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My APR K04 install,experience

Banshee1

Go Kart Champion
sorry... I meant a constant amount of power lost regardless of how much horsepower or torque the engine makes. Example: a constant 25hp lost whether the engine is making 200 or 300 hp. But I suppose that point is moot because more power usually means higher temps which would increase drivetrain loss.

I really should stay away from these technical questions...
 

grambles423

Automotive Engineer
sorry... I meant a constant amount of power lost regardless of how much horsepower or torque the engine makes. Example: a constant 25hp lost whether the engine is making 200 or 300 hp. But I suppose that point is moot because more power usually means higher temps which would increase drivetrain loss.

I really should stay away from these technical questions...

No no, I see what you mean. I think I have a fair answer for you.

In regards to the question, both instances you described are roughly the same thing, except one is a percentage function of the power provide which would increase with power increases and the other is just a constant 25HP off.

200 HP at assumed 10% loss = 180WHP
150 HP at assumed 10% loss = 135WHP
200 HP at 25HP constant assumed loss = 175WHP (12.5%)
150 HP at 25HP constant assumed loss = 125WHP (17%)

However, lets get technical with it:

What makes the power? The force pushing down on the piston which turns the crank. This force is generated by a number of things (Cylinder Pressure, Temperature, Fuel Heating value, Bore, Stroke, etc. etc.)

The engine power is roughly described, in theory, like this. Taken from another thread I did this in:

Brake Horsepower (Watts) = N*Displacement(in cubic Meters)* (RPM/2)* nc*nm*nth*nv*Qhv*(F/A)*Air Density

N = Number of cylinders
Displacement = Bore*Stroke*pi/4
RPM/2 = Must be placed in Revs/Second = RPM/2 * (1/60 {s/min})
nc = Combustion efficiency = about .98-.99 on newer cars (can be calculated further, but these estimations are fine)
nm = mechanical efficiency = Function of RPM/heat/etc range of about .8-.93 (can be calculated further, but these estimations are fine)
nv = volumetric efficiency (what percentage is your TB open?)= 100% at WOT (Possibly a little more depending on the flow. Most I've seen is 108%)
nth = thermal efficiency = 0.8*(1-[compression ratio^(-.35)])
Qhv = Heating value of the fuel = 43,000,000 J/kg

Air Density = Pressure Entering / (287.2 J/kg-K * Intake Temperature)
Pressure Entering = Atmospheric Pressure * Pressure Ratio (This is a function of RPM) - J/m^3

Now that you have the power the engine makes you can determine how much force can be placed on the crankshaft to provide the neccessary torque at the flywheel. This is a function of material properties and mechanical efficiencies which decrease/increase throughout the rev band due to fluids heating up and metal expanding when hot.

Nevertheless........what an automaker displays as their "specific output" is what it has been measured at on the engine dyno and calculated through various equations and testing.

NOW...onto Driveline loss

Now that you know what your engine makes how do you quantify it through the wheels?

Easy: Power = Difference in Kinetic Energy over the amount of time it takes

Easiest way to do that is to dyno it in a controlled enviorment. Normally, this "constant" weight and constant air temp and etc. etc. is propelled by your wheels. This is a great indication of the power through your wheels...but it doesnt really coorelate to what your engine is making because of the weight of the driveshafts, gears, wheels, tires, hubs, etc. etc.

You could do a velocity run with a certain scan rate in VAGCOM but that accounts for drag forces which will make your power output significantly lower.

So how can you relate wheel HP to crank then? Well....you can theorhetically calculate it, but that leaves room for error (Plus it gets really confusing quick. Fluids dynamics + thermodynamics + variating degrees of freedom, frictional factors, stress analysis, plastic yielding effects with respect to temp), or you can do a very long process:

1) Dyno your engine
2) Using the same dyno, dyno your engine + Trans (1 for every gear since the mass changes for different gears
3) Using the same dyno, dyno your engine + trans + driveshafts
4) Using the same dyno, dyno your E + T + DS + Hubs
5) Using same dyno, dyno your E + T + DS + Hub + Wheels

This will take various fixtures to mount the dyno to...but would be one of the most accurate ways to relate your efficiencies together and finally provide a coorelation between brake and wheel horesepower.

