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Discussion Starter · #1 · (Edited)
Forte speed in each gear. Manual, automatic, and DCT - years 2014-2017

Can you cite your source or show math calc please?
Yes, I can, sir.

So, even before I got into Forte SX I researched the car. I always compare gear ratios before I make a decision. Actually, I initially was not so happy with Forte SX MT as the gears are so short and 6th being way shorter than my 2009 Elantra that was 5 speed.
Anyway, then I did same thing with my trade of Forte MT into AT.
See the graph showing calculated, theoretical speeds in each gear vs engine speed. It is calculated using information found on KIA Media and Service manual found online. Either both are wrong or I correct... Links below.

2016 Kia Forte5 Specifications
and
Second generation YD (2014-2016)

As for calculations - it goes as follows.

(everything in metric system).

Engine speed / gear ratio / final ratio x wheel circumference

Unit check:
engine speed: revolution/minute
gear ratios: unitless
wheel circ.: mm*

* - actually it should be mm/revolution. The problem is that this is lenght that the car will cover during one revolution of the wheel. Otherwise, the units check will not work...

You must add conversion to seconds (60s/minute) and then 3.6 to get m/s into km/h

Then, you set two points: say 5000 rpm and 7500 rpm. This will give you two points for the graph. Do it for each gear and you land with sets of coordinates for your graph

Disclaimer:
The final result might be a little off due to conversion into miles/hour. I simply used 1.6 factor instead of 1.60934... Also, I used the ideal size of the wheel. More wear on the rubber, or different size, or even different pressure will cause some minimal changes.


Dashed lines: MT
Solid lines: AT



I hope that covers the topic.
If more comments are needed, please do not hesitate to ask.
Transmission 200.jpg


Now, since information is available... let's add 2017 into it.

Manual is exactly same. There is no automatic anymore and instead you get DCT. 7 speed dual clutch.

Graph is attached. Compares DCT and MT.
Basically all gears are taller starting 3rd. 6th is very tall, even higher than 6th in Auto, while 7th - that is like a low engine speed cruising. I bet with any movement of the gas it will be dropped out on a highway.

Transmission DCT.jpg


And one more. Per request.

2017 DCT (solid) and 2016 AT (dashed).

Transmission 2017 DCT 2016 AT.jpg
 

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That looks dead on with RPMs on my Auto at any given speed in gear. I've ran to 135 mph plus several times and it shifts out of 5th into 6th right around 130 mph. Cruise at 80 mph in 6th yields 3k rpm so your conversion seems solid to my anecdotal evidence
 

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Discussion Starter · #3 ·
2017 DCT added as well.
 
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Wow that much taller gearing in 3rd up may actually make the new dct slower than the 6spd auto. really there's a spread advantage but it's all top end with taller gears more suited to improved mpg over acceleration. Has any sites or mags posted an instrumented test of the 1.6t and 7spd fortes? I seem to recall that C/D test of the new VT yielded slower times than before.
 

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Could you do a chart overlaying the new dct vs 6spd auto... just curious to see a visual representation of how much they actually differ
 

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Discussion Starter · #6 · (Edited)
Wow that much taller gearing in 3rd up may actually make the new dct slower than the 6spd auto. really there's a spread advantage but it's all top end with taller gears more suited to improved mpg over acceleration. Has any sites or mags posted an instrumented test of the 1.6t and 7spd fortes? I seem to recall that C/D test of the new VT yielded slower times than before.
Well, the engine mapping is different now.
It allegedly can hit max torque at 1500 rpm... so maybe that's the reason they added so tall gears. Regardless, none of the transmissions allow for hitting 60 mph in 2nd gear.

I wonder what is better - shorter quicker gears or a bit longer, taller ones when it comes to 1/4 mile or 0-60. On one hand short gears would be better for better using the power band, but then longer gear is better for turbo...


Anyway, per request, graph attached above. This time DCT is solid and AT dashed.
I though about putting all three together, but the graph was too crowded to see anything.


EDIT.
Oh, and speaking of tall gears. You should see Optima Turbo. 6th gear can take you all the way to 250 mph at 6500 rpm. Hence, it means that at 1820 RPM you cruise at about 70 mph... and that is automatic, not DCT. Darn tall gears. However, Optima T gives you 260 lb*ft at 1350 rpm... that is - WOW.
 

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Does anyone make an overdrive sixth gear for our manuals? I'm surprised how short geared it is, reminds me of my '86 Jetta GLI and especially with a sixth gear there it seems there is no reason it shouldn't be taller and get a bit better freeway mileage. I know the trans itself is made by Mitsubishi but I'm sure it's made to the ratio Kia specified and I'm still just utterly shocked Kia dropped the ball on this to get better fuel economy.
 

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Discussion Starter · #10 ·
Does anyone make an overdrive sixth gear for our manuals?
Nope... but you could drop in 6 speed (AT) from Sonata and have very long gears...

I also disliked very short gears. I mean all of them. 1st is very short. You do not even reach 60 mph in 2nd. I would rather have 5 gears with much larger ratios. And the transmission was the main reason I traded it in for automatic.
Still, though, AT has short gears. 6th is taller at least.
 
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