300GT

I'm not personally looking to run 93 gas with the stock tune instead of 87, just wondering if anyone else had heard/read this before. I think what the guy who posted it on another forum wastheorizing was that Ford tells you it's fine to run on 87 gas because they'll sell more cars that way, but the car will actually put down more power running 93. Kinda how back in the day manufacturers would understate HP so that insurance costs would be less $$$. I suppose the only way to test this theory would be to dyno the same car on 87 and 93 and see if there is a measurable difference in RWHP. Wonder if anyone has done that?

GidyupGo

Most folks don't bother with 93 until the tune. I wonder if the statement is true, and all we would have needed was to put 93 in there and the computer does the rest?

samus720

Yeah, it would be interesting to find out. I don't really see how it could make a difference, but we'll see.

howarmat

the car i am sure can adjust a little but not enough to get good gains.....remember there is alot to play with in a tune like tables and such that the stock tune will not change without the tunes that are provided by brenspeed or Bamachips

samus720

So with those tunes are you actually getting a gain of some kind (HP&TQ) over 87 or are you just able to burn the fuel without problems?

GidyupGo

I don't have a custom tune, but I will run 93 next time I fill up and if there is any change in my normal fuel economy, that would mean something is changing.

samus720

Yeah, I'm gonna run this tank empty and switch to 93 tune. I won't be able to tell much difference in the driving I'm sure. But the fuel eco numbers will speak for themselves if there's a difference.

mhconley

The OP specifically mentioned STOCK. Of course an 89, 91 or 93 octane tunewith that grade will boost performance. I was referring to stock.

I know Shell V-Power is only in their premium grade, that's why I use Chevron -they put their detergents, Techron, in all their gasoline grades.

Martin

mhconley

That would be an interesting experiment. My caronly has 400 miles on it so I think I'll let it break in a little longer before looking at fuel economy. I know I tried several tanks of 91 octane premium in my 2002 Taurus with the 3.0L Duratec 24Vand got considerably worse gas mileage. I'm talking 20% worse than it got on 87 octane -<22 vs.27+. I was quite surprised. Now if economy was what motivated me I'd have bought the Civic I test drove. I crave the V8 rumble and thrust against my back.[sm=devilgrin.gif]

When I get my CAI I'll be getting specific tunes for both 87 and 91 octane.

Martin

samus720

Well, I know that if you run a higher grade of fuel in a lower compression engine tuned for lower octane that it can cause spark plug fouling sooner. The fuel doesn't burn off completely and it probably fouls your cats as well. (Read this in owners manual for my truck[&:])