well since FL got rocked this weekend there isnt much gas left
i needed to get back to school today so i had to get some 87 .
i filled up just over .5 tank and got 200 miles on it
i usally only get 270 with a full tank

so i got about 2-3 mpg better then with 93
it pinged if i went into boost but i was on the highway so there wasnt a need to.

has anyone else noticed this?

the whole way home i was worried a srt10 was gona pull up next and i wouldnt be able to do anything . but i havent had the pleasure yet

 

only reason you got better gas mileage because you stayed out of boost

 

ive actually made myself go through a tank with out going into it before and i didnt get to much better

 

I agree! Well i guess it doesnt hurt if u keep the rpm's real low. but i dont really know.

 

The only difference in fuel is the octane rating and it's ability to avoid detonation and burn properly in it's environment. As mentioned you were staying off the power and your ECM may have read detonation that you werent even aware of and went into some conservative settings also.

I read somewhere that going 65 mph compared to 55 mph cuts your mpg by 25%. Knowing what my truck is supposed to get and what I get, this comes out about right. Even if I don't do hard launches at all on a tank of gas, I still drive fast and get poor mileage.

 

i was runnin about 85 i usally go about 80
so i dont no

my dads excursion had a power stoke in it at 55 it read 26mpg
at 65 it said 15 so i agree with that

but i was going faster then normal today

 

pull the s/c belt off (real easy) and then you should safely be able to run 87 octane.

our engines are LOW compression for the s/c. with the s'/c belt removed, you won't have to worry about detonation.

 

if u pull the s/c belt off ur adding a hellova lot of restriction. wehn the belt is on the rotors turn making air go with them, but when the rotors do not turn the air must be force AROUND them (as opposed to flowing WITH the rotors)

 

Every morning I tell myself that I won't get into boost, in order to get over the 260 - 270 miles per tank I've been getting. Then....
I leave the house! It's so hard not to, when you're driving in morning traffic and it's so easy to pass someone and take off! I drive 80 miles a day, 5 days a week. ( due to living in Fort Lauderdale and working in Miami). I wish I had a beater, but funds don't permit.

So, until I can pick up a secondary beater for daily duties, I'll try NOT to get into boost.

( Yeah, I'll believe that one as much as he TRIES to quit smoking)
- alter ego.


- Jake

 

my rotors still turn with the belt off.


Here you want to stay out of the boost:

Find your boost bypass valve. when the engine is running the valve is open (unless under negative vacuum)
The plunger on the bottom of the boost bypass is connected to a lever. when that lever comes down and touches the stop, you are making boost.

Unsrew the stop, go to the hardware store, get the same bolt, just 2" longer and put it in there.


Poof: your boost bypass valve will not close and you will never be in boost, no matter how much you floor it.

 

so is it safe to run without boost at WOT....does the computer compensate for it? or is it still dumping in extra fuel? Ive always been curious what it feels like to just run N/A.

 

Although I suspect that a change is driving habits is the correct explanation (or perhaps some measurement flaws), the higher the octane, the lower the available energy of the fuel.

Premium fuel is regular fuel with stuff added to it to keep it from exploding early. The additives do not produce power, yet displace the fuel, which does. So the additives lower the amount of power that burning the fuel can provide.

It's a small effect, but worth mentioning here.

 

Lower octane fuel actually burns FASTER than higher octane. That's why it's more prone to detonation.

This effectively INCREASES your timing and can result in higher gas mileage.

 

Do the Lightnings have an 'anti-knock' sensor like the 4.2L F150's?

I know the 4.2 will retard timing if it experiences detonation.

 

"pull the s/c belt off (real easy) and then you should safely be able to run 87 octane."

03/04 Cobra guys say running the engine with the s/c belt off can cause serious engine damage. Never understood why??? Can anyone explain?