Which Octane for new SS?

[ss4jb]

Just got my SS Friday. I was wandering which grade of gas most of you use? I know the book says 91 octane, recommended, but not required. It gets pretty hot and humid down here around Houston, I need some advice.

[trailnablaze]

Just got my SS Friday. I was wandering which grade of gas most of you use? I know the book says 91 octane, recommended, but not required. It gets pretty hot and humid down here around Houston, I need some advice.

Look through this thread. Maybe it will help. I always run 94 in mine.

http://forums.trailvoy.com/showthread.php?t=8231&highlight=Octane

[GM2376]

Just got my SS Friday. I was wandering which grade of gas most of you use? I know the book says 91 octane, recommended, but not required. It gets pretty hot and humid down here around Houston, I need some advice.

Always run at least 91 octane or else u will hear engine knock. I dont know what octane your premium is in Texas..its 93 in michigan...but dont run under that.

[vizsla1822]

The difference between 87 octane and 91 octane is about $4 a tankful. Always run at least 91 octane in your SS. Why settle for less octane and less preformance?

Vizsla1822
red jewel tintcoat SS

[ImpalaSSpeed96]

Yea, I'd just run what it says. I had the Truck for less than 2 weeks before it was programmed so I really have no choice but why run crap in a high performance motor? I personally think timing is knocked back enough to run fine on regular but what the hey, 3-4 bucks......:duh:

[MisterP]

Get your SS tuned and run 93-octane :thumbsup:

Mr. P. :)

[SuperSS27]

I run 89, and i haven't noticed a drop in performance or timing with the dashhawk.:undecided

[PROSPHOTO]

:offtopic: not about octane...but review this site to determine what gas brands you should run in your truck. This is going to be equally, if not more, important for the life of your truck than the octane :yes:

http://www.toptiergas.com/

[ScarabEpic22]

Run the highest octane you can (91 is good, 93+ is better) and use a Top-Tier gas like Shell or Chevron.

[SS Blue]

Im sure you will think Im :weird: for this, but after the first few tanks of 91, I switched to regular to see if any knock occurred, nada. I have been running regular since (now at 9100 miles) with no knocking or pinging or any noise coming from the engine but a purr.

Im sure that in some cases the better octane helps (especially if your engine does knock) but so far so good. The biggest reason I tested the lower octane regular was how many miles Im expecting to put on my SS (probably 25k a year :duh:) so that $3-$4 a tank would probably be $500 bucks a year.

Trust me though, at the first sign (or sound) of trouble, I'll switch. My point I guess is try it, if your TBSS sounds fine, it might just give you a few more bucks (especially if your wife gives you grief about the money you spend on it in the first place) to tune your SS down the road! :thumbsup:

P.S. As somewhat of a newb in the high performance V8 engines go, maybe someone can talk me out of my reasoning...aka is this "bad" for my ride? If it may be causing damaging down the road, let me know why etc...

Thanks!

[PROSPHOTO]

SS Blue,

These (and all) late model vehicles will not (under most conditions) show signs of failure (including knocking)...failure might not be the best word http://www.unixboard.de/vb3/images/smilies/sm-nachdenk.gif

What I'm trying to say is, with the PCM programming in late model vehicles, when the PCM detects a concern (like engine knocking), it will adjust the operating parameters accordingly. This will take place and you, as the driver, will never know there was a change. If 91 is recommended, and you switch to a lower octane gasoline, the PCM will retard the timing so that no spark knock will occur.

If you're filling up with a good quality, lower octane gasoline, you'll never see (or hear) any sign of trouble from using it. Your engine just won't be performing to its potential :no:

[ScarabEpic22]

SS Blue,

These (and all) late model vehicles will not (under most conditions) show signs of failure (including knocking)...failure might not be the best word http://www.unixboard.de/vb3/images/smilies/sm-nachdenk.gif

What I'm trying to say is, with the PCM programming in late model vehicles, when the PCM detects a concern (like engine knocking), it will adjust the operating parameters accordingly. This will take place and you, as the driver, will never know there was a change. If 91 is recommended, and you switch to a lower octane gasoline, the PCM will retard the timing so that no spark knock will occur.

