Why does the GT3 sound so different to the regular flat-6?

[Steviebeee]

Please bear with me here !

Both cars use a flat six? Is it purely down to the configuration of the manifolds that make that wonderful sound??

Even regular flat-6 engines with performance exhausts sound nothing like the GT3 engine, they almost sound like a completely different cylinder configuration?

So, come on techies, what makes the sound so special?

PS: I'm not taking induction, or rev limit. In particular I'm taking that spine tingling frequency that starts at around 4800 upwards. Although ringing it out to 8400 (or there abouts!) is particularly glorious

[mollytherocker]

I assume you know its a completely different engine?

MTR

[Steviebeee]

MTR,

come on man. I know that much!

I just wondered what made them 'sound' so completely different?

Surely engine internals can only effect the end result by a small %?

I remember reading somewhere that the aggressive cam profile was what gave the Alfa 2.5 V6 its legendary sound. So, what is it that gives the GT3 engine the sound that makes us all go weak at the knees??

I've always wondered, as the regular flat-6 is just sooooooooooo different.

[Magic919]

Valve timing and lift will be making a big difference to the sound. My X51 996 sounds quite different to the standard engine in the higher rev ranges.

I think the GT3 may just advance valve timing and not have the extra lift. Haven't driven a GT3 yet, but I'm booked to drive both the latest GT3RS models in March. Can't wait to hear them.

[Steviebeee]

Ah,

that does make sense. I'm pretty sure the GT3 has variocam and what I'm hearing, later on around 4800rpm is the change in valve lift/duration.

BUT, the overall sound is just completely different.

When I used to run a fairly high powered Evo, I remember collecting it when it had gone from just over 400 to 500hp. Part of the upgrade involved swapping out the Manifold and down pipe (and HUGE turbine ). It sounded like a completely different engine, hence why I'm asking if alot of it is down to the manifolds and exhaust.

[Magic919]

I'm sure the intakes themselves contribute and I expect the same of the exhausts. Later GT3s have some flaps in the intakes I read somewhere and those opening will change the effective length and tune the note a bit too.

[Steviebeee]

Magic919 said:

Valve timing and lift will be making a big difference to the sound. My X51 996 sounds quite different to the standard engine in the higher rev ranges.

I think the GT3 may just advance valve timing and not have the extra lift. Haven't driven a GT3 yet, but I'm booked to drive both the latest GT3RS models in March. Can't wait to hear them.

Does the X51 upgrade not have different manifolds?

[Matt Seabrook]

The first video is a Vauxhall 16v making about 75bhp per litre

http://www.youtube.com/watch?v=R73PKMwgPI4

The second is the same basic block and head but making 140bhp per litre

http://www.youtube.com/watch?v=dLIANFe-orM&lis...


Engine internals/induction can make quite a difference.

[Steviebeee]

Matt Seabrook said:

The first video is a Vauxhall 16v making about 75bhp per litre

http://www.youtube.com/watch?v=R73PKMwgPI4

The second is the same basic block and head but making 140bhp per litre

http://www.youtube.com/watch?v=dLIANFe-orM&lis...


Engine internals/induction can make quite a difference.

Thats cheating! ITBS make a HUGE difference lol

[Magic919]

Steviebeee said:

Does the X51 upgrade not have different manifolds?

On my 996 certainly exhaust manifolds. Visible intake parts look standard to me.

[Matt Seabrook]

Steviebeee said:

Thats cheating! ITBS make a HUGE difference lol

Yes may be but bhp does make even the same engine sound different. The GT3 has more bhp per cc than the other 911's so even if it had the same exhaust and induction it will sound different.

[J-P]

Magic919 said:

Valve timing and lift will be making a big difference to the sound. My X51 996 sounds quite different to the standard engine in the higher rev ranges.

I think the GT3 may just advance valve timing and not have the extra lift. Haven't driven a GT3 yet, but I'm booked to drive both the latest GT3RS models in March. Can't wait to hear them.

Same here! When are you going?