Turbo backpressure? What turbo backpressure?
 

I logged turbine inlet pressure and generated the plot below.

X axis is RPM
Y axis is TIP-MAP (kPa)
color is boost

The darn GT2560 operates in crossover (MAP > TIP) in most conditions below 4200 RPM, by over 1 psi. The sucker makes 5 psi of boost by like 2200 RPM BTW.

At 15 psi of boost, TIP-MAP is 5 psi at 5700 RPM and 10 psi at 6800, 12.5 psi at 7400.

BTW at 15 psi of boost, my intercooler has 1 psi of pressure drop at 5000 RPM and 2 psi at 7400.

My exhaust has 4.5 psi backpressure at peak power and probably 2 psi in the midrange (I will log this next)

https://www.miataturbo.net/attachmen...1&d=1335070846

lol is there anything you haven't logged on your car yet?

what are your EGTs that correlate to that scatter plot?

Enthalpy drives the turbo and includes heat, pressure, and dynamic energy effects. with a hot, high volume flow rate exhaust, you'll spin that turbine.

I'm sure with VVT and some spark retard you can get more time in crossover.

Bauce.

Very interesting.
Ive always heard that with a good turbo setup with a free flowing exhaust, that the pressure in the IM should be a bit higher than in the turbo manifold, I just never knew by how much.

Any idea what typical NA backpressure values would be?

Typical NA backpressure will be 4-5 psi at peak power.

My turbo shows TIP-MAP < 5 psi to about 6000 RPM.

Food for thought.
_______________

EGT sensors have a very slow response time. The data will be worthless without sustained loading like on a dyno or very high speeds.

which EGT sensors are you talking about, they very on what type of thermocouple you use, like shielded vs unshielded.

Jason what exhaust mani are you running?
(sorry for off topic)

looks like a shielded thermocouple.
http://www.omega.com/pptst/JTIN.html
exposed junction, k type, innconel

The graph looks vaguely like a penis.

:laugh: U know how I know you're gay?

Jacopb inwanna measure my studf too.

What sensor u use?

No it do not. Let me show u what one llook like.