MC: How fast is the M Coupe?

[pal]

Some of my friends were thinking about doing the Texas Standing Mile later this year. Their rules are pretty relaxed and you can pretty much go flat out ...

Question is what can an M Coupe with the S54 motor hit in the standing mile? Given people are seeing 104-106 mph in the 1/4 mile, I fugured another 3/4th mile should allow us to hit 155 mph ...

Thoughts and experiences?

http://texasmile.net/

Pal

[HotDogWater]

no idea, but if you stay in 5th, you don't have to worry about the 155 mph limit :)

[Caddyshk]

no idea, but if you stay in 5th, you don't have to worry about the 155 mph limit :)That's a myth by many accounts I've read.

[Dammmittt]

Some of my friends were thinking about doing the Texas Standing Mile later this year. Their rules are pretty relaxed and you can pretty much go flat out ...

Question is what can an M Coupe with the S54 motor hit in the standing mile? Given people are seeing 104-106 mph in the 1/4 mile, I fugured another 3/4th mile should allow us to hit 155 mph ...

Thoughts and experiences?

http://texasmile.net/

Pal

It'll take you more than a mile to get to full speed. I'd wager 140-145 tops. But, it's been a while since I've gone that fast...it's hard to remember really. It doesn't take long to get to 120, but from there on it goes slower.

[HotDogWater]

That's a myth by many accounts I've read.

Not that I've tried it myself, but I've read of at least one other person on the boards doing so:
http://www.bimmerfest.com/forums/showpost.php?p=3178327&postcount=30

[Ron Stygar]

Not that I've tried it myself, but I've read of at least one other person on the boards doing so:
http://www.bimmerfest.com/forums/showpost.php?p=3178327&postcount=30

Maybe the speedo error.

[Palantirion@BMS]

That's a myth by many accounts I've read.
-Nope, I've verified it personally. Redline in 5th = 166mph.

[Ron Stygar]

-Nope, I've verified it personally. Redline in 5th = 166mph.

Red line is 166?
Is the 166 from the speedometer?

[Palantirion@BMS]

Red line is 166?
Is the 166 from the speedometer?
-No, the tach. And math.
Gear: 5th
Ratio: 1.000
Final Drive: 3.62
Tire Circ.: 80.4 (for 275/35R18)
MPH @ 7900rpm: 166

Or from my spreadsheet: (7900/C145/D145)*((I145/12)/5280*60)

[Screamer]

Isn't the redline at 8200rpm though? Or at least over 8000..?

[Ron Stygar]

-No, the tach. And math.
Gear: 5th
Ratio: 1.000
Final Drive: 3.62
Tire Circ.: 80.4 (for 275/35R18)
MPH @ 7900rpm: 166

Or from my spreadsheet: (7900/C145/D145)*((I145/12)/5280*60)

What did the speedometer say?

[Zuzax]

At a 60-130 event held at a 1/4 dragstrip with a 2,100 shutdown area (3,980-ish feet total) the best I was able to attain before having to shut down (braking rather hard) was 129 mph, measured with a Driftbox. I didn't feel so bad when a Gallardo couldn't hit 130 either in the space available.

Based off of that, my guestimate is that you might hit 150. My few trips to 150+ on the open road have shown that the higher-end portion takes LOTS of road, and damn near as much time as it took to get to 130.

[Palantirion@BMS]

What did the speedometer say?
-Dunno for sure, didn't want to take my eyes off the road any longer than necessary at the time. I know it crossed 160 and I thought it was near 170. But again, I wasn't focused on it like I was on the tach.

[Ron Stygar]

-Dunno for sure, didn't want to take my eyes off the road any longer than necessary at the time. I know it crossed 160 and I thought it was near 170. But again, I wasn't focused on it like I was on the tach.

When I initial trialed the Auto Enginuity, unlike the Z3, the Z4 tach was dead nuts.
Speedometer was off 4 MPH in the middle.
Now that I have my own Auto Enginuity, I will save some files for both.
Waiting for my new Dell M1330 lap top to show up. Supposedly Thursday.

