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Each cylinder bank / exhaust is producing gas pulses moving down from the manifold and the cross pipe partially combines and smoothes the pulses reducing exhasut noise and the smoother gas flow improves the gas extraction from the cylinders.
Whether there is any difference betwwen an X exhaust layout and a 8-2-1 combined layout I do not know,, but a sinngle exhaust would be larger diameter and might affect ground clearance. The exhaust note produced by the Stag is quite distinctive.
Some very clever design on the original Stag exhaust.
Most V engines have roughly the same length from the cylinder head to the balance pipe on both sides of the engine. On the Stag one downpipe runs forwards and the other backwards. Both sides of the system are roughly the same length however, as the rearward facing downpipe has an extra loop around the rear axle to gain the length missed compared to the forward pointing side.
This has the effect that rather than the exhaust pulses arriving at the balance pipe evenly spaced, they arrive sometimes with a short space between them, sometimes with a longer one.
It is this odd spacing that gives the Stag engine its distinctive burble.
On most of my Stag engined cars the design of my home built exhaust manifolds means the two halves of the system are very close in length and they all lack the distinctive Stag burble.
The closest one to it is in my Estate. This has regular Stag tubular manifolds (one forward, one back). However the exhausts from the balance pipe backwards are the same length.
This has the effect that the burble tends to come and go at different points in the rev range.
Its a very complicated business getting an exhaust to perform without getting boom periods at certain rpm which can be extremely annoying.
The reason I have Triumph TR straight through silencers on all my V8 engined cars is that they are cheap. Six cylinder TR owners buy the twin "performance" systems and find they have a really bad boom period between 3000 and 3500 rpm, just where you spend most of the time driving. The end result is that a lot of them get fed up with them and put them on ebay, then I used to buy them cheap (5 sets in all)
These silencers work really well on my V8s, they are quiet and don't lose any performance which is just what I am looking for!
Neil
Neil
TV8, efi, fast road cams and home built manifolds. 246bhp 220lbft torque
Some very clever design on the original Stag exhaust.
Most V engines have roughly the same length from the cylinder head to the balance pipe on both sides of the engine. On the Stag one downpipe runs forwards and the other backwards. Both sides of the system are roughly the same length however, as the rearward facing downpipe has an extra loop around the rear axle to gain the length missed compared to the forward pointing side.
This has the effect that rather than the exhaust pulses arriving at the balance pipe evenly spaced, they arrive sometimes with a short space between them, sometimes with a longer one.
It is this odd spacing that gives the Stag engine its distinctive burble.
On most of my Stag engined cars the design of my home built exhaust manifolds means the two halves of the system are very close in length and they all lack the distinctive Stag burble.
The closest one to it is in my Estate. This has regular Stag tubular manifolds (one forward, one back). However the exhausts from the balance pipe backwards are the same length.
This has the effect that the burble tends to come and go at different points in the rev range.
Its a very complicated business getting an exhaust to perform without getting boom periods at certain rpm which can be extremely annoying.
The reason I have Triumph TR straight through silencers on all my V8 engined cars is that they are cheap. Six cylinder TR owners buy the twin "performance" systems and find they have a really bad boom period between 3000 and 3500 rpm, just where you spend most of the time driving. The end result is that a lot of them get fed up with them and put them on ebay, then I used to buy them cheap (5 sets in all)
These silencers work really well on my V8s, they are quiet and don't lose any performance which is just what I am looking for!
Neil
TR owners also get rid of the twin (wheel barrow) exhausts because they cause exhaust glass egress into the cockpit. Side exits are less prone to this.
cheers Tim.
Some very clever design on the original Stag exhaust.
Most V engines have roughly the same length from the cylinder head to the balance pipe on both sides of the engine. On the Stag one downpipe runs forwards and the other backwards. Both sides of the system are roughly the same length however, as the rearward facing downpipe has an extra loop around the rear axle to gain the length missed compared to the forward pointing side.
This has the effect that rather than the exhaust pulses arriving at the balance pipe evenly spaced, they arrive sometimes with a short space between them, sometimes with a longer one.
It is this odd spacing that gives the Stag engine its distinctive burble.
On most of my Stag engined cars the design of my home built exhaust manifolds means the two halves of the system are very close in length and they all lack the distinctive Stag burble.
The closest one to it is in my Estate. This has regular Stag tubular manifolds (one forward, one back). However the exhausts from the balance pipe backwards are the same length.
This has the effect that the burble tends to come and go at different points in the rev range.
Its a very complicated business getting an exhaust to perform without getting boom periods at certain rpm which can be extremely annoying.
The reason I have Triumph TR straight through silencers on all my V8 engined cars is that they are cheap. Six cylinder TR owners buy the twin "performance" systems and find they have a really bad boom period between 3000 and 3500 rpm, just where you spend most of the time driving. The end result is that a lot of them get fed up with them and put them on ebay, then I used to buy them cheap (5 sets in all)
These silencers work really well on my V8s, they are quiet and don't lose any performance which is just what I am looking for!
