tws1098

would i be wasting my time by using sniper to tune my car for 93 octane with no real performance mods? currently it is tuned for 87 with snipers conservative tune.

99GTvert

You should see a gain with the higher octane tune. How long does it take to make a tune? I don't think it would be wasteful, however on a near stock car, going from 87 to 93 tune isn't going to be a night and day difference.

tws1098

it doesnt take long, but i figured if you guys said it was a waste of money running high test i wouldn't bother.

H0SS302

you will get a bump in power with the 93 octane tune, not much but you will get 5-10 easy.

MJH78

so you already have the sniper? why not just try it and see...

cliffyk

The SF 87, 91, and 93 octane tunes are identical in every way--they create the same base tune with global timing bumped by 2° (scalar Global Spark Adder), and the range based timings bumped by 1.5° to 2° (in the Spark Borderline table, based on load and rpm)--these are safe numbers because the OEM tune is so pathetic.

The reasons for these all being the same are lawyers, and that the manufacturer (all, not just Sniper) of the tuning software has NO control over what octane fuel you are actually running, or whether you have run at least 3/4 tanks of 91 or 93 through before making the changes.

If you are really running 91 octane you can add 1.5° to the global spark modifier (on top of the SF base tune), and 1.0° to 1.5° to the range based spark modifiers. If running 93 you can add 2.0° to 2.5° to the global and 1.5° to 2.0° to the range based settings.

I run +2.5° for the global adder, and +2.5° for the higher load borderline settings--this is with 93 octane, a 180°F thermostat, and running 12.5:1 AFR (a bit richer than many recommend) at WOT.


Do NOT mess with the fuel settings unless you have a wide band O2 system.

H0SS302

I guess I should have mentioned that.. AFTER you add timing to the tune, ping it then knock it down some, thats where your power will come from. The Special Forces package is all end user based. You have to make the changes to the tune to get results.

cliffyk

+1000, that's what makes it so great for those who want to really tune their cars, as opposed to those who want to load a tune into their car...

tws1098

I have had the program for a little while, but have not messed with much of what you are talking about. I appreciate the good information and will start tinkering with it soon. Is it true that with a better tune it is possible to actually get better gas mileage when bumping up to 91 or 93 octane?

cliffyk

Just changing the octane selection will change nothing. This is true for most, perhaps all, handheld tuners for the liability concerns I stated above.

As to fuel economy, and in particular "Is it true that with a better tune it is possible to actually get better gas mileage when bumping up to 91 or 93 octane?"... No/maybe.

In general aftermarket tunes will not improve it or make it worse--after all, fuel economy was the primary goal of the generally terrible OEM tune.

A tweaked premium fuel tune (again as described above) will probably make the added cost (a piddly $1 to $2 a tank full) a break-even proposition. However all things being equal more power = more fuel...

I run a tweaked 93 octane tune, pay a whopping $0.20 a gallon more ($3.00 more for a dead empty tank) for fuel, and generally don't give a rat's back-end about it.

Hell, I spend about that for each beer at the local pub--you need to get your priorities straight...