[Ron Stygar]

-Dunno for sure, didn't want to take my eyes off the road any longer than necessary at the time. I know it crossed 160 and I thought it was near 170. But again, I wasn't focused on it like I was on the tach.

Did you see the model case post from Jon Maddux?

[pal]

So far my highest speed has been in my old Supercharged GTI VR6 where I hit 147'ish on the speedo (about 142 'ish corrected) and that was on the Pocono Long course ... so I want to def try and beat that with the M Coupe under controlled conditions.

Looks like the standing mile might be able to get me there :-)

To Ron's point, the only cars I have owned with dead on speedo (compared to a GPS measured speed) have been my 2 past Audi TTs.

[Palantirion@BMS]

Did you see the model case post from Jon Maddux?
-Yes I did, thanks. I still want to try to get an exact replacement case from the BMW Art Car series to put my Art Car in. Haven't had time to look into it.

[Dammmittt]

I never touched the redline in 5th...something about all those spinning parts with low mileage on the car...seemed like a bad idea...

[RussRamz]

Maybe the speedo error.

+1

Definitely speedo error. I have confirmed a built in speedo error on my Z4 as well as my M6 using my vBox. Shall I make another video to demonstrate?

[Caddyshk]

-No, the tach. And math.
Gear: 5th
Ratio: 1.000
Final Drive: 3.62
Tire Circ.: 80.4 (for 275/35R18)
MPH @ 7900rpm: 166

Or from my spreadsheet: (7900/C145/D145)*((I145/12)/5280*60)When does the actual rev limiter kick in on our cars? I'm typically focused on the road - I hit the limiter in 4th once on an open stretch, never gone so far as 5th gear at speed. based on the tach lights I figured the limiter would kick at 8,000rpm, perhaps I'm wrong?

[Dammmittt]

When does the actual rev limiter kick in on our cars? I'm typically focused on the road - I hit the limiter in 4th once on an open stretch, never gone so far as 5th gear at speed. based on the tach lights I figured the limiter would kick at 8,000rpm, perhaps I'm wrong?

I think pal is right about 7900...it makes sense for it to kick on 100 rpms before redline to protect the engine.

[Ron Stygar]

I think pal is right about 7900...it makes sense for it to kick on 100 rpms before redline to protect the engine.

Then how would you get to 8000?

<img src="http://bimmerfest.com/forums/attachment.php?attachmentid=146767
&stc=1">

[awdonald]

Gps...

[Dammmittt]

Then how would you get to 8000?

<img src="http://bimmerfest.com/forums/attachment.php?attachmentid=146767
&stc=1">

I dunno...upgraded software? Maybe it kicks on at 7800 with that chart...anyone want to hook up a camera and make a movie?

[Zuzax]

Gps...
+1 Get a VBox or a DriftBox or some other GPS-based measurement device. DriftBoxes worked great at the 60-130 event, and you can download data and speed graphs to PC as well.

[Rosspbig]

So if you get to 160+ in 5th gear and then shift into 6th is it going to kick you back down below the governer?

[Palantirion@BMS]

So if you get to 160+ in 5th gear and then shift into 6th is it going to kick you back down below the governer?
-I heard yes, but haven't tried the shift to 6th myself.

[pal]

When does the actual rev limiter kick in on our cars? I'm typically focused on the road - I hit the limiter in 4th once on an open stretch, never gone so far as 5th gear at speed. based on the tach lights I figured the limiter would kick at 8,000rpm, perhaps I'm wrong?

My experience has been a touch over 8000 rpms ... when I was at Pocono in March, I could hold 3rd at 8000 and did try to get kicked out a couple of times and it is a gentle push when you try to get past 8000. I was impressed how well the motor let you hold redline ...

[phat]

Ran out 5th gear to redline and the speedo read 270km/hr.

