Ecobust Analysis

[Ecto1]

I found this video on utube and found it enlightening. I haven't seen it on the threads before but if it has been discussed already please indicate the link.




(couldn't figure out how to link the video into this page.)


It's from Tuned By Nishan/Speed Perf6rmanc3.

The theory is that exhaust 'reversion' is causing the detonation/head gasket failures/head lift resulting in ecobust. I'm curious to know if other professional ecoboost engine builders buy the theory.

FYI.

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[Coyote Chase]

I found this video on utube and found it enlightening. I haven't seen it on the threads before but if it has been discussed already please indicate the link.




(couldn't figure out how to link the video into this page.)


It's from Tuned By Nishan/Speed Perf6rmanc3.

The theory is that exhaust 'reversion' is causing the detonation/head gasket failures/head lift resulting in ecobust. I'm curious to know if other professional ecoboost engine builders buy the theory.

FYI.

Glad to see someone else is just as curious! I have a thread on another site with some interesting feedback!

 

[Buldawg76]

I found this video on utube and found it enlightening. I haven't seen it on the threads before but if it has been discussed already please indicate the link.




(couldn't figure out how to link the video into this page.)


It's from Tuned By Nishan/Speed Perf6rmanc3.

The theory is that exhaust 'reversion' is causing the detonation/head gasket failures/head lift resulting in ecobust. I'm curious to know if other professional ecoboost engine builders buy the theory.

FYI.

I have seen that same video before as well and it has some very good insight into the issues surrounding the ecoboom and internal exhaust passages in the head.

BD

 

[Radiation Joe]

The reversion theory is just that. A theory. If exhaust pressure becomes excessive, then the residual exhaust in the cylinder just acts like excessive EGR and reduces the chance of detonation. Excessive residual exhaust in the cylinder just reduces the volume of intake charge. This reversion theory is BS. Stop believing what you see on YouTube.

 

[Buldawg76]

Ok so if exhaust reversion is BS, then why exactly can you buy shortie and long tube headers for most any engine ever made and why does the powerband/peaks of any engine depend/vary with choice of header/cam selections. Exhaust reversion/scavenging is a very real factor and useful tuning choice for the intended purpose the engine will be built perform. It is most certainly not just theory.

How many years have you been building/racing vehicles for a career/living.

BD

 

[jdsfly]

The EGR system wasn't designed to combat detonation. It was designed to combat peak combustion temperatures that create oxides of nitrogen, a pollutant. The way they are designed, It's not possible to flow excessive exhaust gas, from an EGR malfunction.
The ecoboost's factory turbo is very small. When you tune it close to 400 WHP, the turbo starts to become a restriction to exhaust flow. The exhaust starts to stack up and creates more heat and pressure in the cylinder, which can lift the head or create a detonation event, which lifts the head. The open deck 2.3 ecoboost doesn't have much mating surface between the cylinders, which is where the head gasket usually fails. The failure is most commonly in cylinder 2 or 3, as those exhaust ports don't flow as well as 1 & 2.
There are a couple of fixes. If you want to tune up to around 400 WHP, it would be safer to do it with a larger, less restrictive turbo. Also, you could add stronger head studs, and a better head gasket. Personally, I wouldn't tune to more than 370 WHP, on the stock turbo.

 

[Jaymar]

Ok so if exhaust reversion is BS, then why exactly can you buy shortie and long tube headers for most any engine ever made and why does the powerband/peaks of any engine depend/vary with choice of header/cam selections. Exhaust reversion/scavenging is a very real factor and useful tuning choice for the intended purpose the engine will be built perform. It is most certainly not just theory.

How many years have you been building/racing vehicles for a career/living.

BD

Not the same thing. Exhaust reversion interrupting the momentum of a column of gas is one thing but causing excessive cylinder pressure? C'mon, think about that one. It still leaves with enough energy to drive a turbine in addition to the already mentioned factors from @Radiation Joe.

 

[Buldawg76]

The EGR system wasn't designed to combat detonation. It was designed to combat peak combustion temperatures that create oxides of nitrogen, a pollutant. The way they are designed, It's not possible to flow excessive exhaust gas, from an EGR malfunction.
The ecoboost's factory turbo is very small. When you tune it close to 400 WHP, the turbo starts to become a restriction to exhaust flow. The exhaust starts to stack up and creates more heat and pressure in the cylinder, which can lift the head or create a detonation event, which lifts the head. The open deck 2.3 ecoboost doesn't have much mating surface between the cylinders, which is where the head gasket usually fails. The failure is most commonly in cylinder 2 or 3, as those exhaust ports don't flow as well as 1 & 2.
There are a couple of fixes. If you want to tune up to around 400 WHP, it would be safer to do it with a larger, less restrictive turbo. Also, you could add stronger head studs, and a better head gasket. Personally, I wouldn't tune to more than 370 WHP, on the stock turbo.

I agree with all you state concerning the EGR systems used on older cars when feul/timing controls were not as advanced as they are today. There are still some cars that use EGRs but it's not as prevalent with the much better control systems we have today. It was exactly for control of combustion temps and oxides of nitrogen by diluting the intake fuel charge with unburned spent exhaust gases.

The reason cylinders 2&3 are the ones most affected by exhaust backpressure issues is because they have the shortest path for the backpressure to travel to enter the cylinders as compared to the longer runners of cylinder 1&4. Just as you state the higher power you try to achieve out of the stock turbo the more backpressure you create and end up in ecoboom territory. It is all a balancing act with any high-performance engine tuning/build. Parts must be matched for the intended purpose.

