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Discussion Starter #1
Simple question guys...is it a good idea to run 100octane (advertised, known to be 103-104) w/o a Safc? I have a walbro255 as my only fuel mod...so i know im already running rich..no i dont got an egt or datalogger to check knock or timing...but what would YOU advise? yes/no. thanks ;)
 

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Is it leaded? It's safe to run alright, because changing the octane won't alter the a/f mixture, but it can kill your O2 sensors if it's leaded. Other than that DSMs love race gas, happy boosting.
 

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Discussion Starter #3
sorry, it is UNleaded :D..will it cause my car to run REAL rich? will it burn too quick? etc. etc. etc. ?? thanks for posting.
 

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What are you boosting at? If you are still at the stock boost setting..you probably dont need high octance gas. But it will not hurt the car if you do run it. Running the 100 octane will just decrease knock.

Before I got a S-AFC I ran Xylene in my car. My car ran well with xylene, and you can pick it up at a local hardware store.
 

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I'll say it again, octane does NOT affect your a/f ratio. Running high octane fuel means you can run more boost safely.
 

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emagdnim said:
I'll say it again, octane does NOT affect your a/f ratio. Running high octane fuel means you can run more boost safely.
This is true, octane by itself won't affect the a/f ratio. However, if the Specific Gravity of said race fuel is different then it'll change the a/f ratio some. That's a different thread though so just know your fuel. ;)
emagdnim is also right about being able to run more boost safely. The better knock protection of the higher octane fuel will allow you to turn up the boost some and run a leaner a/f ratio for more power.

At reasonable boost levels with the stock turbos I wouldn't worry about it at all.

Drop some unleaded 100 octane fuel in that bad boy and go V8 killing. It costs a bit more, but is worth it! I would't bother running it every day though and get yourself a S-AFC, EGT and a pocketlogger stat!
 

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WHAT IS OCTANE RATING?
Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine setup to ensure complete burning of the gasoline by the engine for maximum power, and fuel economy. So if the octane rating is too high for your setup and the burn is too slow then you will probably experience loss of power (barely noticable). This loss would be due to the flame front not covering enough area in the cylinder when TDC arrives. If the octane rating is too low for your setup then you will run into preignition, detonation, or knock which will result in the engine trying to defend itself by pulling the timing. This will be a noticable power loss, and potentially damaging to the engine. To sum up, rediculously high octane may have a negative effect on the performance of your engine, but it is fairly safe. Not enough of an octane rating will have an even more drastic negative effect on your engine that may be harmfull to the engine.
 

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Discussion Starter #8
Well here are my mods

free mods
k&N FIPK
hrc ic pipes w/ 1g bov
hrc o2 eliminator dp
custom 3" testpipe
apexi n1 catback
profec b @ 14/17 (low/high)
walbro255lph fuelpump (no rewire-loud as fawk!)

with these mods right now im pretty sure im running a tad rich..100unleaded shouldnt be a PROBLEM right? thanks guys...
 

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Discussion Starter #10
lol calm down...care to explain? im a newbie when it comes to fuel (as you've prolly noticed)
 

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I'd love to explain but I already have and so have a few other people, read this thread over and over again.
 

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1 fast POS said:
WHAT IS OCTANE RATING?
Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine setup to ensure complete burning of the gasoline by the engine for maximum power, and fuel economy. So if the octane rating is too high for your setup and the burn is too slow then you will probably experience loss of power (barely noticable). This loss would be due to the flame front not covering enough area in the cylinder when TDC arrives. If the octane rating is too low for your setup then you will run into preignition, detonation, or knock which will result in the engine trying to defend itself by pulling the timing. This will be a noticable power loss, and potentially damaging to the engine. To sum up, rediculously high octane may have a negative effect on the performance of your engine, but it is fairly safe. Not enough of an octane rating will have an even more drastic negative effect on your engine that may be harmfull to the engine.
Holy shit I love this reply. THANK YOU. You have cleared up something for me that I've wondered about for a long time.
I put 100 octane in my car, and it got SLOWER! I always run 94.
 

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TSITALONGUY03, you can find it at most drag strips, and is you're lucky some gas stations may have some. The best way to make high octane fuel is to mix the highest you can get form the pump (91 or 93 usually) and mix tolulene (will also clean shit out, and cheaper here) or xylene in with it.
 

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I ran 116 on my small 16g at the track. I didn't turn up the boost my first run (left it at 15 lbs), and the car bogged the whole way down the track.... fell flat on it's face on the launch, and in between every shift (not to mention it was slow as dirt). I cranked the boost up some, and leaned out my afc, and the car was a rocketship.

-Craig
 

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Exactly. For the people that need an explination on this: Octane lets you run more boost and run leaner at that because it resists detonation better (to sum up this thread).
 

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My car bogged like hell on that fuel (100), and I couldn't turn the boost up at all without complete failure. It felt like fuel cut-- like hitting a tree. I was afraid to lean out too much on my afc, Because I don't have an EGT. Hey, lithium, what are your settings? (If you don't mind)
 
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