E85 changes exhaust tone? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Votlon · 05-12-2016, 10:33 PM

I got some tomei uel headers and i've been running e90-80 from a local gas station for the last 5k miles. Never had a problem and love e85

I decided I should put some 91 with some detergents in the tank for the hope of cleaning a little, so I ran the tank down to e45 with 91 from shell and was just driving around a little and the car seriously sounds different!

I normally pull from any gear around 3k rpm to get around cars but at e45 I need to pull from 3.8k-ish to hit the powerband. My guess is since the headers are uel and the powerband is different, the air is colliding at different intervals in the headers making a really different exhaust note.

Just a theory but I'm gonna get a good mic and test it to find out! :p

Tcoat · 05-13-2016, 06:16 AM

Is the car tuned for E85 and you are running other mixes?

Votlon · 05-13-2016, 06:27 AM

Car is tuned for flex fuel, which could use different cam timings between 91-e85, id have to check

But i mainly run e85 only

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jasonojordan · 05-13-2016, 07:22 AM

Hopefully you have a flex fuel module that pulls timing for different fuels...

Votlon · 05-13-2016, 07:55 AM

Quote:

Originally Posted by jasonojordan

Hopefully you have a flex fuel module that pulls timing for different fuels...

Yeah I run Dtuning's module (:

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steve99 · 05-13-2016, 08:15 AM

Quote:

Originally Posted by Votlon

I got some tomei uel headers and i've been running e90-80 from a local gas station for the last 5k miles. Never had a problem and love e85

I decided I should put some 91 with some detergents in the tank for the hope of cleaning a little, so I ran the tank down to e45 with 91 from shell and was just driving around a little and the car seriously sounds different!

I normally pull from any gear around 3k rpm to get around cars but at e45 I need to pull from 3.8k-ish to hit the powerband. My guess is since the headers are uel and the powerband is different, the air is colliding at different intervals in the headers making a really different exhaust note.

Just a theory but I'm gonna get a good mic and test it to find out! :p

As the flex fuel sensor detects lower content of ethanol it signals the ecu. The ecu then adjusts the fueling and ignition timing for the new ethanol content. The difference in ignition timing from petrol to E85 can be up to 10 degrees or so. This is likely to change the exhaist note as well as the power and torque charasteristics of the engine. some tunes may also adjust the intake and exhaiust cam timing as well and boost levels on turbos

Votlon · 05-13-2016, 08:17 AM

Quote:

Originally Posted by steve99

As the flex fuel sensor detects lower content of ethanol it signals the ecu. The ecu the adjusts the fueling and ignition timing for the new ethanol content. The difference in ignition timing from petrol to E85 can be up to 10 degrees or so. This is likely to change the exhaist note as well as the power and torque charasteristics of the engine

Yeah thats that i was thinking too,
But the question of the day is will it be louder! :p we will find out tomorrow or today I guess I dont sleep enough!

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Tcoat · 05-13-2016, 08:35 AM

Quote:

Originally Posted by Votlon

Yeah thats that i was thinking too,
But the question of the day is will it be louder! :p we will find out tomorrow or today I guess I dont sleep enough!

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May not be "louder" but will have a different tone and resonance which could be perceived as loud. The actual volume probably doesn't change much.

babydriver · 05-13-2016, 09:57 AM

What a cool discussion! Thanks guys.

MisterSheep · 05-13-2016, 10:21 AM

Personally, while on E85 both I and my GF had noticed the exhaust tone become more refined yet even maybe a little quieter. I think the tune is why this happens.

clayrush · 05-13-2016, 11:34 PM

Quote:

Originally Posted by MisterSheep

Personally, while on E85 both I and my GF had noticed the exhaust tone become more refined yet even maybe a little quieter. I think the tune is why this happens.

LOL. My girlfriends car is opposite. At least with the supercharger.

05-12-2016, 10:33 PM	#1
Votlon Senior Member Join Date: Sep 2015 Drives: Scion FRS \|\| Ducati 899 Location: Long beach, CA Posts: 105 Thanks: 29 Thanked 31 Times in 23 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	E85 changes exhaust tone? I got some tomei uel headers and i've been running e90-80 from a local gas station for the last 5k miles. Never had a problem and love e85 I decided I should put some 91 with some detergents in the tank for the hope of cleaning a little, so I ran the tank down to e45 with 91 from shell and was just driving around a little and the car seriously sounds different! I normally pull from any gear around 3k rpm to get around cars but at e45 I need to pull from 3.8k-ish to hit the powerband. My guess is since the headers are uel and the powerband is different, the air is colliding at different intervals in the headers making a really different exhaust note. Just a theory but I'm gonna get a good mic and test it to find out! :p

05-13-2016, 06:16 AM	#2
Tcoat Senior Member Join Date: Jul 2014 Drives: 2020 Hakone Location: London, Ont Posts: 69,845 Thanks: 61,656 Thanked 108,286 Times in 46,456 Posts Mentioned: 2495 Post(s) Tagged: 50 Thread(s)	Is the car tuned for E85 and you are running other mixes? __________________ Racecar spelled backwards is Racecar, because Racecar.

05-13-2016, 09:57 AM	#9
babydriver Hit the road and I'm gone Join Date: Oct 2014 Drives: 2015 FR-S Burnt Orange (Hot Lava) Location: Austin, TX Posts: 1,844 Thanks: 733 Thanked 1,786 Times in 973 Posts Mentioned: 10 Post(s) Tagged: 2 Thread(s)	What a cool discussion! Thanks guys. __________________ Slip, slidin' away.

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05-13-2016, 06:27 AM	#3
Votlon Senior Member Join Date: Sep 2015 Drives: Scion FRS \|\| Ducati 899 Location: Long beach, CA Posts: 105 Thanks: 29 Thanked 31 Times in 23 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Car is tuned for flex fuel, which could use different cam timings between 91-e85, id have to check But i mainly run e85 only Sent from my SAMSUNG-SM-G870A using Tapatalk

05-13-2016, 07:22 AM	#4
jasonojordan Senior Member Join Date: Jul 2013 Drives: 2013 satin white brz limited Location: Cottage Grove MN Posts: 1,049 Thanks: 162 Thanked 511 Times in 326 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	Hopefully you have a flex fuel module that pulls timing for different fuels...

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