anyone use Octane booster in their 991.2 GT3?

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03-30-2018, 12:32 PM

#46

CAlexio

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Quote:

Originally Posted by ONEOFEW

To this date I haven’t found a octane booster that stopped the pinging on a carbureted , non computer controlled car. I’m a big believer of blending some race fuel , i know it gets the job done .
Both my F12 and GT3 briefly ping on low revs, Unfortnatley all we have in so cal is 91 at the pump, even that’s questionable if it’s really 91, so yes I do blend 10 gal of 100 in the F12 n 5 gal in the GT3 14gal fuel tank , No more ping and very noticeable change in the throttle response

This still implies that any higher octane fuel is available, or that you can keep a drum in your garage. So for those of us for whom neither solution is possible, you (and others on here) are saying the octane boosters from the store are worthless?

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03-30-2018, 12:46 PM

#47

GrantG

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Quote:

Originally Posted by FourT6and2

Is E85 something that would work in place of actual 100 octane unleaded? To mix with 91 I mean.

No, don't try that. Ethanol burns at a totally different air/fuel mixture than gasoline. Aside from the potential negative effects on your fuel system, adding E85 to your GT3 is not something the ECU can cope with. It's not a Flexible Fuel vehicle. It would run too lean.

I use two switchable fuel maps in my EVO to be able to use 91 Octane gasoline or E85 (I have to run the tank nearly dry before switching fuels, changing the fuel map in the ECU (developed on a Dyno), and adjusting the Boost Controller to match). I also had to add much higher flow fuel injectors and pump in order to take advantage of the potential benefits of E85 (easy, cool-running, and reliable 425hp and 435 ft-lbs on 2.0L motor with stock turbo). And it only costs $1.85 per gallon for 106 Octane (but uses lots of it).

I go way out of my way to avoid the usual E10 fuel that we have in CO. I find one of the few stations that still sells pure gasoline for the GT3:

https://www.pure-gas.org/

Last edited by GrantG; 03-30-2018 at 01:03 PM.

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03-30-2018, 12:50 PM

#48

FourT6and2

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There are a few gas stations here that have 100 Octane. But they are really far away. I'll have to fill up some jerry cans.

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03-30-2018, 01:06 PM

#49

GrantG

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Quote:

Originally Posted by FourT6and2

There are a few gas stations here that have 100 Octane. But they are really far away. I'll have to fill up some jerry cans.

Toss a little Sta-bil in the jerry can if you're going to store long term...

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03-30-2018, 02:26 PM

#50

FourT6and2

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Quote:

Originally Posted by GrantG

Toss a little Sta-bil in the jerry can if you're going to store long term...

What is considered long term?

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03-30-2018, 02:34 PM

#51

GrantG

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Quote:

Originally Posted by FourT6and2

What is considered long term?

How about 3 months or more (this is probably on the cautious side)...

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03-30-2018, 02:38 PM

#52

FourT6and2

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Quote:

Originally Posted by GrantG

How about 3 months or more (this is probably on the cautious side)...

Cool, thanks.

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03-30-2018, 03:00 PM

#53

991carreradriver

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I have used Torco for years, no issues on my last two tuned 911's.

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03-30-2018, 03:25 PM

#54

ilovecarbs

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Quote:

Originally Posted by GrantG

I use two switchable fuel maps in my EVO to be able to use 91 Octane gasoline or E85 (I have to run the tank nearly dry before switching fuels, changing the fuel map in the ECU (developed on a Dyno), and adjusting the Boost Controller to match).

I have an ethanol content analayzer and a flex fuel map through a cobb accesport on my STI and the ECU makes air/fuel adjustments automatically on the fly. If cobb made a flex fuel map for the GT3 I'd jump on it in a heartbeat.

