Many factors must converge before the correct turbo can be selected for a given application.. Beyond the cartridge issue- conventional, single ball bearing or a dual ball bearing - the proper housing sizes, wheel sizes, wheel trims and turbo family must be gleaned. This "basic tech questions" write up focuses on the questions you should ask when working with a turbo supplier, and why you should ask them.

Also the turbine side selection process will determine the unit's spool up capabilities and impact its maximum flow and exhaust restrictiveness. The compressor section is responsible for maximum boost, and the range of the engine speeds where appreciable boost is realized.

1) What engine are you turbocharging?

This will help get a ball park figure on displacement and determine the type of valvetrain in question.

2) What's the engine's displacment?

Knowing the displacment will help specify if the engine is being bored and stroked so the proper turbo family can be identified.

3)What's the static compression ratio?

The compression ratio is a determining factor of peak boost, which will impact the turbo size decision.

4) What type of fuel are you running? ( E.g. gas, diesel, alcohol)

The boost requirements for these types of fuels vary greatly.

5) What type of transmission is the running?

See question six..

6) If it's an automatic, what is the stall speed of the torque converter?

The stall speed dictates where in the powerband an auto shifted engine will make the most use of the boost.

7)What's the Horsepower of the stock engine?

The horsepower figure determines the starting point.

8) What's the maximum horsepower expected?

It gauges the seriousness of the application and helps select the proper turbo family

9) What's the maximum engine speed expected?

It helps to illustrate the powerband, which provides useful data for turbine size determination. Namely, to select a turbine side that will achieve peak efficiency below the max rpm.

10) What's the maximum boost expected?

It acertains compressor performance.

11) Will the application be intercooled?

Intercooled helps establish the ultimate efficiency of the turbo system an selection of wheel trims, etc.

12) What's the intended use of the vehicle? ( Street or Track)

The powerband of a street turbo is much wider than that of a race turbo, which spends a great deal of time in a very short power band as small as 2000rpm. Also engine speed expectations are much higher on a race turbo, while a street unit will be less of a top end power player and more of an all around performer. Spool up characteristics/ expectations will vary greatly between the two as well.

13)What's the important rpm range?

This should be discussed in detail so both parties are on the same page. This question locates the exact range of efficiency that the turbo will aim for. How it will spool, where in the powerband usable boost hits and how efficient the compressor wheel is at boost levels realized within the selected rpm range.

14)Have you fortified the internals of your engine?

This question will help you tell whether you've taken the correct steps needed before bolting on the boost. If you're throwing around 25psi and 450whp numbers for your B series and haven't built the engine you have some work to do.