF there are 0 traction issues the z51 will run to the 60 & 300 ft quicker and untimely be a lower ET than a base car with taller gears 1-4.
that being said i also believe the base car "might" run 1-2 mph faster at the strip.
I believe the base could be just A little quicker with no options.With A Z51
Loaded up with options is heavier.
They lowered the 1st gear to help the 0-60 but 4th is the same. They increased the spread between the gears 1-4. Making the base closer ratio and has the better ratio's. The base is stronger strength wise too!
Perhaps of interest, the Z06 has a 2:29 first gear, which has more to do with strength than not needing the 2.97 1st gear in the GS/Z51 for power!
Tremic rates the torque capability based on the max achievable torque, which is 1st gear.
The 2.97:1 is rated at 460 ft-lbs = LT1
The 2.29:1 is rated at 635 ft-lbs slightly under the Z06, LT4.
Then how do they deal with the extra torque of the ZR1? Wondered, then it was reported that limit ZR1 engine torque when in 1st gear! The tires could not handle anyway!
But they did one thing with the ZR1, they beefed up the spider gears that are a weak link in all C7's.
So those who plan on increasing the power of the LT1 or think they would benefit with the 2.97 gears in a Z06 when using slicks-best get the new spider gears!
I believe the base could be just A little quicker with no options.With A Z51
Loaded up with options is heavier.
I also believe that to be true. I purposely ordered my base 1lt manual car with the ZF1 package for the Z51 tires and wheels. The car at least 100 lbs lighter than a Z51 car making 0 -60 times the same.
Tadge also published the drag numbers and the Z51spoiler adds downforce at the expense of drag. It will reduce trap speed.
Personally, I don't think the very small Z51 rear spoiler will hurt MPH in a 1/4mile drag where speeds are only 115 to 118 mph for no more than a second. I have not seen stock Z51 cars trapping any different than base stock stingrays with manual transmissions. For the street I will take the lower weight any day.
Tadge shows a CD of 0.30 for the base car and 0.35 for the Z51. That is 16.7% higher! Drag is a factor at highway speeds and is proportional to speed squared so at 115 it is a big factor. It's the highest percentage of the required HP at 75 mph! That's what MPG is better at 55 mph.
Getting and apples to apples comparison at a drag strip is not easy. There are equations that can quantify the difference using the drag coefficient and the frontal area (that you can estimate) that will tell you the difference in HP required at a given speed.
PS: Looked this up to start you off: Air drag is the major force slowing a car at speed.
This is a simple equation and you can google to quantify the extra hp needed at 100 mph with a Cd of 0.30 versus 0.35:
Air Force pushing on car = FAir = A/2 × Cd × D × v2 with
A frontal area of the car in m2,
Cd drag coefficient,
D density of air (1.29 kg/m3) and
v velocity in m/sec.
Rationalizing the 2 equations for cars with the same frontal area, the aerodynamic force required to propel that car at the same speed (past 60/75 mph where it is most significant use of hp) is proportional to the difference in Cd, therefore the Z51 will talk 16.7% more force or 16.7% more hp (again from about 75 to 115 mph.) Spoilers add drag!
Tadge shows a CD of 0.30 for the base car and 0.35 for the Z51. That is 16.7% higher! Drag is a factor at highway speeds and is proportional to speed squared so at 115 it is a factor. It's most of the required HP at 75 mph! That's what MPG is better at 55 mph.\
Getting and apples to apples comparison at a drag strip is not easy. There are equations that can quantify the difference using the drag coefficient and the frontal area (that you can estimate) that will tell you the difference in HP required at a given speed.
Interesting info for sure. Are there any other factors on a Z51 car like different front air deflectors or spoilers, wider tire and wheels and extra weight that create more drag and not as slippery cutting thru the air ??
^^
Well it does not have a center front air dam that increases drag! The Chevy Volt has an air dam as low as the Vette as GM states to increase mpg on the highway! It was eliminated on the Z51, many Z06 and Grand Sports (like mine) as Tadge finally admitted to reduce the tendency for oversteer at very high speeds! They require slight understeer at high speeds. It performs both functions, reduced drag and provides front end downforce. To much front end downforce promotes oversteer!
Spoilers add drag. Visualize sticking a board the size of the spoiler out the window at 75 mph! Probably could not hold on to it! For the same downforce a wing produces less drag and if you can properly configure a diffuser it would be even less drag for the same downforce. An F1 racecar can generate over 1000 pounds of downforce with a diffuser! Between the diffuser and front and rear wings the car generates more downforce than it's 1550 pounds! It could drive on the ceiling!
Probably the simplest thing to do to cut drag is to lower the car.
Some information about spoilers on the decklid. 1/4" to 1/2" tall spoiler will actually decrease the car's coefficient of drag and not increase downforce.
My Mercedes sedan has a 1/4" tall stamped in spoiler(Gurney lip) on the steel deck lid who's purpose is the make the car slip through the airstream saving fuel. It's purpose is not to increase downforce.
1/2"to 1" tall spoiler(Gurney lip) will NOT increase the car's coefficient of drag but will add some downforce.
My C6 Z06 has a rear spoiler(Gurney lip) that is 7/8" inch tall that is designed to increase downforce while not adding aero drag.
Spoilers above 1" in height will add both drag and downforce.
^^^ That was an approach used to reduce low pressure that forms behind the car so they did not have to use a long tapered tail!
Have lots or auto aero info in this PDF I condensed from a 300 page book I recently purchased on race car aero to better understand diffusers- if interested: http://netwelding.com/Rear_Diffuser.pdf
Below are some pics of cars I mention including one with a small spoiler type lip.
Early Ferrari used the upturned rear bill to reduce the low pressure area formed behind car that essentially pulled it back!
This old long tail Porsche used another approach to get smother air flow behind the car.
Even this very early Bugatti used a tapered tail! That's Ettore Bugatti who know something about aerodynamics but not what is known today! F1 teams spend millions improving their cars with their own wind tunnel testing and computer programs during the season to make small gains race to race!
06-15-2018, 08:07 PM
M7 Z51 vs Base gear ratios?
Tadge also published the drag numbers and the Z51spoiler adds downforce at the expense of drag. It will reduce trap speed.
