pump gas question

M87

Active Member
No question, go with Shell.
Ethanol is used to boost octane but it has less energy per unit than gas so you would have to burn more of it to make the same power.
There are a half dozen other things that make ethanol bad, and I could go into the long explanation but the simple answer is stay away from ethanol in race bikes.
Period.
 

Arctic Donkey

Active Member
If this is for the mighty SV, pump 87 from pretty much anywhere as long as it is reasonably fresh. I agree that built motors may need more octane, but as an example it took me until this last round on my built motor to equal my lap time of last year on my stock motor :( pump gas = more money for beer ;)
 

Blaknwite

Member
Thank you gentlemen for your considered and thoughtful responses. You first two should remove the red noses and big shoes at your convenience.:D
 

Blaknwite

Member
AD, the SV is mapped for 93 Octane. Considered running VP T4 or VPR but it seems that is likely of no benefit. VP promises a 2 -4% boost in HP which is miniscule. I can gain thT with a good sh*t to lighten the load or lay off the ale the night before.
 

DEFBOY35

Well-Known Member
but the ale the night before helps with the sh!t in the morning, 6 of one half a dozen of the other.
 

Arctic Donkey

Active Member
I have measured a few SVs and they all came in at ~10.8:1 (Suzuki claims 11.5:1). Removing the middle layer of the head gasket will bump it up by ~0.5 and it will still run just fine on 87. It would be a bit of a pricey exercise but it would be cool to find out the results if your bike was mapped for 87.
 

M87

Active Member
In the days before ethanol, 87 octane actually had more energy than 91/93 octane, however the higher octane gasoline allowed higher compression and, with that, higher power.
But now 87 octane MUST contain 10% ethanol by law (total sales of all grades across the country must average 5% although actual numbers are closer to 6-7%)
Oil companies LOVE ethanol for many reasons, not the least of which is that it is cheaper than gasoline.
According to their own figures, gas companies admit there is a 2% loss in power by using 10% ethanol but they say "most people won't notice". Look around their websites and you will find the data.
If you use 87 instead of ethanol free 91 you are losing around 2% and saving, what, about 20 cents a litre? Race fuel costs many times what 91 costs and still nets only 2-4%, and then only with tuning.
As far it being too small an increase to bother with, I don't know about SVs but on a 600 a $1800 exhaust only nets you 3-5% increase in power.
In fact, young Mr. Carlson's super fast 636 only makes about 10% more power than the average 600.
2% ain't much but it's all the little things put together that make a difference.
 
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Dean

Active Member
The only reason I run race fuel (VP C12) is that my compression ratio is a little high and it needs it. Otherwise, I always mapped for the lowest non-ethanol fuel I could find. I buy my fuel by the drum and the only thing that C12 gives me is very high octane ratings, which allows me to run cooler, as my engine build needs that.
 

Omerta

Member
Complicated question... mixing ethanol gives the fuel a lower energy density but higher RON octane rating. It would be very dependant on your engines characteristics whether the higher energy density or aggressively advanced timing will give you more power.
 

YZF1000jon

Well-Known Member
Esso 91 is also non-ethanol. One of the upsides of ethanol is its ability to absorb moisture and get it out of the system, good in cars, and the winter, it does absorb moisture out of the air over time, which is generally not good for race bikes. If you don't mind ethanol, Husky also has 94, but as mentioned, under 11:1 really doesn't need the higher octane. I have had Carb issues in the past with other outlets, but never with Shell or Esso 91, good clean gas from busy stations is key. Early carb'd R6s in stock trim actually made more power on regular than premium due to ignition timing, but like oil and tires, it really is a personal preference.
 

ronin26

Active Member
This. Typing this because i need more characters...

No question, go with Shell.
Ethanol is used to boost octane but it has less energy per unit than gas so you would have to burn more of it to make the same power.
There are a half dozen other things that make ethanol bad, and I could go into the long explanation but the simple answer is stay away from ethanol in race bikes.
Period.
 

ronin26

Active Member
aaaannndddd this

In the days before ethanol, 87 octane actually had more energy than 91/93 octane, however the higher octane gasoline allowed higher compression and, with that, higher power.
But now 87 octane MUST contain 10% ethanol by law (total sales of all grades across the country must average 5% although actual numbers are closer to 6-7%)
Oil companies LOVE ethanol for many reasons, not the least of which is that it is cheaper than gasoline.
According to their own figures, gas companies admit there is a 2% loss in power by using 10% ethanol but they say "most people won't notice". Look around their websites and you will find the data.
If you use 87 instead of ethanol free 91 you are losing around 2% and saving, what, about 20 cents a litre? Race fuel costs many times what 91 costs and still nets only 2-4%, and then only with tuning.
As far it being too small an increase to bother with, I don't know about SVs but on a 600 a $1800 exhaust only nets you 3-5% increase in power.
In fact, young Mr. Carlson's super fast 636 only makes about 10% more power than the average 600.
2% ain't much but it's all the little things put together that make a difference.
 

Schramm

Member
Ethanol also requires less air, something like 9:1 instead of 14.7:1. It'd be great if you had a bike tuned and built to run on pure Ethanol. Cheaper, 110 octane, and needs very little air fuel ratio.
 
Ethanol also requires less air, something like 9:1 instead of 14.7:1. It'd be great if you had a bike tuned and built to run on pure Ethanol. Cheaper, 110 octane, and needs very little air fuel ratio.

Not less air, more fuel for the same amount of air. Upgraded injectors and fuel pump are required.
 

Schramm

Member
Speaking with AFR that means the same thing. But ya if your pushing an engine to it's limits, air is going to be the limiting factor. But ethanol will make up for it's smaller LHV by the fact you can pump so much fuel into the cylinder with the same amount of air. Same principle is why we use NOS. I'd like to tune an engine one day on pure ethanol. It would be fun.
 
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