I have a book here called " TURBO rear world high-performance turbocharging systems", it has tons of info on how to pick the best turbo for your needs. Included are compressor maps of the hx40w which can help you in your effort.
It is also alot more money to spend. 2 turbos vs 1, is it really going to spool up faster? If you get a single turbo with the correct A/R you will not have any issues with a slow spool up.
Like you say, correct pick of a turbo (s) and other system aspects will create a good system function with no "lag" problems. If someone has room for a large turbo, and does not mind routing the exhaust to one side of the engine then the single is a good option. Inline engines for example are better suited to single turbos vs a V8 that has big cubes and exhaust on both sides. One major advantage that the twins have to me is that they leave me with a true dual exhaust in a managable 3" diameter. For race only cars this is less important since they may only run a 6" downpipe but I like full dual exhaust on my street cars for the V8 rumble. Keep in mind though two smaller turbines have lower polar moment of enertia than a single larger turbine to create the same power. I will not bore you with the proof in numbers. Quicker spooling with two smaller turbos vs one large one. What is REALLY cool is the tractor pullers who use turbos feeding each other to create over 100 psi of boost!
hmm. 100psi. Guess we will need a girdle, halo, and trash can for all the little pieces left of the block.:eek2:
I say use a single if it fits your needs. A single will spool slower. But a properly sized turbo should spool fairly close to a set of twins. It's kinda like say my dog is bigger than yours because my dog weighs 101 pounds and your dog weighs 100 pounds. They are both big dogs, and yes I chose big dog analogy on purpose. In other words at the end of the day with a single or a twin you will be driving the big dog.
