[AndyR83]

Hello,

I'm trying to learn about the use of higher than standard octane fuels in a 335i. I have put nothing but 93 octane gas in this car since the day I got it. I have a JB4, and I have all the normal performance mods in a pile on the garage floor waiting to be bolted on (DCI, air scoops, catless DP's, FMIC, chargepipe, BOV.) When I get all of this stuff on, I was going to switch from map 1 on my JB4 to map 5. I've been reading about map 7, and was curious about the power differences between maps 5 and 7.

In my area there isn't much high octane fuel available. The airport sells avgas (100LL) which is leaded fuel. Since I will still have secondary cats and o2 sensors, I'm hesitant to run this in my car. I've looked around and there seems to be nothing but negative feedback on this.

There's a place 17 miles from me that sells "260 GTX" which, according to the Sunoco Race Fuels page, is a 98 octane unleaded fuel. Is this worth investigating further? Is 98 octane "good enough?" Do I need 100? Is the avgas as potentially damaging as I've read? These seem to be my only options after an exhaustive search of fuels in my area (zip 18447.)

Thanks in advance for any input.

[shogun14z]

thanks for the post. i have these same questions.

[Dave W.]

Def do not run leaded gas. It'll foul the O2 sensors and cats.
You should also have a tune on the car that can take advantage of the higher octane by either raising the boost a little or raising the timing a little. How much does 98 cost?

[JamesM3M5]

If you can compare Motor Octane Number - MON - that will be more representative of the fuel's capabilities. Sunoco does publish MON, I believe. RON is Reasearch Octane Number, and the pump number is the average of the two. MON will always be lower, since it is tested at a higher IAT and higher speed.

Leaded fuel, even the 100 LL (low lead) will still foul the cats quickly. There are cats in the DPs and the mid-section. It will not harm O2 sensors in the short term, but for long term, it makes them slower to respond and less accurate. You will need to replace the pre-cat O2 sensors after a while, but it takes many many tankfuls to foul the wideband LSU 4.9 on leaded fuel. If you are completely catless (for off-road use only, right ?), leaded fuel would be a great choice.

260GTX is good fuel, used in Grand Am as the spec fuel, but I have no experience with it in the N54. You would probably be better served finding an E85 station - cheaper, and the JB4 has autotuning maps for E85 compatibility. Run at least a calculated 30% E85 and log. Regardless of using higher octane gasoline or E85, you should definitely log.

[AndyR83]

Unfortunately, as far as i can tell, there is no place to get e85 here.

[Stucks]

racegas.com

search....you never know if a local station has 100 octane available!

[AndyR83]

That's where I started, and how I found out the 260 GTX is for sale 17 miles away

[Bimmer305]

I have been running E85 mix for the last 2 months. Tomorrow I'll be running on 110 octane, I'll let you know the difference

[E90Company]

Originally Posted by Bimmer305

I have been running E85 mix for the last 2 months. Tomorrow I'll be running on 110 octane, I'll let you know the difference

That's leaded fuel. Don't do it

[Stucks]

Originally Posted by E90Company

That's leaded fuel. Don't do it

+1

[turb0mik3]

Leaded fuel can only be accepted for a track day and if you don't have cats. Even then it fucks with the O2 sensor and you could have a very rough day. Just get 109 unleaded... lol.

[Bimmer305]

Damn, I didn't know it was that bad

The only reason I got it is because I'm hitting the track tomorrow and only got 5 gal.

Should I mix it with regular gas? I'm thinking on mixing it with my current E85 mix

[AndyR83]

Yeah, that's the same boat I'm in. I'm keeping secondary cats to reduce exhaust smell, so I don't want to kill them with leaded gas.

[cn555ic]

Get meth and you can run race gas all the time!

[AndyR83]

But where do you buy meth? I cant even find a place that sells high octane gas.

[cn555ic]

Methanol injection.

[AndyR83]

A guy on one of my local car enthusiast forums tipped me off to a station in my area that sells CAM2 at the pump for 9.95. Has anybody used this? I didn't see it listed on racegas.com. Would I run it straight or mix in with 93? Would I want to run jb4 map7 with this or stick to 5? (Fbo without meth.)

Thanks!

[Stucks]

Originally Posted by AndyR83

A guy on one of my local car enthusiast forums tipped me off to a station in my area that sells CAM2 at the pump for 9.95. Has anybody used this? I didn't see it listed on racegas.com. Would I run it straight or mix in with 93? Would I want to run jb4 map7 with this or stick to 5? (Fbo without meth.)

Thanks!

Is it leaded? Theres 2 places near me that sell race gas. One has CAM2 listed as being 110 octane (leaded). The other has CAM2 listed as 100 octane unleaded. Find out what they mean by "CAM2" first before purchasing.

[WickedB]

Originally Posted by Stucks

Is it leaded? Theres 2 places near me that sell race gas. One has CAM2 listed as being 110 octane (leaded). The other has CAM2 listed as 100 octane unleaded. Find out what they mean by "CAM2" first before purchasing.

Right. His buddy was probably referring to this one:


Gotta love the motor city... 110octane, 100octane, TurboBlue 104 to 116octane, E85... You name it we have it...lol.

[saxon]

Originally Posted by Bimmer305

Damn, I didn't know it was the only reason I got it is because I'm hitting the track tomorrow and only got 5 gal.

Should I mix it with regular gas? I'm thinking on mixing it with my current E85 mix

E85 will make more power than any fuel out there for a turbocharged
Vehicle, if you can run e85 then do it

[Bimmer305]

Originally Posted by saxon

E85 will make more power than any fuel out there for a turbocharged
Vehicle, if you can run e85 then do it

I recorded some logs with this race gas and I didn't see much difference if any at all from my E85 mixture, other than white tail pipes hehe. (and I'm only running 40% ethanol)

Ethanol from now on.

Also map 7 is a baby compared to a well adapted map 5..