Octane question - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

mcdoogle6969 · 10-10-2013, 07:27 AM

Hey all, I've been noticing that a lot of our BP stations around here are getting rid of their 93 (10% ethanol) and replacing it with 91 (100% pure)

So my question is, with higher horsepower levels, which would be better? 93 with 10% ethanol or 91 pure gasoline? I run meth as well.

JANNETTYRACING · 10-10-2013, 09:06 AM

Quote:

Originally Posted by mcdoogle6969

Hey all, I've been noticing that a lot of our BP stations around here are getting rid of their 93 (10% ethanol) and replacing it with 91 (100% pure)

So my question is, with higher horsepower levels, which would be better? 93 with 10% ethanol or 91 pure gasoline? I run meth as well.

You will need to take out some timing.

Rhino79 · 10-10-2013, 09:10 AM

93 with 10% is less prone to knock than pure 91. Agree with ted, drop the timing.

Unreal · 10-10-2013, 10:59 AM

93 e10 is better than 91 as the two nice guys above said.

BullF-16 · 10-10-2013, 11:57 AM

Nothing 16oz of Torco cant take care of when added to 12-13 gallons of 91

mcdoogle6969 · 10-10-2013, 12:14 PM

Thanks guys

Badbubba · 10-10-2013, 01:17 PM

Why? Do they start with 93 octane gas and add 10% ethanol? If so, I would agree with the others above. Or do the oil companies factor in the higher octane rating of ethanol and blend it with a lower octane of gas to achieve 93 octane? Not doing the math, but would think that the gas would be around 92 octane for the blend, if that's how it is done, so still better than 91 straight.

Iam Broke · 10-10-2013, 01:33 PM

Actually the specs are about 2 points higher leaving the refinery to leave some margin of error. 93 Amoco Ultimate is 95 when it leaves the blending station in the refinery. The gov't frowns on the octane being below the r+m/2 at the pump.

The ethanol is splash blended at the terminal into the trucks. We refine gasoline and buy the ethanol, prob why BP is getting away from it.

Ultimate USED to be shipped in it's own tankers exclusively when it was still Amoco to keep the quality up, not sure that's the case since BP bought Amoco in '99. Too easy to get some dilution with leftovers (87) in the tankers.

Question for the OP...Do the 91 pumps still say Amoco Ultimate up there? Might be coming from a different refinery.

mcdoogle6969 · 10-10-2013, 10:40 PM

I haven't checked, I'll have to pay more attention next time. All I know is that 3 BPs that I use to go to for 93 all changed over to this "pure" 91. Which I'm not too thrilled over. I may start putting some race fuel in.

Iam Broke · 10-11-2013, 04:52 AM

You could always splash in your own ethanol with E85 to raise the octane a few points.

There is a calculator online at http://www.intercepteft.com/calc.html to determine the octane/percentage blending your own.

The stock fuel system can handle a 1:1 blend (E47) but you need a tune for anything over around 30% ethanol to keep from popping a CEL for excessive positive fuel trims. The fuel trims adjust for the extra fuel needed after driving a few miles and the fueling carries over into the WOT fueling for positive fuel trims also. I ran 30% E with no issues when I was stock.

Avoid leaded race fuel as it will destroy your O2 sensors over a short time.

mcdoogle6969 · 10-11-2013, 10:18 AM

Quote:

Originally Posted by Iam Broke

You could always splash in your own ethanol with E85 to raise the octane a few points.

There is a calculator online at http://www.intercepteft.com/calc.html to determine the octane/percentage blending your own.

The stock fuel system can handle a 1:1 blend (E47) but you need a tune for anything over around 30% ethanol to keep from popping a CEL for excessive positive fuel trims. The fuel trims adjust for the extra fuel needed after driving a few miles and the fueling carries over into the WOT fueling for positive fuel trims also. I ran 30% E with no issues when I was stock.

Avoid leaded race fuel as it will destroy your O2 sensors over a short time.

