Ecobust Analysis

Buldawg76

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You make some good points! Especially concerning air fuel mixture. Exhaust back pressure will affect your AFR, as well as your fuel trims. Your ECU may interpret received data to indicate rich conditions, when you're actually running lean. Our ECUs will make the nessary corrections, but it takes time to react, and when I'm running at wide open thottle... the last thing I'm thinking about is what that ECU needs!
Most motors are blown up and very few blow up!
Correct, the ECU is adjusting the AFR based on the upstream O2 reading from spent exhaust gases but the issue I see is that the O2 reading is not capable of accounting for any backpressure/reversion that is occurring in the combustion chamber or turbo housing before the exhaust turbine wheel that could lead to momentary a rich or lean condition. Since the fuel is direct injected into the cylinder and there is no mass air flow sensor on our ecos the fuel ratio being injected is based on the signals from the TPS desired/actual positions, RPM, MAP and O2, inferred EMAP readings to determine the AFR the cylinders are operating in at each combustion event.

There is some lag between the actual and desired AFR possible if the Backpressure ratio gets over 1.5 to 1 for an extended amount of time. The ECU does react in milliseconds worth of time but at 5/6K rpm that could still be too late. I would not want to be close to 2.0 to 1 if at all possible.

Thats why a bigger turbo gives some more lead way in controlling the AFR and backpressure since its flows the exhaust more freely and reduces backpressure while increasing power at lower boost levels. Installing an actual EMAP gauge instead of relying on an inferred value to log the EMAP to MAP ratio is the best means to be able to tune and adjust accordingly IMO.

BD

 

shogun32

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Installing an actual EMAP gauge instead of relying on an inferred value
have a recommendation? Sensors don't cost THAT much. How come we keep finding Ford resorting to inferred values be it oil temp or CHT etc instead of instrumenting the damn thing?

Hmm so I guess a less restrictive downpipe and post-cat piping could be construed as a "margin of safety" improvement?
 

Buldawg76

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have a recommendation? Sensors don't cost THAT much. How come we keep finding Ford resorting to inferred values be it oil temp or CHT etc instead of instrumenting the damn thing?

Hmm so I guess a less restrictive downpipe and post-cat piping could be construed as a "margin of safety" improvement?
See post 19 in this thread for video recommendation on how to construct a EMAP gauge system.

The head port, turbo manifold and turbo are the main restrictions in the system, a 200 cell cat would help also but unless you go to a bigger turbo the post cat system flows plenty to not be a significant restriction IMO.

BD
 

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Correct, the ECU is adjusting the AFR based on the upstream O2 reading from spent exhaust gases but the issue I see is that the O2 reading is not capable of accounting for any backpressure/reversion that is occurring in the combustion chamber or turbo housing before the exhaust turbine wheel that could lead to momentary a rich or lean condition. Since the fuel is direct injected into the cylinder and there is no mass air flow sensor on our ecos the fuel ratio being injected is based on the signals from the TPS desired/actual positions, RPM, MAP and O2, inferred EMAP readings to determine the AFR the cylinders are operating in at each combustion event.

There is some lag between the actual and desired AFR possible if the Backpressure ratio gets over 1.5 to 1 for an extended amount of time. The ECU does react in milliseconds worth of time but at 5/6K rpm that could still be too late. I would not want to be close to 2.0 to 1 if at all possible.

Thats why a bigger turbo gives some more lead way in controlling the AFR and backpressure since its flows the exhaust more freely and reduces backpressure while increasing power at lower boost levels. Installing an actual EMAP gauge instead of relying on an inferred value to log the EMAP to MAP ratio is the best means to be able to tune and adjust accordingly IMO.

BD
Your right! It takes time and data for our ECUs to figure out, that the condition exists and then more time to make the nessary adjustments to prevent exhaust reversion, which can lead to engine damage.
Racers, builders and tuners running non USA engineered DITC cars from around the world have been aware of these issues for decades and know how far they can push their cars. We're still learning!
 

Coyote Chase

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have a recommendation? Sensors don't cost THAT much. How come we keep finding Ford resorting to inferred values be it oil temp or CHT etc instead of instrumenting the damn thing?

