Will 3.08 Gears Improve MPG? My Friend Think it Will.....I Don't

[Tony_GT_14]

I love my 3.73's and average 26-27mpg@60mph (I drive 36 miles one way per day). I have no intention of switching gears, but my friend is arguing that 3.08's will improve my MPG's.

I think it would drop the RPM's too low at 60mph, lug the motor, and possible cause the same if not worse gas mileage.


What's everyone think?

 

[manolith]

I think it would save but you will more than likely have to cruise at a faster speed. Somewhere around 75mph and you might see a small increase in mpg. Not because the car is not consuming more fuel but because its covering more distance with only slightly more of fuel then at 60mph on 3.75s. Sorry I'm a bit buzz tonight and start to think nerdy.

 

[hitmix300]

i avg 2mpg better than my friends 3.73 2011

i have a 3.15 2013

the truth is though you will never be able to calculate the mpg perfectly. way to many variables like hills, wind speed, fuel quality, temperature outside & much more. your RPMs are lower at the same speed = better mpg, in my head op:

 

[turbosha]

You will lose some torque will 3.08's so the engine may work harder to accelerate . Thus use more fuel. I think 3.31's is a good balance of acceleration and mpg's.

 

[Tony_GT_14]

Thanks for the replies! I have no intention of changing my gears (LOVE the acceleration). But my friend was just absolutely sure that 3.08's would HAVE to improve mileage at 60mph. I live on country roads and figured it up today and the computer is about dead on. I'm happy with 26-27.

I just think at 60mph 3.08's wouldn't do a damn thing. The RPM's would just be too low and lug it. IMO.

Keep the thoughts coming! Thanks!epper::banana::dancenana:

 

[manolith]

right now i would settle with 3.08s lol. i am not sure if i have the balls to do a top speed run with them on big and littles. at 7k rpm 188mph and 200+ at 7500. i doubt the stock shortblock would last long enough to reach those speeds with the power it would require anyways.

 

[SCalla1384]

Around town no. Highway yes.

Around town with 3.08's you'd have to give the gas pedal more effort. That's what affects gas mileage more then rpm.

 

[kingnut]

If you were cruising all day the 308's would definitely get better gas mileage. The car isnt going to be bucking at 60 mph in 6th due to low rpms.

 

[Tony_GT_14]

Damn, looks like I lost my argument. :cryying:

Still wouldn't give up my 3.73's! I'm extremely pleased with 26+mpg :thumbsup:

 

[clbailey]

Yep had 3.08s in my 75 camaro. Upgrade improved the mileage as I had to string the lower gears out to just get up to speed.

 

[65sohc]

Around town no. Highway yes.

Around town with 3.08's you'd have to give the gas pedal more effort. That's what affects gas mileage more then rpm.

Actually the opposite is true. Best mpg is achieved with a combination of large throttle opening (less pumping loss) and low rpm (less frictional loss). With TiVVT it is almost impossible to "lug" one of these engines. My Boss is perfectly content to cruise at 40 mph in 6th gear so I would imagine 60 with 3.08's wouldn't be a problem.

 

[Zevox]

I only get like 20mpg with my 3.73's so if you're getting 26-27 I wouldn't think of changing them, which it seems like you aren't.

I have to say we had a truck with 4.10's one time and traded it for one with 3.73's and I know every truck is different but the one with 4.10's got like 2mpg better. Same with my truck I traded in for this car. I had 4.10's and was getting around 17-18mpg and my Dad's truck with 3.55's gets around 15-16. So higher isn't always better for fuel mileage...

 

[acrbill]

I would guess there is an easy way to figure it out. Calculate what RPM the 3.08s would put you at then lower your speed until you hit that RPM with the 3.73s.