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Ecobust Analysis

Buldawg76

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Our ecos do not have mass air flow sensors so they do not actually measure air flow at all but rather use a speed density system that relies on three main inputs from sensors to calculate air flow from a predetermined map in the PCM. They base air flow on throttle position (TPS sensor) or in the ecos case the desired throttle position desired by the driver's right foot and the actual throttle blade position commanded by the PCM (it will never be 100% WOT like in a cable operated system), engine rpm measured by the crank sensor and manifold pressure/boost measured by two sensors, one in the outlet of the IC and one in the top if the intake that also measure intake temps. It looks at coolant and cylinder head temps as well as other sensors but the main signals it uses for fuel/timing delivery is TPS/RPM/MAP.

BD
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ihasnostang

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here's a log of boost pressure vs Exhaust MAP – The inferred measurement of exhaust gas backpressure in the exhaust manifold pre-turbine .

emap.JPG
 

Buldawg76

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here's a log of boost pressure vs Exhaust MAP – The inferred measurement of exhaust gas backpressure in the exhaust manifold pre-turbine .

emap.JPG
The graph is too small to see the numbers and color of which is boost pressure versus exhaust map so cannot make any conclusions from it.

BD
 

Hi-PO Stang

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So, would a better flowing head design eliminate some of the issues described ?
 

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Buldawg76

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So, would a better flowing head design eliminate some of the issues described ?
I would think equal length exhaust runners to the turbo would certainly help.

BD
 

ihasnostang

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i also logged this parameter from cobb. Its confusing because i checked both parameters back to back with the car idling and they read 14.7 psi but this one only peaks below 25psi. even if one of these is absolute pressure and not gauge pressure things don't quite add up.

Exhaust BP – The inferred measurement of exhaust barometric pressure in the exhaust manifold pre-turbine.

ep.JPG
 

Buldawg76

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i also logged this parameter from cobb. Its confusing because i checked both parameters back to back with the car idling and they read 14.7 psi but this one only peaks below 25psi. even if one of these is absolute pressure and not gauge pressure things don't quite add up.

Exhaust BP – The inferred measurement of exhaust barometric pressure in the exhaust manifold pre-turbine.

ep.JPG
Actually, it does make sense with at idle the boost is a negative pressure signal with it being in a vacuum in the intake and will only go into positive boost at throttle openings above idle and is dependent on how far you push the go pedal as to the max boost you will see. With an OTS cobb tune or the FP tune 24-25 psi boost will be the max you will see at WOT, my FP tune maxes out at 24psi.

The exhaust BP on the other hand will always be a positive number since it is doing work driving the turbine wheel so should be close to 14.7 at idle and rise when under positive boost against the intake's airflow being boosted by the resistance to the intake turbine wheel being spun by the exhaust flow.

What you don't want to see is the exhaust BP to increase more than the boost pressure by over a 1.5 to 1 ratio. Example would be 24 Psi intake boost and 36+ psi exhaust BP readings. Ideal is 1 to 1 or as close as possible to that ratio as possible.

BD
 

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whole lot of misinformation and speculation in this thread.

i wonder what ford's warranty team and engineering team might offer to this discussion.?
 

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i wonder what ford's warranty team and engineering team might offer to this discussion.?
I believe they would say: "We ship the cheapest solution possible to the user and given that 98.5% of Ecoboom users never rev their engines past 4000 RPM we're confident 99.3% of all shipped engines will survive the 5 year powertrain warranty period. They may then start falling over like 3 day old fruit flies but we don't care because it's not our problem but the ever gullible consumer's. Why make the effort on 'good' when 'good enough' will suffice?"

I don't know if a reed valve would help prevent any reverse flow but it is my esteemed opinion that if you're opening the throttle with any serious intent it should be done with no less than 3500RPM on the clock.

Something has definitely changed in EB tuning from Ford over the years. My 2019 would immediately peg the boost gauge (23'ish PSI) even at fairly small throttle. And the car would go nowhere. My 2022 sits in negative unless I'm say a good 25% into the throttle (have to pull up a gauge for actual % throttle desired) at which point it slowly adds a little boost. Even if you floor it the PSI only goes to about 10 till you're north of around 4000 RPM and then it'll go up to 15 and then fairly quickly to max.

Short of driving like a racer-boy moron, I almost never see boost in normal commuter daily driving. And definitely not over 5psi.
 

