Ethanol/Exhaust Question

butt_yodel · Mar 2, 2023

I am running ZFG 93, noticing a huge difference in exhaust burble behavior with E30 in the tank. Not overly concerned about it, just wondering why the E30 makes so much more noise at parking lot speeds. A full tank of 93 (E10) hardly burbles at all.

Bonus question: any technical reason to avoid crappy E-85 gas (actually measures E70), as long as I’m accounting for the difference for my E30 mixture?

edit: I have FenFab catted DPs and the Thermal 3”.

UNBROKEN · Mar 2, 2023

Don’t know about the exhaust note but as long as you blend E30 is doesn’t matter if it’s starting as E85 or anything else as long as you wind up at 30.

TMac · Mar 2, 2023

I have no idea what your idea of "exhaust burble behavior" is. But at "parking lot speeds" (which I assume is low speed operation at partial throttle), I simply can not envision any possible reason that the sound would be different.

butt_yodel · Mar 2, 2023

I just mean that it’s generally louder, tends to pop and crackle more. “Low speed operation at partial throttle” is pretty dead on. It’s super loud primarily after switching, then seems to settle down. Wondering if maybe the ECU is adjusting. Or maybe I’m making shit up. No difference in regular driving, other than the ridiculous power bump
Thanks to both

TMac · Mar 2, 2023

I'm not saying you're making s... up. I just can't figure out any logical or mechanical reason you would be hearing "pop and crackle" at low speeds. And, the ECU is not "adjusting", at least not in those ways. Assuming you're correct in your hearing, it would have to be something else. Are you getting gas from a different station? The only possibility I can see is possibly water (which bonds to ethanol) in enough quantities to cause that sort of behavior.

butt_yodel · Mar 2, 2023

Will ethanol typically fill up a catch can quicker? I almost overfilled mine after having been used to running regular 93. The contents of the catch can was a lot more viscous, almost like there was water in it. For the first 10,000 miles it was more like a thick chocolate milk. Could very well just be some bad fuel I'm getting at this station.

Edit: Some googling revealed some research papers mentioning differences in exhaust note when blending ethanol. Kinda interesting https://www.uotechnology.edu.iq/tec_magaz/volum292011/No.7.2011/text/Text (16).pdf

TMac · Mar 2, 2023

I read through the info you provided in your link as I have hundreds of other SAE papers on similar subjects. And when you post about "catch can" issues, I'm betting your ethanol has in some form been contaminated by water.

If you read through the paper it also says " It is noted that the noise level emission depends on the engine operating condition rather than the ethanol content."

This means that due to the flame speed of ethanol it can have an increased decibel level given certain conditions, (under load), but it doesn't make any sense that it would be "louder" under "parking lot speeds" unless there were other factors.

But thanks for supplying the information.

butt_yodel · Mar 2, 2023

Glad this Explorer community has people smarter than me, lol. Thanks for the good info as always

Big Turk · Mar 2, 2023

I can testify that my ST does a little snap, crackle, and popping when it is first started for about 30 seconds, then it settles down.

Big Turk · Mar 2, 2023

And I only run ethanol free gas.

TMac · Mar 3, 2023

Big Turk said:

First thing I would look for is small exhaust leak that goes away as the exhaust system tightens up as it warms up.

Big Turk · Mar 3, 2023

TMac said:

Thanks for the reply. It has done it from new (September 2020) and has not worsened over time. I just thought it was normal for a little fuel to get through while it warmed up. I will have to put it on ramps and observe a cold start from below.

mycbtech · Mar 3, 2023

I would say that after mixing E with my 91 tune up to E30 as well as moving to E50 I too will hear a slight difference in the exhaust note. Also if accerating then abruptly letting off the gas (say in first gear accel to 3000 RPMs then let off) there can be a pop which I would assume would be excess fuel not being burnt then hitting the cat.

DetroitST · Mar 3, 2023

I'm on straight e85 and I've never heard any kind of snap, crackle, or pop. Sounds like an exhaust leak.

mycbtech · Mar 3, 2023

DetroitST said:

eh, probably not. sound is not consistant as an exhaust leak and is intermittent. If it was an exhaust leak it would be repeatable.

UNBROKEN · Mar 3, 2023

Mine does it also…the burbles and pops are definitely more prevalent with E30 on a 93 tune or the E50 tune over a straight 93 tune. Mostly when letting off the throttle after some low speed, steady state driving.
And I can assure everyone it’s not an exhaust leak.

butt_yodel · Mar 3, 2023

Just threw in some E85 to top off my tank. Pops are back. I can live with em

twin001 · May 22, 2023

Big Turk said:

Ethanol is actually GOOD for FI or high compression engines. The days of elastomers not being compatible with ethanol are gone, so no need to worry about that. You will see a slight drop in fuel economy with ethanol as it is less energy dense, so the ECU commands the system to flow more. However, it is a bit cheaper so your fuel costs will offset. The biggest reason to use ethanol in our turbocharged Ecoboost is for the knock benefits. Your ECU won't pull timing at the top end and it is definitely noticeable! Highway on-ramps are much more fun, unless you have a Prius in front of you.

Stone17 · May 23, 2023

Do you still need to change your engine oil more frequently when running E50 or E85?

TMac · May 23, 2023

Stone17 said:

There are numerous academic studies available online which address this situation. The consensus is that higher amounts of ethanol do contribute to higher ring and bore wear. So, it's probably not a bad idea to change your oil more often.

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Ethanol/Exhaust Question

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