Copying the amazing 2011 hyundai elantra manual shift

[Ladogaboy]

According to Hyundai, the final drive is 4.333 / 3.065 (MT/AT).

[mans]

Originally Posted by Ladogaboy

According to Hyundai, the final drive is 4.333 / 3.065 (MT/AT).

4.06 for the manual '97 saturn

[Daox]

Originally Posted by mans

quoted from a magazine review of the 2011 hyundai elantra:

(quote
Cruising in sixth gear at around 80 mph with light throttle yields an impressive indicated average fuel economy of around 50 mpg...

I'm gonna have to call BS on this. It didn't seem right when I read it and it certainly doesn't seem right once I ran a few numbers.


Elantra:
Height - 56.5 in
Width - 69.9 in
Cd - .28
Cda - 6.45

Throwing those numbers into our aero and RR calculator shows that the engine would have to be running at 42% efficiency to get that mileage! Quoting wikipedia...

Modern gasoline engines have an maximum thermal efficiency of about 25% to 30% when used to power a car.

Also, if you compare it to some of the other vehicles in the speed vs mpg charts posted you'll find that number rediculously optimisitc. It even beats out the Prius which is a more aerodynamic and smaller vehicle and we know the atkinson cycle engine is more efficient than an otto cycle. The cda of the Prius is of 5.83, a solid 10% lower than Elantra. That means their engine has to be 10% + more efficient than the Prius to make up for the aero losses. Call me skeptical, but I don't see that happening.

[Ladogaboy]

It's the power of direct injection.

[Daox]

Are you seriously saying that direct injection is responsible for increasing an engine's efficiency by over 30%? That is diesel engine territory. Diesels get their additional efficiency from a lot more than direct injection.

I don't know what the writer was thinking when he wrote that, but its just bad journalism.

Allow me to backup my info a bit more. Here are some actual numbers on the Elantra's straight hwy mileage per a Popular Mechanics review. It still gets quite good mileage, but 50 mpg at 80 mph is not going to happen unless you can drive downhill to every destination you travel.
http://ecomodder.com/forum/showthrea...tml#post285060

[drmiller100]

Daox, where have you been????????

weeks and weeks go by with no moderator, and all of a sudden someone with some common sense shows up and screws everything up!!!

Will you be sticking around????

[PaleMelanesian]

Umm... the new Elantra isn't direct injected. The 1.6 in the Accent is, but the Elantra's 1.8 is still MPFI.

Wayne at CleanMPG tested the stickshift elantra with cruise control. RPM is about 2400 at 60 mph (ie not that great). Note that these numbers are right in line with PM's shown above.

MPH - MPG
60 - 46.9
65 - 44.3
70 - 39.1

50 mpg at 80 mph is dreaming. I believe you could see that for a moment on the instant mpg readout, but you couldn't maintain speed at that mpg level.

[tru]

Originally Posted by mans

quoted from a magazine review of the 2011 hyundai elantra:

(quote


Cruising in sixth gear at around 80 mph with light throttle yields an impressive indicated average fuel economy of around 50 mpg—helped, in part, by a tall top-gear ratio of 0.633. More erratic driving at lower speeds lowered our average to just below 30 mpg—spot on with the EPA city estimate of 29 mpg.

Read more: 2011 Hyundai Elantra Review - Hyundai Elantra Test Drive - Popular Mechanics"
(end quote)

I take this as, we let off the gas and the mpg's hit 50 briefly

[cfg83]

mans -

Originally Posted by mans

4.06 for the manual '97 saturn

I found this for playing with gear ratios :

Gear Ratio Calculator - Cargister

CarloSW2

[theycallmeebryan]

Originally Posted by tru

I take this as, we let off the gas and the mpg's hit 50 briefly

You beat me to it.

I could be driving a school bus equipped with a fuel gauge and it could read 50mpg for an instant if i let off the throttle on a downhill down 80mph, too.