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Underbody braces, turbos and more!

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PostPosted: Thu Sep 05, 2002 9:02 am 
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Joined: Thu Dec 27, 2001 9:50 am
Posts: 545
Location: Cracow, Poland
Hi!<br>I'm going to race (1/4 mile) on saturday and I'll use 99 or 102 (for wrc cars) octane fuel. How much should I advance timing??? I'm going also to remove exhaust (except header) and use 165/55/13 P700F tyres. And also how high should be idle???<br>Thnx for any help! <p></p><i></i>


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PostPosted: Thu Sep 05, 2002 10:59 am 
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Joined: Fri Aug 23, 2002 11:30 am
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Location: Barbados
To give a ballpark figure would be wrong, as advancing ignition timing varies on the engine/head design/compression ratio/gas etc. The good thing is that you have access to high octane (slow burning) fuel. You have to tune the car on a trial and error bases (best done on a dyno). Start @ around 10-12 deg. BTDC. Tune with the exhaust on or it will be difficult to detect the knocking that may occur. Tune with both no load (Flat revving) and Load (on road driving). Listen for the knock in both cases.<br><br>Presently, I have my car tuned to idle @ 12deg and full adv @ 38 deg using normal pump gas. With higher octane fuel 98+ you should be able to run @ 15deg idle. PS remember to brigde the terminal connector in the engine bay when setting the timing. <br><br>Just one question. Where did you get the 102octane fuel.<br>Mandingo. <p></p><i></i>


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 Post subject: ahhhh
PostPosted: Thu Sep 05, 2002 5:45 pm 
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Joined: Tue Jan 29, 2002 7:41 pm
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Location: Armstrong British Columbia
higher octane gas DOES NOT AS FAST. this is sooo wrong<br><br>higher octane does not slow down the rate of combustion. WHAT R U SMOKING<br><br><br><br>also DO REMOVE THE WHOLE EXHAUST SANS HEADER. this doesn't even work on v-8 cars. you rcar will run slower<br><br>oh yeah get some real small dia, wide race slicks. anything else is a waste of time<br> <p></p><i></i>


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 Post subject: Fuel Octane Rating - 101
PostPosted: Fri Sep 06, 2002 7:05 am 
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Location: Barbados
Murr you got to kiddin'<br><br>The octane rating of fuel 89,102 etc, specifies the ratio of octane-to-heptane within the particular fuel. Due to molecular structure of octane (carbon chains),it handles compression very well and requires a much higher compression than other carbon base fuels such as pentane and hexane. The operative word there, being compression. <br><br>There are two igniters within an internal combustion engine, Spark and Compression. With regards to this post, advancing the spark timing cause the mixture to ignite sooner. However, due to the compression characteristics of the higher octane fuel, the mixtures would reach total combustion later, allowing the piston to travel more in the compression stoke without apposing pressures (on the piston) from the expanding gases the combustion process. These apposing pressures causes knock.<br><br>This is what I meant by SLOW BURING fuel. The fact that it combust later in the compression stoke gives the false impression that it takes longer to burn. That is as layman as I can put it.<br><br>Happen tuning.<br>Mandingo<br> <p></p><i></i>


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PostPosted: Fri Sep 06, 2002 9:25 am 
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Joined: Thu Dec 27, 2001 9:50 am
Posts: 545
Location: Cracow, Poland
I don't have 102 octane fuel (maybe I'll get it, but I won't have time to tune the engine). But sometimes mechanics from rally teams sell it, sometimes is used aircraft fuel (but I don't know it's abilities). Also as I know european octane number is slightly different from US. We use standard 95 octane fuel, premium is 98 and shell sels V_Power 99+ (99 or more octanes- used by ferrari F1 as they say <!--EZCODE EMOTICON START :) --><img src=http://www.ezboard.com/intl/aenglish/images/emoticons/smile.gif ALT=":)"><!--EZCODE EMOTICON END--> ). I've bought 99 and I'm trying to get rid of normal fuel now.<br>Also my exhaust has 3 silencers, so it isn't very good for racing (it's good for low /middle rpms for better torque). So it won't make it worse. Also engine sounds then like hayabusa! <!--EZCODE EMOTICON START :D --><img src=http://www.ezboard.com/intl/aenglish/images/emoticons/happy.gif ALT=":D"><!--EZCODE EMOTICON END--> . Slicks aren't so easy to get, also track isn't so bad to use those pirellis (they have superb traction). If not I'll get 195/50/15 from my brother's miata <!--EZCODE EMOTICON START ;) --><img src=http://www.ezboard.com/intl/aenglish/images/emoticons/wink.gif ALT=";)"><!--EZCODE EMOTICON END--> <br><br>Thanx for anything and wish me luck.<br>PS. Last time I was 3rd in my class on bad tires and stock fuel, just beaten by 140hp fiat seicento and a formula car (something like f3) with 1.3 engine. It wasn't bad, and many 2.0 haven't had better time.<br>PS.2 My friend says, that we should remowe all doors and hatch to get it lighter (approx 80-100kg). What do U think about it??? (I know - it's silly...) <p></p><i></i>


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