Hmm so I guess a less restrictive downpipe and post-cat piping could be construed as a "margin of safety" improvement?
The PSI to PSI monitoring system is fairly simple. The EMAP to MAP system is a little more complicated, your have to locate a read/record only circuit within your ECU and then make tuning adjustments to achieve your desired ratio, based on your risk level.
Screenshot_20221120-130300~2.png
 


Coyote Chase

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I assembled a class winning IMSA RS car when I was still in high school. I've performed the calculations and tuned both intake and exhaust runner lengths to improve volumetric efficiency. I was building/tuning dual Weber 4 cylinder engines before you were born. I'm a recognized expert in the nuclear power industry regarding acoustic phenomena in steam lines.
Your turn.
You guys have me beat!! I'm just a righty tighty, lefty loosey type of guy who puts it all on the line, every time I pull into the staging lanes...
Screenshot_20221107-092254.png
 

Buldawg76

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You guys have me beat!! I'm just a righty tighty, lefty loosey type of guy who puts it all on the line, every time I pull into the staging lanes...
Screenshot_20221107-092254.png
Yep, and you're getting quicker every pass you make gaining knowledge a 1/4 mile at a time. :):thumbsup:

BD
 
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Ecto1

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You make some good points! Especially concerning air fuel mixture. Exhaust back pressure will affect your AFR, as well as your fuel trims. Your ECU may interpret received data to indicate rich conditions, when you're actually running lean. Our ECUs will make the nessary corrections, but it takes time to react, and when I'm running at wide open thottle... the last thing I'm thinking about is what that ECU needs!
Most motors are blown up and very few blow up!
So, IFF: (If and only if, ladies. From basic calculus) the ECM cannot determine the amount of fuel for the current Compression stroke based on the previous Exhaust stroke, THEN: it is not only possible but probable that the AFR will be WRONG for the current compression stroke. If the amount of exhaust gases remaining in the cylinder are substantial then the AFR will be VERY wrong. I believe this gives credibility to the analysis from the video of EcoBust based on exhaust gas reversion.

The issue is how much exhaust gas would it take, based on max boost at max RPM, to contaminate the intake air charge to the point of detonation? And enough detonation to lift the head? More than 20% of the cylinder? More than 10%? I suspect that cylinder temps also play a critical role in detonation but I have no idea how to determine or guesstimate them for such a scenario. And is it actually the increase in cylinder temps, due to exhaust gas restriction (or reversion) &/or the inevitable flawed AFR, that is the actual culprit in EcoBust?

The man once said: "One accurate measurement is worth a thousand expert opinions." But how would you make such a measurement? :facepalm:
 

Buldawg76

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So, IFF: (If and only if, ladies. From basic calculus) the ECM cannot determine the amount of fuel for the current Compression stroke based on the previous Exhaust stroke, THEN: it is not only possible but probable that the AFR will be WRONG for the current compression stroke. If the amount of exhaust gases remaining in the cylinder are substantial then the AFR will be VERY wrong. I believe this gives credibility to the analysis from the video of EcoBust based on exhaust gas reversion.

The issue is how much exhaust gas would it take, based on max boost at max RPM, to contaminate the intake air charge to the point of detonation? And enough detonation to lift the head? More than 20% of the cylinder? More than 10%? I suspect that cylinder temps also play a critical role in detonation but I have no idea how to determine or guesstimate them for such a scenario. And is it actually the increase in cylinder temps, due to exhaust gas restriction (or reversion) &/or the inevitable flawed AFR, that is the actual culprit in EcoBust?

The man once said: "One accurate measurement is worth a thousand expert opinions." But how would you make such a measurement? :facepalm:
Thats the million dollar question.?

Installing an actual pressure gauge like shown above and in the video in post 19 in the turbo manifold will tell you the ratio of boost psi to backpressure psi between the intake and pre turbine wheel in the head/manifold. Then the math/engineering theory can start to be figured out. I am sure ford has it pretty well calculated but then they are also constrained by costs and production numbers that the bean counters make the rules to live by.

BD
 

Coyote Chase

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So, IFF: (If and only if, ladies. From basic calculus) the ECM cannot determine the amount of fuel for the current Compression stroke based on the previous Exhaust stroke, THEN: it is not only possible but probable that the AFR will be WRONG for the current compression stroke. If the amount of exhaust gases remaining in the cylinder are substantial then the AFR will be VERY wrong. I believe this gives credibility to the analysis from the video of EcoBust based on exhaust gas reversion.

The issue is how much exhaust gas would it take, based on max boost at max RPM, to contaminate the intake air charge to the point of detonation? And enough detonation to lift the head? More than 20% of the cylinder? More than 10%? I suspect that cylinder temps also play a critical role in detonation but I have no idea how to determine or guesstimate them for such a scenario. And is it actually the increase in cylinder temps, due to exhaust gas restriction (or reversion) &/or the inevitable flawed AFR, that is the actual culprit in EcoBust?