I'm far from anywhere near stock. My 02 sensors are tuned out. Running the squash return style fuel system. I'm going to be running two tunes. Ones on pump gas, other is pullied with c16. I'm just trying to figure out what I should run for pump gas. I'm going to have to search around and see if there's any place around here with 93 still.

strych9 · 10-11-2013, 10:21 AM

Quote:

Originally Posted by mcdoogle6969

I'm far from anywhere near stock. My 02 sensors are tuned out. Running the squash return style fuel system. I'm going to be running two tunes. Ones on pump gas, other is pullied with c16. I'm just trying to figure out what I should run for pump gas. I'm going to have to search around and see if there's any place around here with 93 still.

Your O2 sensors are "tuned out"? Huh? Not completely; how does the system monitor your AFR? Do tell.

Iam Broke · 10-11-2013, 12:09 PM

He could have a speed density (VE) tune and not use the O2's. Guess we should have read his 7 page build thread. :-/

Unreal · 10-11-2013, 12:44 PM

SD has nothing to do with not using O2s. He could have the tune locked in open loop. I've seen it before. Not sure why some people do it unless it is a race car, but it is easy to disable closed loop feedback and just run it that way.

10-10-2013, 07:27 AM	#1
mcdoogle6969 Drives: 2010 Camaro SS, 2008 Heritage 300C Join Date: Jun 2009 Location: Wisconsin Posts: 1,911	Octane question Hey all, I've been noticing that a lot of our BP stations around here are getting rid of their 93 (10% ethanol) and replacing it with 91 (100% pure) So my question is, with higher horsepower levels, which would be better? 93 with 10% ethanol or 91 pure gasoline? I run meth as well. __________________ BUILD THREAD

10-10-2013, 10:59 AM	#4
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	93 e10 is better than 91 as the two nice guys above said. __________________ Nick Corvette Z06 -1200ish rwhp

10-10-2013, 11:57 AM	#5
BullF-16 USAF retired! Thank God! Drives: 2011 1SS, 1LT red,1LT/RS SGM 98Z28 Join Date: Jul 2011 Location: North Texas Posts: 2,799	Nothing 16oz of Torco cant take care of when added to 12-13 gallons of 91 __________________ HKE LSX427(Mast blk lbl 305 6bolt LS7heads, PatG231/246 blower cam, RWHP/TQ: 1281/1133 SNL Performance Custom Twin PT6766 BB turbos 4 to 25psi selectable on the Boost Leash controller, Squash dual 400LPH/ID2000s, ALKY 4 gal meth, Autometer AFR/Bst/oilpres/oiltemp/fuelpress gauges, Pedders Justice road crs pkg: All HD bushes, supercar 12kg coil overs, supercar ZL1 sways, camber plates all setup by JusticePete! :Gforce 9" 35spline S-Trac, 1500hp Outlaw axles, 3.5"alum DS, Monster Triple disc; 4xForgeline 19x10.5 4xBridgestone 305/30R19 RE-11, CTS-v calipers/rotors/Cobalt friction XR1/3 pads

10-10-2013, 12:14 PM	#6
mcdoogle6969 Drives: 2010 Camaro SS, 2008 Heritage 300C Join Date: Jun 2009 Location: Wisconsin Posts: 1,911	Thanks guys __________________ BUILD THREAD

10-10-2013, 01:17 PM	#7
Badbubba GrINned & JUICEd Drives: 15STI, 10Expy, 10 2SS/RS M6, 47KB1 Join Date: Nov 2009 Location: Pittsburgh, PA Posts: 1,247	Why? Do they start with 93 octane gas and add 10% ethanol? If so, I would agree with the others above. Or do the oil companies factor in the higher octane rating of ethanol and blend it with a lower octane of gas to achieve 93 octane? Not doing the math, but would think that the gas would be around 92 octane for the blend, if that's how it is done, so still better than 91 straight. __________________ GPI SS3 Cam & stuff,N.O. Plate(dedicated fuel tank,progressive,fuel hose upgrade,remote opener,heater,console switches),LNC2000,CTAP,ARH 1 7/8" LTs/gutted cats/X pipe/mufflers,Jet Hot coated LTs,GPI HPT Tune,CAI, Scoop,Rx Catch Can,Gates heater hose relocation, Remote clutch & auto brake res,Metco loop,Momentum Tunnel Brace,TSW Nurb 18",555 & 05,Pfadt trailing arms & toe rods,Autometer WB,Fesler Pillar Pod,LED strips (int),Lloyds floor & trunk mats,LED DRL/front turn & license plate,DRL harness,VLEDs tail lights,Plasticoat Bowties. Ord: Oct 5, 2009 Rec: Nov 19, 2009 13.17@112.6 stock

