" @G0TB00ST - you can check out other people's garage - I didn't know about that for awhile after I joined - thought that might help. "

" lol - I have a bad habit of doing the same thing "

" You didn't read my post - I said:

"The S65 has made 700 HP (post said this hasn't been seen on the S65) - and it makes torque across a very wide power-band, something the N54 is INCAPABLE of doing - why isn't that seen as important?"

The power-band of the S65 and the N54/55 are two completely different animals. I was referring to the shape and length of the output curve. One is perfectly flat and long - the other is not. An engine builder strives to have a torque curve that is perfectly flat - like an electric motor as an example. The longer that plateau extends (RPM) - the better also.

The redline of the N54/55 isn't going to increase to S65 levels without some insane amount of work - and turbos that can breath. As you said - they shouldn't even be compared at this level. One is made for a completely different purpose. "

" The more I think about this, I would almost bet there is a direct correlation between piston dwell and maximum acceleration of the piston - but am too tired to read/think about it. This guy explains most of what has been said: http://ftlracing.com/rsratio.htm "

" I think I posted this before somewhere - but this video is amazing: http://www.youtube.com/watch?v=NbXlCtpXTHQ

That's the 3.5 liter VAC S54 with straight cut gears. Basically a race car for the street - ridiculously responsive/high revving/simply awesome. "

" Most people measure piston speed though by looking at the mean/average. 3 o' clock and 9 o' clock are the two places that piston speed will "generally" be the highest - at this point, it comes down to stroke length, crank pin angle, etc... The longer the rod is, the less force at TDC...

I am just not sure how this practical/feasible it would be to obtain this information needed to measure this correctly. It can be described by math, but mean/averages are always good for general purposes.

I guess it makes sense to look at max/min, but then you have to toss in weight to actually factor in anything that matters (gs/forces). I think this is why mean is used as a general term to relate to engine speed. IDK if that helped at all. "

" As the title says, all I can say is WOW. I dropped my M3 off for service today (and some other minor things), and they gave me an X1 to take home. I always liked the X1, and was hoping it was the 3.0 liter turbo - but as I was walking up, noticed the xDrive28i symbol. I though this was just the 3.0L NA I6 engine that I have driven before.

The first thing I noticed was that the car had a TON of torque. I attributed this to the 8 speed transmission, and drove the rest of the way home from the dealership in stop and go traffic (not sure I like auto start/stop btw). Anywho, I had a business meeting after work - and since it was well past rush hour, finally got to drive it spiritedly down LSD (our main/8 lane road along the lake). I was shocked that this iteration (thinking at the time it was the N53 [I really haven't kept up with the non-S engines to be honest]) of the motor gained so much power. It really felt quick - especially considering it was an SUV.

I kept telling myself that the badge wasn't right - and that it was instead the N55 or something, but sometimes it just didn't feel powerful enough to have 300 HP - then other times, I felt it did. I kept going back and forth, not knowing what the hell was powering this thing. A N53, N55 - and didn't even CONSIDER a 4-cylinder N20. I did notice on the highway, that I could mash the pedal down all the way - and lift off again very quickly without any response from the engine (a la N54/N55). I then had no idea - it had to be turbocharged, but just didn't feel right as an N55. This is getting too winded...

Pulling into my garage, I was in 2nd (from a stop - up a hill to my spot) - and gave it about half throttle - and heard the turbo whistle. I popped the hood, and there it was. A 4-cylinder; I swear to God this thing didn't feel rough. It wasn't as silky smooth as a I6, but it was DAMN close. At high RPMs, you would be hard pressed to tell the difference.

As far as power goes - for the MPG this thing gets, this engine would be something I would recommend to ANYONE buying this car. Yes, the N55 has a bit more torque, and a bit more power - but to be honest, this is so close, I doubt most people would notice. Oh, and the trip computer says I still have 400 miles left in the tank. I am literally so giddy over this - I think that little engine is so awesome now - with a tune, it would probably crush the N55 stock. "

" It's hard to explain sometimes - especially when dynos are factored in...

A dyno should read the same - given proper calibration - for a given car in any gear. Yes, a car in 1st gear will rotate the drum to a small amount of speed in a short amount of time; a car in 6th gear will accelerate/rotate that same drum to a large amount of speed in a large amount of time... These two speed/time values are exactly the same when divided. The only reason that I have read to use as close to a 1:1 ratio when dynoing your car is because there is less parasitc loss in the higher gears than lower. In other words, 1st gear saps more power than 6th due to the fact that the engine has to spin these gears much faster in 1st than in 6th. This means more heat, more friction, etc...

One thing that a dyno WILL NEVER SHOW is how gearing will affect the actual accelerative force of a car. That's not the point of a dyno - the point of a dyno is to measure the engine's average power output - that's it.

To keep things simple, think of the equation for HP: HP = TQ * RPM / 5252 (speaking imperial here)... Torque and RPM are EXACTLY EQUAL in contribution to power. If you have 1 extra lb-ft of torque than I do, but I have the capability to spin my motor 1 RPM more than you - we have the same exact power capability.

Now take gearing into consideration. We all know your car accelerates harder in a lower gear than a taller gear. This is something everyone can agree on - and surely has "felt" 1st gear pulling harder than 6th while driving any car. Take the simple example of two cars both making 300 ft-lb of torque from 0 RPM all the way to 5000 RPM (redline). Both cars have the same gears. One car gets a "tune"
- we'll just say a lightened valve train to keep this simple. This newly tuned car has a redline of 6000 RPM - and still can create the same amount of torque at this new RPM. Without changing gears, we can see that the horsepower for the tuned car went up ((6000 RPM instead of 5000 RPM) * TQ/5252). Power for this car went up exactly 20% - torque at the crank is still the same. "