ok so what's the difference when you feed the evo 94,93,91? I'm not going to even to to 89 or 87.
Is there a noticable difference? What exactly is the difference when it comes to the performance?

 

Sunono 94...because I can

 

I can to, I'm just woundering if there is a difference and what they are.

 

I'm not aware of any 94 around here... I've gone to Sunoco's and they all have 93... I'd like 94.. Just because you can...!!

 

I live in California and I'm thinking of buying a EVO. But I have heard rumors that the lame 91 octane gas with all the environmentally friendly additives will make the EVO put out a lot less hp. Is this true?

 

lets stay on topic!

difference when you feed the evo 94,93,91?

 

I'm no expert, but generally the higher octane gas will reduce the chances of knocking. Because the hydrocarbons are structured differntly (more compact, less surface area) it takes more to make them detonate. So, if you're running considerable levels of boost (which even a stock evo is) the higher the octane, the less likely you'll get premature combustion. That's all I can tell you from my limited car/chemistry experience.

 

thanks, how about performance wise, like horsepower and etc?

 

I have no 94 or higher so I use 93, but the higher the better why just is. Use octane boost if you do not have 93 or better.

 

I suspect it is putting out less hp. Mitsu claims 271 hp when using 98 RON gas, CA AZ CO etc don't have 98 RON gas. Using the formula (RON+MON)/2 and a sensitivity to knock of 10 you get :

(96 RON + 86 MON)/2 = 182/2 = 91 (RON+MON)/2

So just singling out the RON number CA AZ CO are at 96 RON.

We're still waiting to here whether shiv's low wheel hp figures for the Evo ( ~180 whp ) are due to sick evo's or sick gas or the again something else

 

Unless I'm mistaken you're not going to see any gains in HP due to gasoline. As zx6r indicated, bad gasoline or lower octane levels that cause knocking will reduce your performance, but it doesn't seem like to me that having higher octane gasoline is going to net you any gains over factory specs. People run higher octane gasolines through performance engines to counteract the knocking caused by high engine temps and compression.

 

But that was the point of my post. The factory spec is 98 RON. In CA,CO,AZ etc the best we can get without to mixing in 100 racing gas is 96 RON. So everytime we fill up we're giving the engine below spec fuel and it's gonna make adjustments to compensate ( dare say I less power, fuel economy etc ).

 

I know, I was simply pointing out that it's not likely that you'll see any gains by using higher octane gasoline. I agree completely with your statements about seeing a decline in performance due to weaker than needed gasoline.

 

91 But only because I have to

 

I am in Las Vegas =91. I just tried running a tank with 2 1/2 gal of 100 race gas mixed in and it definately makes a difference in power in 5k-7k rpm range.