The ultimate F50 exhaust project

As mentioned in the reply above we're now starting to get into the nitty gritty of the design of the exhaust - the only technical things that we have been fairly insistent on is that the exhaust should have the following:


i) a multi-channel configuration which will allow both silenced or unsilenced output. (The silenced output will, we think, based on our experience of F50’s running with different rear exhaust layouts give the engine some low rpm backpressure by passing gasses through a silencer, and in doing so, we hope will boost torque and performance at low revs which is lost when you fit the straight-through rears.


ii) PROPER performance manifolds which are back pressure optimised – as opposed to the Tubi’s which, although an upgrade from stock, still retain the OEM’s compromised underlying layout minus catalyst.


iii) Adequate heat management either by way of thermal insulation around key components or another solution such as double-walled manifolds (which is what the Tubis are). When comparing to stock, shedding those endless catalysts, we’ve already seen reduces temperatures. Can we improve on the Tubi and drop temps further which will may assist in dropping intake manifold temperatures too?


iv) Light weight. Remember – on the OEM exhaust those enormous rear mufflers are being suspended from the gearbox and sit BEHIND the rear axle line which is a critical position for the balance. In any car you want to bring as much mass as possible in between those two axle lines. We need a lightweight multi channel configuration so the rear muffler we build can’t be enormous, otherwise we’ve lost a further opportunity to improve VS the OEM and VS other products like Tubi/Fuchs.


So – the design has started, and it has already evolved a fair amount; to give you an idea - the very first manifold design being considered was the following:


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It was decided not to opt for a 6-1 design as it makes backpressure optimisation fairly challenging, instead we have gone for a 6-2-1 design as shown below:


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The manifolds are ALL equal length and they are joined in order of ignition - this allows us to maximise exhaust flow which will aid scavenging and thus overall power. NOTE: firing order of the F50: 1, 12, 5, 8, 3, 10, 6, 7, 2, 11, 4, 9.


We now have confirmation (thanks to @ Bas Jaski pics) that the MS Racing manifolds have joined the first and last 3 cylinders together, making our design a real departure from the norm. (thank you Sir for your helpful, constructive, and above all positive, contribution!)


The next challenge is deciding how best to incorporate the dual channel muffler/straight pipe into the exhaust. We’re looking at space and all the other requirements above and are tending towards the drawing below….

It’s worth nothing that it’s highly likely we’ll have the exhaust gasses exit in an “X” before leaving the car in an effort to smooth out and possibly lift the tone of the exhaust note and get rid of that “tonelessness” present on F50’s with straight through systems. This directly addresses some of the (confused) feedback we’ve heard already in this thread about how the F50 wearing different exhausts can sometimes just create “noise” instead of sound. Naturally, we’ll want the “valve open channel” to be as low backpressure as possible to really free up the engine at high revs to maximal power output and this may have implications for the X-configuration and whether we do put it into production.


Anyway, we’re still considering this and it will clearly evolve a fair amount before we see it in the metal:

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Updates to follow shortly!

 

Time for the next update - but first let’s address a few points with regards to our chosen layout thus far!

So, the 599 GTB/GTO manifolds have been mentioned by @SolidState, he has correctly pointed out that many have claimed the biggest change to the sound came from the 6-1 manifolds on the GTO when compared to the 6-2-1 manifolds on the GTB. We’ve done some further research and we agree that the manifold layout does indeed have dramatic effect on the sound…but the pipework layout and collector alone are not entirely responsible.

As you can see below on the GTB manifolds you have 6 manifolds leading into 2 primary catalytic converters, these then feed into a collector which feeds into the secondary catalytic converter.

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On the GTO you can see they have opted for 6 manifolds leading into 1 primary catalytic converter, this then feeds directly into a set of link pipes that lead to the rear silencers

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So yes, the 6-1 was a significant factor in the difference in sound – but in reality, it was the also the elimination of a primary and secondary catalytic converter that made a difference.

Now we get a bit more technical and get into why we did NOT choose a 6-1 layout for our Capristo F50 exhaust and why Ferrari may have chosen that layout for their V12’s since the 599 GTO.


The Technical thinking behind our Chosen Manifold Configuration

Well we modelled a number of layouts and what we found, on the F50, is that we actually get a better exhaust gas scavenging effect from a Y-style “2 into 1 ” collector than a direct 6 into 1.


The manifolds on each bank, although bolted to the engine as single pieces collect in banks of three to eventually feed into a Y configuration which eventually gives one output going to the catalyst/silencer.

The function of this “Y” configuration can be compared to an X-pipe on silencer, when it comes to scavenging. In short, the first “3-1” collector of the first pipes of the manifold (remember we’ve ordered the pipework in line with the F50’s ignition order) creates a suction effect for the next the 3-1 collector of the second set of pipework.

