Power setting and big tires

[Ldub]

Mostly, I'm talking about tires with similar width to stock. Certainly, no wider than 285mm and treaded for street. I think we can all conceed monster mudders have another purpose.

http://www.google.com/url?sa=t&rct=j...DQkWUlEwVSb2fQ

I think the most telling quote from the comments is:

"I agree with the sweet spot. Installing a vacuum gauge is the best method of finding it."

This is why, with the tires, etc that I run, I get better mileage with 4:77's than I did with 4:30's...

And yes, I know all my percentages, & how to properly manipulate the buttons on a calculator.

A little over 2k on the tach is my sweet spot, but the vac load @ whatever speed, with whatever gearing, with whatever tires, will be the tell.

Far too many variables for a definitive answer to a general question.

[89Vette]

Wow. I never drove my Corvette (on the hwy) between 40-60 -- for a LONG stretch. The only speed where I've measured MPG is 70. And, it was in the 30mpg range -- sixth gear.

About the slowest I'd drive in 6th w/o lugging is 60 -- even then steep uphills would require 5th. So, I'm not sure the same approximation applies to the vette. (If so, It must get well over 30mpg in reality.)

That vacuum idea is very good. Not sure how cheap/easy -- but good. OTOH, gut instinct had already told me much over 2k rpms would cause a drop in MPG.

The other issue (and part of the point of this thread), is whether the power option actually improves MPG (vs normal mode) for larger diameter tires -- especially for city driving.

:cheers:

[Ldub]

Wow. I never drove my Corvette (on the hwy) between 40-60 -- for a LONG stretch. The only speed where I've measured MPG is 70. And, it was in the 30mpg range -- sixth gear.

About the slowest I'd drive in 6th w/o lugging is 60 -- even then steep uphills would require 5th. So, I'm not sure the same approximation applies to the vette. (If so, It must get well over 30mpg in reality.)

So comparing apples & oranges shows me...what?

That vacuum idea is very good. Not sure how cheap/easy -- but good. OTOH, gut instinct had already told me much over 2k rpms would cause a drop in MPG.

...And gut instinct is a good substitute for???
Yeh, I'd go with that too...

Re: vac gauge...

Ummmm...yeah, you would have to be able to splice into a vac line, & find a firewall grommet, & mod a universal a pillar pod...not too difficult...

The other issue (and part of the point of this thread), is whether the power option actually improves MPG (vs normal mode) for larger diameter tires -- especially for city driving.

The tc locks @ lower rpm in "normal", @ hwy speed.

Power mode has never been a friend of mileage for me.

:cheers:...

[89Vette]

So comparing apples & oranges shows me...what?

Well, how great my Corvette is, of course!

...And gut instinct is a good substitute for???

Well, more accurate methods, of course.

Ummmm...yeah, you would have to be able to splice into a vac line, & find a firewall grommet, & mod a universal a pillar pod...not too difficult...

And, not spend any money for a short, temporary measurement!

The tc locks @ lower rpm in "normal", @ hwy speed.

Best I read the chart, it may not be much different with light throttle openings.

[89Vette]

BTW... Interesting cup holder(s). Where'd you find that? What's it hook into, the vent?

I also just got a HotWheels VX. I like where you keep yours!

[Ldub]

I also just got a HotWheels VX. I like where you keep yours!

It duzzin always work out so gud...

Sometimez it are fallz out da window @ thuh wrong time...

[89Vette]

OMG, doctor! I think the baby is breached!



Couldn't resist. First thing that came to mind (after "WTF...How he'd get that VX down there!")

[Ldub]

OMG, doctor! I think the baby is breached!



Couldn't resist. First thing that came to mind (after "WTF...How he'd get that VX down there!")

Oh that...

It required a "special" talent, that only I, & one other guy, (didn't Randii flop there that year too?) have mastered...