Turn it up till it blows up!

 

8 PSI on a 16G does not equal 8 PSI on a 20G nor does it equal 8 PSI on GT30R nor does it equal 8 PSI on a GT35R.

In other words, the turbo size determines the amount of power output at the set boost level.

And to further answer this, I'd say the tuning determines all of the "safety" of the engine, not the boost level.

 

But doesn't a bigger turbo produce more heat, and more lag?

 

And to add to that, the Heat produced on a 16G @ 8 PSI does not equal the Heat produced on a 20G @ 8 PSI, or a GT30R @ 8 PSI or a GT35R @ 8 PSI.

The Larger turbo's produce less heat at the same boost levels as the smaller turbo's do. Heat can be a demon when trying to find that range of safety.

 

lag yes, but with a better top end.. thats why properly matching the turbo to engine and application is important to take advantage of the setup. More heat, not necessarily, remember bigger turbo requires less turbine/compressor rpm to reach a certain boost than a smaller one. More rpm more heat.. Its true though, higher boost higher heat.. so bigger turbo could have more heat in some situations. Thats where intercooler sizing comes to play

 

Turbo size can incorporate lag, but this also contingent upon the driver's need, setup of the system, tune and turbine A/R. All of these factors can and will alter throttle response.

With respect to efficiency of the turbocharger, a compressor map would be needed and the air flow and pressure ratio would need to be plotted on it to get a rough idea of the turbo's efficiency. If you are planning on using say a 16G at 1 BAR+ of pressure on this 2.4L, you will see it's a terribly inefficient as one company found out quickly, which is why you may choose a larger turbo for higher power needs.

Also, let's not forget that turbo efficiency has a lot to do with respect to charge temps, but also the overall design of the charge cooling system plays a roll too. It may be water/air or air/air and each will have their own pros and cons with respect to the overall good for that particular app. In the end, a quality intercooler system will help keep charge temps more in line, but will not make up for a poor choice in turbocharger overall. A GT22 on this car is not a good choice no matter what setup it's on.

Lastly, the tune on the system can GREATLY alter response to the turbocharger, the engine's performance, power curve and reliability. Procedures such as anti-lag can be amazing for LARGE turbos on small displacement engines. How else do 1.6L Hondas run GT40Rs? (also they rev out to 9K+ sometimes)