10-10-2013, 09:10 AM	#3
Rhino79 Drives: 2010 Camaro SS L99/Auto Join Date: Jul 2011 Location: Cabot, AR Posts: 2,827 View My Garage	93 with 10% is less prone to knock than pure 91. Agree with ted, drop the timing.

10-10-2013, 01:33 PM	#8
Iam Broke PHAT B33 Drives: 2012 TF3 Camaro 2SS/RS M6 Join Date: Jun 2012 Location: Dark of the Moon Posts: 1,460 View My Garage	Actually the specs are about 2 points higher leaving the refinery to leave some margin of error. 93 Amoco Ultimate is 95 when it leaves the blending station in the refinery. The gov't frowns on the octane being below the r+m/2 at the pump. The ethanol is splash blended at the terminal into the trucks. We refine gasoline and buy the ethanol, prob why BP is getting away from it. Ultimate USED to be shipped in it's own tankers exclusively when it was still Amoco to keep the quality up, not sure that's the case since BP bought Amoco in '99. Too easy to get some dilution with leftovers (87) in the tankers. Question for the OP...Do the 91 pumps still say Amoco Ultimate up there? Might be coming from a different refinery. __________________ Another 1 of 371 '12 T3 LS3 M6's built. Last edited by Iam Broke; 10-10-2013 at 01:51 PM.

10-10-2013, 10:40 PM	#9
mcdoogle6969 Drives: 2010 Camaro SS, 2008 Heritage 300C Join Date: Jun 2009 Location: Wisconsin Posts: 1,911	I haven't checked, I'll have to pay more attention next time. All I know is that 3 BPs that I use to go to for 93 all changed over to this "pure" 91. Which I'm not too thrilled over. I may start putting some race fuel in. __________________ BUILD THREAD

10-11-2013, 04:52 AM	#10
Iam Broke PHAT B33 Drives: 2012 TF3 Camaro 2SS/RS M6 Join Date: Jun 2012 Location: Dark of the Moon Posts: 1,460 View My Garage	You could always splash in your own ethanol with E85 to raise the octane a few points. There is a calculator online at http://www.intercepteft.com/calc.html to determine the octane/percentage blending your own. The stock fuel system can handle a 1:1 blend (E47) but you need a tune for anything over around 30% ethanol to keep from popping a CEL for excessive positive fuel trims. The fuel trims adjust for the extra fuel needed after driving a few miles and the fueling carries over into the WOT fueling for positive fuel trims also. I ran 30% E with no issues when I was stock. Avoid leaded race fuel as it will destroy your O2 sensors over a short time. __________________ Another 1 of 371 '12 T3 LS3 M6's built.

10-11-2013, 12:09 PM	#13
Iam Broke PHAT B33 Drives: 2012 TF3 Camaro 2SS/RS M6 Join Date: Jun 2012 Location: Dark of the Moon Posts: 1,460 View My Garage	He could have a speed density (VE) tune and not use the O2's. Guess we should have read his 7 page build thread. :-/ __________________ Another 1 of 371 '12 T3 LS3 M6's built.

10-11-2013, 12:44 PM	#14
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	SD has nothing to do with not using O2s. He could have the tune locked in open loop. I've seen it before. Not sure why some people do it unless it is a race car, but it is easy to disable closed loop feedback and just run it that way. __________________ Nick Corvette Z06 -1200ish rwhp