View Full Version : High altitude 3.0s

Mtn. Mike
02-13-2006, 05:06 PM
Hey gang,
Wondering if it is absolutely necessary to run 91 oct on a Neuspeed chip for the 3.0 My service mgr. said not to bother running anything over 87 oct in my current setup because at altitude the additives in the higher octane fuel will negate any benefit. Also, has anyone dealt with G&G Import Auto Clinic as they are the Neuspeed flash programming guys in CO. Thanks

02-13-2006, 05:22 PM
I have a feeling that you and I are and will be the only high altitude 3.0 for a while. I say that because you are the only other one on this board that I know of, and I have been looking around for a while. As for the oct. question. Sounds like nonsense to me. Higher oct. will almost always help an engine perform better. I am assuming your service manager is Rick Purdy? Hes a nice guy but dont take what he (or anyone else @ Ed Carroll) says as the absolute truth. I am trying to get some stuff worked out @ the nearest GIAC tuner for some High Oct. programming, and my guess is that a gain of 20-30 HP is POSSIBLE. Not that it will necessarily happen, but it could. Your sig says that a S/C is in your future, if that is the case then I wouldn't even bother w/ a chip. The gains wouldn't be worth what you could save and put towards the S/C, which will need a GIAC program to run anyway. Again, good to see another 3.0 cruising above the mile marker, sorta [;)]

edit: You have the 6sp in that bad boy right?

02-13-2006, 05:48 PM
I'm not sure if this will help out at all, but back in the beginning the correct octane fuel you were supposed to use was based on the engine's compression. i.e. a compression of 1:9.1 would equate to using 91 octane gas. But that's at sea level, and that's why you won't see very much 93 octane gas at higher altitudes...because the 91 acts almost the same at altitude as the 93 does at sea level. Now, a lot of this has changed because of turbochargers, chips, higher compression engines, etc, etc. but it's a good rule of thumb. Now, as far as I know, the 3.0L straight out of the box is a ratio of 1:10.1. (fairly high compression) I'm sure Audi has de-tuned it a little to handle the lower octanes of fuel, but I wouldn't go lower than 91 if I were you.

What I would bet is that you're supposed to run 93 octane (or higher) with that chip, but because it's so hard to get, the 91 is OK at higher altitudes. You probably shouldn't go lower than that or your car will run pretty crappy. For instance, I am not chipped, but if I run 88 octane (mid-grade) I can get away with it, because the engine can retard the timing far enough to handle it, but if I drop down to 85 I get a CEL after a little while.

*EDIT* (from the first post) it has nothing to do with the additives in the gas, they put the same additives in all three grades generally. The only time that additives would affect it is if they still use oxygenated gasoline in Colorado. The oxygenated molecules don't burn as hot as straight gasoline molecules do so that's when you would have less than normal performance.

02-13-2006, 09:11 PM
stock 2.8 @ 6k to 8k feet. 91. Any less and it would run crappy. But the same was true for my 1.8 16v and VR6.

02-14-2006, 11:07 AM
good point cbass, as they do put the same additives in all grades of gas. Plus, those additives are just detergents that are suppose to clean the engine. The only reason I can think of they would tell you a lower octane fuel would work just as well is because of the ethonal they put in all gas in CO. Regardless of the ethonal I wouldn't do that to your car, always put the higher grade in if you can.

Mtn. Mike
02-14-2006, 12:13 PM
I actually haven't had any trouble running the 87. No plug fouling, no knocking, I might be losing something low end, but my speeding tickets attest to the top end (of course I've never really opened it up.)
Good info on gas stuff from cbass and rckymtn3L. I've been putting some 91 in to treat my baby nicely as of late and probably will continue to do so. My service guy has been Ray Upp at Phil Long in C Springs. Has hooked me up on a number of occasions. Sounds like the guy at Ed Carroll might not be the best. I won't mind a trip to CSprings to get service. They kind of overlook all my mods and still do warranty stuff.
I have the Sport Shift Tiptronic. Not as ideal as the 6 speed, but when I got it last year, I was pretty gimped up from injury and it was too good a deal to pass up (2003 3.0 Avant Q with 5000 dealer-driven miles [as the 24-hour service veh.] for $26,000)


02-14-2006, 05:26 PM
Not a bad deal on the auto. Ed Carroll isn't terrible or anything, but I dont really listen to what they say either. As for the gas, I was thinking about it and there really isn't any reason to put less than 91 oct in, unless you feel like trying to save some almost insignificant amount of $$$ by getting the cheaper stuff. Your car will thank you.

02-14-2006, 11:51 PM
IIRC.... simple rules about octane to remember is that the higher the octane level, the lower the volatility. And the volatility goes up with lower octane. Having a chip done on a NA engine does not raise the compression rate, so the need for 93 octane is not required. The only performance gain I’ve noticed from going to 91 to 93 on a NA engine is on my ducati, the compression is 12.5:1

02-15-2006, 12:03 PM
By "volatility" you mean flash point Im assuming. As for the chip, your right in that it wont raise compresion (thats mechanically dictated) but it will advance timing. W/ more advanced timing a higher octane rating will benefit you, not immensely but some. For a race fuel that is rated at a higher oct. it will increase power output, but that is because of the actual energy/BTU's that the gas itself contains and not its resistance to predetonation.