BR-Performance Stage I M5 F10 + RPi GTM Exhaust + Downpipes

[MCarsFan]

Originally Posted by gmd2003

My stock tune M6 CP tops out at 169mph on the speedometer which in my car is 159 mph gps by vbox . So all good but you need to go faster to prove no limiter

That's great for you - all our speedos on our cars over-read..M5s are mass produced so I am pretty certain all of our cars are pretty close in terms of specs stock. You're probably doing around 155-159 mph, but I don't need to prove anything.

I have driven cars before and seen what happens when the limiter is there - the car starts to shut down power and shudder. I have seen my M5 on this very Dyno at 155mph shut down in 5th before I got the remap done. On this same Dyno after being remapped it was doing 169mph in 5th. In 5th..

That was the Dyno speedometer measuring speed, not my cars. Dyno's measure true speed, the margin for error on a roller is less. EAS was used specifically to remove this type of argument. Most guys in SoCal know EAS and know their Dyno. This is a two wheel drive Dyno. Front wheels are on blocks and the speed is measured by the Dyno, not by the car.

[gmd2003]

Originally Posted by MCarsFan

That's great for you - all our speedos on our cars over-read..M5s are mass produced so I am pretty certain all of our cars are pretty close in terms of specs stock. You're probably doing around 155-159 mph, but I don't need to prove anything.

I have driven cars before and seen what happens when the limiter is there - the car starts to shut down power and shudder. I have seen my M5 on this very Dyno at 155mph shut down in 5th before I got the remap done. On this same Dyno after being remapped it was doing 169mph in 5th. In 5th..

That was the Dyno speedometer measuring speed, not my cars. Dyno's measure true speed, the margin for error on a roller is less. EAS was used specifically to remove this type of argument. Most guys in SoCal know EAS and know their Dyno. This is a two wheel drive Dyno. Front wheels are on blocks and the speed is measured by the Dyno, not by the car.

I said in my post it was 159 mph by 20hz gps lol . The dyno is measuring the roller speed , the actual cars speed is affected by tire / wheel total diameter , hell even tire pressure affects that . So no the "dyno speed" is far from definitive even if it is calibrated to your exact wheel/ tire diameter which I seriously doubt it was . Just run the damn car on a track a post a real Gps speed , 1/4 mile ET /trap, 60-130mph etc . I could care less what it dyno's to be honest although a delta from stock or a previous tune would be helpful . I know the ECU is cracked and its a real tune , I and many others want to see what it can actually do in real life .should be well into the 130's trap .

[MCarsFan]

Originally Posted by boots

Your very welcome Br-performance. For those of us who chose to send in our ecu to you are grateful that you guys cracked the code, provided a solid tune and provide us great service. As you already know Rob and Gunder are happy w the way their cars drive. And since I drove Gunders car before he did after receiving the tune I know for a fact that his car runs like a bat out out of hell. Mine arrives late tomorrow and I appreciate how efficient the turn around time was due to my work schedule so be prepared for a review once installed on Friday.
Btw, I told Gunder what you said in our email and had him
Brian C.

Look forward to your review!

[Boss330]

Originally Posted by gmd2003

The dyno is measuring the roller speed , the actual cars speed is affected by tire / wheel total diameter , hell even tire pressure affects that . So no the "dyno speed" is far from definitive even if it is calibrated to your exact wheel/ tire diameter which I seriously doubt it was.

You might want to rethink that statement

The velocity of the surface of the tire equals the velocity of the car (not counting tire slippage/tires spinning). Tire diameter affects the rpm needed for the tire to achieve that velocity. A smaller diameter tire needs a higher rpm to reach the same velocity on the thread surface that a larger diameter tire has at a lower rpm (rpm of the wheel/tire).

So, if the thread surface of a tire has a velocity of 150MPH, the car will also move at 150MPH (if there is no slip between tire and road surface). And that means that the rollers on a dyno also will represent the MPH the car travels at. And if you had two different cars with different diameter wheel/tire combos on the same dyno, you would see that the rpm of the wheels would be different at 150MPH (or any other speed).

So changing tire diameter, deflated tires etc, affects the engine rpm needed to maintain the same speed (since diameter of the tire is affected). But the velocity of the tire (as shown in illustration below) equals the velocity the car is moving at (or the rollers reads).

[gmd2003]

Originally Posted by Boss330

You might want to rethink that statement

The velocity of the surface of the tire equals the velocity of the car (not counting tire slippage/tires spinning). Tire diameter affects the rpm needed for the tire to achieve that velocity. A smaller diameter tire needs a higher rpm to reach the same velocity on the thread surface that a larger diameter tire has at a lower rpm (rpm of the wheel/tire).

So, if the thread surface of a tire has a velocity of 150MPH, the car will also move at 150MPH (if there is no slip between tire and road surface). And that means that the rollers on a dyno also will represent the MPH the car travels at. And if you had two different cars with different diameter wheel/tire combos on the same dyno, you would see that the rpm of the wheels would be different at 150MPH (or any other speed).

