Effect of octane on max timing
Effect of octane on max timing Lets say I'm tuned for 93 octane and see 18 deg at WOT(above .6 @ 4000+) and have zero knock.
If I run it on 100 or 104 how much timing should I be able to add?
If I run it on 100 or 104 how much timing should I be able to add?
Re: Effect of octane on max timing Bump
C'mon guys... someone has to have an idea. I have this 5 gal. of 100 octane just staring at me, waiting for me to put it in.
Was just going to use it to test for false knock, but I have that out of the way.
C'mon guys... someone has to have an idea. I have this 5 gal. of 100 octane just staring at me, waiting for me to put it in.
Was just going to use it to test for false knock, but I have that out of the way.
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Joined: Nov 2001
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From: Raleigh, NC
Re: Effect of octane on max timing I have no scientific formula for you.
But, I've taken 93 octane to between 97 and 100 and was able to add 2 to 3 degrees of timing with about the same KR.
Hope that helps.
Of course, keep in mind if you make PE/RPM changes at the track, among other things, as you tune at the track, you throw the octane variable out the window if you are using KR as a gauge for this.
I think that's why no one answered your question. As with many things, there are so many variables. Heck, I can get .5 avg KR on one run in the street and get 2.3 on another. Just too screwy.
Now on the track, my KR stays pretty consistent with the same tune.
But, I've taken 93 octane to between 97 and 100 and was able to add 2 to 3 degrees of timing with about the same KR.
Hope that helps.
Of course, keep in mind if you make PE/RPM changes at the track, among other things, as you tune at the track, you throw the octane variable out the window if you are using KR as a gauge for this.
I think that's why no one answered your question. As with many things, there are so many variables. Heck, I can get .5 avg KR on one run in the street and get 2.3 on another. Just too screwy.
Now on the track, my KR stays pretty consistent with the same tune. Re: Effect of octane on max timing Thanks... thought you would be able to say something like, "if you increase octane by x points, you can add in x timing safely." Oh, well guess I'll just do it the old fashioned way... a little bit at a time.
John,
I'm seeing 5, 5 1/2 at around 6-6400 on the stock compression. I have the hi/lo octane tables set for 16 deg. in the lower right WOT area. I can probably go a little higher(18) but I'm still getting the bugs worked out in the midrange.
John,
I'm seeing 5, 5 1/2 at around 6-6400 on the stock compression. I have the hi/lo octane tables set for 16 deg. in the lower right WOT area. I can probably go a little higher(18) but I'm still getting the bugs worked out in the midrange.
Re: Effect of octane on max timing 16 degrees of timing sounds pretty low for 6 lbs of boost I have heard of folks running 18-21 degrees? I'd ask other folks what timing they are running.
With 100 octane you might be able to add a few degrees and pick up some horsies but is it 3 degrees or 6 degrees or ???
What does your car trap or dyno now?
With 100 octane you might be able to add a few degrees and pick up some horsies but is it 3 degrees or 6 degrees or ???
What does your car trap or dyno now?
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Re: Effect of octane on max timing this wont answer your question, but first how about adding timing right now on pump gas until you DO get a little knock.. at least then you know where the octane will start helping you.
also i wouldnt tune a street car for race gas.. cuz there will always be a time when you are just too busy or lazy to put the low timing table back in it (been there) and that is just not smart.
its more fun anyway to turn up the boost than the timing when you dont have any knock
also i wouldnt tune a street car for race gas.. cuz there will always be a time when you are just too busy or lazy to put the low timing table back in it (been there) and that is just not smart.
its more fun anyway to turn up the boost than the timing when you dont have any knock
TECH Fanatic
Joined: Nov 2001
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From: Las Cruces, NM
Re: Effect of octane on max timing Also probably just as important as boost, is were you are at in the efficiency range of the turbo or supercharger. If you running the turbo at its max flow then you are going have pull timing and richen up the full mixture. This why you can run some turbo systems (Incon) at relatively low boost pressure, make good power and run considerable leaner/more timing than some of the less efficient systems.
Gary
Gary
Tire Smoking Tranny Blowing Director
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From: Barto PA
Re: Effect of octane on max timing ya dont set that low. Mines set at 19 and with knock itslike 14 and it runs like crap up high 
.
Off topic I got my car running right again. Wonder if I could borrow your autotap?
.Off topic I got my car running right again
. Wonder if I could borrow your autotap? 