Fabio421

I wonder how close it will come to crossover. Will the turbine inlet pressures be logged?

I love this thread

ptuomov

The car's got about 750 test miles on it by John with different exhaust configurations. The final exhaust config is probably just days away.

Fabio421: The pressures will be logged, but that system is not yet ready. I just ordered the pipes, fittings, and sensors from Summit for exhaust pressure measurements.

I do have a simulation that is matched to Garrett's turbine pressure ratio and mass flow data, which predicts the car running pretty close to to cross-over.

8 psi simulation:
Engine RPM,3000,3250,3500,3750,4000,4250,4500,4750,5000,5250,5500,5750,6000,625 0,6500,6750,7000
Exh Pres,4.9,6.5,6.9,7.4,8.0,8.4,8.9,9.4,9.7,10.2,10.3,10.5,10.7,10.9,11.2,1 1.5,11.9
Boost,5.4,7.9,7.8,7.8,7.8,7.8,7.7,7.7,7.7,7.7,7.6,7.6,7.6,7.6,7.6,7.6,7. 5

12 psi simulation:
Engine RPM,3000,3250,3500,3750,4000,4250,4500,4750,5000,5250,5500,5750,6000,625 0,6500,6750,7000
Exh Pres,4.9,8.6,9.1,9.6,10.2,10.8,11.3,11.8,12.2,12.7,12.9,13.2,13.5,13.6,1 4.0,14.2,14.7
Boost,5.4,11.8,11.8,11.8,11.8,11.7,11.7,11.7,11.6,11.6,11.6,11.6,11.6,11 .6,11.5,11.5,11.5

(Simulations and $4.01 get you a venti non-fat latte with tax at Starbux, of course.)

Benton

Wow, just checked this thread. Great job on having a plan, sticking to it, and making it happen. I can't wait to see videos.

ptuomov

One of the things that I want to do is check the actual exhaust manifold and turbo downpipe pressure readings and compare them to my simulated values.

I decided to get two pressure sensors from AEM, 3.5 and 2.0 bar absolute:



I'll hook the 3.5 bar sensor to the exhaust manifold and the 2.0 bar sensor to the turbo downpipe. The problem is that the sensors' operating temperature range is -4F to 221F. That's not compatible with the exhaust gas heat, especially in the exhaust manifold.

To deal with the heat problem, I got some 3/16" stainless tube, a bunch of sleeves, nuts, and AN/NPT adapters. Those came in from Summit long before AEM has even processed the sensor order, what's up with that?



I wanted to get a thin tube so that there's a lot of surface area to volume. Since the exhaust gas doesn't flow in the tube, I am figuring that I don't need a very long cooling tube, but we'll see.



I test flared one end, and I have to say that this is a whole lot easier than bending and flaring 5/8" stainless tube.

Bob Rouleau

Just a note to explain, user tttt has been banned since he has been permanently banned under a different name and chose to return in spite of the rules.

AO

And no one got to post a talking monkey? Bummer...

Iwanna928

That thing is going to be sick. Awesome project, awesome job. Can't wait to see the finished project!

ptuomov

I am also adding one of these wideband lambda sensors into the system to log the AFRs and set up a joint WOT+lean condition audio alert:



I want to mount this guy in the exhaust manifold before the turbo. The problem is that it gets a bit hot there for any sensor. I don't want to exceed the sensor specs:

Do I understand it correctly that the 02 sensor needs a significant amount of flow, which means that I can't just run a tube from the exhaust manifold to cool the sensor mounting surface to below 900 F?

Fabio421

Why would you want to mount it before the turbo? What would be the advantage to that?

AO

+1

I don't see any advantage to mounting it before the turbo. However, if you did you could try building a heat sink, but I'm not sure you could scrub enough heat off to protect the sensor.

ptuomov

Just because!

Actually, a couple of other reasons as well. This is all speculation and ideas at this point.

- If the sensor is fast (as the Bosch sensor is) and mounted before the turbo, it's in principle possible to combine the unfiltered output with the crank/cam position sensors and detect a significantly lean/rich individual cylinder. Not enough to fine tune mixture, but enough to detect a persistent misfire, for example. The turbo mixes all the gasses and pulses to the point that this is no longer possible downstream of the turbo.

- I know that the wideband sensor controller has to measure exhaust gas pressure and exhaust gas temperature in the process of measuring the AFR. It would be sweet if I could just hack the controller and get both the temperature and, more importantly, pressure signals out of the controller box. This would really help cutting down the number of sensors and cooling pipes needed.

- Mounting a wideband sensor both upstream and downstream of the turbo allows one to measure how much mixture is burned in the turbine. I think there may be benefits from valve event timing such that right before the turbine has spooled, some unburned mixture is passing to the exhaust manifold. This mixture then bruns in the manifold and in the turbine, spooling the turbine slightly earlier. (For this same reason, turbo cars of the future will all have at least one cat pre-turbo.)

At this point, I am just exploring the possibilities. Brainstorming of sorts, crazy theorizing. I will probably get none of the above done.

AO

The innovate stuff does not have a very fast sample rate. I tried using it for knock logging and IIRC it max's out at 32 samples/sec. Nowhere even close enough for what you're thinking about.

Now the Bosch sensor might be fast enough, but you'd need a different data logger or engine mgmt system to take advantage of it.

ptuomov

Since the sensor can handle 1300F gas temperature, a short pipe would take care of that as. A more common problem is the sensor body temperature limit of 900F, which can be cured with just a couple of copper plates, one in each end of the cooling pipe. The problem is to then get enough flow thru the pipe, which probably would require a small 3/16" pitot tube inside a larger 5/8" slash cut tube. Now it's all complicated enough that it's probalby not worth doing in any case.

Roy928tt

Besides the problem with excesive heat I believe there is a problem with pressure affecting the accuracy of the sensor as well, maybe the problem is more related to gas density rather than pressure, still I seem to recall somebody telling me there is an issue.
I reckon it was on original minis with the 5 port head he wanted to measure the mixtures of the 3 individual runners before the turbine to see if mixtures were the same across all four cylinders, but oxygen sensors wouldn't work in the pressurised atmoshere.

Anyway just something to be aware or wary of.

Cheers Roy

ptuomov

Yes, it's difficult log anything at the required sampling rate. The volume of data would overwhelm most loggers.

The Innovate wideband controller, however, might be fast enough. It must be damn fast if it's able to control the sensor. Unless I've misunderstood these sensors, here's how they work. First, there's a part that's like a regular narrowband sensor that gives a reading for above or below stoich but doesn't have good resolution or accuracy away from stoich. Second, there's an oxygen pump that is controlled by the Innovate controller. If there is excess fuel, pumping enough oxygen will burn it and make the end result measure close to stoich by the "narrowband-like" sensor. The controller operates the pump at various duty cycles (in case of Innovate) and tries to keep the mixture at stoich. The actual end measurement is based on the amount of oxygen that must be pumped into the sensor to make it burn the mixture clean.

There are reports on the web that the unfiltered analog output from the Innovate controller is fast enough to show individual exhaust pulses up to about 2000 rpm. If one could tap into signals inside the controller box, I bet one could go quite a bit higher.

This is all science fiction speculation. I don't understand enough about this stuff to implement any of this. But it's fun to think what might be possible.