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Complete mental block on exhaust manifolds


Hybrid_From_Hell
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Hi All,

VERY shortly I am about to have a custom exhaust made,

date is booked and I am "Collecting" bits in a box for the day ahead.

I have a pair of 'JED' Big bore exhaust manifolds, see pic :

post-22-1219763137_thumb.jpg

As you can see there are 2 and they are different,

having restudded faced off and generally got them ready

I am now having a mential block as to which goes on which side,

I THINK the bigger / longer one goes Drivers side, and the smaller / shorter one goes Passenger side ?

These are just like 3.9 twin exit manifolds, just the internals / ports / holes etc are much bigger.

Can some kind person confirm if I am right / wrong re sides please :blink:

Nige

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And one more Question if anyone is feeling kind :)

RR 3.9 twin pipe downpipes.

Can some kind soul please measure and advise me of :

The OD of one the twin pipes

The LENGTH from the flange to manifold to the point the 2 pipes join together - ie the length of the downpipes,

and is the length of the twins same both sides ?

:)

Merci Buckets Bowcoupe

Nige

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WELL.... as I literally have two of these sitting on the driveway....

Passenger side: 150mm to ~centre of the first bend, then another 220mm to the join.

Drivers side: 120mm to ~centre of first bend, then another 570mm to the join.

That help?

:)

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WELL.... as I literally have two of these sitting on the driveway....

Passenger side: 150mm to ~centre of the first bend, then another 220mm to the join.

Drivers side: 120mm to ~centre of first bend, then another 570mm to the join.

That help?

:)

So drivers side 2 tubes length (per tube) is around 370mm

and the Passenger 690mm

:blink:

If I read that right then THAT explains the conv I had today re RR std pipes not being 'balanced' secondarys :lol:

Is the OD about 38mm ?

Thanks for this, I have got to have 2 x 50mm ODs with a tube length of around 18" EACH pipe

and then to 2.5inch single tubes into Y and then either 2.75" or 3 inch (if it will fit) plus Lambda Plug

370mm vs 690mm :blink:

Nige :blink:

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Both are OD is ~38mm (with a tape measure, I see 40mm TBH...) going into what looks roughly 53mm OD pipe (difficult to tell as it's bent there, and I don't have the Y piece to hand).

Remember though... that one manifold is shorter than the other, so the full length of the secondaries will vary depending on what they measure up as -as you have these, I'll let you do that bit ;)

Sounds like a nice system you are looking to build :)

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Yes its going to be fun getting 3" from Y piece backwards, I am helping the maker all day so we both are happy at the end of it, JED (John Eales) has said 3" is best by far - but a piggy to fit with spaces and tolerances.... so if that seems a nightmare it may have to be 2.75" but time will tell :(

Appreaciate your help greatly :)

it has helped me see in my mind the finished article.

Apart from the bigger bore - ie Internal manifolds matched to exhaust ports and huge exhaust porting in the cast manifolds exiting with 50mm OD - means std of 2x 38mm vs 2 50mm and then 3" etc and matched lengths etc the 4 into 2 into 1 gives massive bottom end grunt over 4 into 1 - let alone the bore size changes too :)

Nige

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