If you're filling up with a good quality, lower octane gasoline, you'll never see (or hear) any sign of trouble from using it. Your engine just won't be performing to its potential :no:

Exactly. Perfectly worded response, and the ECM in the V8 will just pull more timing than it normally run to compensate for the lower octane. You will notice more power when running 91+, especially when tuned (in fact I dont think any tuner for the SS sets up their tunes for anything less than 91).

If 87 works for you, go ahead using it as I can understand your rational. Personally I would never run anything but 91+ in a LS2, but thats me being completely OCD and anal about my truck.

[SS Blue]

That makes sense to me. Thanks for the response. Now, will the engine notice when I switch back to the higher octane?

P.S. again sorry for the newb questions, I havent been excited (or worked on) about a vehicle since my first car (69 Camaro SS) (DOH! :duh: I wish I still had it, sold it back in the late 80's)

Thanks again!

[cvordemesche]

Even @ $3 a gallon in Cincy, I 'SHELL' out the $$ for the premium. I have accidentially put 89 in it, with no noticiable difference, but why risk it? I drove over 2K a month and it's still worth it!!!:)

[PROSPHOTO]

That makes sense to me. Thanks for the response. Now, will the engine notice when I switch back to the higher octane?

Thanks again!

Glad to help out :yes:

Yes it will, but gradually...what will happen is the PCM will adjust for the lower octane; then when you switch back to a higher octane, it slowly pushes the timing more advanced. It will run "knock" tests while you're driving the vehicle (you won't know) where it will advance the timing and "listen" for detonation. After running this test, it will adjust the timing to reflect the results.


...p.s. Under User CP, click edit profile and fill out some info for us :cool:

[TrailBlazer LS]

I'm not trying to be a smart azz. But why buy a high performance vehicle and not run higher performance fuel?

Mark.

[SS Blue]

Glad to help out :yes:

...p.s. Under User CP, click edit profile and fill out some info for us :cool:

Done!

Thanks again for your help!

[ScarabEpic22]

Glad to help out :yes:

Yes it will, but gradually...what will happen is the PCM will adjust for the lower octane; then when you switch back to a higher octane, it slowly pushes the timing more advanced. It will run "knock" tests while you're driving the vehicle (you won't know) where it will advance the timing and "listen" for detonation. After running this test, it will adjust the timing to reflect the results.


...p.s. Under User CP, click edit profile and fill out some info for us :cool:

Yes it will, it should notice pretty quickly. I know the I6 goes into re-learn mode everytime you put 5+ gal into the tank (probably like a 1/4 tank) and you can definitely feel it after that.

[CodyC6]

Do the tunes make PCM unable to retard timing as needed when lower octane is used? I know the tune I got on my other LS2 requires 93 octane and a 160 stat.

[S8ER01Z]

I'm not trying to be a smart azz. But why buy a high performance vehicle and not run higher performance fuel?

Mark.

Because if the initial ECM tune doesn't take advantage of the higher octane you are just throwing away money. Some vehicles have low enough compression and the right tune from the factory to get away with 89 octane.

[ScarabEpic22]

Do the tunes make PCM unable to retard timing as needed when lower octane is used? I know the tune I got on my other LS2 requires 93 octane and a 160 stat.

No, the ECM for the LS2 can still adjust for lower octane, however when you are tuned you will loose a lot of performance and probably get audible knock. Just dont do it and run 91+ (or whatever you can get where you live, I can only get 91 all the time and 92 occasionally).

No t-stat requirement for the SS, but I would recommend a 170F one if you decide to swap.

[RAT Raceway]

I'm Lucky! I have Sunoco on the pump right down the street! But it is $5.30 a gallon!:crazy: :weird: $50 gives you about 1/2 a tank!:laugh: :laugh:

Sure make the truck run good! You can tell a diffrance!

Ross

[SStbSS]

I also run 89 in my SS and have no problems we only have 87 89 93 by me. I used to run 93 with my diablo tune and just recently switched to 89 w/tune and it runs better/faster. its not my imagination.