Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB

- Scion FR-S / Toyota 86 GT86 General Forum (https://www.ft86club.com/forums/forumdisplay.php?f=2)

- - E85 changes exhaust tone? (https://www.ft86club.com/forums/showthread.php?t=105700)

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

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

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

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

Quote:

Originally Posted by jasonojordan (Post 2651365)

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

Yeah I run Dtuning's module (:

Sent from my SAMSUNG-SM-G870A using Tapatalk

Quote:

Originally Posted by Votlon (Post 2651152)

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

Quote:

Originally Posted by steve99 (Post 2651399)

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!

Sent from my SAMSUNG-SM-G870A using Tapatalk

Quote:

Originally Posted by Votlon (Post 2651402)

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!

Sent from my SAMSUNG-SM-G870A using Tapatalk

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.

What a cool discussion! Thanks guys.

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.

Quote:

Originally Posted by MisterSheep (Post 2651474)

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.