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      02-02-2014, 04:51 AM   #311
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Originally Posted by swamp2
Ease up on the accusations and borderline insults, you are massively guilty here of misreading/misinterpreting my words and driveling them back out with a completely false interpretation of my very clear statements. Really, shape it up.

Originally Posted by Boss330 View Post
It seems that you think I believe the V8 warble comes from an uneven firing sequence per crank rotation/angle... And since it doesn't I'm wrong.
No, I understand exactly where it comes from. No need then and no need now for such a treatise. It's real simple - cross planes have consecutive firings in one bank of the V, flat planes does not. Both designs have an equal crank angle between combustion events. No need to write a book to explain this. And thus, as I said, it is more about those firings being routed to the same header and section of the exhaust.

Originally Posted by Boss330 View Post
In a flat plane crank V8 all 4 pistons on the same bank are in sync.
Absolutely not, I know you know this, but your language is entirely incorrect/sloppy here.

Originally Posted by Boss330 View Post
They are grouped 2 and 2 together with 180 degree of crank rotation separating TDC for the two groups.
Yes, exactly.

Originally Posted by Boss330 View Post
There is NO way that the "state of tune" can eliminate the 2 cylinders firing out of sequence, neither can a exhaust system after the collectors on the headers.
I never said that at all, that is 100% misreading and reading into what I wrote. Again, I said that overall state of tune (perhaps loosely given by specific output), along with redline and along with exhaust are more important factors than crankshaft geometry while under load (actually driving). I also said that some exhaust routing trickery could basically eliminate the cross plane V8 warble and we agree on this.

Originally Posted by Boss330 View Post
It has to be done before the collectors, just as BMW does on the S63tu and Ford did on the GT40.
Yes, agree.

"Warble", a good/accurate term, is fundamentally a low frequency phenomena. I contend that at any significant use rpm, although some folks may be able to tell the difference between flat and cross plane V8s, the differences substantially diminish. Yes, the effect is still present as the same basic phenomena is happening, just sped up. But compared to idle it is undoubtedly diminished. How about tuned cross plane V8 Corvettes? Why do they not sound much like an M3 V8 (again cross plane). We've had this debate before but I claim that at high load and high rpm an M3 with nothing more than a cat back sounds closer to a V8 Ferrari than a V8 Corvette. The fundamental reason is the redline, exhaust system differences and state of tune (compression ratio, specific output, etc). Sound is fundamentally determined in spectral content, that is by the number of combustion events per second, higher rpms gives correspondingly higher frequencies simply NOT present at lower rpms. This is a major effect.

Lastly I also contend that turbo charging an engine gives it a huge change in sound and it also makes a bigger difference to overall sound than flat vs. cross plane (again while under load).
With your accusations towards me and misreading of my posts in the other thread, I thought you were man enough not only to dish it out but also to take criticism. It seems no... You have a habit of doing personal attacks whenever someone disagrees with you, and then claiming that you have never said what you HAVE said... You have repeatedly said that state of tune has more to do with sound than the crank layout.

If you can't hear the difference between a Ferrari V8 at 8000rpm and a E92 M3 at 8000rpm, then you must be one of the few...

Just as you write long essays on "your" subjects to explain things, so should I be allowed to when you clearly have shown a lack of elementary understanding of the two V8 concepts. Something so basic, that I know of NO other disputing it... Instead you attack me and my English (something you have also done to others on these boards that have English as their second language).

So, a S65 sounds similar to a Corvette until the 'Vettes redline and then the S65 changes into a flat plane crank V8 sound?

Sorry, but I have not yet heard a S65 with a exhaust sound remotely like a flat plane V8. Come to think of it, neither do a NASCAR V8 sound like a flat plane V8 either... And they do 8000+ rpm...

Like it or not, the cross plane sound is present even at redline, not as a burble that you easily hear at idle, but as that off beat exhaust sound (not that it sounds bad, just different from a flat plane exhaust). That character is not present in that GT40 nor in a flat plane V8, nor in a I4 engine. But at least you now acknowledge that you have to use 180 degree headers (as per Ford GT40 and S63Tu) to replicate the flat plane sound. Something I have said all along... But isn't "only" at idle the sound differs, it is all through the rev range:

And at what rpm does this straight piped F430 sound more like a cross plane V8 than two I4 engines?

And does this sound more like a Corvette or a Ferrari V8

Last edited by Boss330; 02-02-2014 at 08:43 AM..
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