Rolling Road Day... results

[K11SS]

well i aint got any way to post the actual graph yet but i will get this up asap 4 you but i got ... 68.4 BHP from my standard Super S with only mod bein K&N which dont change much

was a really good day got some pics i think will post also asap

there was a 200sx there with 172bhp n a starlet turbo with 142 bhp my mate n his 2.0 vectra got 120 so it aint that bad

gonna start modding now exhaust to start then cams etc etc

 

[hughes_16v]

68bhp. your car should have 75 standard.

 

[Raceworx]

depends where you talking 68.4 at the wheels is good.... 75BHP will be the BHP at the fly...

 

[richmicratwista]

how come you lose BHP from the fly to wheels anyway??

 

[James]

Took this from "car-videos.com":



Horsepower and Torque "At the Wheels"

Now when we're talking about automobiles, the amount of horsepower or torque generated at the flywheel is not very useful when determining acceleration. What is useful, however, is horsepower and torque "at the wheels". The problem here is that drivetrains cannot be perfectly efficient and pass 100% of the power of the engine through its components to the wheels. Some of the power is lost for several reasons. Generally 15-25% of engine power never makes it to the wheels. Different types of drivetrains will have different levels of efficiency. Generally, drivetrains with more weight and those with more components will be less efficient.
Let's use my own car for some sample calculations. In stock form, it has 165 hp @ 5600 RPM and 166 lb-ft @ 4000 RPM.
Dyno results have shown that the car has around 127 peak hp at the wheels. That's a 23.03% loss. Note that this is higher than most cars because of the heavy and sophisticated all-wheel-drive system.
Here's a chart to show how the power and torque change before they reach the wheels. Although, the efficiency loss is difference for each gear, we'll assume that 127 peak hp is attainable in every gear. At 5600 RPM, the flywheel torque calculates as 154.7 lb-ft. Calculating the same efficiency loss (23.03%) as horsepower, this would come out to 119.1 lb-ft.

To prove the accuracy of the wheel torque numbers, let's look at the example of 1st gear. Using the Speed/RPM Calculator, we can determine that the vehicle will be traveling at approximately 27.5 mph in 1st gear at 5600 RPM. Using the Tire Size Calculator, we can determine that the circumference of the tire is approximately 78.16 inches. Let's calculate the RPM of the tire:​

27.5 mph = 145,200 ft/hour
145,200 ft/hour = 1,742,400 in/hour
1,742,400 in/hour = 22,294 revs/hour
22,294 revs/hour = 372 RPM​

Now we know that there is 127 hp generated at the wheels. If we use the horsepower formula above:​

127 HP = (Torque * 372 RPM) / 5252
667,004 = Torque * 372
Torque = 1793 lb-ft​

Notice the difference between 1793 and 1735. This is caused by the reduction of the tire's size when fitted onto the vehicle. ​

Hope that helped, if anything looks wrong there feel free to correct me

 

[Ben]

James, seriously - get a hobby lol too much time on ur hands, help me learn how to do this HTML lark lol

 

[goldstar0011]

But do you understand that James?!

All I know is the factory BHP is flywheel but wheel BHP is the real value (like RMS wattage for speakers)

 

[James]

Yes, the way I see it is it's all about losing energy and efficiently, you know - all that stuff in physics.

Some of the energy (15-25%) is lost to heat etc between the fly and the wheels, therefore the fly hp is always more than the wheel.

That's my take on it anyways.

 

[Titch]

You lose most power through Transmission, hence why the power at the Fly is always more that at the wheels. Thats where 75 brake is (at the Fly)

 

[mike]

68.4bhp at the wheels is around 86.4-89.4bhp at the fly depending on how well looked after the car is.

The transmission loss is between 18 and 21, dont let any RR tell you that the loss is more as these figures are from THE source of K11 tuning

 

[K11SS]

the guy who did it for me said it was bout 85 at the fly so im well chuffed

now to do exhaust n get the limiter raised