M3 vs C63

swamp2 wrote

hp is a decent but approximate "shorthand". It assumes that gearing is chosen in an ideal fashion and many compromises must be met with respect to the gear choices. One compromise there is the limitations of gear ratios in automatics. There is no way MT gear choices mimic automatics exactly - why - automatics have this inherent limitation from using planetary gear sets. With manuals (and sequentials and DCs) the designer chooses the exact ratio they desire. And of course in a performance car they are typically optimized for performance. The other reason why this is an approximation is as follows. Assume two cars making the same peak hp one with more torque one with more revs. This assumes that when accelerating hard at the same speed both vehicles are always making roughly the same power. The number of gears and choice of ratios can go a long way in insuring you keep a motor in its sweet spot for more of the time. This assumption of equal power is again a decent approximation but far from exact. (torque to the wheels - losses)/weight remains the clearest and most precise formulation.

Swamp, what I said was: "If one car is making more power than another at the same weight and at the same speed, it will accelerate harder than the car making less power at that point, regardless of gearing or the torque it's making."

Jesus, Swamp. You say horsepower is approximate but torque at the drive wheels is exact? What are you thinking? If you have 10.000% more power at a given speed, you have 10.000% more torque at the drive wheels. Not even 9.999 or 10.001 percent more. 10.000% more.

Jesus.

Hans Delbruck wrote

MB-AMG is working on direct injection for the 6.2l

Autoweek reports the DI version will have 580-600 HP

They just need to work on a decent chassis and I am sold.

bruce.augenstein@comcast. wrote

Swamp, what I said was: "If one car is making more power than another at the same weight and at the same speed, it will accelerate harder than the car making less power at that point, regardless of gearing or the torque it's making."

Jesus, Swamp. You say horsepower is approximate but torque at the drive wheels is exact? What are you thinking? If you have 10.000% more power at a given speed, you have 10.000% more torque at the drive wheels. Not even 9.999 or 10.001 percent more. 10.000% more.

Jesus.

That is not what I said. I slightly abstracted your (true) statement to the following - two cars with the same peak hp and weight will overall accelerate the same. You may have not said this explicitly, but you have said "hp and weight are all that matter" enough times I think it is a fair characterization of your belief. Yes or no? I am not arguing with your EXACT statement, it is true. My contention is that your statement that hp is an excellent shorthand for torque to the wheels is not all that accurate and that (torque to the wheels/weight) is better. A case where this expression would be a better prediction of acceleration would be the case of two vehicles with identical peak hp, one with a low rpm high torque engine and an automatic transmission with only 4 gears vs. the other having less torque a higher redline and 6 or 7 truly optimized gear ratios.

bruce.augenstein@comcast. wrote

I'm not avoiding anything. I don't have an argument against your reasoning, and never had - but it's pretty much pointless. You (and I, and others) are obviously missing something.

I believe both engines weigh what the manufacturers say they weigh, and I believe they're both weighed against a European standard, much like our U.S.-centric SAE standard for engine weights. I just don't know what that standard is, or how it may affect the results, if at all.

Bruce

Well something pretty significant must be "missing" somewhere because my reasoning (that you agree with) is entirely inconsistent with your statement in your second paragraph. Sure would be nice to know.

bruce.augenstein@comcast. wrote

I believe both engines weigh what the manufacturers say they weigh, and I believe they're both weighed against a European standard, much like our U.S.-centric SAE standard for engine weights. I just don't know what that standard is, or how it may affect the results, if at all.

Bruce

I wouldn't consider "202 kg according BMW standard" as an European standard.


Best regards, south

swamp2 wrote

...You may have not said this explicitly, but you have said "hp and weight are all that matter" enough times I think it is a fair characterization of your belief. Yes or no?...

No.

Once again, what I said was that at a given speed and weight, the car making more power (obviously at that speed and weight) will accelerate harder than one making less power (yet again at that speed and weight), regardless of torque or gearing.

Peak horsepower to weight will give you a reasonable approximation of acceleration from rest in terms of speed at distance, and a lousy approximation of ET at distance.

If memory serves, this general topic was the subject of our first dustup (Oh! Be still my heart!), wherein I said that time to speed and time to distance were essentially unrelated (complete with examples), and you said (complete with lecture) that that couldn't possibly be true - obviously talking about something else entirely.