Neil
Neil...This begs a question on my part. One of my future plans in my renovation is to incorporate quad exhaust pipes utilising a mirrored system of the stainless twin pipes on the rear right comprising of a mirrored version of the short intermediate connecting pipe feeding into a single modified "Y" for the twin tail pipes. This does away with the longer pipe that runs from right to left around the diff thus altering the total length.
I appreciate the exhaust note / burble will change with quads anyway but is this going to unbalance the exhaust gas flow ? I will also be using stainless steel Phoenix tubular manifolds.
Apologies to Klaus if hi-jacking your original post.
I have quad pipes on my system. 2" pipes throught from pheonix manifolds, no crossover as I was advised by Vortex it was not needed when they built the system. I went with their suggestion as I feel you don't go to a firm that have been building specialist systems and not be advised by them. Still has the stag burble and I'm happy with the noise levels.
Many thanks for the interesting answers. Before I asked I speculated that the connection/balance pipe has something to do with the way the gas pulses improve filling and emptying the cylinders.
Concerning the burble: years ago I have changed the routing of the pipes at the diff as shown in the picture. I didn't notice any change in the exhaust burble.
Now I'll hi-jack my own topic:
I think- as far as I remember- since 30 years I have always placed the probe into the LH (drivers side) exhaust pipe when checking the CO value. As I have now an old but freshly calibrated gas analyser I played around and measured for the first time in the RH exhaust pipe. Result: 0/zero CO. So I put a piece of cloth into the LH pipe end and measured again the RH side. Result: same as the LH side. So something seems to block slightly the RH system and the balance pipe came into it's function. I think it is the RH silencer which has another resistance than the LH one.
Any further idea?
Hi Klaus.
That is a strange situation.. As each carburettor is providing half the combustion mixture for each tailpipe, the CO reading and volume of exhaust gasses from each pipe should be the same, regardless of each carburettor setting. In which case each pipe should give the same reading (as they do on my Stag). The balance pipe would have no effect on this.
Sometimes the sound deadening material in the silencer can come loose and cause a partial blockage. If you rev the engine a bit, is there clearly less "Puff" from the R/H pipe than the left?
Mike.
Neil...This begs a question on my part. One of my future plans in my renovation is to incorporate quad exhaust pipes utilising a mirrored system of the stainless twin pipes on the rear right comprising of a mirrored version of the short intermediate connecting pipe feeding into a single modified "Y" for the twin tail pipes. This does away with the longer pipe that runs from right to left around the diff thus altering the total length.
I appreciate the exhaust note / burble will change with quads anyway but is this going to unbalance the exhaust gas flow ? I will also be using stainless steel Phoenix tubular manifolds.
Apologies to Klaus if hi-jacking your original post.
Cheers ..Ray
Simple answer is it change the sound but make virtually no difference to performance/economy
Neil
Neil
TV8, efi, fast road cams and home built manifolds. 246bhp 220lbft torque
This is mine, I thought it would be quieter as it's been done with 304 small bore stainless tail pipes, but seemed to "Bark" during high acceleration, developed a bit of a drone laterly , but have removed them to remove underseal from boot floor so will check position clamps etc on replacement.
Hi Klaus.
That is a strange situation.. As each carburettor is providing half the combustion mixture for each tailpipe, the CO reading and volume of exhaust gasses from each pipe should be the same, regardless of each carburettor setting. In which case each pipe should give the same reading (as they do on my Stag). The balance pipe would have no effect on this.
Sometimes the sound deadening material in the silencer can come loose and cause a partial blockage. If you rev the engine a bit, is there clearly less "Puff" from the R/H pipe than the left?
Mike.
Mike. I never noticed less "puff" from th RH pipe. I'll start the engine when it gets a little warmer here and come back to your question.
Meanwhile: has anyone ever seen a Stag exhaust silencer from inside? Any pictures? Is it an absorbtion or a reflextion type?
Hi Klaus.
That is a strange situation.. As each carburettor is providing half the combustion mixture for each tailpipe, the CO reading and volume of exhaust gasses from each pipe should be the same, regardless of each carburettor setting. In which case each pipe should give the same reading (as they do on my Stag). The balance pipe would have no effect on this.
Sometimes the sound deadening material in the silencer can come loose and cause a partial blockage. If you rev the engine a bit, is there clearly less "Puff" from the R/H pipe than the left?
Mike.
Update:
Mike, I reved the engine a bit and yes there is clearly less "Puff" from the R/H pipe. It can well be that the sound deadening mat (partly) blocks the silencer.
I have then blocke the balance pipe with a handmade gasket and and made a test run: during acceleration the exhaust sounds more like a F1 racer. But I'm not a car poser...
Measuring the CO content: both exhaust pipes the same and no "Puff" difference.
Klaus
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