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108 oct gas how far can you push it?

Old 10-20-03, 01:06 AM
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108 oct gas how far can you push it?

I have switched from running 104 unleaded to 108 unleaded.

this past weekend BDC and I tuned my car on the dyno. We worked our way up to 23psi which netted us 476rwhp and 383torq

how do we know how much farther we can go on 108 before we change to the next grade up in race gas?

we want to work the car up 30 psi.


also do the a/f change with the higher you go in oct?
we have been trying to keep the a/f in the low 11's
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Old 10-20-03, 11:04 PM
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Are you on the T66, or the S300? Higher octane will tend to read leaner AFs, by .1-.3 points on a piston engine, I would Imagine that would translate over to a Rotary. I do not think it is actually leaner though. I would call Peter at Tech Edge for an explanation. Any dynos, or Turbo specs you'ld care to share? Thanks, and good work, Carl
BTW where is your O2 sensor, if it's too close to the turbo you can be reading as much as a full point richer than you really are. ~18" is good, stock location is a problem potentially.
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Old 10-22-03, 11:44 PM
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this was on the S300 108oct 23 psi a/r around 11.3 - 11.5

476rwhp and 383torq temp was around 85 deg ambient.

my PLX wideband O2 is about 12 - 14 inches from the back side of the turbo.

http://www.teamfc3s.org/forum/showth...threadid=20300
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Old 10-23-03, 04:23 PM
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Location seems fine, Ive boosted 28psi(avcr)on my TO4S without incident on the street on straight 100(this was not on purpose) in third gear. That was on a Mike Johnson(used to be JRE motorsports) E6K tune(conservative fuel/timing). His comment on my incident was that the maps were good to 30psi, and not to worry, except that I should be running 108 or higher if I planned on running it there regularly. As you know, I am no expert, just sharing my experiences. I am going the T66 route for sure at this point, as I am out of money, and I already own the T66 Q trim. It's a .81 undivided, I'll start there since I have a street port, not a BP. Good job, and good luck, Carl
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Old 10-25-03, 01:46 AM
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ha we found out today that what we though was 108 turned out to be 112 leaded. so much for my wideband sensor!!!
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Old 10-25-03, 09:51 PM
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better higher than lower
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Old 10-25-03, 10:17 PM
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Also leaded gas burns cooler. Dude just use C-16 Leaded. Why push it with the unleaded?
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Old 10-25-03, 10:51 PM
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YUP, we can run ~35 psi on C16 on the Sup........
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Old 10-26-03, 12:47 AM
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yeah we desided that too. if we going to do it do it right.
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