For all of the 91 Octane users...

From what I have read here, there are quite a few people that mix racing fuel with their 91 octane gas to try to avoid performance loss (timing pulled by ECU).

Has anybody gone so far as to dyno their car with and w/0 the mixing? I am curious to see just how much of a performance hit we are actually taking when we go with straight 91 octane. And, ultimately, is it worth it to spend the extra cash?

 

bump

 

I mix 5 gallons off 76's cool blue 100 octane per fill up. The gains are definately noticable when u are running 94 octane. As for what the dyno graph would be just find a stock EVO from CA on **** 91 and a dyno graph of the lucky East coast guys with 93-94 octane

Its usualy about 10-15hp difference and below boost drivability is awsome car has some ***** below 3K and boost is alot more fun as well although it is not cheap at about $4.99 a gallon but to me performance and getting the most out of my EVO is everything. But as soon as I get a Xflash I will stop using 100 as the car will run a hell of alot better with the car tuned.

just my .02 hope it helps

chris

 

If you read Vishnu's website about their original dyno runs with the evo with 91 and ten 93 you will see that a few extra octane does make a noticable difference. If you are like me and are willing to drop thousands into my car to make it faster, then why not spend an extra $7.50 per tank once in a while to enjoy a little extra go power? Plus, with my xede, I have a 93 octane map that REALLY makes a difference.

 

So what is the least amount of racing fuel do you think we can put in without a performance loss? There is a point at which we are just wasting $$$ right?

 

On a stock evo I would mix to get to 93, or 94 at most. After that, I don't think you'll get anything more out of it. Most bang for the buck at 93.

 

Referring to Unocal's Racing Fuel Mixing chart...

3 gallons of 100 octane mixed with 11 gallons of 91 octane will give us approximately 92.9 octane.

4 gallons of 100 octane with 11 gallons of 91 will yield approximately 93.4 octane.

Given that we have a 14 gallon fuel tank, a maximum of 4 gallons of 100 octane per tank seems adequate right?