Now check this out! I went up against a 335 coupe manual. We were even in 3rd and 4th. 5th was even for a few seconds and then he pulled HARD (at least 3-4 cars) while winding out 5th to redline. We did 3 runs and same everytime. I kept it on it for a bit at close to 8000k and could not catch him but he didn't pull away anymore once I was getting close to 8K

[Caddyshk]

Ran out 5th gear to redline and the speedo read 270km/hr.

Now check this out! I went up against a 335 coupe manual. We were even in 3rd and 4th. 5th was even for a few seconds and then he pulled HARD (at least 3-4 cars) while winding out 5th to redline. We did 3 runs and same everytime. I kept it on it for a bit at close to 8000k and could not catch him but he didn't pull away anymore once I was getting close to 8KLikely the torque at the specific RPM - Stock to stock I've seen our cars destroy 335's in pulls and off the line, however I'm guessing your test to be a little unique.

[Caddyshk]

Ran out 5th gear to redline and the speedo read 270km/hr.

Now check this out! I went up against a 335 coupe manual. We were even in 3rd and 4th. 5th was even for a few seconds and then he pulled HARD (at least 3-4 cars) while winding out 5th to redline. We did 3 runs and same everytime. I kept it on it for a bit at close to 8000k and could not catch him but he didn't pull away anymore once I was getting close to 8K
(270*0.62)*(0.96)=160.7mph

Thanks!

[Dammmittt]

Ran out 5th gear to redline and the speedo read 270km/hr.

Now check this out! I went up against a 335 coupe manual. We were even in 3rd and 4th. 5th was even for a few seconds and then he pulled HARD (at least 3-4 cars) while winding out 5th to redline. We did 3 runs and same everytime. I kept it on it for a bit at close to 8000k and could not catch him but he didn't pull away anymore once I was getting close to 8K

Stock vs Stock, the higher HP of the M Coupe should win every time, especially at high speed. If he's got some turbo tuning, it makes more sense.

[apexstrafer]

He had to have some tuning done. I've done the same kind of runs with a totally stock 335 and pulled away in 4th and 5th.

Should probably get that RPI intake to even things out in case I run into a chipped 335...

[Dammmittt]

He had to have some tuning done. I've done the same kind of runs with a totally stock 335 and pulled away in 4th and 5th.

Should probably get that RPI intake to even things out in case I run into a chipped 335...

Or you could give ESS a call and keep the power rankings what they should be :)

[apexstrafer]

Once the warranty is out, that's the first call I'll make ;)

[phat]

Likely the torque at the specific RPM - Stock to stock I've seen our cars destroy 335's in pulls and off the line, however I'm guessing your test to be a little unique.

Ya it was unique and probably won't happen again. But he definitely pulled hard in the upper middle of 5th gear. After I shifted to 5th (4th at 8K) we were still equal for a bit then all of a sudden just pulled hard 3-4 cars until 260ish and then the distance stayed the same up to 270+ish. I looked at the tach for a sec and it was very very close to 8k.

Do 335 manuals have a speed limiter as well or does it work the same way as the z4m which allows 5th gear to be maxed out? He didn't have an aftermarket exhaust but "maybe" some ecu tuning hence the pull and top end of 270ish.

[phat]

He had to have some tuning done. I've done the same kind of runs with a totally stock 335 and pulled away in 4th and 5th.

Should probably get that RPI intake to even things out in case I run into a chipped 335...

Its weird 4th was dead even pretty much but 5th it pulled hard. I assume it was chipped now but I really don't think that RPI intake will make that much difference based on how it pulled. One thing I don't understand in our runs was how it was even in all the gears but then as we are well into 5th it just pulled ahead 3-4 cars.

The last run one I was in 4th at 160 and went to 270.

[Caddyshk]

Its weird 4th was dead even pretty much but 5th it pulled hard. I assume it was chipped now but I really don't think that RPI intake will make that much difference based on how it pulled. One thing I don't understand in our runs was how it was even in all the gears but then as we are well into 5th it just pulled ahead 3-4 cars.

The last run one I was in 4th at 160 and went to 270.4th to 270 is impossible.