Whats easier? Assuming constant percentage difference calculated from factory dyno and vendor dyno? or the process described above? Remember, no dyno is the same. All calibrations are different for various altitudes and temperatures and etc. etc.

1/4 Mile times are a good indication of power. Its as simple as how long did it take to propel this 3000lb vehicle in a 1/4 mile and what was its final speed?
 

bvlgari

Ready to race!
Can anyone tell me why I have so much hp lost when I did my dyno at dyno dynamic machine? My ride is only 4 months old, stock gti mk6 dsg, and 18 inch wheel with toyo R1R.
Whp: 171
Wtq: 180

I thought this car should have 210hp and 260 torque. I sent my car to vw service center, they said everything is all right, the reason I got such low hp is cause by the wheel (18 inch so is heavier) and the tyre and dyno dynamic will show lesser whp compare to other dyno machine like dynojet.. Also they told me the torque I'm getting is exactly 260 torque (manufacture number), apparently they said theres a format for them to refer. this is like 20% lost in hp and 30% lost in torque..

Somehow I feel something doesn't make sense here..
 

Banshee1

Go Kart Champion
Your technical knowledge is immensely superior!

Most of it makes sense. Thanks dood
 

grambles423

Automotive Engineer
Your technical knowledge is immensely superior!

Most of it makes sense. Thanks dood

I hope it did man. I felt I got lost in a sea of physics there for a second.

Back on Topic: Apologies gregprep :)
 

Evan@APR

Banned
ok, i see your stage 2 dynos. I think that's fair then. WHP verse brake hp is obviously different. Originally i was referring to brake hp.
I also have only seen k04 dynos on 91 octane. Have you seen any on 93 with the version 2 tune? The only thing i can find on youtube is 313 whp on the version 1 tune.

I think we're splitting hairs here. If you take 80 brake horsepower, with 15% drivetrain loss, you are looking at 68 whp. If you did it with 90 brake horsepower, you are at 76.5 whp. If you take APR's number of 366 hp minus stage 2 of 274, you are at 92 horsepower. So it's pretty close.

Greg.... I know it's not 93, but there's some solid APR K04 dyno info from CA in this thread: http://forums.vwvortex.com/showthre...x-Take-Two&p=75230311&viewfull=1#post75230311
 
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gregsju29

Go Kart Champion
cool, thanks Evan. 313 whp on 91 with the s3 intercooler is pretty nice. That's right at 360 brake hp. I know USP is having their party coming up in February which is half off dyno services, maybe i'll dyno on 93 and see if I come up with anything different. I know with the stage 1 tune there's only 4 hp difference, but maybe with k04, it's a little more.
 

Isj

Go Kart Champion
cool, thanks Evan. 313 whp on 91 with the s3 intercooler is pretty nice. That's right at 360 brake hp. I know USP is having their party coming up in February which is half off dyno services, maybe i'll dyno on 93 and see if I come up with anything different. I know with the stage 1 tune there's only 4 hp difference, but maybe with k04, it's a little more.

Found a dyno vid USP motorsport put up with the k04 v2 software. I'm sure this is with 93 octane

 

gregsju29

Go Kart Champion
Well I have put about 800 miles on my car since going k04, and my clutch is already slipping. As a background, I only have 4k miles on the car/clutch, so I was hoping to get at least 10k out of the clutch. It's definitely still driveable, and the more it heats up, the better it feels. However, I wasn't expecting it to slip so soon. It slips the worst in third and 4th, but I can even feel it slip a little in 6th on the highway when flooring it. With install, that should be about another $2k invested. k04 is not for the faint of heart!
 
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