Noob question

syko says

Active member
i dont think youd want to try 87 oct with a 3sgte.. knocking can occur. higher octane reduces knock/detonation/pinging (all the same thing iirc).


PS. yes i know gas prices hurt me too. + my mpg is pretty horrible :D
 

syko says

Active member
im not too sure as to how it would react if you just put it in and not boost. boosting with 87 may cause knocking (because of the higher temps of the engine). :shrug: maybe someone can clarify this.
 

Gary

Moderator
Pro: cheap
Cons: poor performance, ecu retards timing, one good knock can foul stock knock sensor (a new one is not cheap) and 2 worst case scenarios are blown HG and damaged internals.
 

toayoztan

Moderator
Also, look at it this way:

the difference between 91 and 87 octane is usually around 20 cents

20 cents on a complete full tank of 18 gallons saves you $3.60

let's say gas is 2.50 per gallon, that means 3.60 will give you 1.44 extra gallons.

1.44 extra gallons let's say at 20mpg on the alltrac gives you 28.8 miles

So...do you reallly want to risk your engine for an extra 30 miles? To some, that lasts an extra couple days, to others that isn't much at all (it's all relative).

Or, you can look at it more general. From the math given above, you gain an extra 1.6 miles for every gallon you purchase of 87 vs 91. That isn't much in the short run.

I wouldn't risk it for 30 miles :wink:

Bryan
 

syko says

Active member
toayoztan":1cj0umiy said:
Also, look at it this way:

the difference between 91 and 87 octane is usually around 20 cents

20 cents on a complete full tank of 18 gallons saves you $3.60

let's say gas is 2.50 per gallon, that means 3.60 will give you 1.44 extra gallons.

1.44 extra gallons let's say at 20mpg on the alltrac gives you 28.8 miles

So...do you reallly want to risk your engine for an extra 30 miles? To some, that lasts an extra couple days, to others that isn't much at all (it's all relative).

Or, you can look at it more general. From the math given above, you gain an extra 1.6 miles for every gallon you purchase of 87 vs 91. That isn't much in the short run.

I wouldn't risk it for 30 miles :wink:

Bryan

VERY well said bryan. the moral of the story is: we have 18 gallon tanks? i thought it was 16? :shrug: the other moral of the story is: wow, you guys pay cheap for gas :D (i pay around $3.15). naw but you get the point :wink:
 

toayoztan

Moderator
Thanks, but i could go further! At 3.15/gallon, that's even less miles you get through "savings" of the 87 vs 91.

But we can look into this even further. Our cars (given mpg and tank size) is geared around 340-400 miles on a tank (depending on car condition and driving habits).

Let's say we do get only 30 miles (again, depending on car condition and driving habits) extra choosing 87 over 91. That's only roughly 8-10% increase in gas mileage.

It's all relative, but 8% to me does not justify risking my engine for the things Gary mentioned.

And guys, if we were THAT worried about gas mileage, how much to pay for gas, etc, then we shouldn't (and probably half of us wouldn't) have bought an alltrac :wink:

Bryan
 

Gary

Moderator
toayoztan":2691l3mu said:
And guys, if we were THAT worried about gas mileage, how much to pay for gas, etc, then we shouldn't (and probably half of us wouldn't) have bought an alltrac :wink:
QFT
 

theUNYTEDone

Moderator
i thought our tanks are 13gal?

also, at gary: what's QFT?

quite fricken true? :lol: :D

honestly...gas mileage isnt TOO bad unless youre comparing a big block chevy engine to a civic.

anything AROUND 20mpg to me is pretty good. maybe not if you commute long distances, but in that case...get a civic!
 

toayoztan

Moderator
theUNYTEDone":2sxdddnz said:
i thought our tanks are 13gal?

also, at gary: what's QFT?

quite fricken true? :lol: :D

honestly...gas mileage isnt TOO bad unless youre comparing a big block chevy engine to a civic.

anything AROUND 20mpg to me is pretty good. maybe not if you commute long distances, but in that case...get a civic!

What makes you ever think we had a 13 gallon tank? That's a little more off than thinking we had a 16 gallon tank.

Do you not let your gas tank run close to E, and then fill up a full tank? Just curious, because some people don't let it get that near empty.

Bryan
 

___Scott___

Active member
The OP has an ST165 which has a 15.9 gallon tank. I don know what size an ST185 has, but since it's heavier I would expect it to be bigger.
 

SuperWhite92

New member
___Scott___":3ajkstwz said:
The OP has an ST165 which has a 15.9 gallon tank. I don know what size an ST185 has, but since it's heavier I would expect it to be bigger.

18 gallons, 16ish before the fuel light comes on
 

theUNYTEDone

Moderator
toayoztan":3kpvkkp2 said:
What makes you ever think we had a 13 gallon tank? That's a little more off than thinking we had a 16 gallon tank.

Do you not let your gas tank run close to E, and then fill up a full tank? Just curious, because some people don't let it get that near empty.

Bryan

actually brian, my gauge is off. i'll fill up and drive about 1 mile, and it reads 1/2 tanks. at about 10 miles im back on Echo.

sorry about the 13Gal...thought i read it somewhere.
the most i ever fill up is about 6 gallons at a time.
 

db

Active member
SuperWhite92":264zqt20 said:
syko says":264zqt20 said:
so does that mean we have 2 gallons of 'reserve gas'?

Yes, if not more. I have gone 55 miles with the gas light on constantly.

My fuel light comes on with about 4 gallons left (14 used up). I got 375 miles on a tank once, with the light illuminating at about 300 miles. I was in a rural part of North Dakota at 2 am, and they don't have gas stations open all night, nor pay at the pump.
 

toayoztan

Moderator
One rule of thumb used for when the gas light comes on is when you have about 1/8 of a tank of gas left.

For 18 gallons, that makes it about 2.25 gallons, which seemed to coincide with the way my car works (and from what Shaun said about 2 gallons left in reserve).

Bryan
 
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