[jsc]

Its weird 4th was dead even pretty much but 5th it pulled hard. I assume it was chipped now but I really don't think that RPI intake will make that much difference based on how it pulled. One thing I don't understand in our runs was how it was even in all the gears but then as we are well into 5th it just pulled ahead 3-4 cars.

The last run one I was in 4th at 160 and went to 270.
If you are at altitude (eg Alberta or parts of BC), then the Z4M is losing about 10% of it's horsepower compared with sea level, whereas the 3.0L turbo is probably losing only about 3%. At the higher speeds the Z4M also loses ground due to higher aerodynamic drag than the 335i

[Dammmittt]

If you are at altitude (eg Alberta or parts of BC), then the Z4M is losing about 10% of it's horsepower compared with sea level, whereas the 3.0L turbo is probably losing only about 3%. At the higher speeds the Z4M also loses ground due to higher aerodynamic drag than the 335i

I still disagree with the way the auto industry finds the drag coefficient, since the 335i is longer, the total drag is likely about the same or greater than the M...but I dunno if we want to go down this path again.

[jsc]

I still disagree with the way the auto industry finds the drag coefficient, since the 335i is longer, the total drag is likely about the same or greater than the M...but I dunno if we want to go down this path again.
It is all a case of simplification of drag in the automotive industry. With an aircraft the drag is fundamentally confined to 3 separate types of body - lifting surfaces, fuselage and engine nacelles. This means that it is relatively easy to define and calculate the drag properties of each body. An automobile doesn't really have any well defined specific shapes, has very variable vortex shedding properties and ground effect causes significant distortion of any conventional calculations of lift and drag.

A car is really a much more complex aerodynamic body than an aircraft, causing the only practical approach to aerodynamics being via wind tunnel measurements and refinement, not through theoretical or numerical aerodynamics. I think that if the automotive industry went to the same depth in aerodynamics as the aerospace industry, it would probably increase the development costs several fold and employ more aerodynamicists than engineers, but return very little from a product refinement perspective.

[Dammmittt]

I hear you.

But, I think that throwing a Cd out there as a performance indicator is misleading, especially since they just use the frontal area as the reference area. Since a car isn't a flat plate, and it doesn't have a constant area like a brick, using that area to non-dimensionalize the drag is extremely sketchy. I think that even if they used the average frontal area it would be better, and using the profile would probably be the best they could do.

So, say that a certain auto manufacturer takes a model, puts it in a wind tunnel at a certain velocity, etc. They find the drag, and non-dimensionalize it using the frontal area. Now, scaling the model doesn't affect the Cd, cuz it has the same shape. They do the same thing for every model, and non-dimesionalize it, then publish the Cd.

Now, some dude with a wind tunnel, puts his car in his wind tunnel at a different velocity, proceeds to do the same thing, and gets a different Cd. Now who's right? Well...they both are, and at the same time they're both very wrong, cuz viscosity effects depend on the actual vehicle shape, which isn't constant like the automobile industry thinks it is, so it's going to vary more than the pressure drag that varies with the dynamic pressure. Even pressure drag depends on the actual vehicle shape...

So what's the point? :dunno:

[jsc]

I hear you.

But, I think that throwing a Cd out there as a performance indicator is misleading, especially since they just use the frontal area as the reference area. Since a car isn't a flat plate, and it doesn't have a constant area like a brick, using that area to non-dimensionalize the drag is extremely sketchy. I think that even if they used the average frontal area it would be better, and using the profile would probably be the best they could do.

So, say that a certain auto manufacturer takes a model, puts it in a wind tunnel at a certain velocity, etc. They find the drag, and non-dimensionalize it using the frontal area. Now, scaling the model doesn't affect the Cd, cuz it has the same shape. They do the same thing for every model, and non-dimesionalize it, then publish the Cd.

