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Safe boost increase w/ race gas?

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Old Apr 13, 2006, 09:35 AM
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If you dont change your tune then AF will probably stay the same. But you can safely run a much leaner AFR with race gas.
Old Apr 13, 2006, 09:49 AM
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Since this thread is still going, I did turn it up to 24lbs and the air/fuel was very close to the same, maybe leaner by a couple of tenths. And it felt good as hell.
Old Apr 13, 2006, 02:34 PM
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It is totally up to you. Obviously with higher octane you can run higher boost and a leaner a/f ratio. Personally, i run 114 leaded race gas all the time. It gets expensive but it is cheaper than having to buy parts for a full build since i am a boost junkie, haha. Good luck.
Old Apr 13, 2006, 02:35 PM
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WHTEVO, haven't you had to buy parts to fix things anyway! =P
Old Apr 13, 2006, 02:43 PM
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Originally Posted by WHTEVO
It is totally up to you. Obviously with higher octane you can run higher boost and a leaner a/f ratio. Personally, i run 114 leaded race gas all the time. It gets expensive but it is cheaper than having to buy parts for a full build since i am a boost junkie, haha. Good luck.
About what % of fuel did you take out for 114 octane?
Old Apr 13, 2006, 02:49 PM
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Originally Posted by Warrtalon
WHTEVO, haven't you had to buy parts to fix things anyway! =P
I am talking about in my Evo. The talon hasn't seen anything over 93 octane; which is the car i had to change out parts in. It was because of the tune, nothing else.
Old Apr 13, 2006, 02:50 PM
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Gotcha. Assumed you would do the same thing for any of your cars (re: 114oct) based off your comments about being a boost junkie.
Old Apr 13, 2006, 02:52 PM
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Originally Posted by Jeff_Jeske
About what % of fuel did you take out for 114 octane?
What do you mean what percent did i take out? When i do run it i wait until my tank is about empty then i fill it with 114. Then when that is gone i fill it again with 114 and so on until i decide to do some 93 octane, then the cycle repeats itself so to speak. So it is seeing a full 114. DO NOT run leaded gas if you are running a cat and the stock o2 sensors. I am running no cat and only one wideband.
Old Apr 13, 2006, 02:55 PM
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Originally Posted by Warrtalon
Gotcha. Assumed you would do the same thing for any of your cars (re: 114oct) based off your comments about being a boost junkie.
Yes i do the same for any of my cars. The talon is still in the process of getting a full tune for 91 octane then we will move on up to higher octane gas. The talon is basically a full out race engine , the Evo is not at that point yet although i have a **** load of stuff sitting at the house waiting for me to put it on.
Old Apr 13, 2006, 02:55 PM
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WHTEVO, he means like removing fuel with your tuning device...what % fuel did you remove for the AFRs to be where you want them...
Old Apr 13, 2006, 02:58 PM
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I run it around a 12.5 a/f ratio +- a little when on race gas. It will all depend on your mods on how much changing it will affect your a/f ratio to be "safe". I would not go off of my settings unless your car was setup exactly like mine. Make sense?
Old Apr 13, 2006, 04:18 PM
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this may seem like a total n00b question, but last time i raced, i dumped in a half tank of 110 leaded w/ about 1/4 tank of 91, drove to the track, cranked the MBC about 6 full turns, and raced. Someone asked me if i had "reset" the ecu i.e. unplugged the neg. terminal on the battery. I hadn't, but didn't think that it really mattered. Does it make a difference?
Old Apr 13, 2006, 04:33 PM
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Originally Posted by Warrtalon
You will be 100% fine at 24psi even on a 50/50 mix of 93/110. There's no secret to determining octane. It's just basic math. If you have half 93 and half 110, then your octane is the average of the two, which is 101.5 (basically). On that octane, you can run 24-25psi all day. You would be better off with unleaded race gas, if it's available, since you can't retune, but although you may run a little richer, you will overcome that by pushing an extra 2-3psi without fear of knock.

What do you mean what happens when you get knock? Do you mean how do you know if you're knocking, or are you actually asking what the side effects of knock are? I was kinda hoping you would know that or could find it from searching, but if your engine is knocking, the ECU will pull timing, which lessens power. Also, knock damages the engine...
Hey Warrtalon, do you know a good place to get unleaded race gas around baltimore or dc?
Old Apr 13, 2006, 06:35 PM
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You dont need to reset the ECU to run more boost. Don't worry about it.

As for the % question. When I run 100 octane I pull 4% fuel to get to 12.0:1 AFR. I was wondering how much fuel you pull when you run 114 or C16.
Old Apr 13, 2006, 07:09 PM
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Originally Posted by WHTEVO
I run it around a 12.5 a/f ratio +- a little when on race gas. It will all depend on your mods on how much changing it will affect your a/f ratio to be "safe". I would not go off of my settings unless your car was setup exactly like mine. Make sense?
I assume that you run 12.5 when you are drag racing and not when you are road racing. I read that road racing/hotlapping requires lower AFRs than drag racing. I would imagine that 11-11.5 would be good for a 20 min road racing/hotlapping with 100 octane gas.


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