Dear collective.

I am just starting to look at the exhaust for the V6 and thinking of bringing both 3-1 manifolds forward to merge into one, similar to certain TVR's with the Rover V8's. the output from the Tee piece will then turn 90 degree and exit either side.. See below, as you can see, i have the room to do it.


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The main advantage of this is that i will only have to buy one Cat and silencer. I am not after a high performance system as you can see from the Ford ST220 manifolds but if i can build it to be as good as or better than OEM, i will be happy.

FYI, the ouput from the 3-1 is 2.5 inches which is a little big but if i then tee the two into another 2.5" instead of the 3" that is on the picture, i should maintain adequate back pressure.

OR should i not be so stupid and just take each manifold out each side with perhaps a balance pipe running forward.

Comments and advice gladly accepted

Peter

My opinion only
Back pressure? Who needs it?
It's more about tuned lengths to get the gasses scavenged and that takes the inlet manifold length into account as well as cam duration etc
Therefore the exhaust will mostly be a guesstimate and as such your best approach is a simple 3 to 1 from each side exiting individually
KISS Keep it simple etc
Balance pipe is not needed and will only complicate the gas flow
Having equal length primaries of the right diameter is probably the best option

As snapper has stated, no need for a balance pipe on 6 cylinders as long as the fire left to right.

Taking out the front will increase heat in the engine bay, not the end of the world but investing an extra £150 in cat and silencer would provide a neater solution IMHO

Agreed that a twin system is simpler and thanks for the recommendations. One issue with this is the actual noise I will hear whilst driving, I will only hear a 3 cylinder engine through the rhs silencer or am I overestimating this?

I'd have agree about the heat build up, my Zetec had issues and that only produced 190hp.

Have a look in my photo archive under MD7 exhaust, including cats it cost less than £300.

Regards Dan.

That's the downside, if you stand either side it sounds like 3 cylinders.

Cheers Mark, that's what I am afraid off, one of the attractions of the V6 to me is the noise. I have driven a few Cobras that sound great on a drive past but are disappointing when driving due to this issue.

Dan, from the drivers seat, what does the Alfa sound like with the twin side pipes?.

Cheers Mark, that's what I am afraid off, one of the attractions of the V6 to me is the noise. I have driven a few Cobras that sound great on a drive past but are disappointing when driving due to this issue.

Dan, from the drivers seat, what does the Alfa sound like with the twin side pipes?.

Can't comment yet. Hopefully the great man with the Alfa Dax will be along soon with a first hand opinion.

Dan.

My Alfa engine with two separate systems sounded awesome! At tick-over, it sounded more like a 5 cylinder Audi as you could hear one side more than the other which gave it an off-beat sound but once the taps were opened, it was glorious! I'll see if I can find a video of it.
I tried it with a link pipe, and it made no more, or less, power but it quietened it down a bit. It was sharing the pulses between two silencers. Same with a cross-over pipe. I now have a Pug V6 with two 3-1 fanimolds feeding a central collector and then out one side to an open pipe. It's far too loud so I've found a silencer to fit.
Pug V6 with 3-1 each side then a collector. Open pipe with a pretend silencer....


This one is the Alfa V6 with a 3-1 on each side. You can just about hear the sound over the wind noise....



[Edited on 15/7/15 by owelly]

Can we just crush this back pressure myth once and for all? Back pressure is always the enemy of performance. The bigger the back pressure the harder the engine finds the exhaust clearance of the cyl, meaning less fresh charge is brought in, meaning less power.

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Originally posted by scutter
Can't comment yet. Hopefully the great man with the Alfa Dax will be along soon with a first hand opinion.

Dan.

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Thanks to all, that Alfa sounds sweet on the twin pipe set up. i will take the asy way and run a two silencer set up