Hypothetical Turbo restriction question
 

Rally rules require a 34mm restrictor on a single turbo Or
22mm restrictors if you use dual turbos (not sequential, but side by side )

which is going to flow more air ?

The plane takes off!

(2) x 22mm diameter is roughly equivalent to (1) x 31mm area-wise, so if I had to guess I would say 34mm flows better (approx. 20%).

aaah, when i converted it to square mm i think i had 800 to 907 but i wasn't sure if there's more that affects it than just Square mm , (venturi affect?)

The restrictor must be maintained for a minimum
distance of 3 mm measured downstream of a plane
perpendicular to the rotational axis situated at a
maximum of 50 mm upstream of a plane passing
through the most upstream extremities of the wheel
blades (see Appendix B drawing 254-4). The external
diameter of the restrictor at its narrowest point must be
less than 38 mm, and must be maintained over a
distance of 5 mm to each side.



In case of an engine with two parallel compressors, each
compressor must be limited to a maximum intake
diameter of 22.6 mm.


don't suppose you are itching to do some prototyping on max flow restrictors or somethign?

KSTech is wholesale with Rallispec. They have done this already:
http://www.rallispec.com/prod_turbo.htm

I would love to play with this stuff... but, engineering and fab time is $85/hour. :D

You're wasting your time. The overall flow of both restrictors is close enough that even if the dual turbo setup flows a little more, it's never going to be better in terms of reliability, weight, and heat.

The only reason the rules specify a size for dual turbos is so the poor schmucks that have dual turbos from the factory can run them legally. No one in their right mind is going to choose a dual turbo over a single for rally... it's not the 1984 Group-B era.

Plus, there are tons and tons of proven setups for single turbo Subaru motors. And just a few home-built dual setups that I would cringe to think about going off-road with. Unless your plan is to get a JDM Legacy TT motor... and even then, why bother?

Check this out, if you haven't already, Alex.

http://www.dirtyimpreza.com/forums/s...ad.php?t=10876

ya reliability and being able to bum a spare off someone are strong points for rally. using a GC or GD where most parts interchange really helps us out.

My motor is a 2.2T from a 92 legacy turbo , haven't figured out heads yet, its probably a 2012 project