So changing tire diameter, deflated tires etc, affects the engine rpm needed to maintain the same speed (since diameter of the tire is affected). But the velocity of the tire (as shown in illustration below) equals the velocity the car is moving at (or the rollers reads).

Nope you need to think about yours . Tire diameter doesn't affect the rotor speed but you still need to know tire diameter to calculate how many tire rotations occur for every rotation of the drum . And tire rotations do affect the speed of your car boss .

[Boss330]

Originally Posted by gmd2003

Nope you need to think about yours . Tire diameter doesn't affect the rotor speed but you still need to know tire diameter to calculate how many tire rotations occur for every rotation of the drum . And tire rotations do affect the speed of your car boss .

All of that is true, but tangential speed of the tire equals the speed of the car. And thus the roller speed is independent on wheel diameter on the car... What you are pointing out is that you need to know tire/wheel diameter if you want to CALCULATE tangential speed (or vehicle speed) based on rpm of the wheel. Here we allready know the tangential speed since that is measured by the rollers. If you want to calculate rotor speed from tangential speed, you would need tire diameter of course.

Tangential speed is explained better here:

http://en.wikipedia.org/wiki/Speed#Tangential_speed

Tangential speed[edit]

Linear speed is the distance traveled per unit of time, while tangential speed (or tangential velocity) is the linear speed of something moving along a circular path.[4] A point on the outside edge of a merry-go-round or turntable travels a greater distance in one complete rotation than a point nearer the center. Travelling a greater distance in the same time means a greater speed, and so linear speed is greater on the outer edge of a rotating object than it is closer to the axis. This speed along a circular path is known as tangential speed because the direction of motion is tangent to the circumference of the circle. For circular motion, the terms linear speed and tangential speed are used interchangeably, and both use units of m/s, km/h, and others.

Rotational speed (or angular speed) involves the number of revolutions per unit of time. All parts of a rigid merry-go-round or turntable turn about the axis of rotation in the same amount of time. Thus, all parts share the same rate of rotation, or the same number of rotations or revolutions per unit of time. It is common to express rotational rates in revolutions per minute (RPM) or in terms of the number of "radians" turned in a unit of time. There are little more than 6 radians in a full rotation (2π radians exactly). When a direction is assigned to rotational speed, it is known as rotational velocity or angular velocity. Rotational velocity is a vector whose magnitude is the rotational speed.

Tangential speed and rotational speed are related: the greater the RPMs, the larger the speed in metres per second. Tangential speed is directly proportional to rotational speed at any fixed distance from the axis of rotation.[4] However, tangential speed, unlike rotational speed, depends on radial distance (the distance from the axis). For a platform rotating with a fixed rotational speed, the tangential speed in the centre is zero. Towards the edge of the platform the tangential speed increases proportional to the distance from the axis.[5] In equation form:
v \propto \!\, r \omega\,,
where v is tangential speed and ω (Greek letter omega) is rotational speed. One moves faster if the rate of rotation increases (a larger value for ω), and one also moves faster if movement farther from the axis occurs (a larger value for r). Move twice as far from the rotational axis at the centre and you move twice as fast. Move out three times as far and you have three times as much tangential speed. In any kind of rotating system, tangential speed depends on how far you are from the axis of rotation.

When proper units are used for tangential speed v, rotational speed ω, and radial distance r, the direct proportion of v to both r and ω becomes the exact equation
v = r\omega\,.
Thus, tangential speed will be directly proportional to r when all parts of a system simultaneously have the same ω, as for a wheel, disk, or rigid wand.

The point is that the tangential speed of the tire can't be different to that of the car (unless you are doing a burnout). Smaller diameter, means the wheel revs needs to be higher to achieve that same tangential speed. Just like as on the merry go round example above.

[gmd2003]

Originally Posted by Boss330

Are you quite sure...

Tangential speed is explained better here:

http://en.wikipedia.org/wiki/Speed#Tangential_speed

The point is that the tangential speed of the tire can't be different to that of the car (unless you are doing a burnout). Smaller diameter, means the wheel revs needs to be higher to achieve that same tangential speed. Just like as on the merry go round example above.

Tangential speed of the tire and the speed of a car are two totally different things Boss . A smaller diameter tire has to rotate many more times to get a car to x speed than a larger tire . This is why when you place a smaller diameter tire on your car the speedometer error becomes greater and it reads a higher speed than you are actually traveling ( at least speedometers on older cars that are tied to number of wheel revolutions ) .

[Boss330]

Originally Posted by gmd2003

Tangential speed of the tire and the speed of a car are two totally different things Boss . A smaller diameter tire has to rotate many more times to get a car to x speed than a larger tire . This is why when you place a smaller diameter tire on your car the speedometer error becomes greater and it reads a higher speed than you are actually traveling ( at least speedometers on older cars that are tied to number of wheel revolutions ) .

It seems you are confusing tire rpm and tangential speed here As you point out if you place a smaller diameter tire on your car, speedo error increases. This is in fact a very good example of what I posted in my previous thread and the merry go round example. The further from the center (larger diameter), the higher the tangential speed will be at the same rpm. Decrease diameter and you need to increase rpm to maintain the same tangential speed (just as happens when you put smaller diameter tires on a car).

