c5vette73

Will there be a significant difference in fuel economy between base and Z51?

jdhommert

Probably about 1-2 MPG. Base has LRR tires and a .42 7th gear compared to a .48

elegant

Car for car, about 1 MPG. However, I will predict that Z-51 owners have a much heavier right foot, resulting in at least 2 MPG less.

OnPoint

I can't imagine even worrying about it on a modern Corvette. IMO they get - and have since C5 - impressive fuel mileage, particularly considering their performance.

sallen619

I'm disappointed that Z51 will not have the same 7th gear as the Base car. The 7th gear should be just for fuel economy.

rcallen484

Aren't the trannies the same with the difference due solely to rear end ratios?

VRMMMM

Z51 for me, I am fine with giving up 1 or 2 or whatever mpg, hell I'm only getting 18 mpg average now with my 2010 Camaro SS. I am sure I will be very happy with the improvement in more than one way.

RocketGuy3

Rear end ratio? You mean final drive ratio? I don't think I've ever heard the term "rear end ratio".

rcallen484

Final drive ratio takes transmission gear ratio AND differential (rear end) ratio BOTH into account in arriving at its figure. You really don't know the rear end ratio of your Corvette? Very basic concept.
http://forums.corvetteforum.com/c1-a...ar-ratios.html

sallen619

Nope.

I believe the automatic Z51's get a different rear end ratio.

The manuals (not sure if this includes the automatics) have a different 1st-3rd, 5th, (6th?) and 7th gears in the transmission.

BRCC

Correct, the Auto's standard rear axle is 2.56 and Auto Z is 2.73, internals on the 6L80 remain the same.

Gearhead Jim

Really?

JoesC5

The auto's have the same transmission ratios but the base has the 2.56 rear end and the Z51 has the 2.73 read end.

For the manuals, all have the same rear end but the transmission gear ratios are different between the base and the Z51. The only transmission gear that is the same for both is 4th gear at 1:1

Auto trans has the same rear gear ratios at the base C6/Z06 and the manual trans base C7 has the same transmission ratios as the base C6/Z06 and the C7 Z51 has the same ratios as the c6 Z51/GS.

The manual trans is only different between the C6 and the C7 in that the C7 has that 7th gear added(.42 on the base and .48 on the Z51).

rcallen484

Thank you for that comprehensive explanation

RocketGuy3

It's possible that I've been using the term "final drive ratio" as a misnomer. I always thought final drive ratio referred to the ratio from the output of the transmission (so not including the transmission gearing) to the wheels. So changing anything from the driveshaft to the wheel diameter could impact it, but it sounds like my definition was wrong.

EDIT: But I guess even given that definition, the term "rear axle ratio" still can make sense if it just describes the ratio of the driveshaft to the rear axle or something?

Gearhead Jim

For me, the simple way to think of "rear end ratio": how many turns of the driveshaft going into the differential does it take to produce one turn of the axle(s)?

If it takes 3 turns of the driveshaft to get one turn of the axle, then we say it has a rear end ratio of 3.00

Understanding what's happening is easy, it's the vocabulary that trips us up.

rrm

The new 911TT and the s model don't even offer a manual trany. Porsche has maintained for some time that the "tipt" is faster in shifting than is the manual no matter who is driving. Thus the 0-60 times of 3.4 with the auto and 3.6I with the manual. I have had both a 911TT and a 2009 ZO6 but I still have to ask. Do the 2009-2012 GS Vette proclaim the same?...rrm

Bill17601

So do us all a favor..relate that to the OP. does that mean a Z51 gets less miles per gallon? Or does that mean a Porsche gets better gas mileage because it is lacking in horsepower?

SCM_Crash

Wrong topic?

AORoads

I'm not sure what you are asking. The OP started by asking about mpg difference, if any, betw. base and Z51. The topic moved to gears in trans and rear axle ratio. And included auto and manual trans ratios.

Which one of the three topics above is your question?