Exhaust X-pipe
Discussion
Just wondering if anyone has tried adding an x-pipe to a speed 6 exhaust system? It's an easy enough mod and it would seem to be a good mod to boost low end torque and maybe add a touch more top end power as it improves exhaust scavenging. It would also potentially reduce that harsh sometimes unpleasant rasp and motorway drone that the S6 is prone to, especially with straight through silencers.
Just a thought as the BMW M3 and M3 CSL benefit from an x-pipe, so I'd imagine a TVR S6 would too?
Just a thought as the BMW M3 and M3 CSL benefit from an x-pipe, so I'd imagine a TVR S6 would too?
this is something I`ve often wondered about myself.
the trouble is, as with all things tvr, is getting it to fit in the right place within the exhaust system and still fit on the car.
it would have to be reasonably close to the engine to have any advantagous effect, which means on our cars running along the side of the gearbox, not a lot of room there, or, half way down the car above the chassis plate where , on the sag, the 2 cherry bomb type pipes are, but I feel that this may be too far away to give any effect for helping scavenging.
on a similar subject I have been considering a 6-2-1 system, by fitting a y piece on the exit side of the cats then running in a single 3" pipe to the chassis closing plate half way down the car, then another y piece going into 2 off 2 1/2" pipes to the back of the car.
depends if there is room to incorperate a y piece behind the cats, and room to run a 3" pipe along the side of the gearbox.
something to play with over the winter on my list of jobs to try
the trouble is, as with all things tvr, is getting it to fit in the right place within the exhaust system and still fit on the car.
it would have to be reasonably close to the engine to have any advantagous effect, which means on our cars running along the side of the gearbox, not a lot of room there, or, half way down the car above the chassis plate where , on the sag, the 2 cherry bomb type pipes are, but I feel that this may be too far away to give any effect for helping scavenging.
on a similar subject I have been considering a 6-2-1 system, by fitting a y piece on the exit side of the cats then running in a single 3" pipe to the chassis closing plate half way down the car, then another y piece going into 2 off 2 1/2" pipes to the back of the car.
depends if there is room to incorperate a y piece behind the cats, and room to run a 3" pipe along the side of the gearbox.
something to play with over the winter on my list of jobs to try
I have done it on a t350 I rebuilt . The engine was built to 4 litre RR plus some other tweeks . The customer has sold the car without putting it on a dyno so I cannot say if there was a benefit . I put the join on the pipes just after the cats but if doing it again ( which I would on my own car ) would consider the fitting as this was tricky . David
The tuscan doesn't have those cherry bombs above the mid chassis plate, just plain pipes so this might not be a bad spot. It's just after the gearbox and typically where most cars have the x-pipe located.
I think however though that the key is to ensure as closely as possible that the pipe length from each collector to the x-pipe is the same. This ensures the exhaust pulses (240 deg apart from each bank) arrive at the x-pipe separately so don't restrict one another but result in pulses downstream of the x every 120deg in both pipes instead.
As I understand it, it's this combination of pulses that increases the volume flow downstream of the x-pipe as it's less turbulent which in turn creates a slight vacuum behind it and hence the improved scavenging. Also each exhaust pulse effectivly "sees" twice the pipe diameter to pass through at the x-pipe, therefore creating less overall restriction.
The ECU running the engine as two 3-cylinders is in this case irrelevant as it has no influence over the exhaust pulse phasing which is what an x-pipe capitalises on.
I think however though that the key is to ensure as closely as possible that the pipe length from each collector to the x-pipe is the same. This ensures the exhaust pulses (240 deg apart from each bank) arrive at the x-pipe separately so don't restrict one another but result in pulses downstream of the x every 120deg in both pipes instead.
As I understand it, it's this combination of pulses that increases the volume flow downstream of the x-pipe as it's less turbulent which in turn creates a slight vacuum behind it and hence the improved scavenging. Also each exhaust pulse effectivly "sees" twice the pipe diameter to pass through at the x-pipe, therefore creating less overall restriction.
The ECU running the engine as two 3-cylinders is in this case irrelevant as it has no influence over the exhaust pulse phasing which is what an x-pipe capitalises on.
Edited by dvs_dave on Thursday 3rd November 19:30
plasticman said:
I have done it on a t350 I rebuilt . The engine was built to 4 litre RR plus some other tweeks . The customer has sold the car without putting it on a dyno so I cannot say if there was a benefit . I put the join on the pipes just after the cats but if doing it again ( which I would on my own car ) would consider the fitting as this was tricky . David
so did you use a cross pice, or go 2 into 1 dave?dvs_dave said:
The tuscan doesn't have those cherry bombs above the mid chassis plate, just plain pipes so this might not be a bad spot. It's just after the gearbox and typically where most cars have the x-pipe located.
Dave the S model doesn't have the cherry bombs there but lots of the standard cars do, might be possible to make a cross pipe where the pipes run along the gearbox, then cut down and flare the ends of the standard pipe to fit.clive f said:
plasticman said:
I have done it on a t350 I rebuilt . The engine was built to 4 litre RR plus some other tweeks . The customer has sold the car without putting it on a dyno so I cannot say if there was a benefit . I put the join on the pipes just after the cats but if doing it again ( which I would on my own car ) would consider the fitting as this was tricky . David
so did you use a cross pice, or go 2 into 1 dave?OK, stupid thought probably from a layman, but as we have two cats, which cause heat problems, could the join be before one slightly large cat and then back into two pipes afterwards. The thought is that the diameter of a single cat wouldn't be much more than each of the ones we have, and the extra space around it would aid heat dissipation. Doesn't have to affect gas flow other as far as i can see
Right, into my trench and await the incoming fire............
Right, into my trench and await the incoming fire............
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