The man once said: "One accurate measurement is worth a thousand expert opinions." But how would you make such a measurement? :facepalm:
100% correct!
Between LSPI (low speed pre-ignition) and exhaust reversion, due to head and turbine design... My motor is doomed to detonate.
Some information, shared by BD is the max boost of the Ford Performance tune. 24 lbs and that's my cut off. My motor is actually "de-tuned", not to exceed 24 lbs of unrestricted boost or adjust the ETC (electronic thottle plate to create what I call false boost). And even after installing the Precision Turbocharger, I will remain at 24 lbs, until the data from my logs (with the addition of an EMAP sensor) can be examined. Which will hopefully answer your 2nd question.
 
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Buldawg76

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I believe I have seen where the cobb OTS tunes can reach 25 psi boost at times depending on conditions but have no firsthand experience myself yet. I do have an AP to use in the future after the 3/36 warranty of the FP tune runs out.

BD
 

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Correct, the ECU is adjusting the AFR based on the upstream O2 reading from spent exhaust gases but the issue I see is that the O2 reading is not capable of accounting for any backpressure/reversion that is occurring in the combustion chamber or turbo housing before the exhaust turbine wheel that could lead to momentary a rich or lean condition. Since the fuel is direct injected into the cylinder and there is no mass air flow sensor on our ecos the fuel ratio being injected is based on the signals from the TPS desired/actual positions, RPM, MAP and O2, inferred EMAP readings to determine the AFR the cylinders are operating in at each combustion event.

There is some lag between the actual and desired AFR possible if the Backpressure ratio gets over 1.5 to 1 for an extended amount of time. The ECU does react in milliseconds worth of time but at 5/6K rpm that could still be too late. I would not want to be close to 2.0 to 1 if at all possible.

Thats why a bigger turbo gives some more lead way in controlling the AFR and backpressure since its flows the exhaust more freely and reduces backpressure while increasing power at lower boost levels. Installing an actual EMAP gauge instead of relying on an inferred value to log the EMAP to MAP ratio is the best means to be able to tune and adjust accordingly IMO.

BD
Doesn't the waste gate play into this to limit back pressure caused by the turbo size?
 

Buldawg76

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Doesn't the waste gate play into this to limit back pressure caused by the turbo size?
Yes, it is part of the controls used to limit the backpressure/reversion but to what actual extent or affect it has I am unsure of. It should open to release the excess backpressure past the exhaust turbine but how much or when is one of the questions we need answered.

BD
 

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I believe I have seen where the cobb OTS tunes can reach 25 psi boost at times depending on conditions but have no firsthand experience myself yet. I do have an AP to use in the future after the 3/36 warranty of the FP tune runs out.

BD
Correct. When I was running an OTS Cobb tune, I hit 25+ plus.
 
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100% correct!
Between LSPI (low speed pre-ignition) and exhaust reversion, due to head and turbine design... My motor is doomed to detonate.
Some information, shared by BD is the max boost of the Ford Performance tune. 24 lbs and that's my cut off. My motor is actually "de-tuned", not to exceed 24 lbs of unrestricted boost or adjust the ETC (electronic thottle plate to create what I call false boost). And even after installing the Precision Turbocharger, I will remain at 24 lbs, until the data from my logs (with the addition of an EMAP sensor) can be examined. Which will hopefully answer your 2nd question.
I suspect that both a max boost pressure AND a max RPM will likely be necessary to prevent detonation which can damage the engine. I'm sure that in the Ford OE & "Performance" tunes both restrictions are accounted for. But when modifying to increase performance these limits must be addressed in the 'custom tune', regardless of the turbo bolted to the head. The base turbo can only produce so much boost. The PP turbo can only produce a little bit more. But the NX2 & the BW Atmosphere turbos can produce a LOT more boost. With the custom tunes the max RPMs can also go up quite a bit in the aftermarket turbo equipped cars. So here the tuners must provide these limits to (I think) BOTH boost AND RPMs. It would seem that either could overwhelm the exhaust path from the head through the turbos.

It will be interesting to see what your additional sensor shows if & when you get it assembled and installed. How will you collect sensor data? Is this from the AccessPort? Does the AccessPort have provisions for additional sensors that are not part of the original engine system? Or do you have to install a separate gauge and collect data manually?
 

 
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