Now, some dude with a wind tunnel, puts his car in his wind tunnel at a different velocity, proceeds to do the same thing, and gets a different Cd. Now who's right? Well...they both are, and at the same time they're both very wrong, cuz viscosity effects depend on the actual vehicle shape, which isn't constant like the automobile industry thinks it is, so it's going to vary more than the pressure drag that varies with the dynamic pressure. Even pressure drag depends on the actual vehicle shape...

So what's the point? :dunno:
With age, you come to expect and accept imperfection :)

From a drag perspective, the Cd for a car operating anywhere under about Mach 0.3 is pretty constant, additionally as full scale models are normally used, the Reynolds Number and Froude Number don't need to be taken into consideration from a viscosity perspective as the fluid dynamic conditions are the same as in the wild. This is a bane to most aerospace windtunnel work. It really is a different approach, which looks crazy from an aerospace perspective, but is totally valid for any automotive aerodynamic work that isn't aimed at land-speed record attempts and the like.

[phat]

I noticed that ESS has software for the z4m ecu that brings fuel cut up to 8200. What would be the new top speed in 5th? It also eliminates the limiter so what would the top speed be in 6th based on a non modded stock car (stock power).

[Dammmittt]

With age, you come to expect and accept imperfection :)


:cry::rofl:

[Dammmittt]

I noticed that ESS has software for the z4m ecu that brings fuel cut up to 8200. What would be the new top speed in 5th? It also eliminates the limiter so what would the top speed be in 6th based on a non modded stock car (stock power).

There are calculators out there that'll figure that out for you (but I don't have one). RPM x gear ratio x final drive ratio x pi x tire diameter

[///Mug]

Figuring on paper with a mathematical formula is one thing, but at some point doesn't aerodynamic drag come in to play?

[Dammmittt]

Figuring on paper with a mathematical formula is one thing, but at some point doesn't aerodynamic drag come in to play?

What do you mean?

[///Mug]

As speed goes up, it takes more power to overcome the wind resistance. Sort of like when riding a bike. If you've ever ridden a bike in a tucked riding position going 20mph then all of a sudden sit up, it takes more power to maintain that 20mph.

So while you can theoretically figure top speed in gear by using a mathematical formula, I think you also need to plug in the drag coefficient too. There's a reason why those F1 race teams spend millions of dollars on wind tunnel time. They're trying to eek out every last bit of performance by making their car more aerodynamic.

[Dammmittt]

I see what you're saying, but top speed in 5th gear isn't drag limited, and no matter what the drag is on the car, the mathmatical formula for calculating the speed at a given rpm/gear holds. The amount of work the drag is doing on the car increases like a dashpot force with increasing velocity, but as long as the power being generated by the car is enough to overcome the drag work, you're ok.

Basically, as the drag increases it takes longer for you to climb RPMs, but as long as you can get there (and you're tires aren't slipping on the pavement), the speed formulas hold...hope that makes sense...

I'm sure jsc will let me know if screwed any of that up :)

[Palantirion@BMS]

I hear you.

But, I think that throwing a Cd out there as a performance indicator is misleading, especially since they just use the frontal area as the reference area. Since a car isn't a flat plate, and it doesn't have a constant area like a brick, using that area to non-dimensionalize the drag is extremely sketchy. I think that even if they used the average frontal area it would be better, and using the profile would probably be the best they could do.

So, say that a certain auto manufacturer takes a model, puts it in a wind tunnel at a certain velocity, etc. They find the drag, and non-dimensionalize it using the frontal area. Now, scaling the model doesn't affect the Cd, cuz it has the same shape. They do the same thing for every model, and non-dimesionalize it, then publish the Cd.

Now, some dude with a wind tunnel, puts his car in his wind tunnel at a different velocity, proceeds to do the same thing, and gets a different Cd. Now who's right? Well...they both are, and at the same time they're both very wrong, cuz viscosity effects depend on the actual vehicle shape, which isn't constant like the automobile industry thinks it is, so it's going to vary more than the pressure drag that varies with the dynamic pressure. Even pressure drag depends on the actual vehicle shape...

