Ok, on turbo exhaust manifold design.



1. How important is it to have or not to have a split versus common pulse coming from the two rotors in a 13BT? Supposing that Im using a split pulse turbine housing on the turbo.



2. How important is it to have or not to have equal length in both rotor runners to the flange?



3. Getting them equal length means the runners have to be longer and is the longer runners a good feature?



4. What is the ideal internal diameter for the runners?



Has anyone done experiments with comparisons giving actual dyno power results?



Thanks

1. divided will give you better response



2. theoretically any benifit to a "tuned" manifold will be lost to difference in length, but i dont know in reality by how much



3. a couple of people on the evil forum, say 27-29". i think basically you want the turbo in the same place as an na header would collect



4. ideal would be the same diameter as the port opening in the rotor housing? this might depend on your power level, peak rpm

I woulden't build a manifold any other way than divided and equal length



27-29"?! I've herd 13".



My ID runner size is 1.68" I'm running the cosmo exh sleeves which have a smaller exit size. The next manifold I build will have 2" ID main runners to match regular sleeves.

the lenghth should just push the "tuned" effect around the power band. longer = more toward the lower end shorter = more toward the high rpm