bored out

I have a stock 07 GT.

I am a firm believer in giving my car the best so I only feed it 93 Octane. Will this increase my performance at all over 87?

P.S. I ripped em good in second the other day after filling up with 93, definately worth MSRP, lol.

At least I know my car will be ready for a C&L Racer and 93 Race from Bamachips!

Bullitt995

Without a tune it won't do anything.

Willie

In simplest terms, the higher the octane rating the more resistant to detonation an engine will be. If an engine's specs (compression ratio, cam timing, ignition timing, etc.) are such that the calculated minimum octane is 87, there should be zero detonation with 87 octane (hypothetically).
So if the minimum requirement by the manufacturer is 87, there is nothing to gain (except a deeper hole in your wallet) by using higher octane fuels.

From a performance perspective, the one most important change would be ignition timing. Almost all engines will run stronger with more timing. However when timing is advanced, detonation becomes a factor. This is when you need to run higher octane. Running higher octane in and by itself is a waste of money.

Louie

The lowest grade gas here is 95RON (~93 octane US), so I could never compare it to 87, but once I filled up with 100RON gas in Germany and there was absolutely no difference in performance, since I didn't have a tune at the time.
Save yourself the money and don't use 93 unless you add a tune.

mikeelia

I WISH I could get 93 octane in SoCal! I have a 91 tune which works fine with 76 brand fuel and detonates with Shell. Don't even talk to me about the no-name brands. I put on too many miles to run racing fuel regularly, and not only for cost, but also because of having to drive 30 miles extra [15 each way] just to put in a couple of gallons of 100 octane at the pump!

Mike E

don_w

I can't even find 100 octane at the pump here in SD.

n00bstang

as long as it makes you feel better about yourself, lol.
keep using 93.

pville piper

As I understood it, using a higher octane gas would give the car at the most 5 hp. This is due to the knock sensors allowing the engine timing to advance. However, this was done with 89 vs. 87, not 91 or 93 as the ECU won't adjust the timing that far.
But I have also heard that running too high of an octane can also drop your hp slightly. So which is right?
But 5 hp either way can be just the difference in the testing of the car, weather conditions or error of the Dyno or setup so who's to say. If it makes you happy to spend an extra $3 bucks a tank then do it. But wouldn't you rather get a tune for a stock setup that uses the 93 octane and gives you real performance? That is what I would do.
If you get it from Bama tunes and then add a CAI later on I believe he will update the tune for free. Good deal if you ask me... But then I do have that Bama Chips smile!

The Reverend

Yes 93 octane will give you a perfomance increase. The ECU will advance the timing for each point of octane. Ask any good Ford tuner. I have personally seen the timing advance with higher octane. Don't listen to the "Nay" sayers unless they have proof to demonstrate that it does not improve performance. Also some higher octane gasoline have detergents that help with reducing valve deposits. I only use Shell 93 octane V-power gasoline. Shell is a tier one gasoline company and they have a credit card that pay 5% cash back, each month, one month behind.

Bullitt995

Over a very long extended period the computer MIGHT advance the timing. I seriously doubt it however. It's not worth the hp or two you would pick up anyway.

SixtySix

Ok, I'll bite. Explain to me which sensor takes care of automatically advancing the timing based on the octane rating of the fuel? And let's go ahead and ask a good ford tuner right now... Tillman, Doug. Like to shed some light on this

pville piper

They don't... From what I understand the ECU will advance the timing until the knock sensors tell it to back off. This is a limited range and from what I had read it really won't do a lot and is ment to compenstate for poor grades of gas. Again, I have never read anything that states that it will give you more than 5 hp and never read more than the general statement that "using higher octane gas will give you an easy 5 hp". Using 93 octane without a tune is a waste of money.

SixtySix

Oh, believe me, I know that. I'm just trying to impart some actual "facts" into this "Myth"

And actually since you brought it up, I don't believe the ECU just keeps on advancing timing until the knock sensors kick-in either. There is a certain amount of timing built into the stock tune, that's what the timing tables are for. If that was true then it would be quite possible to get a performance gain just by using a higher octane fuel.

When tuned for it, the timing tables are adjusted with the tune to take advantage of the additional headroom a higher octane fuel provides.

Without modifying the timing tables, the tune (ECU) stays within it's stock parameters and will only retard timing if a knock is detected.

