Spiking pump gas with racing fuel - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Smokinbuffalo · 03-20-2016, 03:35 PM

So I was reading in the manual that our cars are designed for 93 octane, but all I can find around here is 92 octane. So I started playing around with adding some 101 octane to a tank to try and raise the octane to 93. I wasn't sure I would see a difference, but it has been noticeable. It feels much smoother at low RPMs and 3rd gear is much more usable for taking turns. I think the ECU must be pulling timing at low RPMs with 92 octane (especially with the e10 stuff).

I did the math, and it take 1.4 gallons of 101 octane to a tank of 92 octane in ours cars to make 93 octane. To make 94 octane it takes 2.8 gallons of 101 pert tank of 92. The problem is 101 octane is hard to find, and it's expensive. It runs about $11 a gallon. I have heard that some auto parts stores can order 5 gallon cans of high octane gas.

I have run a few tanks of ethanol free 92 spiked with ethanol free 101 octane now, and really notice a difference in the way the car feels. Is it worth the extra and hassle and expense? Probably not, but I recommend trying it out some time.

gtslow · 03-20-2016, 04:09 PM

I would love to see that on a dyno.

Ultramaroon · 03-20-2016, 04:19 PM

I'm going to guess there's a noticeable difference.

There. I said it.

Pete156 · 03-20-2016, 05:53 PM

Running 92 E0 all the time, I frequently 'spike' the tank for autocross or spirited runs. My boosted car feels crisper and snappier when I add those two gallons (even the occasional backfire sounds different). Wish it didn't cost me an extra $20 each tank but sometimes it's worth it

starscream1201 · 03-25-2016, 09:59 PM

Wouldn't 92 octane with an octane booster additive be a cheaper option?

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Mr.ac · 03-25-2016, 10:21 PM

Piff cry babies.
We are stuck with 91 here in California. So far it's runs great on this piss water gas.
Just pump 92 and be glad you don't have to deal with 91.

jawn · 03-25-2016, 10:22 PM

It would be easy to find out if it's making a difference. Get a datalogger and check your IAMs.

ZOMFGAARON · 03-25-2016, 11:21 PM

Quote:

Originally Posted by starscream1201

Wouldn't 92 octane with an octane booster additive be a cheaper option?

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Doubt it octane boosters offer such low percentages of gain.

I think there was a post about this way back when op where someone had a calculator on how much 91 you had to add too racing fuel to get 93 for here in California.

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VitViper · 03-26-2016, 10:30 PM

Put 1 gallon of E85 in with your fill up. It'll help a fair amount and it's cheaper than race gas. It's also a small enough amount that it won't shift the stoic ratio of the mixed fuel enough to cause any concern (and part throttle fuel trims will take care of it as well).

03-20-2016, 04:19 PM	#3
Ultramaroon not playing cards Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 32,395 Thanks: 53,053 Thanked 37,228 Times in 19,308 Posts Mentioned: 1118 Post(s) Tagged: 9 Thread(s)	I'm going to guess there's a noticeable difference. There. I said it. __________________ service manuals

03-25-2016, 10:21 PM	#6
Mr.ac [insert cool phrase here] Join Date: Aug 2015 Drives: BRZ Premium Location: Central Coast CA Posts: 2,368 Thanks: 709 Thanked 1,559 Times in 930 Posts Mentioned: 30 Post(s) Tagged: 0 Thread(s)	Piff cry babies. We are stuck with 91 here in California. So far it's runs great on this piss water gas. Just pump 92 and be glad you don't have to deal with 91. __________________ New daily driver - Subaru BRZ Premium Weekend fun/track car - '91 MR2 Turbo Gen3 Old daily driver - '88 MR2 Supercharged

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gtslow Senior Member Join Date: May 2012 Drives: 2015 Halo FR-S Location: Puyallup, WA Posts: 328 Thanks: 87 Thanked 233 Times in 132 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	I would love to see that on a dyno.

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03-26-2016, 10:30 PM	#9
VitViper Senior Member Join Date: Oct 2014 Drives: '15 FRS Location: Oregon Posts: 221 Thanks: 8 Thanked 280 Times in 127 Posts Mentioned: 42 Post(s) Tagged: 1 Thread(s)	Put 1 gallon of E85 in with your fill up. It'll help a fair amount and it's cheaper than race gas. It's also a small enough amount that it won't shift the stoic ratio of the mixed fuel enough to cause any concern (and part throttle fuel trims will take care of it as well).

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