tubular exhaust manifold advice

[Revolution]

Ok from what I have gatherd is when dealing with a tubular exhaust manifold , longer runners would produce more hp, but a shorter runner manifold would produce more torque and a faster spool.

So hear is my dilema I have an evo 3 16g and will be building a manifold for this turbo .
Before I go any further please dont comment on "why not just get a ported 2g or evo3 manifold". Reason being why I dont want to go that route is because I want a constant 2.75 diamiter through the tubing wich will dramatically increase flow and power, plus with the material I will be using I'll save alot on weight.

Ok so keeping the length of the manifold the same do I;

A) make the runners longer by introducing a high arck from the head flange to the turbo flange .

B) make it a strait through pipe desing only introducing the bend cm's from the turbo flange keeping it as stock like as possible.

I hope some one could help me figuer wich design would benefit the most.

 

[jdmawd]

these are the only 2 headers i would put on my car.

$500

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$1200

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[DSMJim]

Many major racers used to run long tube headers and switched back to shorter runner headers. Some have found that tuning was easier with a much longer tube however the overall HP was just not there.

Kenny Tran is a good example of this he ran a long tube header for a long them then went back to a shorty style. He found it just made more power which was more desirable over the entire RPM range than the small amount of extra tuneability they gained from the long tube header.

On a full race car the runners can be much longer because the exhaust is a lot hotter coming from the head so less cooling happens vs. a regular street car. Also full race cars are designed for only one thing, going fast at WOT between 6000-10000rpm so low end torque and spool are not things taken into consideration when making a manifold.

The manifolds we make (not 4G63 howver) for 240sx and Honda's are the shortest runner possible. On the dyno we found a shorter tube manifold made the same power as a long tube and the turbo acctually spooled faster with a shorter tube vs. an equil length. We have yet to prove any benefit in the 1/4 mile and on the dyno with an equil length manifold on our 460whp Miata or 450hp Civic we finished a while back.

If your planning on running your car on the street then making the runners as short as possible would be my recommendation based solely on my own experience with manifolds and dyno's and my own personal car.

 

[sweet97]

these are the only 2 headers i would put on my car.

$500

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$1200

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What's the name of the 450. headers, DNP? And who are the suppliers? best price where? Thanks, Mark

 

[sweet97]

these are the only 2 headers i would put on my car.

$500

You must be logged in to view this image or video.

$1200

You must be logged in to view this image or video.

What's the name of the $500. headers, DNP? And who are the suppliers? best price where? Thanks, Mark