Bruce

swamp2 wrote

Well something pretty significant must be "missing" somewhere because my reasoning (that you agree with) is entirely inconsistent with your statement in your second paragraph. Sure would be nice to know.

Yes, and yes.

Bruce

Edit: PS - The only thing I initially came up with is that if the Euro standard includes the flywheel/flexplate, that would give the Merc perhaps a thirty pound advantage.

I've abandoned that, however, because then you'd have to publish separate engine weights where there was a choice of transmission (which I have never seen), and in addition, the bimmer would come in at something close to 400 pounds sans that dual-mass monstrosity, obviously pirated from an old u-boat. I just don't believe that given the V10 parent is pretty damned heavy.

southlight wrote

I wouldn't consider "202 kg according BMW standard" as an European standard.


Best regards, south

Do you know what the standards are? Do you think they're different?

No challenge here. Just looking for someone to add something that moves us a little further along.

Bruce

bruce.augenstein@comcast. wrote

Do you know what the standards are? Do you think they're different?

No challenge here. Just looking for someone to add something that moves us a little further along.

Bruce

Unfortunately not. Almost seems like there is no binding standard for engine weights, so Merc states "dry weight" and BMW according to their own standard. In what regard if anything these methods differ would be really interesting to know. I'll keep looking for some information.

Do you happen to know what usually is contained in the engine's weight? It's not only the 'block' itself but also some ancillary units, isn't it?


Best regards, south

southlight wrote

Unfortunately not. Almost seems like there is no binding standard for engine weights, so Merc states "dry weight" and BMW according to their own standard. In what regard if anything these methods differ would be really interesting to know. I'll keep looking for some information.

Do you happen to know what usually is contained in the engine's weight? It's not only the 'block' itself but also some ancillary units, isn't it?


Best regards, south

The SAE standard is covered under #J2038, but I don't know all (or probably even most) of the specifics. I've been told that it includes the intake and throttle(s), so under that standard, the bimmer may suffer a bit against the Merc. We're talking pretty small potatoes here, though.

Bruce

bruce.augenstein@comcast. wrote

The SAE standard is covered under #J2038, but I don't know all (or probably even most) of the specifics. I've been told that it includes the intake and throttle(s), so under that standard, the bimmer may suffer a bit against the Merc. We're talking pretty small potatoes here, though.

Bruce

Yes, pretty small potatoes. Another way to look at it: The BMW parts catalogue lists the M3 S65 'short engine' at 139kg, this means the difference between the block and the weight according BMW standard is as much as 63kg. What parts could be included for that difference? All this is quite meaningless as long as we don't know anything about the 6.2l Merc engine (don't know the engine code), though. So knowing the block weight of that engine would be something to start with.


Best regards, south

Edit: Of course, that SAE standard is only available through subscription.

bruce.augenstein@comcast. wrote

...I said that time to speed and time to distance were essentially unrelated (complete with examples)...

Hi Bruce. Not sure what you mean above by "essentially". I wasn't a part of the discussion you referenced, but would be curious to see it. Can you point me toward that thread?

lucid wrote

Hi Bruce. Not sure what you mean above by "essentially". I wasn't a part of the discussion you referenced, but would be curious to see it. Can you point me toward that thread?

It's here, in note 79, plus Swamp's answer and the eventual heat (from me).

Hans Delbruck wrote

MB-AMG is working on direct injection for the 6.2l

Autoweek reports the DI version will have 580-600 HP

Good LORD.....

bruce.augenstein@comcast. wrote

No.

Once again, what I said was that at a given speed and weight, the car making more power (obviously at that speed and weight) will accelerate harder than one making less power (yet again at that speed and weight), regardless of torque or gearing.

Peak horsepower to weight will give you a reasonable approximation of acceleration from rest in terms of speed at distance, and a lousy approximation of ET at distance.

Well every time someone mentions torque to the wheels and gearing you always "quick draw" the same line, and it is basically a quote, "all that matters is hp and weight". When you play this card you leave off important and very limiting caveats (that are mentioned above) that are covered by torque to the wheels and gearing.



