Quote:
Originally Posted by mcrews
You said:......"all in all its not that bad driving around town but on the highways it runs into an issue. I have no problem doing 70 ir 80+ but. after 60mph the aero kills mpg. cruising @ 55mph @1850 rpm the scan gauge would net between 24 and 26mpg. @70mph @2500 rpm it would be getting 12-14mpg :/ and by 80 its down past 9mpg."
you 'claim to have done research'........
not here!
or you would have NEVER made the comment in red!
So here we go.......
It's the gearing, not the aero that kills the mpg after 60mph.
And reading ANY of the 70 posts on the topic would help you understand that.
Engines have a sweet spot.
Hell, my car is very aerodynamic and I've done all the right mods. But if I go above 70 the mpgs go down!!!!
It's because the engine is turning too many rpms and is past the sweet spot.
search ABA testing.
go find a stretch of freeway and run at 50, 60, 70 & 80. establish a base line for your stock vehicle. run a/c on and a/c off.
log it by resetting the sg each time.
If you run tires that are 6-7% taller (read my posts) then you can see that your speed will increase for the same rpm.
And again, IF YOU WOULD READ, you'd see that we arent talking about .
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tire to strut is not the only clearance issue with a car. assuming you are at stock height? and have no wheelwell clearance issues. or do you rub on tight turns but dont care?
jumping up from a 55-60 sidewall in my wheel size makes the tire go from 29-35lb. you do realize my stock tires are 27.7" right? and not a 24" I dont just have 18s and 40 series tires. my stock tires wouldnt even fit on your car so when it comes to the weight you wouldnt even understand.
and yes. even in drag racing when you cant go wider you go taller. but thats drag racing. ide have to go narrower and taller to keep a stock contact patch. wider and taller = larger contact patch and more drag. and try to find tires that will do that for 18s. or even 16s. (I cant place a wheel under 16" on my vehicle as it will hit the 11.1" brakes caliper.)
I may not be an economy guru but I know my cars and performance.
and apparently you have never dealt with a square vehicle? and gearing is not the easy fix for everything. any lower and ide be going 55 in 4th gear. 55 in 5th gear is hardly even giving it gas. you have to realize one small detail.
the older elements had a 4spd auto. and a 5spd manual. and the 4spd was fine to drive. the new 5spd auto is just the 4spd with an extra overdrive each gear and the final is all the same. they just added a .5xx after the .7xx so I really think the gearing and larger tires is far from an easy fix. dont get me wrong. if it was a 5spd manual with a .8xx 5th gear or the 4spd auto with the .7xx 4th gear YES it would be worth a shot.
does it look like a gearing problem?
apparently you've done some testing with your car and assume every vehicle is the same. if you would like me to prove to you that my vehicle has a crappy cd and over 60mph it gets much harder to force itself through the air I will.
hell if you dont believe me you can come visit and run the tests yourself.
@ 60+ it is so apparent the drag that I dont even need to use my brakes. let off the gas and it feels like im braking. and that is with a heavy set of wheels that wants to stay in motion not slow down.
clear enough for ya? I think its time you did more research...