Gas premium 93 octane??? that sucks

[JensNonsens]

hi,

is 93 octane the highest you can get at a gas station here in Amerika?? I m not sure if that really is good for the motor. I didnt have the chance to check out a shell gas station for the Vpower...

anyways, 93 octane is the lowest octane gas you can get in germany, the next step is called "super" with 95 octane and "super plus" with 98 octane. But you can also get 100 Octane like the shell Vpower or Aral.


What do you guys use in your big bore engines???

Thanks.

 

[Frosty]

RU talkin about pump gas... where I live in NY the HIGHEST octane available at the pump is 93... we have 89, 91 and 93 only.

I run 93 octane, but do not have more than 180 psi compression.

 

[guiness92]

the sunoco in nj carries 94 octane which most of us run, there is also an airport here that sells av gas fairly cheap.

 

[MADMAT]

Sunoco 94 is the highest in Ohio, other than race gas at a couple of places. I think that is 110 octane.

 

[douglee25]

180 psi will even tolerate 89 octane with stock timing. What kind of compression are you running?

Doug

 

[nikad58]

180 psi will even tolerate 89 octane with stock timing. What kind of compression are you running?

Doug

:bigeyes: 91 octane out here is the best we have..

 

[Freestyleriverrat]

I know at S&S powersports across the river in Indiana they sell VP race gas for something like 50 bucks for 5 gallons :bigeyes: I run 93 octane in my ski though......I'll take convenience over performance. If they sold 100 octane at the station I would be all over that.

 

[sflsurfrider]

I know at S&S powersports across the river in Indiana they sell VP race gas for something like 50 bucks for 5 gallons :bigeyes: I run 93 octane in my ski though......I'll take convenience over performance. If they sold 100 octane at the station I would be all over that.

higher octane doesnt make your ski perform better.

 

[gj_fx1]

The numbers may not be the same. In the US the num on the pump is an average of research and motor octane. I'd think if 93 is the lowest in europe they are likely using a different system.

 

[douglee25]

higher octane doesnt make your ski perform better.

Exactly. You only need enough octane to prevent detonation. If you run more octane than you need, you're just wasting money.

Edit: In fact, using higher octane than what is actually needed will cause deposits in your engine to form. Higher octane also requires a greater ignition temperature to burn which, in turn makes your engine run hotter.

Doug

 

[Frosty]

Exactly. You only need enough octane to prevent detonation. If you run more octane than you need, you're just wasting money.

Doug

Is there an easy way to calculate what octane requirements you need for a particular set up?

I just changed over to 35cc domes with a freeride ported cylinder, std bore 701, stock 38mm carbs, FPP-wet pipe, OEM timing. Planning to stick with 93 octane... should be fine, but was concerned about WOT runs...

 

[sflsurfrider]

Exactly. You only need enough octane to prevent detonation. If you run more octane than you need, you're just wasting money.

Edit: In fact, using higher octane than what is actually needed will cause deposits in your engine to form. Higher octane also requires a greater ignition temperature to burn which, in turn makes your engine run hotter.

Doug

if the ignition is kept stock, the engine will run cooler on a higher octane fuel.

 

[JensNonsens]

higher octane doesnt make your ski perform better.

I dont think thats right, of course you wont add a lot of hp, but the combustion sure will be more smooth and cleaner. actually the octane number is a reference value of anti-knock properties.

I dont know how much psi; the motor has ~ 940 ccm.

The system must be the same. But with increasing gasprices and smaller motors that they ll have to build here in the us, I think you will reach those ocatane figures soon :biggrin:

@JrMagoos, what do you recommend??

 

[Freestyleriverrat]

higher octane doesnt make your ski perform better.

True but it allows you to run higher compression which will give you more hp/torque. Plus the race gas or aviation fuel does not have all the addatives like pump gas and should burn cleaner, hotter and smoother/faster. Plus it smells better :crazy:

 

[Matt_E]

Jens, real quick: The fuel quality here and in Europe is almost identical. Here, an average of Research Octane (RON) and Motor Octane (MON) is used. In Europe, only the higher RON (but less meaningful than MON) is used.

 

[yamaslut]

Jens, real quick: The fuel quality here and in Europe is almost identical. Here, an average of Research Octane (RON) and Motor Octane (MON) is used. In Europe, only the higher RON (but less meaningful than MON) is used.

yeah.... my car says 95 RON and it runs great on 93 MON
Audi A4 30V v6

 

[Jr.]

I dont think thats right, of course you wont add a lot of hp, but the combustion sure will be more smooth and cleaner. actually the octane number is a reference value of anti-knock properties.

I dont know how much psi; the motor has ~ 940 ccm.

The system must be the same. But with increasing gasprices and smaller motors that they ll have to build here in the us, I think you will reach those ocatane figures soon :biggrin:

@JrMagoos, what do you recommend??

In simple terms, the higher octain will control the burn rate of the fuel. basicly slowing it down. A given motor with high compression & agressivly advanced timing reguires a slow burn fuel (high octain) so detonation doesn't take place. if you were to run regular fuel in this type motor, a flash burn would occur & you would surely burn down the motor
the key to building a high output motor is to creat as high a BTU burn output without detonating. a combination of compression, timing advance, squish rate, fuel used, are all key factors. obviously, there is lots more to it. this is just to give you the idea

Jens, Give me the basics of your motor & I'll try to get you a good fuel to use while you are here. as was noted, AVGAS is a good otion for you. it is 100LL & can be purchased at most regional airports

ski ya, Paul

 

[thrllskr]

So basically if some us are still running stock motors, we should be ok with the new gas the stations here in NJ are getting. Should we be getting 93 octane now instead of 89?

 

[douglee25]

if the ignition is kept stock, the engine will run cooler on a higher octane fuel.

Are you talking about the physical engine temperature or flame temperature? If you're talking about flame temperature, you are incorrect. Higher octane fuel requires more energy to burn which will lead to greater combustion temperatures.

Doug

 

[douglee25]

In simple terms, the higher octain will control the burn rate of the fuel. basicly slowing it down. A given motor with high compression & agressivly advanced timing reguires a slow burn fuel (high octain) so detonation doesn't take place. if you were to run regular fuel in this type motor, a flash burn would occur & you would surely burn down the motor
the key to building a high output motor is to creat as high a BTU burn output without detonating. a combination of compression, timing advance, squish rate, fuel used, are all key factors. obviously, there is lots more to it. this is just to give you the idea

Exactly. The greater the octane number, the less chance chance of preignition. This is because the energy required to ignite say 93 octane vs. 87 octane is much greater. An engine with more deposits in the combustion chamber will also tend to preignite, detonate, etc easier than a clean engine due to these hot spots retaining heat and in turn lighting the fuel/air mixture.

Doug