Custom headers...

[Davrianman]

Hi Chaps,

My engine build is finally complete (hurray!), so I am looking at doing the exhaust headers next. I have the following requiements:

2" primarys with 26-28" length before collector (engine is a 434ci)
Cross over pipe
Catalytic converters

I have a pair of factory rear boxes and tail pipes that I would like to use if possible.

My concern is how to get enough room for the primarys and cats before the rear box... I didn't realise how long the standard boxes were until I tried them on the car.

I have seen systems where the primarys come upwards before curving back down to the rear boxes. Is this a good method? Are there any problems with heat buildup near the intake system (I have a kinsler stack injection system)?

The other thing I thought of is to reposition the rear boxes so that they run accross the rear of the car and then cross the systems over... This would give enough room for the cats perhaps but may foul the rear clip... Anyone tried this?

Just after a few ideas really before I go down the wrong route.

Before you ask, I need to use cats as the engine is brand new and based on a new dart little M block.

I will hopefully model the whole system in Catia (a 3D modelling tool we use at work) and then get the pipes computer mandrel bent. Just going to tack assemble then get a pro to weld...

Any sugestions / pics????

Thanks!
Mart

[Davrianman]

Just been doing a quick sketch... Was thinking of something like this....



Edit... But with a cross over pipe before (or after??) the cats.

Edited by Davrianman on Tuesday 24th February 21:49

[ezakimak]

This Build seams like its along the same lines as what your after, just without cats,
http://www.gt40s.com/forum/gt40-build-logs/22164-r...
http://www.gt40s.com/forum/gt40-build-logs/22164-r...
http://www.gt40s.com/forum/gt40-build-logs/22164-r...

this one has some cats.
http://www.gt40s.com/forum/gt40-build-logs/21100-d...

[Steve_D]

Davrianman said:

......But with a cross over pipe before (or after??) the cats.

For space and simplicity make a single back box with both pipes going in and out. In doing so it will become a crossover. Also some have just used cats without a silencer so you may find you don't need the capacity of two back boxes.

I'm guessing that power gains would come from having the crossover nearer the headers but you will still gain the noise cancelling by having the crossover inside the silencer.

Steve

[mkoch1]

I only have 1 muffler but it does run across the back of the car. My header guy also wanted long primarys.

[MattYorke]

That's an interesting install. Seperate exhaust for the wastegate?

[mkoch1]

Yep, makes it nice a quiet under part throttle, then when the boost hit she gets loud.

[Davrianman]

Thanks for the info Chaps.

I hadn't thought of running the cats up the middle and then having the boxes either side like the GT40.. Good Idea... Will have to have a play on the CAD box.

Off to Pete Knights in the morning to set up the ECU... Can't wait to fire her up!

Cheers,

Mart

[Davrianman]

Steve_D said:

Davrianman said:

......But with a cross over pipe before (or after??) the cats.

For space and simplicity make a single back box with both pipes going in and out. In doing so it will become a crossover. Also some have just used cats without a silencer so you may find you don't need the capacity of two back boxes.

I'm guessing that power gains would come from having the crossover nearer the headers but you will still gain the noise cancelling by having the crossover inside the silencer.

Steve

Also a good idea. Starting to think I may have a pair of Ultima Boxes for sale soon....

[ezakimak]

this thread is in the FAQ section, under the first link that stig posted - there is a exhaust thread.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...