as a newbie, i'm not going to get drawn into this with you, so if you wish to continue send me a pm. i will say that if you think there is no relationship between bore/stroke and torque then you're pointing your finger in the wrong direction.

 

No need to continue. I agree that there is a relationship, but it is on a per cylinder BASIS!!

 

Ok guys, I don't know what the hell happened to this thread but lets get back to topic.

The only flaw I see with the 7 speed transmission is the odd spacing of ratios from 4th onwards. Again, MB's limitations have stopped AMG from really flexing its muscles. I mean, they made the engine from the ground-up, would it have hurt to ask Ricardo to make a custom 7 speed for this masterpiece V8? They did it for the Veyron. Also, in that Chrysler supercar contraption (ME412?) the powerplant was a quad-turbo 65 motor with (guess what?) a custom Ricardo transmission.

Maybe I'm asking too much but they way I see it, if my bank can move its customer service to India, then AMG can surely outsource the transmissions!

 

Guys,

It’s not the number of cylinders it’s the displacement (and compression ratio)that makes torque in a normally aspirated engine.

There is no replacement for displacement. Let me correct myself: there is one: Cubic dollars. But for everything else, add the cubes.

Displacement rules the land of torque, because in an internal combustion the engine produces power by burning fuel and air. The key to gaining more power is simply to add more air and fuel. The key limitation is the ability of the engine to intake air. In a normally aspirated engine air is drawn in the engine by the vacuum created during the intake stroke. The larger the engine displacement, the more vacuum produced. It's that simple. More air allows more fuel, and more power follows. M5 has a very short stroke (75 mm) made for High revs vs. the 63 long stroke (94 mm) for more low end grunt.

Torque is the static measurement of how much work an engine does, while power is a measure of how fast the work is being done. Since horsepower is calculated from torque, what we are all seeking is the greatest-possible torque value over the broadest-possible rpm range. Horsepower will follow suit, and it will fall in the engine speed range dictated by the many factors that affect the torque curve.

Increased displacement is the easiest way to achieve increased torque. Very large cylinders and a long stroke offer the greatest cylinder volume and overall piston area for the fuel charge to push against the crankshaft.

Again, the ability to flow air in and out of the engine is the key for power. You can improve breathing by smoothing airflow in and out of the engine, and by increasing valve area. The second way is to simulate a larger displacement through pushing smaller cycles through the engine (M5), in essence by out-revving the other engine but losing torque. That may not be enough to overcome any displacement disadvantages. The M5 motor does a great job producing power quickly with the thanks being given to its lightweight internal parts. This is one reason the M5 can accelerate its mass quickly with out producing gobs of torque (not to mention it’s gearing).

The bigger motor enjoys one big advantage; torque. Big motors (e63) produce lots of it, and produce torque practically everywhere. Smaller motors can produce torque (M5), but in a much narrower rev band. And generally higher up in the rev band, which makes the torque harder to use.

My fingers hurt. Gotta go to the track now. Cheers!

 

 

Your last statement is not quite complete. It should read: typically the more cylinders, the smaller the pistons/bore which equals less torque per cylinder.

If you have two engines of the same size but with a different number of cylinders, and they have similar tuning and volumetric efficiencies, they will produce similar power.

Let's look at the M5 and E63 engines. The M5 uses a 5.0 lt V-10. The E63 uses a 6.2 lt V-8. The peak torque of the M5 is 383 lb-ft and the peak torque of the E63 is 465 lb-ft. That's about 38 and 58 lb-ft per cylinder, respectively. If you make the M5 engine the same size as the E63 engine, it would require 12.5 cylinders. Multiply those 12.5 cylinders by the 38 lb-ft/cylinder M5 torque value and you get 475 lb-ft, which is about a 2% difference from the E63. This 2% difference can be attributed to the tuning/volumetric efficiency components, which appear to be similar between the two engines.

BMW chose to use a V-10 because of the reduced reciprocating weight of the smaller piston/rod assemblies. This reduced weight allows higher RPMs, which translates into more HP, assuming the engine can handle the increased airflow. As a consequence, their 5.0 lt V-10 puts out similar HP figures to AMG's 6.2 lt V-8.

You are wise to disengage from the other poster. He has demonstrated little more than a superficial knowledge of the relavent topics in his posts, and when he can't substantiate his claims, he becomes belligerent and abusive.

