110/90 mix
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Category: Competition
Forum Name: Drag Racing
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URL: https://theamcforum.com/forum/forum_posts.asp?TID=119054
Printed Date: Apr/19/2024 at 4:31am
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Topic: 110/90 mix
Posted By: hacksaw1971
Subject: 110/90 mix
Date Posted: Mar/18/2023 at 11:56pm
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the math said i should have 9.75-ish on my comp. think i missed..... 93 pump ain't doing the trick. can only run 28 deg total with all the ethanol in it here. and it will be going up this summer. so i got some 110 leaded ethanol free. 17.98 per gal. almost 400 bucks to fill my 22 gal tank. but i can run the 36 deg she seems to like with no flat spot or pinging and good plug read. if i was to run a 50/50 110 and 90 ethanol free from the pump do me any good? is there a mathematical way to figure out what the octane would be as i change the mix? thanks
------------- its the little things that make the biggest difference |
Replies:
Posted By: Trader
Date Posted: Mar/19/2023 at 11:01am
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A place to start: https://petroleumservicecompany.com/blog/mixing-fuels-and-calculating-octane/#:~:text=Lets%20say%20you%20mix%203,5%20%3D%200.40%20%28%2040%25%29.&text=So%20the%20octane%20of%20the%20resulting%20mixture%20is%20106." rel="nofollow - https://petroleumservicecompany.com/blog/mixing-fuels-and-calculating-octane/#:~:text=Let's%20say%20you%20mix%203,5%20%3D%200.40%20(%2040%25).&text=So%20the%20octane%20of%20the%20resulting%20mixture%20is%20106. Are you running any vacuum advance? If you are, disconnect/plug it and and see what kind of total advance you can run. Your mechanical advance may also be coming in too early. Typically you want all in at 3200 to 3600 RPM for street driving. But if the mechanical advance is starting to come in at below 2000 RPM with your SCR, recurving the distributor to have mechanical advance start later may also be were you want to start.
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Posted By: Judo390
Date Posted: Mar/19/2023 at 4:13pm
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As a cheaper alternative I buy 100 octane low lead at the local airport and mix it 50/50 with BP Gold ethanol free and have no issues with my 12/1 TRW pistoned 70 390. AV gas here has been running between $6 and $7 a gallon. ------------- 
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Posted By: hacksaw1971
Date Posted: Mar/20/2023 at 9:37am
i have no vacuum advance .... new springs and such has it coming all in at 3500-ish. had a flat spot in the transfer spot in the carb. but going to 13 deg base took that away. i live 15 miles from a small airport and forgot all about 100 octane avgas. going to try that next. it unleaded but has no corn in it... ------------- its the little things that make the biggest difference |
Trader wrote:Posted By: hacksaw1971
Date Posted: Mar/20/2023 at 9:38am
thanks .. forgot all about that. and i got a small airport just down the road... ------------- its the little things that make the biggest difference |
Posted By: garland performce
Date Posted: Mar/21/2023 at 6:20pm
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110 x 5 =550 90x5 =450 550 +450 =1000 divided by 10 = 100 octane Also might look at a additive Called Race Gas have used it in several cars and have used it on the Dyno
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Posted By: hacksaw1971
Date Posted: Mar/21/2023 at 8:37pm
thats what i was looking for ... thanks. ------------- its the little things that make the biggest difference |
Posted By: WesternRed
Date Posted: Mar/22/2023 at 12:12am
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Except you need to divide by 10 not 5 or you will have 200 octane. ------------- I've finally given up drinking for good...........now I only drink for evil. |
Posted By: Sonic Silver
Date Posted: Mar/22/2023 at 8:30am
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Posted By: BU1
Date Posted: Mar/22/2023 at 9:07am
Are you sure about the unleaded part???? Right now I think unleaded aviation fuels are scarce. 100LL (low lead) is the most common av fuel. ------------- AMO #2726 #1 1968 AMX Rally Green 343 Z code 4spd since 1975 #02642 #2 1968 AMX Rally Green 290 N code 4spd since 2019 #02959 |
Posted By: White70JavelinSST
Date Posted: Mar/22/2023 at 5:18pm
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X2 on what BU1 said. I've never seen unleaded av fuel. It may exist but who knows where... BTW, don't let the fuel police see you putting leaded fuel in your street driven car. It is against the law and carries a pretty hefty fine. I'm not sure how it affects race cars. Below is something I found on the web that states it quite eloquently. It's no longer legal to put leaded gas in your car
though, whether it's a classic or not. Don't even think about trying to
do it on the downlow either. If you're found to be driving a car with
leaded gas in the tank, you could well wind up slapped with a hefty
$10,000 fine for your ingenuity.
------------- 70 Javelin SST, second owner, purchased 1972 |
Posted By: garland performce
Date Posted: Mar/22/2023 at 6:23pm
| Yes thanks I changed it |
Posted By: hacksaw1971
Date Posted: Mar/24/2023 at 3:55am
il find out when i get some this weekend. if ya can't run leaded in ya old stuff. kinda makes me wonder whats in that lead additive at auto zone..... and i have tryed the race gass stuff... it made no diff in my charger. ------------- its the little things that make the biggest difference |
Posted By: WhatISit
Date Posted: Mar/28/2023 at 11:27pm
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Have you tried the VP Racing Fuels Octanium? It's a lead free additive that boosts 10 gallons of gas an actual 7 octane points. If you're running 93 but only need maybe 94/95, you could use a maybe 1/3 of the can for each full tank. One can costs $25. Seems like a pretty good option. http://vpracingfuels.com/product/octanium-unleaded/?c=207&" rel="nofollow - https://vpracingfuels.com/product/octanium-unleaded/?c=207& ------------- -www.FasterNLouder.com-<br />'73 Javelin AMX 401 V8 |
Posted By: BassBoat
Date Posted: Apr/08/2023 at 4:40pm
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A couple things. Lead response, the increase in octane per gram per gallon of lead is not linear. It doesn't take a lot of lead to increase the octane of unleaded premium a lot. It is not arithmetic. Lead response varies depending on the base fuel. Lucky that the lead response of catalytically cracked fuel is high. Also lucky that cat cracking is how we get high-ish octane fuel without lead. Typical race gas, the 110-112 stuff has 4 grams per gallon of lead. If you mix 1 gallon of race gas with 4 gallons of unleaded 93, you will end up about 100 octane. |