The only possible benefit to using a higher octane fuel without a tune is the additional headroom it would provide against detonation.

So let's say you live in an area that suffers from very high summertime temps, you could gain performance as a byproduct of your motor not detonating as soon as it would on regular 87 Octane.

Sharky

+1....
If you don't wanna tune it. Just use a good brand name 87 from a corporate store..i.e. Chevron w/techron.

Sharky

Put up or shut up.... No offense but why do ppl still continue to believe this myth. Show me a Dyno sheet before and after... Then i'll shut up.
As it stands now, the only gain you'll see with a high octane/ no tune combo is the psychosomatic, placebo effect type. (all in yer head)

The Reverend

Show me a dyno sheet that does NOT show an increase. I observed two stock mustangs one with 87 octane fuel, mine with 93 octane octane fuel on a dyno and SCT tuning software. The computer showed that the 87 octane vehicle advancing timing less than my vehicle. My car dynoed higher than his vehicle. The tuner explained that FORD's computer has multiple fuel tables based on octane. The computer program indicated that my car switched to a higher fuel map.

bored out

I understand the theories mentioned here but I use 93 because...

1. It would seem that a higher octane fuel would be better for a high performance car, maybe on a small level but still better, not the same as 87. If 100 is better than 93 then why is 93 not better then 87.

2. Fuel can vary from gas companies to octane levels. If you use a good engine oil why not use a better octane fuel.

3. If you ever decide to sell your performance car it is nice to tell a potential buyer that the car has only ever had 93 in it. It shows that you car about what goes into your car and can go a long way to proving your reputation to a potential buyer. Might even get you more money on a sale because the buyer will know the car has been well keep.

4. It feels a bit stronger / more responsive / little quicker. I would advise you guys to try a tank for yourself you may like it better.

5. It is hot in Georgia. If that really helps with detonation in warm weather, then great.

6. It does make me feel better. Did your car ever seem quicker after you washed it? I know mine does. It really comes down to how you perseive the car and how it makes you feel driving it. To each their own!

I wonder what Doug or CR would say about this top?

TillmanSpeed

Okay,

There are good points to both sides of the story here. Using a higher octane on a spark table that is only able to adapt for knock reasons will net you very very few ponies. It will, however burn much cleaner.

Adaptive learning is not to be used as a tuning tool, yet a safety net for the wide range of ACTUAL octane levels that are seen in gas pumps across the states, etc.

All I would have to do is post a spark table from an 87 tune and a 93 tune, and that would be enough to show the great amount of advance in timing (both MBT spark tables and borderline knock).

On a tuned engine, the numbers are amazing. A 93 octane tune could gain as much as 10-25 extra horsepower NA depending on what supporting mods (ie. basic CAI, or LT's, delete plates, etc.) On supercharged applications the difference can be ****-near double, and is neccessary on nearly every application to keep from detonating.

There's no arguing... you're going to get more ponies either way, and a cleaner emission. However the difference is just minimal without the use of a proper tune.

CR
Tillman Speed

DoctorQ

This is good information to know. I guess my concern has been "what tune does Ford put on our stock GTs from the factory?" An 87 tune (and associated spark table), or a higher octane tune (and spark table)? If the stock tune is indeed a higher tune (and spark table), isn't it reasonable to assume that running higher than 87 octane will net more HP?

theedge67

Ford's tune is for 87 octane. That is what the HP numbers are based on when they test the engines. If the engine made an extra 20 hp when you put in 93, why wouldn't they market the engine as 320hp? Ford wants to sell a car that runs on 87.

Some cars are designed to run on premium gas, but can safely be run on 87 as well at a reduced power output. The GTO is one of them. It makes 400HP with 93 Octane gas. If you put in 87, it won't make the advertised 400HP, but will still run ok.

The owners manual says this about premium:

Your vehicle is designed to use
“Regular” unleaded gasoline with
pump (R+M)/2 octane rating of 87.
We do not recommend the use of
gasolines labeled as “Regular” that
are sold with octane ratings of 86 or lower in high altitude areas.
Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your authorized dealer to
prevent any engine damage.

Fuel quality

If you are experiencing starting, rough idle or hesitation driveability
problems, try a different brand of unleaded gasoline. “Premium”
unleaded gasoline is not recommended for vehicles designed to use
“Regular” unleaded gasoline because it may cause these problems to
become more pronounced. If the problems persist, see your authorized

dealer.