 

thanks! them rims are iforged vertex

 

yup, that's me

it's funny cuz i've been a bimmer faithful for the longest time, but as i get older, i'm becoming more attracted to AMG's...

 

while i can agree with you regarding peak torque, there is going to be a big difference in the useable torque between the two configurations. as said, bore/stroke play a larger role and typically a higher cylinder motor yields a smaller number for both. we could debate nuances further but i think in the end we're both pretty much on the same page.

i have no doubt there are many people here that have plenty of knowledge and i'm always willing to learn a few things. btw, thanks for the heads up on the belligerent and abusive part.

 

Abusive?? Now when was I abusive?

Glad you've been warned, newb. Now we can get into it. hehe!!

I agree on displacement, but what if both are the same?
For example, comparing a 6.0L V8 to a 6.0 V12.
I was always under the assumption that the more cylinders would mean a higher TOTAL torque, even though each cylinder would make less.

You are a cool cat, so I am ready to learn....

 

Stop agreeing with me.

 

remember...i stated an "indirect" relationship between more cylinders and less torque. typically (but not always), a higher cylinder engine uses a much shorter stroke in a smaller bore. "peak" torque may still be equal but the total availability of that torque won't be since the longer stroke/bigger bored motor can provide it over a much larger rpm range.

 

Hmm, I guess i was thinking useable power out of the dig, basically like from light to light.

I can see your point in a lap type of race, where overall time is the concern.


So, basically, you are saying that more cylinders tend to narrow the powerband, even if they do have a good peak? If so, I am getting that. If not, give me time and I'll come around.
Assuming we are on the same page on that, could I not argue that the more cylinders can also peak sooner? That may be a bad thing for lap racers, since more RPM is more power and you want to be in a good band at all times; but it would be a good thing for a drag racer as it gives a nice launch. That is more what I was thinking. Make sense?

 

it depends on what you mean by "peak sooner". if you mean earlier in the rpm range, then no. if you mean they can spool up through the rpms quicker to reach their power band, then yes...although time wise it may not be quicker since the long stroke/big bore motor doesn't have to reach those higher rpms to make it's power.

i think it's much easier for racers of any kind to keep their motors in it's powerband. i think the broader power band would be better for the average street racer wannabe type.........like me.

 

interesting that the new 6.3 actually has less torque than the outgoing supercharged V8.. All tests say it doesn;t feel as strong off the line, but obviously revs higher.

 

Well Bilal, it seems once again you were right.

 

While I fully admit that I can't recall the exact reason provided to me by an expert auto mechanic, I'm certain that he informed me of *exactly* this as well.

Something along the lines of more power strokes in a given period of time should result in more torque than a similar engine with fewer cylinders.

 

Luna,

What's up dude? You were MIA for awhile heh? Still up for a few runs?

 

You wanted a video of an E55 and E60 M5--I don't have one. But here is my 2003 S2 racing Steve Dinan's E60 M5 for those that haven't seen this. The E60 rips above 100 mph. I hope you can open this.

http://web.mac.com/markblosil/iWeb/S...%20M5%202.html

 

What the heck is a Dinan S2? I'm confused on this video and what it is supposed to tell us?

 

It is all basic physics and I just don't see what will change with arguing, so I let it go.

 

Dinan is a company that modifies BMW's.
S2 means the Stage 2 package.
Figure 470hp and 419lb-ft torque as per Dinan's website.

It's a mean machine. There used to be one in my neighborhood; black on black.

 

What does that have to do with racing a new M5 in my E?

Impressive video? Heck no.

Keep in mind our strength is in the torque, so finding another car with 470hp and saying it compares to an E55K is just off.

 

Wow--touchy people on this post. Just having fun thinking you all liked cool cars--like I do in the AMGs. I thought the text with the video explained it all. While my car doesn't have the torque of an E55, the video was meant to show the top end performance of the E60 against a car with greater torque but less horsepower.

I passed on an 2006 E55 in favor of the 63, which I will order once the car proves itself in the market. Can't wait.

 

We are far past touchy. We are still king, and as such do not give any respect to the Bimmers. Their past is in making airplane engines. high revving engines that do not need strong acceleration. That is everything an AMG is not, so to show a video of an old M5 getting worked by a new M5 is judt silly to us. Simple as that.

The E63 may or may not perform in a class with the NEW M5, but it will definitely drive like a Benz.