That simply doesn’t exist on the 6 into 1 configuration.


However this does make it critical for us to ensure all the pipework has the same length.


Why didn’t Ferrari choose our layout on their V12s? We don’t know. Our guess? Space. It’s pretty crowded up there at the front of F12/812 and routing exhaust gasses down and back while catalysing them may have compromised the ultimate configuration.


More generally, simplified exhaust “theory” rules say:


· Larger diameter manifold pipes: more power high rpm, less torque low rpm

· Smaller diameter manifold pipes: more torque low rpm, less power high rpm

· Longer pipe length: more torque low rpm

· Shorter pipe length: more torque high rpm



That said, until each manifold configuration needs exhaustive testing once on the car (which we will do) – development in our case is an iterative process.

However, what we’ve tried to do, is to take more/less the same pipe diameter circumference as OEM and create longer pipework to get more torque at low AND high rpm.

When you then couple that with the new de-catalysed, ordered to firing-order, Y-collector, equal-length manifolds, we think we’ve got the ultimate, technically modelled and designed manifold for the Ferrari F50.


At this point we’ll show you what it looks like (Including the silencer):


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The Silencer:



In line with the customers requirements to have F1-style fury whilst also being able to switch the exhaust “off”, we’ve built a dual channel exhaust operated by valves:


Valves closed: gasses travel through a silencer. This silencer will be there to keep the car quiet. Not as feeble as the stock exhaust note, but mild and mellow. The silencer, in doing it’s silencing job, will give the engine some backpressure too, which will again boost the cars lack of low rpm urge, the idea being that the valves will be closed during low rpm usage or indeed when the owner just wants some quiet – functionality, currently limited only to the Japanese made custom exhaust products.


Valves open: As described in previous posts, get the F50’s engine above 4500 rpm and really it doesn’t want backpressure. To that end, the gasses will flow through a direct-exit unsilenced channel with a few key differences:

a) The gasses will be blended in an X-before they exit. This has two effects, it increases the scavenging effect, and it gives the car a smoother, more high-pitched sound. Added to the new manifolds, this car will sound sensational and will address some of the criticism levelled at the “toneless, extreme low/mid rpm noise” of the Tubi straight through, the “underwhelming” sound of the Tubi mufflers, and frankly “pathetic” sound of the OEM exhaust.
(we’re choosing our adjectives judiciously here – for you owners that love the OEM sound and love originality, congratulations - a ‘mere’ 355 sounds more like an F1 car than your F1-for-road-F50. For everyone else out there, those are the words OWNERS used to describe their F50 exhaust setups when they came us asking for an upgrade).


b) A small amount of gasses even in the valve open position will travel through the silenced channel – they always do, even on OEM exhausts. The silencer will therefore be optimised such that it’s not just a means of dampening sound at low rpm, but also to add to the F1 howl at high rpm when it’s barely in use.





No there are no catalysts.
Furthermore the F50’s Emissions Control/OBD apparatus doesn’t have 2 lamdas pre and post cat, so you can remove OEM cats without any CEL -as this car has been running from the start wearing it’s Tubi.
We’ll create enough backpressure through the rear silencer and optimised torque from the new manifold design to no longer require them, and therefore no longer need to choke the engine with the same backpressure at high rpm. They’re gone and so are the absurdly hot temperatures in the engine bay which the F50 is so prone to.

Worried about temperature further? Don’t be. Capristo has been shipping all it’s manifold products with some of the best-in-the-business thermal insulation jackets for years.

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We may well deploy these too if required, but we’ve jettisoned most of that heat by dumping the catalysts.



A note on that X configuration shown in the direct exit channel: That X in the “valve open” channel creates more torque in mid and high rpm by essentially by creating a vacuum for the gases behind.


For those of you that want more detail: We have used the following diameters to optimise Gas Glow based on our modelling to expel exhaust gasses from the engine as easily as possible without compromising low rpm torque (described in detail above).


Manifolds: Ø45mm

Y-collector manifolds: 2x Ø50mm

Exhaust and X-pipe channel: Ø60,3mm

Silencer bypass: Ø50mm


Next step – making up jigs and creating the prototype exhaust with Capristo’s best of the best fabricators, welders and laser cutting:

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There will of course, be more updates.
I hope you now realise we weren’t kidding when we said this was the ULTIMATE exhaust project for the F50.

 

Hey guys,

First of all an apology for the delay in responding to the questions above - we will be coming back shortly with a huge update and answers to everything above!

For now, just a quick couple of pictures to show you where we're at Some serious weight savings!!

Finished exhaust ready for installation
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Edition One plaque on rear silencer
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Tubi exhaust
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Capristo exhaust (incl. heat shielding)
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Parts installed
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