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Coyote Chase

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A 2 to 1 EMAP to MAP (not EMAP to Boost) ratio is acceptable for most non performance turbocharged street cars.
Here's a YouTube video that explains my statement.
IMG_20221104_144546618_BURST000_COVER_TOP~2.jpg
 
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Coyote Chase

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So, would a better flowing head design eliminate some of the issues described ?
A better flowing head is a big plus for any build. But one of our big issues, lays in the A/R of our turbine housing. I also don't like the integrated head, but I don't have much choice, with a limited racing budget.
Screenshot_20221119-143732.png
 
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Coyote Chase

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Screenshot_20221119-143915-027.png

I'm planning on running the Precision "drop in" Turbocharger next season. I'm hoping for a ratio of 1 to 1.5, but don't really know what to expect!??

PS: And it will be equipped with an Exhaust Manifold Absolute Pressure gauge.
 
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Coyote Chase

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Wow! Touchy subject. Thanks for all the feedback.

I guess I'm still trying to understand the cause/effect claimed in the video. The exhaust "manifold" is integral with the cylinder head in these cars to support the twin scroll turbo design. (Well, more to save money WHILE supporting the twin scroll design I guess. That's another story.) The firing order for the engine is listed as 1,3,4,2. The 2&3 cylinders feed one 'scroll' of the turbine while the 1&4 cylinders fee the other 'scroll'. Due to the firing order the cylinder pairs are not fired back-to-back creating a 1 cylinder firing gap to allow exhaust gases to be separated. At higher RPMs less separation. At higher boost pressures AND higher RPM less separation AND more air flow. However, due to valve overlap between the exhaust and intake strokes both valves are open simultaneously for a little while. According to descriptions of the engine's operation there is a negative pressure (vacuum) inside the cylinder while the intake & exhaust valves are both open. So under ALL conditions a little exhaust gas will be drawn back into the cylinder. At least I think it will. Inertia will move most of the exhaust gases out but back pressure will prevent at least some exhaust gas from being expelled, especially at higher RPMs under substantial boost. But if there is sufficient back pressure more than just a little exhaust gas will remain (or be drawn) in to the cylinder. I think this is the gist of the "reversion" argument. While the turbo will attempt to force fresh intake air into the cylinder the exhaust gas will put a limit on the amount of the fresh air that can be drawn/forced into the cylinder. Even though the intake is under boost it's not more than a full atmosphere of pressure (14.7 psi is 1 atmosphere). Unless these tunes are running well above 29.4 psi (2 atmospheres). I don't think they are. So if a trace amount of exhaust gas remains in the cylinder the turbo forces in an almost full cylinder of fresh air. But if a significant amount of exhaust gas remains from back pressure or being drawn back in under 'reversion' now there is much less fresh air in the cylinder. Since this is a direct injection engine the computer will spray in the requisite amount of fuel based on the RPM, MAF, engine temp, etc. It can't measure the amount of fresh air vs exhaust air in the cylinder. At least I don't think it can. If this were a port injected engine then the air fuel ratio would be established in the intake but here it's established inside the cylinder. I don't know what happens when the air charge is contaminated with a significant amount of exhaust gases. The computer is forcing in fuel based on a specific Air/Fuel Ratio. But the computer assumes that the air is fresh air, or almost 100% fresh air. What happens when the concentration of fresh air is less than 90%? Or less than 75%. Will this cause detonation? Remember that the amount of fuel injected is the same regardless of the percentage of fresh air in the cylinder.

In the EGR systems of yore the AFR was established outside the cylinder. Either in the carb, TB, or PI. If significant exhaust gas remained in the cylinder the intake air charge would be reduced but the fuel charge would be reduced proportionally since it was mixed outside the cylinder. I think this results in the same AFR inside the cylinder regardless of the percentage of exhaust gases remaining. Here the AFR is established solely by the amount of fuel sprayed into the cylinder based on assumptions about the air charge being forced in by the turbo. If exhaust gases are significant then the AFR calculations are kaflooey. There is a much higher AFR than predicted. At least I think this is the case. I'm hoping that the engine builders out there understand this WAY better than I do and can offer some constructive criticisms.
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!
 

Coyote Chase

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i also logged this parameter from cobb. Its confusing because i checked both parameters back to back with the car idling and they read 14.7 psi but this one only peaks below 25psi. even if one of these is absolute pressure and not gauge pressure things don't quite add up.

Exhaust BP – The inferred measurement of exhaust barometric pressure in the exhaust manifold pre-turbine.

ep.JPG
I've seen it done 2 different ways, psi to psi and EMAP to MAP. What's most important to me is being able to record the information onto my data logger. And someone smarter than me is going to have to figure that out!
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