Your logs, you took them after welding your wastegate shut? You've actually ridden in a car with a turbo and no effective wastegate and just kept pushing and pushing?

Efficiency range is not limited by boost. Efficiency is an equation of the the mass of air you get in ratio to the volume of air you get. The range of efficiency is where this ratio starts to produce boost and ends where heat counteracts compression enough to start equalizing or even decreasing mass. Efficiency in a turbo is a problem of heat, not boost. This is why we use an intercooler, to extend the ability to dissipate heat from the charge. Nothing else in this process lowers boost pressure, except for a wastegate. Infact, trying to add air mass while heat increases without having an outlet will increase boost pressure


jason

 

(Btw please dont gimme ish about pressure and heat being the same thing. They're not. Othewise we'd use engine heat to create boost hahaha )

jason

 

This is an easy experiment to conduct. Just unhook the vacuum line going to the wastegate, and drive the car at WOT in third gear making sure the rpms are hitting the rev limited. See how long it takes before either boost drops or your engine explodes.

He's right by the way about the efficiency range.

As far as the gauges being tools for general measurement, I agree to a certain extend. However, there is no way that a boost gauge made by a reputable manufacturer has an error correction factor of +-10%. That ridiculous.

 

Re boost drop: if a wastegate is spring driven, it will always default to the spring weight w/o indication. You'd actually have to lock it shut.


Re gauge accuracy: heh its not gauge accuracy I'm questioning, its human accuracy. Remember, I didn't recommend just a digital guage, but one w/ peak hold. Its hard to continuously watch a gauge while driving. Having something else watch and record for you is always more accurate... and much safer.

 

That's a different story. I will agree with you there. Watching a boost gauge while topping out 3rd gear is probably not the most safe way of operating your car.
This is also interesting, I have been noticing that as it is getting cold my boost pressure is rising. I guess not that interesting considering the intake charge is slightly more dense because of the colder incoming air and higher atmospheric pressure, however, it has risen by about 2 psi with only about a 20 to 30 degree change in temp. It is not at an unsafe level of about 17.5; definitely needs to be corrected.