P.S. By the way reading through our our old discussion on the relation of speed at distance vs. time to speed in the post you refer to, I stand firmly by everything I said there. It is PURE MATH and indisputable. If you think I am wrong on the points I made you are calling Newton wrong. As well my statements are completely consistent with your numbers which some believe to be inconsistent on a casual glance.

bruce.augenstein@comcast. wrote

It's here, in note 79, plus Swamp's answer and the eventual heat (from me).

OK, thanks. I'll read that on the plane tomorrow (it's that or car mags), and post on that thread if I have anything to contribute to that discussion.

bruce.augenstein@comcast. wrote

It's here, in note 79, plus Swamp's answer and the eventual heat (from me).

I have witnessed the exact same thing with car vs bike races. I am with you on this one.

I don't understand why so I shouldn't need the flame suit.

swamp2 wrote

Well every time someone mentions torque to the wheels and gearing you always "quick draw" the same line, and it is basically a quote, "all that matters is hp and weight". When you play this card you leave off important and very limiting caveats (that are mentioned above) that are covered by torque to the wheels and gearing.

Feel free to continue cleaning up after me. Then we can have the same conversation, again and again and again...

swamp2 wrote

P.S. By the way reading through our our old discussion on the relation of speed at distance vs. time to speed in the post you refer to, I stand firmly by everything I said there. It is PURE MATH and indisputable. If you think I am wrong on the points I made you are calling Newton wrong. As well my statements are completely consistent with your numbers which some believe to be inconsistent on a casual glance.

Everything you wrote was spot on, and of course completely beside the point I made, and completely beside the point of the OP's question. In other words, your correct statements were completely out of context. I answered the OP's question for you in regard to the M3 vs M5 numbers.

Bruce

bruce.augenstein@comcast. wrote

Feel free to continue cleaning up after me. Then we can have the same conversation, again and again and again...



Everything you wrote was spot on, and of course completely beside the point I made, and completely beside the point of the OP's question. In other words, your correct statements were completely out of context. I answered the OP's question for you in regard to the M3 vs M5 numbers.

Bruce

Many of our disagreements stem from fairly drastically different world views.

Mine is based on and heavily influenced by science - math, physics, engineering, combined with my love of cars. Everything is a variable, everything can change and any value is possible (maybe not to build but to consider). Your is very practical and experiential. You are the classic gearhead gifted with significant understanding beyond most. Basic disagreements like gearing does or does not matter depends strongly on if you are looking at the physics or at actual sporty production vehicles. Surely in terms of equations and engineering gearing makes a huge difference. Mis gear a car, on purpose or on accident, very far away from its optimal gearing and its performance will suffer tremendously. We don't have to worry much about that with real cars because it doesn't often happen or at least not in a really significant fashion. Other disagreements between us are based on similar differences in the way we see things. Your experience and clarity are in general excellent and I always enjoy reading you posts. As well I have learned a thing or two from you. I can only hope that is somewhat reciprocated. Cheers.

335 more torque than M3.
335 looks like M3

...

C63 more torque than the planet
C63 looks like C350. (so? see line immediately above).

End of argument.

What said it best - C63 is way faster in a line than the M. Most of us don't live anywhere near curves. Most of us race in red-light, block long races. Most of us would benefit from a C63.

I got rid of my 07 M Coupe, I looked at an M3 and even an M5 - I ended up picking up the 63. Never liked slush boxes - am totally THRILLED with the 63 and will happily spank any of your E9X M3s. Thank you very much.

No one looks at a M5 seriously and then picks a C63. Those that do are only justifying their purchase.

peet wrote

335 more torque than M3.
335 looks like M3

...

C63 more torque than the planet
C63 looks like C350. (so? see line immediately above).

End of argument.

What said it best - C63 is way faster in a line than the M. Most of us don't live anywhere near curves. Most of us race in red-light, block long races. Most of us would benefit from a C63.

I got rid of my 07 M Coupe, I looked at an M3 and even an M5 - I ended up picking up the 63. Never liked slush boxes - am totally THRILLED with the 63 and will happily spank any of your E9X M3s. Thank you very much.

Too bad you are on the other side of the country, you are in a for a rude awakening if you think the C63 is going to dust DCT M3's.

I can't remember the last time I took a straight line to any destination and drag raced the whole way there.