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Discussion Starter · #1 ·
Does anyone have a reliable way to calculate Wheel Horsepower (WHP) versus Horsepower at the crankshaft (HP) ?

KIA lists the Forte SX at 201 horsepower. I assume that is at the crankshaft (HP)?

Or do I have this all backwards?
 

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We dyno'd stock @ 176 wheel HP. From what we've seen stock can range from high 160's to high 170's at the wheels depending on dyno, transmission, weather, etc.

A general rule of thumb is take 15-18% drivetrain loss for FWD or RWD cars and 22% to 25% for AWD cars.
 

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I'm sure there are some statistics about drive train efficient on our platform somewhere. I have no idea where. They may not even be public. But I would be very surprised if Kia/Hyundai doesn't know exactly how efficient our transmissions are at transferring power from the crank to the road.
 

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That auto dyno , I wonder if it was traction off or on . This car feels a lot more agressive when I disable the trac/stability . On a high load of the dyno I can bet it sets it off . I need to find a dyno day ha ha !
 

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My ballpark numbers I usually go with are similar to 6ths..... I usually say 14% for manuals and 20% for autos
 

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I don't think tcs would matter much on a Dyno because both drive wheels are spinning.... Tcs only works with the rear wheels in a braking situation
 
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I believe there is some variance for fuel used. I read somewhere that Kia's advertised hp number is using 87 octane fuel and running quality 93 octane gas can bump that figure up by 10-15hp once the ecu has adapted.
 

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I don't think tcs would matter much on a Dyno because both drive wheels are spinning.... Tcs only works with the rear wheels in a braking situation
Not exactly . On Kia turbo cars they also retard boost to control power . I'll try to log it when the next snow fall . I read about it on the Kia website then experienced it . The boost holds under 10 psi based on engine load and g sensors Take the traction off then bam 18 psi . On the auto it's worse that the manual . The acceleration Of a stock MT and AT being so close would as if not faster in the auto would either mean more power or more gearing to the ground transferring more usable power to the ground . I doubt it's the gearing or the power that's hindering it. If I get access in the spring to the dyno days ( most time because they love 50-70° pulls ) I'll see first hand
 

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Using the 201hp number and 6th's stock dyno numbers he would be at 12.5% with the M/T. Doing the same with mine it would put me at 17% (166 WHP stock). Someone with the same car as either of ours could easily get on a dyno and have different numbers. Everything from not just grade (87,89,91 or 93) of gas but quality of gas (was it Chevron, Mobil, BP, Shell?) will have an effect on results. Same goes for tires and wheels, lighter means less rotating mass to spin equaling more WHP to the ground. There are so many variables that come in to play that comparing a dyno from one end of the continent to a dyno from the other side is almost useless.
My stock run was done on a 98°F day with roughly 85%+or- humidity and intake temps of 150°F+ and was 166 whp. Seeing a 10-15 hp change from one day to another or place to another is to be expected and almost a guarantee.
 

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Discussion Starter · #13 ·
So 201 HP at the crank and 167 WHP for a stock A/T Forte5 SX? So roughly 17% loss? I guess I should have thought harder about getting the A/T! :(
Oh well, the wife needs to be able to drive it every so often! :D
 

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So 201 HP at the crank and 167 WHP for a stock A/T Forte5 SX? So roughly 17% loss? I guess I should have thought harder about getting the A/T! :(
Oh well, the wife needs to be able to drive it every so often! :D
Also got to remember the auto it a bit quicker then the manual for some reason. Like said above there is so many different things that can give different number. Someone can dyno and post 167WHP and they are back east from me and I can dyno and hit 180whp stock. Weather plays a big role to with numbers to, so if like playwithmymind says it was 85% humidity out and over here is only like 20% and the temp the same out I would probably still dyno higher.

Also is the dyno shops fan they are running on the front good enough to allow a ton of air on the I.C to keep temps down like you are driving on the hwy
 

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I haven't been able to find the gear ratios to look for a difference in auto vs manual.

But the auto puts down less power and is slightly heavier. No reason beyond different gearing for it to be faster at a certain speed. Other than just different testing conditions and manual driver skill. Manual should be substantially quicker with everything being equal.
 

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Ah finally did find them here, had to select the Koup to get relevant ones.
2016 Kia Forte Koup Specifications



So the Manual has taller gears but a shorter final drive. Someone that knows this better needs to explain exactly what that means heh. I just know that taller gear = less acceleration but higher top speed in that gear. But also have to factor in the final drive.
 

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Kia's crank hp numbers is about right for what the cars do stock, with how adaptive this ecu is depending on driving habits and fuel quality power can swing 10-15 hp within a few WOT pulls. pretty standard to use 15% loss for m/t and 20-25 for a/t.
 

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lol thinking outside temps we here me and Vin get 84 degree intake temps all day lol. so with the FMIC we may get even lower. Yeah its been a long standing fight over power numbers of north vs south and the cooler denser more humid air may have something to do with it in the PA area . As for why kia swapped numbers around on the AT and MT . It's always been the case that mt cars are more controllable than AT cars . So with high power , you are not spinning tires all day .They set it so on a Manual you can gauge your feel and want of acceleration as with an auto its push and go. A level 10 upgrade could fix that real quick for an auto changing the torque converter ha ha . But I'm fine with the current setup since I love curves more than 1/4 mile . A good read is looking up gear ratios and how they can help or hurt your build .
Another reason for kia running longer gears is you can get a better use out of the turbo boost range . I found this out with the VW golf 1,8T vs the VW gti 6 speed . the more power the golf made the more it could take the GTI. that may be the case with that the AT is faster .. If you look we have a longer gear ratio so even though you guys rev to 7500 we get the use of the turbos efficiency island more so before the 6500 rpm cut off . If you could understand the new optima 0-60 it works on the same principal with a car that is heavier and has even less power than mine but gets the same standard 0-60 numbers of 7.2 ( traction control enabled ) . But the gearing is more aggressive and they had to add that 7 to make a smooth transition or it would be a sucky jump from 5th to 6th
 

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I believe there is some variance for fuel used. I read somewhere that Kia's advertised hp number is using 87 octane fuel and running quality 93 octane gas can bump that figure up by 10-15hp once the ecu has adapted.
Where did you read that?
 
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