405 Mi16 Exhaust: Why Is It 8 Ports?!

[rodionski 3 1 Cars]

Dear all,

 

A question which has been at the back of my mind ever since I bought my 405 mi16: WHY is the exhaust manifold 8 to 2 to 1, taken that it's supershort and NOT equal lengths?

Why bother going this no doubt more complex and expensive route and not doing a simple 4-2-1 non-equal?

 

I'm about to send a query to Peugeot - it just can't stop bothering me...

 

[JeffR 51]

Dear all,

 

A question which has been at the back of my mind ever since I bought my 405 mi16: WHY is the exhaust manifold 8 to 2 to 1, taken that it's supershort and NOT equal lengths?

Why bother going this no doubt more complex and expensive route and not doing a simple 4-2-1 non-equal?

 

I'm about to send a query to Peugeot - it just can't stop bothering me...

 

Hi rodionski,

 

Don't forget to take the downpipe into consideration too, as it has a centre divider in it & makes the exhaust system actually 2 4-2-1's!

 

[rodionski 3 1 Cars]

Dear all,

 

A question which has been at the back of my mind ever since I bought my 405 mi16: WHY is the exhaust manifold 8 to 2 to 1, taken that it's supershort and NOT equal lengths?

Why bother going this no doubt more complex and expensive route and not doing a simple 4-2-1 non-equal?

 

I'm about to send a query to Peugeot - it just can't stop bothering me...

 

Hi rodionski,

 

Don't forget to take the downpipe into consideration too, as it has a centre divider in it & makes the exhaust system actually 2 4-2-1's!

 

Hi there - fraid you're not quite right.

The 8 runners connect to a 2-fold chamber where from they go straight to the downpipe which is also 2chamber and then in the end part of downpipe they connect to 1 = which makes the system 8-2-1.

But it is the manifold that bothers me - WHY 8 runners?!

[welshpug 1,657]

WHY NOT

[rodionski 3 1 Cars]

WHY NOT

 

for one - production-wise it's much more complex and expensive.

for two - why do such a complex manifold and not make it equal lengths?

[D.B.205 0]

The 309 GTI-16 have the same engine, but another exhaust manifold - they have all equal lengths.

The 8-2-1 exhaust was for 405 and BX. I think the 309 exhaust manifold is better, but 405 and 309 have the same power (on paper).

 

 

[rodionski 3 1 Cars]

The 309 GTI-16 have the same engine, but another exhaust manifold - they have all equal lengths.

 

The 8-2-1 exhaust was for 405 and BX. I think the 309 exhaust manifold is better, but 405 and 309 have the same power (on paper).

 

Yes, you are absolutely right. Worth noting that the 309 one yields +1Nm torque at peak though.

And also, almost no difference in power is most likely due to stock intake which is quite restrictive.

[Guest hossein G]

Just for more torque in the low RPM .

you know the wight problem and flat diagram torque.

 

 

[rodionski 3 1 Cars]

Just for more torque in the low RPM .

you know the wight problem and flat diagram torque.

 

Could it be that the 8 ports were made in order to somehow equal out the flow - say 1 tube of 1st cylinder is shorter, and the 2 tube of the 1st cylinder is longer etc. that could approx make the flow close to equal?