engine sound of a 911

[dougn1]

being a perfectly balanced flat six that fires evenly, i would think my 964 would sound smoother like the howl of an in line six or a V 12 yet it has a lumpy sort of sound. actually i think the eariler 3.2s and smaller do sound smoother. anyone have any insights on this?

[jluetjen]

V12's have twice as many cylinders firing in a given time compared to a 911. So to some degree a 911 at 2000 RPM will sound like a V12 at 1000 RPM.

That being said, you also have to consider such things as intake and exhaust design. If you look at the milder street V12's from Ferrari, they often had each carb throat feeding 2 cylinders which would have created a sound 2x the frequency of a 911's -- assuming that they 360 crank degrees opposed to each other. But if my memory is correct, Ferrari had two adjacent cylinders on the same bank using the same throat, so I doubt that it would be an even pulse. Now something like a 250 GTO had one throat per cylinder and so in that regards would share the intake sound with a 911.

The exhausts on the other hand are similar, but different. Ferrari V12's had the first 3 cylinders in a bank sharing a secondary and then the 2nd 3 cylinders. So each bank would sound like a 911 engine if a 911 had it's secondaries combined prior to the muffler. But 911's have essentially 2 independant exhaust systems sharing the same muffler, so it sounds different. When you have a 911 with megaphones, it will actually sound like 2x 3-cylinder engines as opposed to a BMW straight 6. As a result the frequency will be 1/2 of a straight 6 or a V12.

This is why a 911's engine always sounds so unique and has that distinctive growl rather then the screaming roar of the Straight 6 and V12's.

[donstevens]

I think it has more to do with the rouuting of the exhaust. If you take that 3.6 and route all the exhaust through equal length headers to a single outlet, you'll get the "howl of an in line six or a V 12". Cox Motorsports offers such headers that are very popular in vintage racing. The cars with the 6 in to one exhaust have a very nice howl reminiscent of the group 44 Jags of the late 80s.

[jluetjen]

Don; We agree. You are just a far more pithy writer then I am.

The other thing to keep in mind is the impact of the induction system, especially at higher rev's (or lack there-of in the case of CIS). This is why so many of us love MFI and Carbs. At higher RPM's they make an awsome wail that you'll never get out of a CIS or common plenumed engine. It's also one of the reasons why the CIS cars are generally quieter then the earlier cars.

[Zeke]

I think it has more to do with the rouuting of the exhaust. If you take that 3.6 and route all the exhaust through equal length headers to a single outlet, you'll get the "howl of an in line six or a V 12". Cox Motorsports offers such headers that are very popular in vintage racing. The cars with the 6 in to one exhaust have a very nice howl reminiscent of the group 44 Jags of the late 80s. [/QUOTE] It is an unbeliveable sound.
You know what? This thing sounds pretty good. Notice the joining of both banks before it separates.



http://www.pelicanparts.com/catalog/shopcart/911E/POR_911E_exhaus_pg2.htm#item11

[Leland Pate]

I'll throw in my .02 cents.

I would also venture a guess that the lack of a water jacket surrounding the cylinders and heads gives our motors somewhat of an unusual sound.

At least, when people ask me whay Porsches and VW's have "that sound" this is my reply.