Exhaust Balance Pipes - make any difference?
Discussion
Right from the very introduction of these things for the Cerb, I tried to get my head round how exactly they increased power. Now I know a few people have had them fitted (especially reading the SP exhaust thread) and I'm not trying to shoot anyone down here. I remember reading conflicting arguments for and against, some Indy's saying they worked, others saying its nonesense. Well anyway, today I bought the Jan issue of Practical Performance Car, and low and behold, a small article on balance pipes for V8s!!
Quote "Most V8s benefit from having a balance pipe just after the bell housing. This is because the firing sequence is spread across both banks and each bank has an uneven sequence (two neighbouring cylinders fire one after the other, followed by a long gap). The balance pipe allows some degree of balancing between banks. There's not much total flow in the tube itself so it doesn't need to be very big, but where you put it influences at which speed the thing has an effect. Balance pipes usually increase power and they always reduce noise. There are a few V8s with flat plane cranks such as the TVR AJP8 and Ferrari 355. These engines are unlike conventional V8s and work like two four-pots side by side. For this reason they don't need a balance pipe. V12s tend to be two straight sixes so don't need balance pipes either."
Hmmmm.........
Quote "Most V8s benefit from having a balance pipe just after the bell housing. This is because the firing sequence is spread across both banks and each bank has an uneven sequence (two neighbouring cylinders fire one after the other, followed by a long gap). The balance pipe allows some degree of balancing between banks. There's not much total flow in the tube itself so it doesn't need to be very big, but where you put it influences at which speed the thing has an effect. Balance pipes usually increase power and they always reduce noise. There are a few V8s with flat plane cranks such as the TVR AJP8 and Ferrari 355. These engines are unlike conventional V8s and work like two four-pots side by side. For this reason they don't need a balance pipe. V12s tend to be two straight sixes so don't need balance pipes either."
Hmmmm.........
HarryW said:
That's my understanding of the theory of balancer pipes, X pipes in some American circles 
. However Cyclone has the empirical results that say in his application it worked, which you can't really argue with. Like most, I fail/struggle to understand why 
.
. However Cyclone has the empirical results that say in his application it worked, which you can't really argue with. Like most, I fail/struggle to understand why .I agree with Harry, the theory states to a degree that it will not necessarily add benefit to the AJP V8 and I must admit that it took me a while to come around to why they "might" work. But low and behold on fitting them to my Cerb they most certainly worked, yes the fueling changed considerably (my Cerb was already highly tuned with an Emerald / Whirlwind Induction etc), but once mapped the gains were everywhere. On a bog standard 4.5 the gains although small were also there although a remap is not necessarily required, on the 4.2 I think Joolz sends out a new chip that compensates for a flat spot low down the rev range for fueling. Joolz / 350Matt explain it best, but it revolves around the firing angle and also equalizing the exhaust gas flow, when you factor in that the bore of the exhaust is too small (IMHO) then it's likely that by adding the linked de-cats you are overcoming another TVR restriction - the bore of the exhaust.
Just my opinion, but the results show that they do work on the AJP V8.
Jules.
COuldnt resist replying to this Jules.
All the AJP V8 experts that I speak to agree exactly with the above article. I think your wrong to imply that you have proved conclusively that linked pipes work on the AJP V8, all you are saying is that it appears to have worked on your car.
Some proof would be for you to have non linked decats fitted, that have youe engine re mapped, and see what the resluts are.
I'm open minded, but all the esperts seem to think otherwise, none of the Tuscan racers use linked de-cats, and Scienct dictates that a flat pane crank does not beneft from linked pipes.
All the AJP V8 experts that I speak to agree exactly with the above article. I think your wrong to imply that you have proved conclusively that linked pipes work on the AJP V8, all you are saying is that it appears to have worked on your car.
Some proof would be for you to have non linked decats fitted, that have youe engine re mapped, and see what the resluts are.
I'm open minded, but all the esperts seem to think otherwise, none of the Tuscan racers use linked de-cats, and Scienct dictates that a flat pane crank does not beneft from linked pipes.
Cyclone DID have the non linked decat pipes before the linked ones, the results he speaks of on his car ARE a direct comparison, mapped specifically for the application in each case.
There's more evidence they work in the new SP exhaust, they too have gone linked decat pipes, with hp gains to prove.They have reached the same comclusion completely independant of my work.
What evidence is there from the "experts" that you speak of that they don't work? We have lots of evidence now that they do, where is the other evidence? Where is their back to back testing specifically mapped for each application? Where is their database of cars from which they draw this conclusion? Or is it just "it seems like it shouldn't work so obviously it doesn't" ?
Yes the cerbie is a flat plane crank engine, but it isn't a 90degree "V" with flat plane crank it's a 75 degree "V", therefore the exhaust pulses dont exactly interfere with each other, there is presumably a small cross-over of pressure one way and a *bigger* cross over of pressure the other way through the link, though how you would prove that differential i don't know.
Also the rest of the cerbera system is restrictive, and anything you can do to make the exhaust flow smoother and a lower average flow rather than a series of big individual pulses WILL make the system flow more on an average time frame. How much of the gain is due to "wave form effects" in the pipework before the link I don't know. How much is due to flow-smoothing through the rest of the system i don't know either. But the results are measurable.
