Turbo drive pressure

[bulldog77]

Has anyone installed a gauge to read drive pressure on a stock turbo? What kind of numbers have you seen? Stock and demandated

[Hammerhead]

(04-05-2018 )bulldog77 Wrote:  Has anyone installed a gauge to read drive pressure on a stock turbo? What kind of numbers have you seen? Stock and demandated

IIRC, you have an 870.
The turbo efficiency of them is around 1.8:1, so it should be intake pressure times about 1.8.
A turbo pushing 38psi max will be in the ~68psi exhaust manifold range.

[DLC]

One should be able to monitor drive pressure with Insite?

[bulldog77]

(04-05-2018 )Hammerhead Wrote:  

(04-05-2018 )bulldog77 Wrote:  Has anyone installed a gauge to read drive pressure on a stock turbo? What kind of numbers have you seen? Stock and demandated

IIRC, you have an 870.
The turbo efficiency of them is around 1.8:1, so it should be intake pressure times about 1.8.
A turbo pushing 38psi max will be in the ~68psi exhaust manifold range.

Are those real world numbers or what Holset says? Maybe in some spare time(lmao) I should hook up a gauge and see.

[Rawze]

CM871 measured, no EGR gas flow ...

NOTE: All exhaust pressures data is after subtracting 14.1 psi from the sensor because it reads atmosphere+ unlike the boost sensor which reads zero when at rest.

At idle with turbo at only 15% (slight vacuum), adjusted to absolute minimal fuel consumption ...
-- Exhaust pressure = 0.7
-- Intake pressure = 0.03 psi (Ratio = 23:1 - Inaccurate, cannot be measured by the sensors).
-- Turbocharger rpm = 11.4k
-- fuel flow = 13.7 mg/stroke



At 52 hp, 1240 rpm, cruising with light torque load ...
-- Exhaust pressure = 6.5 psi
-- Intake pressure = 0.89 psi (Ratio = 7.3:1 - Terrible at little to no load or boost requirement).
-- Turbocharger rpm = 30.8k
-- fuel flow = 59.2 mg/stroke

At 412 HP, 1360 rpm, steady 90% engine load (close to full throttle) ...
-- Exhaust pressure = 47.4 lbs
-- Intake pressure = 19.7 lbs (Ratio = 2.53:1 - a more realistic measurement).
-- Turbocharger rpm = 94.3k
-- fuel flow = 274.4 mg/stroke


At 412 HP, 1630 rpm, accelerating bobtail ...
-- Exhaust pressure = 50.6 lbs
-- Intake pressure = 29.9 lbs (Ratio = 1.69:1 - about as good as it gets).
-- Turbocharger rpm = 96.4k
-- fuel flow = 240.2 mg/stroke

===

I have seen 70+ PSI in the exhaust manifolds many times and as much as 90+ on high HP engines when rapidly shifting them during surge. Combine that with a lot of heat and you find out why an EGR cooler or egr component can fail if it is weak.

[DLC]

Thanks for sharing. It's great to see honest real world numbers or what happens.