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      09-01-2007, 09:19 PM   #1
BimmerFTW
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Question Wheel Spin?

Do you guys think the e92 is going to have an extreme amount of wheel spin from a dig?
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      09-01-2007, 09:21 PM   #2
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Depends on what your definition of extreme is. You can roast them pretty good if you try, but it does only have a max torque of 295...
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      09-01-2007, 09:26 PM   #3
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Originally Posted by ChitownM3 View Post
Depends on what your definition of extreme is. You can roast them pretty good if you try, but it does only have a max torque of 295...
Damn i forgot to look at its torque lol. wow, 295 is kind of weak...but doesnt that seem like a bad balance of torque and Hp? 420 vs. 295?
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      09-01-2007, 09:43 PM   #4
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Damn i forgot to look at its torque lol. wow, 295 is kind of weak...but doesnt that seem like a bad balance of torque and Hp? 420 vs. 295?
I was kind of wondering how come the new M3 engine has only 295lb? I understand that it is a high revving engine and that kinda makes up for the low torque numbers but i mean was it not possible to produce/develop a high revving engine with around 400hp but with like 350lb torque?

I mean im no engineer but i think they could have done better.
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      09-01-2007, 09:58 PM   #5
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I was kind of wondering how come the new M3 engine has only 295lb? I understand that it is a high revving engine and that kinda makes up for the low torque numbers but i mean was it not possible to produce/develop a high revving engine with around 400hp but with like 350lb torque?

I mean im no engineer but i think they could have done better.
Yea, im def. thinking the same thing you are...
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      09-01-2007, 11:15 PM   #6
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Moderate peak torque means your drivetrain can be much lighter as the maximum stresses experienced will be lower and parts can be sized accordingly. Modereate torque is not an issue from a performance perspective as long as the engine can rev high and you are willing to drive at high rpms. Go check out the specs on F1 engines. If you are not an engineer, and don't understand why engineers do what they do, there is no point in saying you could have done better than BMW engineers. You are basically saying you don't know what you are talking about, but you can still do better. That doesn't make any sense.
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      09-02-2007, 12:37 AM   #7
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Moderate peak torque means your drivetrain can be much lighter as the maximum stresses experienced will be lower and parts can be sized accordingly. Moderate torque is not an issue from a performance perspective as long as the engine can rev high and you are willing to drive at high rpms. Go check out the specs on F1 engines. If you are not an engineer, and don't understand why engineers do what they do, there is no point in saying you could have done better than BMW engineers. You are basically saying you don't know what you are talking about, but you can still do better. That doesn't make any sense.
lucid, I'll just pick a couple of nits here, neither of which is central to your main points. The first is that I woud be more comfortable if you had said that moderate peak torque per cylinder means your drivetrain can be somewhat lighter. Drivetrains only care about torque per cylinder (for obvious reasons), and they are also subject to significant forces that are somewhat removed from torque-per-cylinder dynamics. These would include the forces generated through drivetrain lash under sudden on-off throttle movements - or even road irregularities (read potholes) under heavy throttle or braking.

The second is that moderate torque with high horsepower in a fairly heavy chassis says that you'll address the issue (from an engineering standpoint) with aggressive gearing. Aggressive gearing can be great fun, but it brings with it a rotational inertia penalty that can be considerable, obviously more so in the lower gears, but really any time you're accelerating hard. That's probably a subject that deserves its own string, especially since it also affects shift points.

OK, those are my nits for the day.

Bruce

PS - The guy actually could've done better than BMW engineers by simply ordering up a bigger motor, cc-wise - such as the 6.2 liter Merc V8.

