So vta smoke...

[Weather Man]

What are backpressures?

They're 2 back pressures (BP) that turbo guys care about. Pre-turbine and post-turbine.

Pre-turbine is the back pressure in your up pipe. Post-turbine is the back pressure in your down pipe.

Generally, pre-turbine back pressure is considered in conjunction with the actual boost the car is making. It is usually expressed as a ratio. For example: with the turbo making 20 psi of boost, up pipe BP is 30 psi, for a 1.5 to 1 ratio.

The general consensus in the turbo world is that as BP ratio approaches 2 to 1 and higher, bad things start to happen. These include, but are not limited to, slow spooling, exhaust reversion (bad) and boost tapering off with RPM. Ideally the ratio would be 1 to 1, but not likely in the real world.

Post-turbine BP is really a measure of how restrictive your down pipe/exhaust is and can greatly influence pre-turbine BP issues. Generally, if a shop thinks BP is an issue, they will drop the exhaust and see what happens. CPRsm has a intial 5” down pipe off their turbo coyote kits, amazing. On my own 08, when I went from a 3” to 4” down pipe, all my boost taper issues went away.

This is just a scratch of the surface. Plenty of stuff on the web, if you want to dig deeper.

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[Brian V]

I have a question Tuscon ..

What color is the smoke that you are observing ?

 

[Tucsonturbos]

I have a question Tuscon ..

What color is the smoke that you are observing ?

Thin screen of blue AKA oil. I get the now and then condensation white smoke but coming from cars from turbo frs, twin/single turbo fd rx7s, supercharged fieros etc.. im decenty knowledgeable the turbo issue signals. Im going to check shaft play/wheel damage this weekend. Im not over concerned since its impossible for it to be in the intake but seems like the mazdaspeed 3 guys had a similar issue with stock turbos burning oil/blowing. Plus more of a reason to finish my custom massive turbo kit ;)

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