Pillow

The Escalade is a torque monster and is not made for any sporting intentions. It is a neglected and beaten mommy mobile and gets el cheapo 87 or E and likes it that way. IDK the tune GM chose to put on the E side, but in theory the E should have a greater HP potential than Premium fuel. As you can see the aftermarket is loving E to extract greater HP out of mild to wild cars. FWIW this week 87 was $2.06 and E85 $1.61.

I don't have a reasonable explanation as to why the stock sports cars are not tuned for E. IMO a simple add on and the aftermarket supports this with FF sensors and tunes.

I have three LS swaps in various phases (71 C10 5.3 LS2 w T5 currently carb, 83 Cherokee 5.3 LS9 SM465 NP208, and 92 Volvo 960 5.3 LS7 T5) and all will be setup for E. Not for the HP, but for the flexibility to run whatever is available.

FWIW the Cayenne and old 911 SC get Premium, but probably a waste for both.

J'sWorld

I have seen e85 get down to the $1.40 area in Austin and I can't wait to get tuned for it. I'd bet the flex fuel vehicles have a weak E tune up help negate the mileage drop.

dr914

I have always used the cheap stuff in my Porsches with knock sensors, but would NEVER use anything but the highest octane in the Porsches that require high octane with no knock sensor. Never had a problem, save a bunch of money, and if I want to drive them in a spirited way and want more power, then gas up with high octane

Pillow

I agree for the stock tunes. Really as long as the ECU supports it, just add the E high flow stock injectors (or aftermarket) plus the Fuel Composition Sensor and you are in business! For LS GM stuff this is easy. Even the old LS ECUs (0411) are capable to run E, you just need to add two wires in the ECU loom to connect the FCS. Plenty on wiring schematics online depending on the application to add into the ECU loom/harness. Also de-capping and having the stock E injectors flowed tested is a good idea for a +T build (plenty of info out there on this).

Sorry to the OP if this is a complete thread derail ATM.

19psi

Because the "tune" is a compromise to run on regular fuel, E85 and still be emission compliant in 50 states...great for grocery getters . No one buying a performance vehicle is going to want to take a hit in HP for flex fuel capability. At the same time, no manufacturer is going to produce a strictly E85 vehicle that can take advantage of the high octane when the fuel is difficult to find and controversial. What happens if the gubment subsidies change and E85 fades away?
Lastly, will a manufacturer be able to produce that vehicle without getting into the gas guzzler bracket?

J'sWorld

The mfg's can do anything they want to. I think this thread is running off on a tangent that could take multiple more. This is about octane and regular gasoline. There are some great answers in this thread and this is a Cayenne forum so the responses should relate to that. I would encourage users to think about how hard it was to find the answers you wanted when you first got the Cayenne bug and all the crap you had to wade through. Of course a different thread could be interesting as long as it is Cayenne related, and in the sake of keeping this forum active and uncluttered this is something we should all think about. Don't forget that there is a general discussion area for topics unrelated directly to the Cayenne.
On a parting note, even though I luvs me some E and built my engine for it the Cayenne blocks and cylinder walls are comprised of 78% aluminum. I had a conversation with Mr. Scott Slausen @ Softronics about why he doesn't tune for E in these and the truth is that the material is not compatible with the corrosive / hygroscopic nature of E.

vu.q.le

I'm almost done with my first full tank of 87 octane on my Cayenne Turbo.
With 100% confidence, the manual indicated that there are knock sensors in place to deal with lower octane fuel. With that said, I wonder if I should continue to use 87 octane for city driving, and I don't drive like a maniac.

hacker-pschorr

Knock sensors are a post combustion sensor, this is very important.

This means the computer compensates after the engine has already experienced a detonation event (knock), by pulling back timing until the knock goes away. At that point the computer has a set time frame before it will try to restore full engine power, and if it sense knocking again, will pull back timing.

Essentially what you are doing is subjecting your engine to detonation over and over and over again. Detonation is never a good thing, ever. The idea behind knock sensors is to save the engine from a fluke, bad tank of gas, something else going wrong that could otherwise instantly destroy an engine without such sensors and safeguards.

There is zero reason to knowingly and willingly subject an engine to this.

The great Smokey Yunick once said (paraphrasing) that if you took all the engines destroyed by detonation and put them on one pile, then take all other failures and put them on another pile together. The detonation pile will be significantly larger.

Is the Cayenne engine built robust enough to withstand repeated detonation over the course of its life running low octane fuel? Only one way to find out, but if the answer turns out to be "no", whatever broke will be far more expensive to fix than the cost of higher octane fuel.

The manual is not wrong, but that doesn't mean it's a good idea. Such statements in the manual exist due to the sales & marketing team not wanting to admit to customers their new vehicles must run on the most expensive fuel possible.
"These engines have knock sensors, no need to run expensive gas......sign here"

There is no way I would ever purposely run low octane fuel in a turbocharged or high compression engine, except at high altitude.

95_993

Typically run Sunoco 93. Detonation causes abnormal forces in the piston, etc. no need to increase the potential of piston skirt/bore contact. Giving this motor all the chances to perform flawlessly through a long life.

19psi

I see I missed this reply from a while back.
Who the do you think you are to tell me what I can and can't discuss in this forum, especially when a user like you has far more posts going off on a "tangent" for this topic?
And before you remind me (as you've done others) about your "build thread" which gives you validity, I personally don't care about it.
In the future, instead of replying to me with your typical pompous d-bag attitude, simply put me in your block list.

cayenne2008

What are you considering high altitude? I Am in denver and climb higher as i go into the mtns.

I've always used 91. Should i think differently?

J'sWorld

Ahhh, I see. Member > User. That's too bad. I'm not offended by you at all so I don't need to block you. Happy holidays!

RSbob

Always use 91. Cracks me up when people buy an expensive luxury vehicle and the cheap-out on recommended octane and potentially damage their engines costing far more than what they are saving. Maybe they should own Toyotas if savings is an issue? Human beings are always such a contradiction it would make Mr Spock poop his pants.

TRINITONY

That is such a true statement, it's amazing how many people still do it. I put 93+ in my old DD E55, once I made the mistake and put either 87 or 89 and I could immediately feel the difference. The pig gets Sunoco or Shell 93 octane.

Avec

While the statements about knock sensors being post-combustion, they are still post combustion on 93 octane, and will listen for knocks in a constant effort to keep timing as advanced as possible, regardless of the octane. Unless I am wrong, and there is a max advance that is within the comfort zone of 93 octane.

That being said, I run 93 octane exclusively. Higher octane give marginally better fuel economy, and seems to run cleaner.