Oops. Did I say that? Been a bad boy again.
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      09-02-2007, 07:39 AM   #8
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Quote:
Originally Posted by lucid View Post
Moderate peak torque means your drivetrain can be much lighter as the maximum stresses experienced will be lower and parts can be sized accordingly. Modereate torque is not an issue from a performance perspective as long as the engine can rev high and you are willing to drive at high rpms. Go check out the specs on F1 engines. If you are not an engineer, and don't understand why engineers do what they do, there is no point in saying you could have done better than BMW engineers. You are basically saying you don't know what you are talking about, but you can still do better. That doesn't make any sense.
You misunderstood me, i never said i could do a better job or that BMW engineers didnt do an amazing job at developing this engine im just saying with the funds they have they probably could have produced something stronger but i guess they are reserving the highly tuned engine version for the CSl.
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      09-02-2007, 07:55 AM   #9
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Originally Posted by bruce.augenstein@comcast. View Post
lucid, I'll just pick a couple of nits here, neither of which is central to your main points. The first is that I woud be more comfortable if you had said that moderate peak torque per cylinder means your drivetrain can be somewhat lighter. Drivetrains only care about torque per cylinder (for obvious reasons), and they are also subject to significant forces that are somewhat removed from torque-per-cylinder dynamics. These would include the forces generated through drivetrain lash under sudden on-off throttle movements - or even road irregularities (read potholes) under heavy throttle or braking.

The second is that moderate torque with high horsepower in a fairly heavy chassis says that you'll address the issue (from an engineering standpoint) with aggressive gearing. Aggressive gearing can be great fun, but it brings with it a rotational inertia penalty that can be considerable, obviously more so in the lower gears, but really any time you're accelerating hard. That's probably a subject that deserves its own string, especially since it also affects shift points.

OK, those are my nits for the day.

Bruce

PS - The guy actually could've done better than BMW engineers by simply ordering up a bigger motor, cc-wise - such as the 6.2 liter Merc V8.

Oops. Did I say that? Been a bad boy again.
Agreed with your points. There are other cons associated with a crankshaft spinning at 8500 rpms such as bearing surfaces.

By the way, do you believe that the Merc engine is slightly lighter than the M3 engine as stated in an article that was posted here? (It was not clear how that measurement was obtained though).
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      09-02-2007, 08:08 AM   #10
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You misunderstood me, i never said i could do a better job or that BMW engineers didnt do an amazing job at developing this engine im just saying with the funds they have they probably could have produced something stronger but i guess they are reserving the highly tuned engine version for the CSl.
If that's what you meant, this table might put things in context. I posted it here before on this forum a few months ago. As you can see, tq and hp per disp of the M3 engine are about 10% less than the F430 engine, which is pretty much state of the art for this cylinder geometry. I would think that it would take a significant investment to close that gap without using DFI--the F430 engine goes into a car that costs significantly higher. And, one also runs into reliability issues. DFI will surely give it another 7-10% or so. But apart from that, I don't think they can extract another 100hp from it without comprimising its durability (it's supposed to last more than 100000 miles), or without forced induction or increased displacement.
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      09-02-2007, 12:37 PM   #11
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Quote:
Originally Posted by lucid View Post
If that's what you meant, this table might put things in context. I posted it here before on this forum a few months ago. As you can see, tq and hp per disp of the M3 engine are about 10% less than the F430 engine, which is pretty much state of the art for this cylinder geometry. I would think that it would take a significant investment to close that gap without using DFI--the F430 engine goes into a car that costs significantly higher. And, one also runs into reliability issues. DFI will surely give it another 7-10% or so. But apart from that, I don't think they can extract another 100hp from it without comprimising its durability (it's supposed to last more than 100000 miles), or without forced induction or increased displacement.
Thanx lucid for providing this useful information. I now understand how ferrari is able to produce a powerful high revving engine. What modifications do you think BMW will do to the engine to achieve more power for the csl?

Good post by the way.
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      09-02-2007, 01:03 PM   #12
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What modifications do you think BMW will do to the engine to achieve more power for the csl?
My understanding is that for the E46 CSL, they modified the intake, camshaft, exhaust valves, and the exhaust system to get 17 additional hp. Intake and exhaust mods are always possible and relatively easy to pull off. I also suspect they might raise the redline slightly to get a few more hp. They would also most likely modify the engine management software. It really doesn't look like they will use DFI on this engine for the E92s (South has written several posts saying the DFI technology BMW wants to use is not ready yet). And I doubt that they will increase the displacement. Actually, BMW has publicly stated that they care more about weight reduction than power increase in the E92 CSL. My personal guess is that it might get another 40-50 hp at most.

