Is this sound due it being an Akrapovic exhaust?

[oxf88]

The 2012-2017 Aston Martin V8 Vantage GTE race car has a gorgeous deep rumble at low revs:

https://www.youtube.com/watch?v=iqevOyb49s8&t=...

very different from the V8 road Vantage.

Which components primarily cause the deep rumble in the video?

The GTE had a custom Akrapovic exhaust (see next post for photo) and the 4.3L road engine was customised:

Wikipedia said:

The larger 4.5-litre engine retains the road car’s cylinder block, heads and crankshaft, but uses competition components, including cylinder heads, con-rods, valves, camshafts and a racing exhaust system. The developed engine features a dry sump lubrication system allowing the engine to be positioned low in the chassis, for an optimised centre of gravity.

.
Does the fact the exhaust is produced by Akrapovic affect the sound, or would any racing exhaust with a short length sound the same?

Do certain replaced components from the customised engine contribute to that deep rumble?

Thanks in advance

Edited by oxf88 on Monday 28th October 03:39

[Krikkit]

An exhaust of similar configuration would give a similar sound, although the road engine would need a more aggressive tune before you got that close. And a flat shift transmission of course.

Below is the exhaust, gives you an idea of how far back they push the engine - the exits are only about 6" ahead of the rear wheels.

[oxf88]

Krikkit said:

An exhaust of similar configuration would give a similar sound, although the road engine would need a more aggressive tune before you got that close. And a flat shift transmission of course.

Below is the exhaust, gives you an idea of how far back they push the engine - the exits are only about 6" ahead of the rear wheels.

I understand the road engine would need more power and the crackle/pop is from the ECU remapping?

I don't know much about transmissions. Could you elaborate on your flat shift comment? Intrigued

[Venturist]

You would get a road car something in the neighbourhood by bolting the race exhaust or one of similar construction, however the changes to the engine internals and the camshafts will change the race cars sound signature as well.

[SturdyHSV]

Nice exhaust manifolds like that will influence the sound a little.
Having no cats will influence the sounds a little.
Having relatively little silencing will influence the sound a fair bit.
Having split side pipes with no crossover between banks (I'm assuming the road going exhaust has a crossover) will influence the sound a bit.
The new camshafts will influence the sound a fair bit, especially at idle.

For clarity, I haven't listened to the video as I'm at work currently, but those things are going to largely ring true regardless as I've been fairly non-committal

[Krikkit]

oxf88 said:

I don't know much about transmissions. Could you elaborate on your flat shift comment? Intrigued

They use a sequential transmission and write the engine map so that there's a brief interruption in the fuel and spark while up changes are done, no clutch involved, and the driver can keep his foot planted on the throttle.

That's why there's such a quick downshift, something you can't replicate exactly in the road car. A dual clutch transmission can get close.

As noted above you need more aggressive came to help the noise too.

[oxf88]

Here's a second video with the car going much slower:

https://www.youtube.com/watch?v=iqevOyb49s8&t=...

Anyone know what causes that deep rumble?

[Warby80]

Its a combination of engine design/tuning, exhaust design etc.

Are you trying to replicate the sound for a road car or something? No single component is going to give you that sound, its a result of the whole package.

Just to add, having watched these at Le Mans they sound incredible in person, almost as good as the Corvettes…

Edited by Warby80 on Friday 4th October 12:59

[oxf88]

Warby80 said:

Its a combination of engine design/tuning, exhaust design etc.

Are you trying to replicate the sound for a road car or something? No single component is going to give you that sound, its a result of the whole package.

Just to add, having watched these at Le Mans they sound incredible in person, almost as good as the Corvettes…

Hi, thanks for taking the time to respond.

Yes. I would particularly like to replicate that really deep low-rev "rumble" but I am unsure whether it's just the inlet manifold, or more. I think I have read/heard several times the cams could cause this?

Edited by oxf88 on Saturday 5th October 05:15

[Venturist]

oxf88 said:

Hi, thanks for taking the time to respond.

Yes. I would particularly like to replicate that really deep low-rev "rumble" but I am unsure whether it's just the inlet manifold, or more. I think I have read/heard several times the cams could cause this?

Edited by oxf88 on Saturday 5th October 05:15

I don’t mean to be defeatist but you’ll be spending a lot of money and making your car a lot worse chasing this particular thing.
Start with exhausts that are so short they come out of the sill and have zero emissions kit at all, then you can go tinkering with cams etc which will also massively change your drivability, idle etc not to mention being probably very hard to find and expensive.

