bigger turbos are better!

[aardvarkash10]

As I have upgraded the mitsus I can state from personal experience that 10psi on a 15g is like 14psi on a 13c. Have the people who are guessing at what actual happens experienced it first hand ? All the bs about the engine not being able to "process" the extra flow! You'll be telling me a bigger intercooler is a downgrade next as it leads to more lag etc etc.

figures or it didn't happen.

I don't disagree that upsizing the turbo will increase top end power - thats kind of a given. Whether that is "better" performance overall is a different question.

Tony's point is also true - to actually get the full value from any single change, other changes are typically necessary.

Absent ANY other change, increasing the size of a turbo while maintaining the same boost pressure will probably not improve real world performance significantly and may well compromise drivablity.

Garrett do a good little series on sizing turbos and the compromises involved. If you haven't read it take a look.

[bluebrickrick]

I'd have been here sooner but had a nasty outbreak of spontaneous internal combustion in my pipe, something to do with non isothermal compressional heating and low relative humidity, despite the intercooler too!. Anyhow I've taken the turbo off again, it seems not all turbos are better...........

Rick ;)

[Laird Scooby]

Welcome along for the ride Rick, sorry to hear of your maladies, have you tried an app to cure them? ;) :D

[TonyS9]

As I have upgraded the mitsus I can state from personal experience that 10psi on a 15g is like 14psi on a 13c. Have the people who are guessing at what actual happens experienced it first hand ? All the bs about the engine not being able to "process" the extra flow! You'll be telling me a bigger intercooler is a downgrade next as it leads to more lag etc etc.

Hadn't thought about the volume issue on the inlet, but would cause more lag yes. I have no opinion as to how significant it is, but bigger intercooler could be better than bigger turbo.

I don't dissagree on your statement above, although I am surprised at the significance of efficiency. The point is that at standard PSI a bigger turbo will not make any improvement, and in fact probably be slightly detrimental as it will be less well matched to the flow and therefore create more heat. The bigger turbo only works better because its peak efficiency is at a higher flow (which you have achieved by increasing the pressure) and it creates less heat.

I also agree that the statement about engine not processing air was not quite right, the turbo builds the pressure and doesn't try any harder than necessary. The flow is dependant on the engine design / throttle position etc. The charge temp is partially dependant on the turbo efficiency at the flow achieved.

[Laird Scooby]

I also agree that the statement about engine not processing air was not quite right, the turbo builds the pressure and doesn't try any harder than necessary. The flow is dependant on the engine design / throttle position etc. The charge temp is partially dependant on the turbo efficiency at the flow achieved.

That's what i actually said, just not quite so eloquently as you did - apologies for the confusion caused by my phrasing.
It also takes more energy to spool up a larger turbo because the turbine wheels are heavier so have greater inertia.