Back pressure

[Pascal]

Hey guys, i have one doubt in my mind. How to really efficient discover or find that i have back pressure and that i need bigger exhaust or turbo housing or or..? How to find out with certain security that i have back pressure? At moment is on the dyno one EVO9 and one SR20DET.

Thanks for answers

Pascal

[figgie]

Back Pressure?

What is this "back" pressure you speak off? I know what pressure is (From a strict Fluid Mechanics perspective which turbos observe), Resistance to the flow of the gas/fluid.

Back pressure? A double negative? or in english. A resistance to the resistance to the flow fo the gas/fluid?

Something does not sound right.

Anyway, you want to measure the pressure delta before the turbo gets the exhaust pulses and after as that will give you the pressure ratio you are seeking in logged data.

[pnanassy]

Measure it.Here is mine:

[Daniel]

What sensor are you using for the exhaust manifold pressure?


Thanks Daniel

[pnanassy]

Same as MAP,4 bar motorola IIRC.Connected with 30 cm steel brake line than 1m rubber hose.Works like a charm so far.

Peter

[stevieturbo]

Might not have the same pressure rating....although others are available.

But Ive used an Omega PX40 ( 0-30psi ) sensor for monitoring pressure on my car.

I use it for cooling system pressure, and also for EGBP.

its a simple PCB mount 0-5v transducer, with a 3mm straight tube fitting, and can apparently handle fluid, as well as temps to 90degC

They are available with different pressure ratings. I initially bought 3 of them to measure before/after the IC, and the cooling system pressure.

[MarkMc]

Hi Pascal,
Depending on the boost pressure you could use a 3bar Delco or a 5 bar sensor. The main thing to remember is you need to remove the heat from the exhaust gases before they burn a hole straight through the sensor. On my car I had (like pnanassy) a some fuel line connected to the exhaust that was long enough to reduce the heat and then a rubber hose from the end of that.

[stevieturbo]

I welded a female brake pipe fitting to my collector for monitoring system EGBP. Then ran about 2-3ft of brake pipe closer to the sensor, which was hooked up with rubber pipe.

That way, when finished with it, I can just screw in a brake pipe nipple, and its sealed up.

If you want to test multiple areas....same again, brake pipe fittings are handy, as you can just unscrew and re-locate quite cheaply

[MarkMc]

I usually weld on a few of our Lambda bosses, then machine up a bung to suit what ever sensor I want to use.

[Pascal]

Thanks guys!

Was been really useful your answers. Cause i was been really in the doubt how to see when i am enough with exhaust. Now this make easy for me to continue. I did start to do some testing with local and Japanese exhaust manifold to determine precision and use of it on my dyno, to understand better that issue. To understand better how much really mean one exhaust manifold or exhaust and the measurement of it. I very much apriciated idea also of Steve Turbo, put trough almost full lenght to measure on more places. That might show efficiency of whole exhaust system.

Will post later some figures from dyno and some logging when i'm done.

Thanks and cheers!
Pascal