So what's the point? :dunno:
-All scientifically aerodynamic talk aside, I KNOW that the Z4 MC is slipperier than an E39 M5 at high speed (say 75-140mph) because I've done several back road cruises in which at WOT my MC kept up or gained on stock and slightly modded E39 M5s. Several different scenarios included different driver WOT times, but after observation and deduction I have concluded that the Z4 MC is unmistakably quicker at high speed (up to 145mph anyway) than the E39 M5. With 64hp less, this must mean that the Z4 MC has markedly less drag. Take from this what you will.

I noticed that ESS has software for the z4m ecu that brings fuel cut up to 8200. What would be the new top speed in 5th? It also eliminates the limiter so what would the top speed be in 6th based on a non modded stock car (stock power).
-172mph, but bear in mind that ESS software also kills the speed limiter, so the car (with enough power) could reach 203mph in 6th. (ROM3N, want to try?)

[Maxinator]

Basically, as the drag increases it takes longer for you to climb RPMs, but as long as you can get there...

That's the question being asked, I believe. What's the drag math to figure out the, "as long as you can get there" part.

Drag is definitely going to affect top speed. If you drove our car (any car) into a steady 60mph headwind, it's top speed related to the ground will be a heck of a lot lower due to drag.

[Dammmittt]

-172mph, but bear in mind that ESS software also kills the speed limiter, so the car (with enough power) could reach 203mph in 6th. (ROM3N, want to try?)

At that point, I'm not sure if the power can over come the drag...but it'd be intersting to do an experiment. I'm sure there are some roads out in the desert where it would be possible...;) I think stock doesn't have much more than 180-185 mph in it...just from my autobahn experiences. With the 550 kit I'd think 203 would be possible, although I'm sure you'd want some more downforce at that speed...

[Palantirion@BMS]

At that point, I'm not sure if the power can over come the drag...but it'd be intersting to do an experiment. I'm sure there are some roads out in the desert where it would be possible...;) I think stock doesn't have much more than 180-185 mph in it...just from my autobahn experiences. With the 550 kit I'd think 203 would be possible, although I'm sure you'd want some more downforce at that speed...
-I've only taken it up to around 166mph, but it felt totally planted (compared to my E39 M5). I even had to take a large sweeper at 150 (en route to 166mph) and it tracked perfectly (no slip). I'm not sure it wouldn't also feel ok crossing 200mph. For comparison's sake, the Ford GT will cross 200mph (eventually) with the same power, more rolling resistance, more weight, and what is probably not as aerodynamic a shape (nostalgia design, vs clean slate). If I'm not mistaken the M6 will cross 200mph with stock power (500hp). The Z06 is limited to sub-200mph only because of its gearing.

[phat]

4th to 270 is impossible.


Really? Starting in 4th and going to 270 is impossible? There is a 5th gear on my car not sure about yours.:rofl:

[Dammmittt]

-I've only taken it up to around 166mph, but it felt totally planted (compared to my E39 M5). I even had to take a large sweeper at 150 (en route to 166mph) and it tracked perfectly (no slip). I'm not sure it wouldn't also feel ok crossing 200mph. For comparison's sake, the Ford GT will cross 200mph (eventually) with the same power, more rolling resistance, more weight, and what is probably not as aerodynamic a shape (nostalgia design, vs clean slate). If I'm not mistaken the M6 will cross 200mph with stock power (500hp). The Z06 is limited to sub-200mph only because of its gearing.

Mine didn't feel as planted, but the bahn I was running on wasn't exactly straight :D

[Caddyshk]

Really? Starting in 4th and going to 270 is impossible? There is a 5th gear on my car not sure about yours.:rofl:

"The last run one I was in 4th at 160 and went to 270."

I don't speak Canadian:rofl:

[phat]

"The last run one I was in 4th at 160 and went to 270."

I don't speak Canadian:rofl:

Your continuing to be a smart ass and it is working. :p

[Caddyshk]

Your continuing to be a smart ass and it is working. :pDon't you mean You're?:thumbup: