[turbo69bird]

here you go justa little added info on the debate.

This was side bar in the article (boosted Expectations)Circa 2003 may issue for anyone whod like to read the rest. Its one of the better turbo sizong articles I have read.

The guys name is Dave andrews an application engineer for garrett There is a myth that multiple turbos are inherently better than a sinlge when it relates to gas turbocharging.
This simply isnt true!

A large single turbo is ALWAYs more efficient than multiple smaller units.

The increase in efficiency afforded by larger results in less back pressure, lower intake man. temps. and often better transient response!

As turbos increase in size they become more efficient.

(Bla blah blah Size VS tip Vs bigger is better.)

"The actual differences between single and twins as it relates to HP can be significant"

For example: On a 400 CI Pro 5.0 engine a well matched turbo can create the same boost pressure as twins, but with 12 psi lower exhaust man. pressure.
The lower pressure results in lower engine pumping losses and aslight increase in V.E.
The two effects include less turbine power required and lower intake temperature(good for octane tolerance).
Its very possible to see 40 dgrees or lower compressor outlet temps. from a good single turbo vs smaller twins.

This translates to a cooler denser intake charge.
"Comparing a larger turbo map to a smaller unit with half the flow will imidiately show the difference in compressor efficiency at a given pressure ratio"