Turbo to exhaust ratio EBP sensor - PowerStrokeNation : Ford Powerstroke Diesel Forum
 
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post #1 of 7 (permalink) Old 09-23-2014, 07:03 PM Thread Starter
tatertot
 
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Turbo to exhaust ratio EBP sensor

Exhaust back pressure question how much is too much. I have read 1 to 1 ratio is the best is that true. I have a 2003 6.0l and nothing I use as a reader will connect to it including the auto ingenuity, scan gauge and SCt live wire. Is there a way to tap into the wires and if so which ones to acquire the correct voltage then change that into a pressure reading (psi). I am monitoring the MAF and Baro right know and both show 14.7 +/-.5 with key on engine off and boost seems ok just trying to give the tuner all the info on the truck so we can tweak the settings before the long haul to Alaska.

2003 F-250 4in turbo back, Blue spring, EGR Delete AFE cold air intake W Blade runner intake, Sinster coolant filter, scan gauge II and sct with egt probe,
MTW HYBRID turbo
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post #2 of 7 (permalink) Old 09-24-2014, 11:16 AM
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Re: Turbo to exhaust ratio EBP sensor

I'd say anything more than 3:1 with normal driving would be an issue. Depending on the driving condition you will see 3:1. I'm referencing the truck cruising, not WOT runs. WOT you will see a high ratio but it will come down as the trans shifts dropping the RPMs.


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post #3 of 7 (permalink) Old 09-24-2014, 08:15 PM Thread Starter
tatertot
 
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Re: Turbo to exhaust ratio EBP sensor

thanks i'll have to look at that. Tonight I will have to start probing the wires and figure out which ones to hook up the breakout box to.

2003 F-250 4in turbo back, Blue spring, EGR Delete AFE cold air intake W Blade runner intake, Sinster coolant filter, scan gauge II and sct with egt probe,
MTW HYBRID turbo
Still rolling on stock sticks 202,000 and counting
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post #4 of 7 (permalink) Old 09-26-2014, 02:40 AM
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Re: Turbo to exhaust ratio EBP sensor

Newby question here- How do you figure this ratio? I have an Edge CTS and trying to figure out if i have a sensor going or not. Thanks!
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post #5 of 7 (permalink) Old 09-26-2014, 11:51 PM
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Re: Turbo to exhaust ratio EBP sensor

Use the Exhaust Back Pressure PID and Boost PID on the Edge. 1PSI Boost and 1PSI EBP = 1:1 ratio.....You should see a higher EBP. So 2psi EBP with 0PSI Boost at idle in park.

When accelerating you may see 20PSI EBP, 10PSI Boost= 2:1 ratio. Good but not great...get those numbers down to 1.5:1 and life is pretty nice.


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post #6 of 7 (permalink) Old 09-29-2014, 03:18 AM
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Re: Turbo to exhaust ratio EBP sensor

The ebp:boost ratio numbers get thrown around a lot without much explanation. Also you really need a mechanical boost and ebp gauge to know what is going on.


There is a common misconception that vgt turbos "always" run higher ebp:boost ratio as opposed to non-vgt turbos. But that is not true. They can and will run a higher ebp:boost ratio when spooling the turbo (only if you desire and command it). You can pick your ebp:boost ratio with a vgt turbo and adjust this through tuning. I have multiple tunes that run at different ratios. (it has more to do with desired ebp or desired boost and not necessarily the actual ratio)


Most people want faster spooling turbos down low, so when you mash the throttle you can see upwards of 20:1 ebp ratio (20psi ebp:1psi boost). But that usually only lasts for a split second until the turbo is spooled. After that split second the ratio drops WAY down to like 1.5:1 (15psi ebp:10psi boost). That is how vgt works. You can manipulate the vanes to create excessive back pressure for a split second which will spool the turbo. A 20:1 EBP:boost ratio will not hurt the motor at those small boost/ebp levels. Heck 20-35psi of ebp is completely normal and wont hurt anything.

When cruising I have tunes that run at a 1.7:1 ratio (10psi ebp and 6psi boost) which seem to spool faster and be much more responsive with much less smoke output. I also have some tunes that run 1:1 ratio (3psi ebp and 3psi boost) Those tunes are usually less responsive and are a little smokier... Interestingly enough they both run about the same egts at the same cruising speeds.


At WOT most people I know see right around 1:1 through 1.2:1 ratio (unless they are throwing a ton of fuel at it). On long hard runs the ratio can start to creep up a little bit to around 1.3:1, which is completely normal and safe. It is the high ratios with higher ebp/boost numbers that you need to worry about. A 2:1 ratio at (90psi ebp: 45psi boost)... that can blow your motor/headgaskets... but that does not happen with vgt turbos unless something is wrong (stuck vanes, bad tuning, etc). The vanes will adjust to keep that from happening.

So...

Cruising usually around 1:1 - 2:1
Mashing throttle and spooling up the turbo can see upwards of 20:1
1/2 throttle acceleration after turbo is spool can see around 1.5:1
WOT runs after turbo is completely spooled usually see around 1:1 - 1.3:1

But it all depends on which tune and turbo you are running


So I don't think anyone wanted to watch a 10 min video... but I pulled out my cell phone and grabbed a quick video to show a little bit of how the vgt duty cycle, EBP, and Boost react together.


The gauge is EBP and you can see boost and vgt duty cycle on the livewire. I know it sounds weird but I recommend watching it a couple of times and stare at different gauges. You just cant see them all at once :rofl:

https://www.youtube.com/watch?v=QrS-V0buGnY


Hope that helps a little bit.
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post #7 of 7 (permalink) Old 10-02-2014, 01:41 AM
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Re: Turbo to exhaust ratio EBP sensor

Great video and explanation, clears up a lot of confusion about EBP vs boost.

Brad
- '05 F250 FX4 Lariat, 147K, Alliant 48v reman FICM, Blue Spring, Glowshift Gauges (FP, EGT, Boost), and no other mods.
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