Last edited by lucid; 09-02-2007 at 04:39 PM.
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      09-02-2007, 03:50 PM   #13
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My understanding is that for the E46 CSL, they modified the intake, camshaft, exhaust valves, and the exhaust system to get 37 additional hp. .
The power increase was 17bhp.

343bhp to 360bhp.
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      09-02-2007, 04:37 PM   #14
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The power increase was 17bhp.

343bhp to 360bhp.
Yes, you are right. Thanks for catching that. 343hp to 360hp DIN. I corrected my previous post.
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      09-02-2007, 05:14 PM   #15
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Agreed with your points. There are other cons associated with a crankshaft spinning at 8500 rpms such as bearing surfaces.

By the way, do you believe that the Merc engine is slightly lighter than the M3 engine as stated in an article that was posted here? (It was not clear how that measurement was obtained though).
Mercedes was purported to have given that figure (199 kg, if memory serves)to the automotive press as part of the announcement.

I have no good reason not to believe it. The M guys have a deserved halo, but Mercedes also knows a thing or two about engines, and as I've previously pointed out, this is the first AMG-unique design, so you know they were going for a home run.

As it stands, they've already rounded third and are pounding toward home, and the BMW throw hasn't quite reached the cutoff man yet*.

These are exciting times.

Bruce

*As an aside, although baseball is a pastoral and slow-moving game, I personally believe the throw home is the most exciting play in all of sports.
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      09-02-2007, 05:22 PM   #16
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Do you guys think the e92 is going to have an extreme amount of wheel spin from a dig?
Yes, DSC off, it will likely have as much wheelspin as your right foot wants. Finding the right launch RPM is going to be key! I could spin them easily on my Z4MC with just a 3500 rpm blip before takeoff! In fact that's how I "lost" to a 335i
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      09-02-2007, 08:07 PM   #17
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Damn i forgot to look at its torque lol. wow, 295 is kind of weak...but doesnt that seem like a bad balance of torque and Hp? 420 vs. 295?
Sweet! This discussion again.
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      09-03-2007, 08:43 AM   #18
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Damn i forgot to look at its torque lol. wow, 295 is kind of weak...but doesnt that seem like a bad balance of torque and Hp? 420 vs. 295?
Well yes, actually.

However, from initial reports, this engine will be a winner. BMW has gone to great lengths to make sure this engine is lively in everyday driving, including top-gear flexibility. Although they seem to have sacrificed a little in terms of peak torque (down perhaps ten or fifteen pound feet from what it could be), this was done in favor of an extremely wide torque curve. Consider that, even though it makes more power per liter than its parent engine, the torque peak is way the heck lower at 3900 rpm, vs 6100 for the V10.

Yeah, I can't imagine anyone not liking more torque, but this engine will not be a weakling in everyday driving, even at fairly low rpm.

Bruce
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      09-03-2007, 11:42 AM   #19
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Originally Posted by Hans Delbruck View Post
Yes, DSC off, it will likely have as much wheelspin as your right foot wants. Finding the right launch RPM is going to be key! I could spin them easily on my Z4MC with just a 3500 rpm blip before takeoff! In fact that's how I "lost" to a 335i
Cool, thanks.
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      09-03-2007, 11:44 AM   #20
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In fact that's how I "lost" to a 335i
"Lost" as in ....?
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      09-03-2007, 11:44 AM   #21
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Originally Posted by bruce.augenstein@comcast. View Post
Well yes, actually.

However, from initial reports, this engine will be a winner. BMW has gone to great lengths to make sure this engine is lively in everyday driving, including top-gear flexibility. Although they seem to have sacrificed a little in terms of peak torque (down perhaps ten or fifteen pound feet from what it could be), this was done in favor of an extremely wide torque curve. Consider that, even though it makes more power per liter than its parent engine, the torque peak is way the heck lower at 3900 rpm, vs 6100 for the V10.

Yeah, I can't imagine anyone not liking more torque, but this engine will not be a weakling in everyday driving, even at fairly low rpm.

Bruce
True....
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