In the example where you put smaller tire diameter tires on your car, what happens is that engine rpm increases since it needs to rotate the wheel at a higher rpm to maintain the same vehicle velocity. But even though the speedometer now reads higher, and the wheel (rotor) rpm is higher, the tangential speed of the tire is still 50MPH if the car moves at a true 50MPH (regardless of the speedo error increasing).

You simply cannot have different vehicle speed and tangential speed of the tire. Unless you are doing a burnout or have tire slippage (which one in reality allways have to some extent).

Tangential speed of the tire equals the speed of the car. And thus the roller speed is independent on wheel diameter on the car... What you are pointing out is that you need to know tire/wheel diameter if you want to CALCULATE tangential speed (or vehicle speed) based on rpm of the wheel. Here we allready know the tangential speed since that is measured by the rollers. If you want to calculate rotor speed from tangential speed, you would need tire diameter of course.

Just think about it:

If you have two tires rotating with a tangential speed of a steady 20MPH. One is 100mm and the other is 200mm diameter, so rpm of the wheels are obviously different. At what speed would they move if you put them on the ground and they still had a tangential speed of 20MPH...

[gmd2003]

Originally Posted by Boss330

It seems you are confusing tire rpm and tangential speed here As you point out if you place a smaller diameter tire on your car, speedo error increases. This is in fact a very good example of what I posted in my previous thread and the merry go round example. The further from the center (larger diameter), the higher the tangential speed will be at the same rpm. Decrease diameter and you need to increase rpm to maintain the same tangential speed (just as happens when you put smaller diameter tires on a car).

In the example where you put smaller tire diameter tires on your car, what happens is that engine rpm increases since it needs to rotate the wheel at a higher rpm to maintain the same vehicle velocity. But even though the speedometer now reads higher, and the wheel (rotor) rpm is higher, the tangential speed of the tire is still 50MPH if the car moves at a true 50MPH (regardless of the speedo error increasing).

You simply cannot have different vehicle speed and tangential speed of the tire. Unless you are doing a burnout or have tire slippage (which one in reality allways have to some extent).

Tangential speed of the tire equals the speed of the car. And thus the roller speed is independent on wheel diameter on the car... What you are pointing out is that you need to know tire/wheel diameter if you want to CALCULATE tangential speed (or vehicle speed) based on rpm of the wheel. Here we allready know the tangential speed since that is measured by the rollers. If you want to calculate rotor speed from tangential speed, you would need tire diameter of course.

Just think about it:

If you have two tires rotating with a tangential speed of a steady 20MPH. One is 100mm and the other is 200mm diameter, so rpm of the wheels are obviously different. At what speed would they move if you put them on the ground and they still had a tangential speed of 20MPH...

The wheel/ tire can have the same speed and different rpm's yes , but is the dyno measuring the speed or drum rotations.At any rate good gains with the tune , I hope to see one at the strip soon for real numbers !

[GunderM5]

#science

[Boss330]

Originally Posted by gmd2003

The wheel/ tire can have the same speed and different rpm's yes , but is the dyno measuring the speed or drum rotations.At any rate good gains with the tune , I hope to see one at the strip soon for real numbers !

I'm pretty sure the dyno reads the drum/roller rpm and then calculates speed based on the drum diameter.

Tangential speed of the drum = tangential speed of the tire = theoretical speed of the car (since there allways is a degree of slip between tire and road/drum, - tangential speed of the drum/tire won't equal vehicle speed 100%, more like 99,99%)

[boots]

Well I'm gonna measure my speed w my trusty garmin

[Boss330]

Originally Posted by boots

Well I'm gonna measure my speed w my trusty garmin

Which is one of the most accurate ways to determine true vehicle speed

[gmd2003]

Originally Posted by Boss330

Which is one of the most accurate ways to determine true vehicle speed

Thank you lol. I thought you'd recommend running the 1/4 mile on the dyno next to get trap speed .

[MCarsFan]

Originally Posted by boots

Well I'm gonna measure my speed w my trusty garmin

You go do that - then everyone will be happy ! Lol

[boots]

Just received my ecu. Game on! No worries rob. It will be done.

[6spdterror]

Originally Posted by boots

Just received my ecu. Game on! No worries rob. It will be done.

Nice!!

[Andym3100k]

Originally Posted by boots

Just received my ecu. Game on! No worries rob. It will be done.

Lol... My was out to them too. Can't wait to get it back hopefully next week....

[boots]

Well heck ya Andy. Glad they were able to give you the answers you were seeking.

[Andym3100k]

Originally Posted by boots

Well heck ya Andy. Glad they were able to give you the answers you were seeking.

Thanks man, as for bigger turbo they need the car to be there so I opt for a stage 2 only which is what they have best now.

[boots]

I think you'll be happy. Mine will be installed w/i the next 6 hours

[Andym3100k]

Originally Posted by boots

I think you'll be happy. Mine will be installed w/i the next 6 hours

Pls keep us posted on the performance, before n after. Thanks.