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03-30-2018, 03:49 PM

#55

GrantG

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Quote:

Originally Posted by ilovecarbs

That's pretty cool! Would be even more useful these days, as E85 has such a wide range of Ethanol in it (not at all constantly 85% anymore - can be much less)

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03-30-2018, 04:29 PM

#56

Speedster911

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Quote:

Originally Posted by FourT6and2

Bakersfield
Buttonwillow Raceway (road track)
located 28 miles northwest of Bakersfield off I-5)

Inyokern
Buttermilk Acres
VP Racing Gas Station
3565 W Inyokern Rd
Ridgecrest, Ca. 93555

Los Altos
VP Gas Station
Los Altos Rancho Shopping center
660 Fremont Ave
Los Altos, CA 94024

Los Banos
DB Corp 76
1963 Pacheco Blvd
Los Banos, Ca. 93635

Madera
Country Club 76
17017 Road 26
Madera, Ca 93638

Manteca
Frank's One Stop
2072 W. Yosemite
Manteca, Ca. 95337

McFarland
Famoso Raceway
33559 Famoso Rd.
Mc Farland, Ca. 93250

Modesto
Modesto Gas
1401 Coffee Road
Modesto, Ca. 95355

Patterson
Fred Frias 76
226 N. 2nd Street
Patterson, Ca 95363

Rancho Cordova
Valley Motorwerks
11401 White Rock Rd.
Rancho Cordova, Ca 95742

Rancho Cordova
Midnight Performance
3282 Luyung Dr
Rancho Cordova, Ca. 95742

Redwood City
Kings 76 Station
975 Woodside Road,
Redwood City, Ca. 94061-3610

Sacramento
Watt Tosco 76
2847 Watt Ave
Sacramento, Ca. 95821

Salinas
Laguna Seca
1021 Monterey-Salinas Highway
Salinas, CA 93908

San Jose
Damar Petroleum
1201 Almaden Expwy
San Jose, CA

San Jose
Goodies Speed Shop
345 Lincoln Avenue
San Jose, CA 95126

San Jose
Almaden Racing Fuel
76 Station at Almaden and Foxworthy
3010 Almaden Expressway

San Leandro
VP Gas Station
1495 Hays Street
San Leandro,CA 94577

Selma
Exxon Gas Tiger Mart VP Racing fuel behind main station
10610 E Mountain View Ave
Selma, Ca. 93662

Sonoma
Infineon Raceway
29355 Arnold Dr
Sonoma Ca. 95476

South San Francisco
Gotelli Speed Shop
321 El Camino Real, 94080

Stockton
VP Racing Gas
1033 W Charter Way
Stockton, Ca 95206

Sunol
Sunol Super Stop
3004 Andrade
Sunol, Ca 94586

Tracy
VP Racing Gasoline
2375 N Tracy Blvd
Tracy, CA, 95376

Turlock
Golden State 76
881 N. Golden State Blvd
Turlock, Ca. 95380

Waterford
JK Service
12405 Yosemite Blvd
Waterford, Ca 95386

Thanks for posting these locations

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03-30-2018, 04:35 PM

#57

Chris88

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I plan to purchase some 100 octane at the Redwood City 76 station today or tomorrow for my touring. Not sure how much to blend in, but will start around 30%. I checked yesterday, and it was around $7.75/gallon.

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03-30-2018, 04:36 PM

#58

FourT6and2

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Quote:

Originally Posted by Chris88

( [% Fuel A] x [Octane of Fuel A] ) + ( [% Fuel B] x [Octane of Fuel B] ) = Octane of Mixture

For 91 Octane and 100 Octane mix:

80%/20% = 92.80 Octane
75%/25% = 93.25 Octane
70%/30% = 93.70 Octane

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03-30-2018, 06:21 PM

#59

Chris88

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Quote:

Originally Posted by FourT6and2

( [% Fuel A] x [Octane of Fuel A] ) + ( [% Fuel B] x [Octane of Fuel B] ) = Octane of Mixture

For 91 Octane and 100 Octane mix:

80%/20% = 92.80 Octane
75%/25% = 93.25 Octane
70%/30% = 93.70 Octane

Thanks! That's very helpful. I'm heading out now to fill up. It's too nice out to work

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03-30-2018, 10:10 PM

#60

ONEOFEW

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Quote:

Originally Posted by CAlexio

I've tired various octane boosters to stop pre-detonation on non computer controlled carbureted cars, it didn't even reduce the detonation.
5 gal of 91 to 1 gal of leaded 111 fuel which I have plenty in my garage stopped the pinging even on a 100F day. 5 to 1 gal of 111 should yield in the neighborhood of 94 oct. Old cars are primitive, air fuel ratio will vary a bid depending on ambinet temperature but timing is on a set curve, remains unchanged. Variable is the fuel, if I can achive 94 octane by blending race fuel vs two bottles of booster in the tank won't do anything what does that tell us?
On my GT3 I prefer to blend 5 gal of 100, having said that if there is non available I rather drive on our crappy 91.

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