Unless GM did something stupid, the "premium required" is to get the max boost and minimal knock retard so you get your money's worth from the cost of the kit. 85 wouldn't hurt the engine but it would be pulling so much timing it you might was well just bypass the turbo!

I ran 87 in my GTO several times and you could feel it pull timing and soften up. For $.20 x 16 or $3.20 per tank, I will run premium (91 around here so I have no idea if it will still pull timing).

On a side note since GM is pretty aggressive in pulling timing (they pull it fast and return it slow and tend to overshoot), it's too bad we can't play with the Stage I calibrations to make the timing tables match the available octane. I would rather reduce the timing tables and not get into pulling it out in the first place.

Alas, we can't unless we want to toss the the whole warranty which I believe is half the cost of the Stage 1 kit (insurance policy for GM for repairs).

If you are worried about resale due to "Premium Required", tell the owner you will swap the two map sensors out and reflash it to stock. You can always sell the 3 BAR map sensors to someone out of warranty and let them flash the PCM with whatever they want. The 3 BAR map sensors and connectors are worth something.

 

The answer may be obvious, but being no genius... Will a stock SS get better mileage with the reduced power of using the lower octane?

 

No. In fact, it may be worse since it is designed to use premium for optimal power and efficiency. In reality I believe most here that have tried it say the economy is pretty much unchanged between regular and premium(on a stock car).

 

Pre-stage gas was 87, mostly...used 91/93 and so no significant change in milage, the main reason for the 87 was, this was when prices went thru the roof, glad I had the option. Post stage, 91/93 only..no change in milage....Ive towed, hauled,empty runs, time restrictive and leasure runs...milage is pretty good. To pis off the 2.4 guys....I can do 120 and pull 15 mpg consistantly....I can do 35 and 70 and get the same each time..30+.... Its good to have power...just takes dicipline to control it....
On 87 pre-stage the power was still good for a 2.0, but after stage, no comparison!

 

Hello, First post here. Picked up my black '08 SS last week with 15k miles. Want to know if anyone has had the Stage 1 installed in or around the Greensboro, NC area? I don't want to take it to a dealer that's not experienced with the install....Thanks

 

Octaine and rating has nothing to so with mileage. It just lets the engine run the higher boost and timing to make more power. It has no effect on MPG at all.

By not getting the better timing and more boost it just kills about 20 HP with no gain in MPG.

Now with the Turbo Upgrade kit you will see a 1-2 MPG gain. GM said it was unexpected and feel it happens because the SS gets up to speed faster and you are off the gas sooner.

When you are off the gas in a SS it shuts the fuel off so it will improve the MPG.

THis was explained to me by the engineer who lead the group that did the Upgrade kit.

 

I am very pleased with the upgrade but did not see an increase in my MPG. Actually, it dropped by a couple 2-3 MPG, not driving it hard. It is a little difficult staying off the boost though! Didn't know until reading through the posts that some realized a gain in MPG and some did not. I did notice at a cold start up there is a little black smoke from the tail pipe. Don't know if others have the same at start up. Runs awesome so I will not complain too much!

 

Pretty common due to the fact of the Direct Injection and that our cars run rich on startup.

 

+1. It probably was happening before the stage upgrade as well. I know mine did it before and after the upgrade.

 

do it worth every penny