Equal length manifolds on a 996 TT
Discussion
I stand to be corrected, but I'm not sure this type of stuff makes a huge difference on a turbo car. If I'm remembering correctly all you want with a turbo is minimal back pressure (as opposed to an NA where you want the right amount and a tuned manifold).
I did have a good book on turbos by an American chap on my desk, but I think my colleagues borrowed it. Otherwise I'd check for you.
I've got experience with these on a Subaru Type R..approx 300bhp out of the box...on the Scoob, you do lose the rumble, it sounds "unique", not like an inline-4, but not a boxer either, deffo weird, but interesting.
In terms of torque, the engine feels stronger at the bottom-end with the unequal length headers. The equals made the engine feel like it's pulling a tad harder at the top end, but weaker at the bottom-end. This is with a 3" downpipe and Blackthorn race-cat out the back of the turbo, so the engine wasn't as strangled at the top-end as standard motors anyway.
I bought the car with the equal length pipes (Tony Law) but they fractured, so changed them back to stock. Def preferred the distinctive rumble of the unequals, so kept them on.
Not *that* relevant, sorry, but it may help!
In terms of torque, the engine feels stronger at the bottom-end with the unequal length headers. The equals made the engine feel like it's pulling a tad harder at the top end, but weaker at the bottom-end. This is with a 3" downpipe and Blackthorn race-cat out the back of the turbo, so the engine wasn't as strangled at the top-end as standard motors anyway.
I bought the car with the equal length pipes (Tony Law) but they fractured, so changed them back to stock. Def preferred the distinctive rumble of the unequals, so kept them on.
Not *that* relevant, sorry, but it may help!
...calling Mr Gollop or Mr Schanke...
I've had the same experience as spenny (on the same car). The headers seemed to focus the sweet spot in the rev range and this could be moved by changing lengths and diameters, but there was always a down side to every variation. When I looked at how much time and money I spent playing around with this, I vowed to never go there again.
Good gains can normally be had just by flowing the internal face of the original manifolds and by ensuring the gas flow into the turbo is a turbulence free as is possible.
200 cell cats might help, but find someone who has used them for a while and check that they won't start give CELs for cat failure after 6 months. Cats tend to be very good at cleaning the gas or unrestrictive. By its nature, a cat needs to create a blockage to generate the heat to get itself working.
I also prefer the off beat sound of boxers on unequal length manifolds.
Good gains can normally be had just by flowing the internal face of the original manifolds and by ensuring the gas flow into the turbo is a turbulence free as is possible.
200 cell cats might help, but find someone who has used them for a while and check that they won't start give CELs for cat failure after 6 months. Cats tend to be very good at cleaning the gas or unrestrictive. By its nature, a cat needs to create a blockage to generate the heat to get itself working.
I also prefer the off beat sound of boxers on unequal length manifolds.
As part of the Ruf Nardo conversion, my car has equal-length manifolds hand-made from Inconel (the same material as F1 cars and the McLaren F1). I cannot say how much they contribute to power/torque as it's part of an overall package.
I believe that anything made of Inconel is insanely expensive.
>> Edited by GuyR on Friday 26th August 14:59
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