We claim 5-8bhp gain from the linked decats .. it's not like it's unrealistic to claim that a flow-smoothing / pressure sharing linked system wouldn't gain that, especially after all the cars i've mapped with std cats, std decats and linked decats show trends consistent with what i claim for them.
Now shush or I'll tell you what this remapped cerbera 4.5 with bosch injectors made ..
There's more evidence they work in the new SP exhaust, they too have gone linked decat pipes, with hp gains to prove.They have reached the same comclusion completely independant of my work.
What evidence is there from the "experts" that you speak of that they don't work? We have lots of evidence now that they do, where is the other evidence? Where is their back to back testing specifically mapped for each application? Where is their database of cars from which they draw this conclusion? Or is it just "it seems like it shouldn't work so obviously it doesn't" ?
Yes the cerbie is a flat plane crank engine, but it isn't a 90degree "V" with flat plane crank it's a 75 degree "V", therefore the exhaust pulses dont exactly interfere with each other, there is presumably a small cross-over of pressure one way and a *bigger* cross over of pressure the other way through the link, though how you would prove that differential i don't know.
Also the rest of the cerbera system is restrictive, and anything you can do to make the exhaust flow smoother and a lower average flow rather than a series of big individual pulses WILL make the system flow more on an average time frame. How much of the gain is due to "wave form effects" in the pipework before the link I don't know. How much is due to flow-smoothing through the rest of the system i don't know either. But the results are measurable.
We claim 5-8bhp gain from the linked decats .. it's not like it's unrealistic to claim that a flow-smoothing / pressure sharing linked system wouldn't gain that, especially after all the cars i've mapped with std cats, std decats and linked decats show trends consistent with what i claim for them.
Now shush or I'll tell you what this remapped cerbera 4.5 with bosch injectors made ..
Edited by trackcar on Friday 29th December 22:31
Apologies for what may be a dumb question, but if the aim is to create as few restrictions as possible and smooth airflow, then how will a baffled rear box outperform straight through sports exhausts that run seperately from manifolds to exit? I only ask as I've just bought a JP system through ACT and its a straight through design. On a seperate point I would have thought one of the best mods any Cerb owner could do was to port match the exhaust ports on the head with the manifolds - the standard matching is very poor creating a large step right at the exit of the head. Surely this will interfere with any pulse tuning effects from the manifold sizing/layout anyway.
longbow said:
Apologies for what may be a dumb question, but if the aim is to create as few restrictions as possible and smooth airflow, then how will a baffled rear box outperform straight through sports exhausts that run seperately from manifolds to exit?
erm i don't suppose it will, but as there aren't any baffled exhausts available for the cerbera i don't know why this would be an issue anyway as all the exhausts i have seen have been perforated pipe/straight through design, just that some are poorly made with many section changes and of too small bore.
longbow said:
I only ask as I've just bought a JP system through ACT and its a straight through design.
yup, and the jp 4.5 pipes are of a good bore throughout.
longbow said:
On a seperate point I would have thought one of the best mods any Cerb owner could do was to port match the exhaust ports on the head with the manifolds - the standard matching is very poor creating a large step right at the exit of the head. Surely this will interfere with any pulse tuning effects from the manifold sizing/layout anyway.
you would think so wouldn't you .. but seems the mismatched port isn't as bad as it looks? The only car i know has been indi tested with different manifolds on is tims own car (engine rebuild, injectors, big bore exhaust, manifolds, short induction and remap) and that didn't make 400 at SRR and only did 12.8 at the pod .. given the spec it should have been 12 sec dead or very low 12s at worst and well over 420bhp .. so what conclusions can you draw from that?
There are things that look bad on the cerbera which are actually nowhere near as bad as you think, and things that look like they shouldn't work but which have been proven many times to work ..
HarryW said:
trackcar said:
[ .. given the spec it should have been 12 sec dead or very low 12s at worst and well over 420bhp .. so what conclusions can you draw from that?
..
..
Defective nut behind the wheel
. BUT it was the one and only run that Paul did , couldn't do any more because the clutchg was ***ed
It does make very good power, at austec very close to Daggarts, at SRR in 3rd it was well down on power with a very spikey graph, a mistery even to charlie so we can't draw any conclusions from that.
BTW julian the manifolds are worth 10+bhp and a decent amount of mid range to, the induction on mine independantly tested at SRR , using as new original silicone pipes and backplates made 18 bhp without mapping, the big bore exhaust also made a good gain.
didn't realise Paul was behind the wheel. If its around Daggarts figures that's pretty high powered then
What torque is yours putting out now Tim, I have this thing about 4.5's and torque at present, as power at 400+hp is getting old hat . Have you spoken to Paul about loaning your intakes for the bench dyno'ng on mine yet
.Well I hold my hands up in that my ideas on tuning come from books, magazine articles and a good understanding of basic physics picked up at uni etc and not from experimental results, which are always definitive. It seems as though the Cerb responds to tweaks in an unusual manner which perhaps isn't that unusual as it is a unique engine.
