Ok I have been trying to think of a way to log backpressure, I know it wont be possible for dataloggers that read from the stock ecu since you need some sort of spare 0-5v sensor input. I was thinking of just buying a metal aem map sensor that reads the highest and for everyone that has a wideband datalogger like innovate or zeintronix you can just calibrate that sensor. The only thing I am not sure of is placement of the sensor to get correct measurements and also if the metal boost sensor from aem will hold up to the heat from the exhaust components. The reason I am interested in this is because lessening backpressure can help a ton, like reducing surge, increasing spool, and increasing the life of your motor and turbo for those who spend big bucks on big turbos especially. Any input or if you know of any pressure sensors that can hold up to high heat or if any of you are logging backpressure please give some input.

 

It will take more time and money to find a given static exhaust pressure than it would be by just buying an exhaust system that has been proven to hold up

 

But you are only looking at the exhaust aspect of it. Turbos also cause backpressure especially when running out of their efficiency range or if the compressor and turbine wheel are not the right match.

 

Back pressure is mostly created by your turbo. (Cat and muffler too, but you would get a test pipe for one and a free flowing for the other). Do you plan to start switching turbos around?

 

You can hook up a normal gauge if you use a coil of copper pipe to cool the air before the gauge. So you could do the same with a MAP sensor.

If your wastegate actuator is standard, then the duty cycle required to hold boost is a proxy for exhaust manifold pressure.

 

Are you referring to the pressure between the exhaust valve and turbine? If so, I can tell you that the stock turbo (with 10.5 HS) makes excessive back pressure as rpm and boost goes up. Enough to open WG on it's own against WGA spring. Adding spring tension does add more boost but also at the cost of efficiency.

This back pressure decreases the engine's dynamic compression, especially w/o MIVEC. This is what makes the X sound so pleasing - higher compression, intake and exhaust varibale camming

 

There was a good post by someone at Forced Performance with graphs, etc, on the green and backpressure. Maybe send a PM to FP and ask them what sensor they use and where in the exhaust manifold, etc they mount it.


Eric

 

Backpressure measurements should be in the collector of the manfold (on the upstream side of the turbine) AND right at the turbine discharge. This way you can separate downstream effects from the turbine's expansion ratio. Both are important.

You will want a 5 bar sensor for the upstream side and a 2 bar sensor for the downstream side. Maybe check with Omega?

mchuang, don't let the naysayers talk you out of this. Exhaust backpressure data is sorely lacking in the aftermarket and is very useful.

 

Yea I am gonna work on it, just need to make sure where the mounting point is needed for correct data acquisition. Then I will just add another map sensor to a 0 - 5v input on my innovate wideband and its not like it will be highly expensive for the extra data. Parts will probably just be a map sensor a fitting tapped into the manifold or downpipe(depends where data is best at) and like someone said some type of copper or aluminum tubing routed to the map sensor.

 

The copper tube method is fine if you're just looking to measure absolutes and don't mind sensor delay. The longer the tube, the higher the time constant, just like when you mount a MAP on the intake manifold.

keep the tubes short if you want to overlay the sensor data to an RPM trace.

 

If you do pull this off I would love to see your results.

What kind of boost control, how much boost, and what kind of WGA will this be with?

 

When I do it, it will probably be around Jan, reason being is that I have been putting together a turbo kit, but I cannot finish it because XMAS is coming(Bahhumbug) Gotta by xmas presents so most of my free money will be dedicated to that. I am pretty sure others are in the same boat lol. I already have a 38mm tial, and I am not sure if it will be stock ecu boost control, or a nice manual boost controller like buschurs, Im going to try pump at 24psi.

 

Found a pretty interesting sensor, heard of it before never thought about it until now

At the bottom but I am sure any pressure sensor could work

http://www.kavlico.com/pages/industr...lications2.htm

 

mchuang, try the stock turbine inlet pressure sensor from a 2003 - 2007 Ford Powerstroke Diesel. I am not sure of the pressure range but it is designed to do what you want and it does give a 0-5V output.

Look at the truck and see how far they mount the sensor from the exhaust pipe, and then take into account that diesel EGTs are lower than on a gasoline engine so you'll have to extend it a bit farther.

Actually the 2008 Ford Powerstroke also has a turbine inlet pressure sensor that may be a more robust design since apparently they had some problems on the 2003 - 2007 sensor (made by Kavlico).

 

you wouldnt happen to have a picture or part#