Number of Turbos

What you do:

Find a balance between the number of turbos and turbo impeller size.

Factors to consider:

1. HiPerMath is currently limited to a range of 0 - 2 turbos. This effects the size of the turbo(s) you use. Two smaller turbos will spool up faster than one big turbo. Spooling up is when the turbo impeller gains rpm (revolutions per minute). Turbos can spin up to 30,000 rpm, so the time it takes to spool up can be significant. However, two smaller turbos will be heavier than one large turbo.

The HiPerMath equation is:

spool time in seconds = turbo impeller size2
                                       (exhaust psi)(100)

Exhaust psi can be assumed to be 30 psi for the above calculation.

2. Weight. The more turbos you have, the more weight is added to the total weight of the car.

The HiPerMath equation is:

turbo weight = turbo impeller size + 50

This includes all the piping and an intercooler.