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Edited by longbow on Saturday 30th December 16:16
HarryW said:
didn't realise Paul was behind the wheel. If its around Daggarts figures that's pretty high powered then
What torque is yours putting out now Tim, I have this thing about 4.5's and torque at present, as power at 400+hp is getting old hat . Have you spoken to Paul about loaning your intakes for the bench dyno'ng on mine yet
.We haven't done any dyno runs on mine since last spring that was on the old rollers, the torque was high but don't have a graph will put it on the new rollers soon.
Yes i'll drop my Cerb down to Austec next week so that Paul can borrow the induction.
longbow said:
Well I hold my hands up in that my ideas on tuning come from books, magazine articles and a good understanding of basic physics picked up at uni etc and not from experimental results, which are always definitive. It seems as though the Cerb responds to tweaks in an unusual manner which perhaps isn't that unusual as it is a unique engine.
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Edited by longbow on Saturday 30th December 16:16
Can't speak for SP , but the standard box has "S" shaped perforated pipe, so similar to the sports systems but probably bigger bore, we have found that on the ACT system by increasing bore size of the whole system to 2 .25" (which is the one you have Longbow) increases power, some of the sports tails available are less than 2" where the bending machines have distorted the pipes, this does restrict power.
All this theory of straight through pipes and increased bore size to exhaust the gasses more efficiently is fine logic, although there is also the need of 'system back pressure' and optimised efficency by decreasing cavitation (although not as volitile in gas form it still exists), there is a fine line between restriction and loss of backpressure in the optimum system, this is where a balance pipe will help the continuity of flow being produced between two banks. Granted the level of efficiency will depend upon the type of 'V' engine, its fueling, set-up and its firing order, but it WILL help.
The usage of a balance pipe will not automatically increase HP, but it will enable a finer/truer optimum set-up and create a more responsive engine and enable a greater power gain.
The usage of a balance pipe will not automatically increase HP, but it will enable a finer/truer optimum set-up and create a more responsive engine and enable a greater power gain.
longbow said:
Well I hold my hands up in that my ideas on tuning come from books, magazine articles and a good understanding of basic physics picked up at uni etc and not from experimental results, which are always definitive. It seems as though the Cerb responds to tweaks in an unusual manner which perhaps isn't that unusual as it is a unique engine.
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Edited by longbow on Saturday 30th December 16:16
They're all straight through designs Windsor .. straight through as in there are no restrictive baffles.
Inside the std back box there's curved pipework, the route is "similar" to that taken by sports pipewrok just that it's enclosed inside a box so you can't see it.
The reason some sports pipes make less power than the free-flowing std back box (imo) is just pure airflow, the cheap sports pipes have bends which are not constant radius (or at least not a generous radius) and the silencer perforated pipe is often of a small diameter.
Often you also find that some cheap sports pipes were designed for the smaller bore 4.2 cerbera and they just weld a slightly larger pipe on the end to fit the 4.5 pipes. These are well known to knock hp of the car. The internal pipe diameter just isn't big enough for 350hp never mind 400+hp.
I don't know why the SP system is so good at flowing, but presumably they will keep that secret anyway it's their design after all
Don't stop reading those books though .. it's where most of us get our ideas from, and having clever people who offer advice in their own areas of expertise of course, but the proof is in back to back testing, and out on the tarmac
ACT said:
longbow said:
Well I hold my hands up in that my ideas on tuning come from books, magazine articles and a good understanding of basic physics picked up at uni etc and not from experimental results, which are always definitive. It seems as though the Cerb responds to tweaks in an unusual manner which perhaps isn't that unusual as it is a unique engine.
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Anyway, back to exhaust stuff, if you took an angle grinder to a standard backbox, or indeed the SP back box, and sectioned it, would it be baffled or not? I'm trying to imagine where the gases go from entering to exiting the backbox that makes it make more power than straight through pipes (am referring to the SP with regard to power increases over normal sports pipes BTW)
Edited by longbow on Saturday 30th December 16:16
Can't speak for SP , but the standard box has "S" shaped perforated pipe, so similar to the sports systems but probably bigger bore, we have found that on the ACT system by increasing bore size of the whole system to 2 .25" (which is the one you have Longbow) increases power, some of the sports tails available are less than 2" where the bending machines have distorted the pipes, this does restrict power.
Exactly right.
cooky said:
All this theory of straight through pipes and increased bore size to exhaust the gasses more efficiently is fine logic, although there is also the need of 'system back pressure' and optimised efficency by decreasing cavitation (although not as volitile in gas form it still exists), there is a fine line between restriction and loss of backpressure in the optimum system, this is where a balance pipe will help the continuity of flow being produced between two banks. Granted the level of efficiency will depend upon the type of 'V' engine, its fueling, set-up and its firing order, but it WILL help.
The usage of a balance pipe will not automatically increase HP, but it will enable a finer/truer optimum set-up and create a more responsive engine and enable a greater power gain.
The usage of a balance pipe will not automatically increase HP, but it will enable a finer/truer optimum set-up and create a more responsive engine and enable a greater power gain.
I agree.
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