vB00STw

Is there any advantage to having a 6 speed tranny rather than a 5 speed?

tiny

more gears, higher top end, better gas mileage

but it all depends on what car it goes into

VaMP

Exactly what he said. It really depends on what kind of driving to you for a 6 speed to be better then a 5 speed. City driving, a 5 speed will be better because the lower gears are a bit longer. But highway travel, the 6 speed will be better because of what tiny said. Someone I know with a ZO6 said they can travel down the highway at 70mph in top gear getting over 40mpg....

DC52NV

well since my car doesn't have an armrest i use my 6th gear as a handrest. very comfortable. my car needs a 6th gear though due to my engine being high compression.

olddude

Yes, more gears, that allows the ratio to be closer between them (spanning about the same total gearing range). This allows the engine to be kept closer to its optimal powerband as gears are changed.

No, top end is seldom found by using an overdrive gear in a modern manual transmission. There is simply not enough engine power to spin it up near the peak power of the engine as you near top end. I cannot think of any double overdrive manual transmission in any vehicle that will get a higher top speed in 6th instead of 5th gear.

Maybe, it can lead to better fuel economy if you run fast enough on the highway (careful! If you lug the engine with 6th gear on the highway without enough speed, you may be far below the optimal volumetric efficiency of the engine and you will get worse economy in 6th vs. 5th.)

BeastlyTA

I loved having 6th gear in my Trans Am. Works really nicely for improving gas mileage.

UtOhCop

A Z06 will never get close to 30mpg let alone 40

avro206

Not 40 but it'll do damn close to 30mpg.

DC52NV

my POS acura doesn't even do 30mpg so i highly doubt a vette is close to that. lol

avro206

okay...here we go---since a few people have no clue as to V8 fuel mileage.

Z06 is rated at 26mpg highway. Now with the super tall 6th geat I bet that might be improved upon a little in the real world. Very common for LS1 F-bodies to get low 30's on the highway. An upside to an engine turning less then 2000rpm.

Whats the Acura do---? 3000rpm?

BeastlyTA

He's right. In my Trans Am I always got low 30's on the hwy and my buddy's '00 FRC Vette gets low 30's too, around 32-33 to be exact.

VaMP

I would like to let everyone know that that is what he claimed. I know he has some modifications done to his car, like tuning, port'n'polish, intake, ehaust....

Cobalt_Supercharged

It all depends on the engine and the gearing. Engines that lack low end torque, i.e. most imports, require a close ratio 6 speed to keep in the powerband. The big V8's use it to improve highway gas milage, by adding an extra overdrive. My dad actually increased his 1/4 mile time by switching from a 3 speed to a close ratio 5 speed in his 55 Chevy. He had to shift more, each shift is power not going to the ground. Had the gears been spaced further apart it might have been a different story.

Rad

my boss has a 2002 zo6, it gets amazing gas milage on the highway. over 40mpg

beerbaron105

its true, in overdrive those things are revving so low, they get excellent highway miles but poor city miles

my b16 civic had **** poor highway mileage, maybe because i was revving at 4000 rpm going 120km/h, horrible!

UtOhCop

IMO i think they should have used the 6spd from the Saab in the Cobalt SS.

97cavie24ls

you also gotta remember a Z06 has 3 times the amount of tq yours has , so it can run around in 6th gear at very low rpm , which helps with gas milage


i think the new 06 Z06 was rated at 26 or 28 on the highway

wesmanw02

It sounds like a no brainer, but there are many factors to consider. For the added cost of using a 6-speed unit, there would not be much of a performance or fuel economy gain. Reason being that the 5th gear in the SS S/C is low enough as it is for good economy, and the 2.0 Eco produces enough power down low that its not hard to keep the engine on the boil (it practically pulls from any RPM as it is )

Now vehicles such as the RSX-S benefit from a 6-speed purely for performance reasons. By having 6 closely spaced gear ratios, the engine can be kept in the powerband more of the time, which means better acceleration, but more shifting. For all those saying that the RSX-S gets better fuel economy on the highway than the SS S/C due to having the extra gear, you have to realize that the RSX-S actually has a higher final drive ratio in 6th than the SS S/C has in 5th gear. Meaning it cranks more RPM's on the highway than the SS S/C does, even though it has one extra gear. The reason for the RSX turning such high RPM's at highway speeds is because the engine doesn't have enough low-nd power to keep the car moving at highway speed in a taller ratio. The Type-S only produces 143ft/lbs of peak torque, meaning it's producing well below 100ft/lbs even at 2500RPM

Vehicles like the Corvette and GTO benefit from 6 speeds because they allow for an extra O/D gear when cruising. At 60MPH, the engines are only turning about 1400-1500RPM, which is practically idleing -yet there's plenty of power still available to keep the car moving without a struggle. So the first 4 gears are for acceleration, 5th is O/D gear 1, and 6th is O/D gear 2 for saving fuel and cruising

DC52NV

yeah, i'm aware of that. didn't mean for people to think i was serious on my post.

phxSS

My 6-speed Focus had worse gas mileage than my SS does.

97cavie24ls

its all good man

Eddie

my z28 when cruising 6th gear at around 70-75 gets low 30, hard part is keeping it that speed long enough to make gas mileage good lol.

MarcS

Wow, that's really good.

Eddie

city driving is what kills a v8's gas mileage. iknow if i'm in traffic my g/m takes a plunge south. but if i'm cruising w/ no traffic at 70, i'm doing good. if i keep it below 80. i swear cruis control is my friend on this car, i cant even tell if i'm doing 100+ in this car it just climbs w/ out even knowing. cruise control will save me from a whole lot of tickets lol.

MarcS

I love cruise control. My ride home from school on holidays and such is about 5 hours. It's makes the trip so much more tolerable.