Quote:
Originally Posted by Boss330
All of my previous replies was posted on an iPhone, not the best tool to type long replies on  |
Fair enough!
I'm well aware of both engine balance, crank design options, rotational inertia, firing order and the like. Again, I freely admit that cross vs. flat plane is a major engine architectural feature, however, again, it is only one component that defines an engines entire character. In my opinion both redline and power delivery as just as important in defining character. Let's think of it this way. Imagine some (odd) hypothetical flat plane V8 engine with every aspect both low performance and even low quality (carburetors, distributor, cast iron everything, no forged parts, no advanced electronics, loose tolerances, heavy, over-designed parts, no variable valve system, no advanced knock detection, etc.). Now compare that engine and an S65 to the F430. Yes somewhat of an extreme example but you should get the point. I believe you are losing sight of the forest for the trees.
Let's talk a bit more about a bedplate design and your component view vs. my system level view. Here is one decent reference for you -
engine builder magazine link.
The BLS engine is not a bedplate design and does not need to be whereas there are fundamental engineering reasons (mostly redline and high peak combustion pressures) why both the F430 and S56 engines are bedplate designs. You can start with any part of the engine (say crank) and work your way out and say that everything else is just an accessory, just a head, just a throttle body, just the cams, just the ECU, etc. However, the fact of the matter is that an engine; sound, performance, efficiency, character, power delivery, longevity, etc. are all due to the sum of the parts comprising the engine system. To minimize the importance of some components also minimizes the key performance benefits those components provide. These "components" certainly are not designed in isolation and certainly can't be picked off of parts bin shelf willy-nilly and successfully integrated into a given engine design. Although neither of us has (nor can get) enough access to design details for the BLS (what is its darn engine code anyway...) nor S65 engines, I would be wiling to guarantee that following both air and fuel from intake and gas tank to the combustion chamber would yield a significant number and of quantitative and qualitative differences. Other differences would be beyond the realm of inspection and would require great engineering insight from OEM. Other engine components and systems would yield a similar array of differences. Because of the overall engineering challenges in getting high specific output and high redlines I contend there will be plenty more similarities among the S65 and F430 than S65 and BLS.
Your comparison between the BLS heads and the M3 heads also falls flat. No BMW isn't the only company with "high flowing" heads. But also the days of hot rodders placing a head on a "flow bench" are long since gone (at least for high end race and high end consumer engines). That work today, as well as modeling the entire intake tract and the actual combustion process is now done on supercomputers using computational fluid dynamics (again it is at least done this way for many high rpm racing engines and some production engines). The torque curves for the S65 vs. the BLS engine in part, demonstrate this system level engineering excellence by BMW M. The BLS engine has a pretty strong drop off in torque beginning as low as 5300 rpm. This not an insignificant detail. You can really FEEL this and it absolutely is detrimental to performance. Again it is a very fine engine, they just did not need the engineering and expense to make it breathe at 8000+ rpm to achieve their design goals, a larger displacement engine with more torque provides that. Just as Ferrari and BMW (S65) went a different direction for a different goal. All of these engines perform admirably they just go about it in a different fashion, and again the resulting CHARACTER of the S65 and F430 are much more similar than those of the S65 and BLS engine.
I think your videos (and now "mine") make my point more than yours. Neither the M3 GTR nor the other videos sounds ANYTHING like a Ferrari to me. In fact, I bet most people, general enthusiasts included, could not identify a flat plane vs. cross plane V8 if somehow that was the only single change to an engine. We don't have the luxury of making such comparisons because flat plane tends to be accompanied by a wide variety of other components and systems that all work together to produce high redlines and flat torque curves.
I'll end with a couple of videos myself that show how radically different exhausts can make the S65 sound. In my evaluation these sound much more like a F430 than either of the flat plane videos you posted. Less so at idle but then again at idle you have much more relative engine noise than intake or exhaust noise
I contend you simply cannot make a BLS Mustang sound like this. Why - primarily redline. Higher redline have just about everything on the engine moving at higher speeds, rotational and linear and this vast array of excitations are what produce the higher frequencies in the sound spectrum.
I think we'll probably have to agree to disagree here. To you crankshaft type is the single most important factor in judging two engines similarity or dissimilarity, whereas to me, both redline and power delivery are either equally or more important. Good discussion! Cheers.