Really, have a look at the options on the market, you’ll get a massive difference just from swapping the cats to 200 cell or deleting them, then there are a variety of back box options OEM and otherwise, I’ve never heard anybody be disappointed with the sound of an Aston V8 once uncorked, before you get into the murky and expensive world of chasing a particular sound from something that is in truth very different to your engine.

[Warby80]

As i said, there isn’t one component singly responsible for the sound, its a combination of all the changes/upgrades to engine/exhaust etc.

For a road car the closest you are going to get is a basically unsilenced exhaust system. It would be pretty antisocial and would get boring quickly.

Also you would need atleast a pair of sports cats or The Mot would be a problem.

[oxf88]

Venturist said:

I don’t mean to be defeatist but you’ll be spending a lot of money and making your car a lot worse chasing this particular thing.
Start with exhausts that are so short they come out of the sill and have zero emissions kit at all, then you can go tinkering with cams etc which will also massively change your drivability, idle etc not to mention being probably very hard to find and expensive.

Really, have a look at the options on the market, you’ll get a massive difference just from swapping the cats to 200 cell or deleting them, then there are a variety of back box options OEM and otherwise, I’ve never heard anybody be disappointed with the sound of an Aston V8 once uncorked, before you get into the murky and expensive world of chasing a particular sound from something that is in truth very different to your engine.

Hi, no you don't sound defeatist at all. From my current posts it's reasonable to assume I am slightly naive and haven't given this much thought. I have spent a few months doing research on this, although I still have tonnes to learn. This is more than just a typical project, I really do like this car and I'm happy to spend time and not rush.

Regarding road legality- I believe one of the independent Aston Martin specialists has fitted a switch for a customer to allow alternating between a road-legal exhaust and a track or race exhaust. So my idea was to have side exhausts along with road exhausts going to the back. Road mode would direct the flow through silencers, track mode would silence it a little and racing mode could bypass altogether. I **think** this is possible.

The aspect I really don't know a lot yet is on the engine. I'm currently teaching myself a lot of this and therefore it's a bit of a steep learning curve.

My current understanding is the high-rev cackle/pops are caused by upshifts triggering the ECU to eject unburnt fuel, which then ignites in the exhaust causing the "pops"? This would require an ECU remap and the short, unrestricted exhaust system. I think this might be easier to replicate than the deep rumble.

Regarding the deep rumble I think this is more-complicated to achieve. As a layman it sounds like it's being caused by a mechanical, rotational component in the engine.

I wasn't sure whether someone could say "yes that deep rumble is being caused by the XYZ because it is ABC", or whether, as you said, it's the entire customised engine contributing to the sound. This is obviously my worst case scenario because it means I would have to get the entire engine.

Edited by oxf88 on Saturday 5th October 17:11

[Lesgrandepotato]

Lumpy cams will give that slightly loose stock car sound and the hunting / shifting idle of a race car.

[faa77]

Lesgrandepotato said:

Lumpy cams will give that slightly loose stock car sound and the hunting / shifting idle of a race car.

Hi, I assume you're referring to this sound?

https://www.youtube.com/watch?v=iqevOyb49s8&t=...

[oxf88]

Been told a flat plane crankshaft plays a role in the deep rumble

[SturdyHSV]

oxf88 said:

Been told a flat plane crankshaft plays a role in the deep rumble

Flat plane cranks generally give a sharp buzzy V8 sound that's like 2 4 cylinders shouting at each other (because it is). Think Ferraris and such.

Cross plane crank gives the lovely mellifluous warble and rumble that everyone loves

[Some Gump]

The switch thing you refer to is probably a pair of cutouts.

https://www.google.com/search?q=exhaust+cutouts&am...

Now i love the aston GTE's as much as anyone,but for a road car i'd advise caution. We had an 80's era vantage and removed the silencers, leaving just long pipes and the 1 box on each bank. It was utterly, utterly awesome. For 5 minutes. After that it was just awful.
Boxes went back on in less than a fortnight, for road use going to >105 dB is just a terrible idea.

[oxf88]

SturdyHSV said:

Flat plane cranks generally give a sharp buzzy V8 sound that's like 2 4 cylinders shouting at each other (because it is). Think Ferraris and such.

Cross plane crank gives the lovely mellifluous warble and rumble that everyone loves

Ah yes, I think the person who told me probably meant cross, not flat

i found this video which gives an awesome explanation how the crankshaft design affects the sound:

https://www.youtube.com/watch?v=-s5bSQIQQsY