100 Octane on Tune Motor
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Super Member
Joined: Mar 2016
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From: Los Angeles
2006 E55 AMG
100 Octane on Tune Motor
Now I dont have a specific tune for 100 Octane but Im dyno tuned for 91 Octane here in cali. I have used 3 gallons of 100 VP with the rest of the tank being 91 and didnt really notice any difference, wasn't really expecting much anyway especially with 3 gallons. Have you guys noticed if you have a tune not for higher octane have you guys gained any power or picked up any at the track as far as e.t or mph. Does the car run any better. My tuner said I can run higher octane there should be room for the ecu to adjust since now its not stock and I think he's reasoning is he left room on the table for timing to adjust. You guys think its worth adding 5-6 gallons to rest of tank being 91?. I've read a bunch of posts on just using 91 with stock tune and specific higher octane tune but nothing that i can find if you are tuned for 91 do tuners leave room on the table for higher octane use. Just in case my sig doesn't show its HD Tuned, BMC Filters and thats it as far as mods. Just purchased a PLM Heat Exchanger.
Last edited by karpetcm; May 1, 2020 at 04:10 PM.
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Joined: May 2010
Posts: 1,227
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From: Chicago
E63 SL55 996TT C5Z06
My understanding is adding five or 6 gallons 100 Octane won’t really offer that much more power, May increase a little bit but not like it would if you were tune for it Which I heard yields around 640-650 max whp but don’t quote me
Some guys who have tunes and issues with occasional misfires have found adding four or 5 gallons of 100 Octane reduces the misfires with the addition of the higher octane that helps reduce knock.
Some guys who have tunes and issues with occasional misfires have found adding four or 5 gallons of 100 Octane reduces the misfires with the addition of the higher octane that helps reduce knock.
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Joined: Jun 2004
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2014 E63S; AMS 100 octane ECU dyno tune; EDOK TCU tune; BB intakes; sprintbooster
My understanding is adding five or 6 gallons 100 Octane won’t really offer that much more power, May increase a little bit but not like it would if you were tune for it Which I heard yields around 640-650 max whp but don’t quote me
Some guys who have tunes and issues with occasional misfires have found adding four or 5 gallons of 100 Octane reduces the misfires with the addition of the higher octane that helps reduce knock.
Some guys who have tunes and issues with occasional misfires have found adding four or 5 gallons of 100 Octane reduces the misfires with the addition of the higher octane that helps reduce knock.
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Joined: Apr 2023
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C43 AMG
Hello everyone,
Sorry to bump this old topic but I have found this very helpful thread (and forum) with Google and I wanted to ask for expert opinions.
I am living in France and own a C43 AMG from end 2018 (390HP engine). The fuel has become very expensive, 90% of the price is Government taxes that are killing us and this is the reason why I am thinking about going for an engine tune to be able to have Flex Fuel : regular gas which is called SP98 here and Ethanol which is E85. The tune cost around 400$ and it does not increase the engine power, only allow to use Ethanol as fuel.
The fact of the matter is that is quite complicated to get the truth about E85 here because it seems like Government does not want to see many people switch to a cheaper option. Thus, I wanted to check with MB owners from other countries with eventually non biaised point of views.
Therefore my question is, is it risky for my engine to do such thing ? I am also considering doing 70% E85 and 30% regular Gas eventually, I will never try it without going through a reprog first.
Thanks in advance
Sorry to bump this old topic but I have found this very helpful thread (and forum) with Google and I wanted to ask for expert opinions.
I am living in France and own a C43 AMG from end 2018 (390HP engine). The fuel has become very expensive, 90% of the price is Government taxes that are killing us and this is the reason why I am thinking about going for an engine tune to be able to have Flex Fuel : regular gas which is called SP98 here and Ethanol which is E85. The tune cost around 400$ and it does not increase the engine power, only allow to use Ethanol as fuel.
The fact of the matter is that is quite complicated to get the truth about E85 here because it seems like Government does not want to see many people switch to a cheaper option. Thus, I wanted to check with MB owners from other countries with eventually non biaised point of views.
Therefore my question is, is it risky for my engine to do such thing ? I am also considering doing 70% E85 and 30% regular Gas eventually, I will never try it without going through a reprog first.
Thanks in advance
Super Member
Joined: Aug 2004
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E550 Coupe 2wd (2016)
I'm mixing my gas with E85 to net 50-55% ethanol. I also have 91 & 100 octane tunes. The 91 tune uses the oem spark timing, which is too much for 91 so it pings and pulls timing.
Adding ~25% eth stopped the ping so it made a nice bit more power. Its not so much the retard that hurt power, but the ecu pulls boost when theres that much ping/retard.
Now that Im at 50% I can not only bump timing, I can exceed the timing in the 100 tune.
It is not a flex fuel car, and is all stock except the tuning I did. I dont use the tune I bought.
So for me the ethanol is nice, but I can also run 91 and retard the timing so it doesnt pull boost. Fyi, for what its worth
Adding ~25% eth stopped the ping so it made a nice bit more power. Its not so much the retard that hurt power, but the ecu pulls boost when theres that much ping/retard.
Now that Im at 50% I can not only bump timing, I can exceed the timing in the 100 tune.
It is not a flex fuel car, and is all stock except the tuning I did. I dont use the tune I bought.
So for me the ethanol is nice, but I can also run 91 and retard the timing so it doesnt pull boost. Fyi, for what its worth
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Joined: Apr 2021
Posts: 846
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From: San Jose, CA
11 E550, 16 AMG GTS, 13 S550
100 is protection it won't increase power because it's not an oxygenated fuel it doesn't actually have more energy in it nor are you burning more of it.
If your tune is for 91 and your timing is conservative to daily drive and you don't have any knock then 100oct is just extra protection in case your EGT's start climbing due to ambient or charge temp. You'd need to specifically run a 100 octane tune which has more timing in it. Timing is secondary to boost anyway, a bad fuel/spark tune is a lot more harmful even if youre not chasing numbers.
If your tune is for 91 and your timing is conservative to daily drive and you don't have any knock then 100oct is just extra protection in case your EGT's start climbing due to ambient or charge temp. You'd need to specifically run a 100 octane tune which has more timing in it. Timing is secondary to boost anyway, a bad fuel/spark tune is a lot more harmful even if youre not chasing numbers.
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Purchase Amsoil at 25% off from me
Chris Tran, Retired Alpha European Autotech Owner
Amsoil Independent Dealer #7236674