BD

 

[Buldawg76]

Not the same thing. Exhaust reversion interrupting the momentum of a column of gas is one thing but causing excessive cylinder pressure? C'mon, think about that one. It still leaves with enough energy to drive a turbine in addition to the already mentioned factors from @Radiation Joe.

If you increase boost pressure past the point that the exhaust port/turbine can flow you will increase backpressure enough at turbine to overcome exhaust flow out of the cylinders and create a higher cylinder pressure than the gasket/head bolts can handle in stock form.

The fact that the 2.3L is an open deck means the cylinders can and do distort quite a bit under WOT boost conditions so when you push those limits over the stock design you end up with blown gaskets/head lifting and cylinder distortion.

BD

 

[Jaymar]

If you increase boost pressure past the point that the exhaust port/turbine can flow you will increase backpressure enough at turbine to overcome exhaust flow out of the cylinders and create a higher cylinder pressure than the gasket/head bolts can handle in stock form.

The fact that the 2.3L is an open deck means the cylinders can and do distort quite a bit under WOT boost conditions so when you push those limits over the stock design you end up with blown gaskets/head lifting and cylinder distortion.

BD

Both true, but not related. There's only so much the poor little block can handle from combustion pressure and temperate. That's a function of the air/fuel/timing that you're cramming into it. All engines will have some limit on that. The internal head sucks for flowing large amounts of gas out and will eventually restrict how much energy you can transfer to a turbine as well. But the notion that there is all this back pressure from the exhaust contributing to cylinder pressure? Not buying that at all.

 

[Buldawg76]

Both true, but not related. There's only so much the poor little block can handle from combustion pressure and temperate. That's a function of the air/fuel/timing that you're cramming into it. All engines will have some limit on that. The internal head sucks for flowing large amounts of gas out and will eventually restrict how much energy you can transfer to a turbine as well. But the notion that there is all this back pressure from the exhaust contributing to cylinder pressure? Not buying that at all.

Well if the flow going in increases to the point it cannot get out faster than its being forced in then it creates a stagnant blockage to flow in the form of backpressure that has to go somewhere and the only option is back into the cylinder during valve overlap creating an overpressure condition in the cylinder that when the compression/ignition event occurs it raise the pressure to the point that either the gasket gives out or the head lifts with the result of failure. Ford will not even repair any engine that has suffered head gasket or head lift failures but rather replace the entire long block due to cylinder distortion and or head damage.

Been fixing cars for a living for 45 plus years so have seen just about every failure possible with all systems in cars that have been told by engineers could/should not be possible and yet they failed just the same.

BD

 

[ice445]

Everyone in here is talking about adding too much power and boost when I see this happen more on completely stock engines. My buddy has an untuned stock 18 that popped its headgasket and scored cylinder #3 at 55,000 miles.

 

[Jaymar]

Well if the flow going in increases to the point it cannot get out faster than its being forced in then it creates a stagnant blockage to flow in the form of backpressure that has to go somewhere and the only option is back into the cylinder during valve overlap creating an overpressure condition in the cylinder that when the compression/ignition event occurs it raise the pressure to the point that either the gasket gives out or the head lifts with the result of failure. Ford will nor even repair any engine that has suffered head gasket or head lift failures but rather replace the entire long block due to cylinder distortion and or head damage.

Been fixing cars for a living for 45 plus years so have seen just about every failure possible with all systems in cars that have been told by engineers could/should not be possible and yet they failed just the same.

BD

Let's assume that the exhaust restriction is so large that it leads to the scenario you described. The exhaust gasses left behind to cause said overpressure would displace the incoming fuel/air charge so there would be less combustion to blow the head gasket etc. You'd have the mother of all EGR so you go back to 1976 power levels which if you recall were terrible. The headers mentioned before increase power by displacing more exhaust to make room for incoming fuel/air charge.

 

[Buldawg76]

Everyone in here is talking about adding too much power and boost when I see this happen more on completely stock engines. My buddy has an untuned stock 18 that popped its headgasket and scored cylinder #3 at 55,000 miles.

With anything mass produced you will have cars that are at the very lower end of tolerance stackup and ones that are at the high end of stackups. so never said that completely stock could not suffer ecoboom from excessive tolerance stackups that put the safety limit right on the edge of failure from the very start. It's the reason no 2 identical cars run exactly the same.

BD

 

[Buldawg76]

Let's assume that the exhaust restriction is so large that it leads to the scenario you described. The exhaust gasses left behind to cause said overpressure would displace the incoming fuel/air charge so there would be less combustion to blow the head gasket etc. You'd have the mother of all EGR so you go back to 1976 power levels which if you recall were terrible. The headers mentioned before increase power by displacing more exhaust to make room for incoming fuel/air charge.

Your description is largely depended on cam centerlines and valve timing which on the new cars is variable so there are scenarios that can lead to increased combustion pressure over the normal limits from high velocity intake charge and extreme exhaust backpressure both over filling the cylinder before both valves close resulting in gasket failure/head lift and cylinder distortion.

Headers work by tuning the exhaust pulses in the header to work in conjunction with the intake pulses so that in an ideal world the pulse in the header will be just arriving at the exhaust valve as the fresh intake charge is about to exit past the exhaust valve right as it closes to keep the most air/fuel charge in the cylinder. Just as the intake valve should be timed to close just as the intake charge is beginning to slow its velocity into the cylinder to capture the greatest amount of air/fuel charge. The cam is the heartbeat of the engine, and the intake and header combo must be matched to that heartbeat to achieve the overall best performance.

BD

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