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Passin Glass
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Discussion Starter #1
What is the minimum octane required for 14:1? I'm told 110 and typically C-14 but others have told me that Av gas at 104 with boost juice will be fine. I'm having a hard time with 600+ a barrel of C-12- C-14 compared to 350 for av gas. It's a true 14:1 motor that is going to get detuned this winter to run pump gas ..but for the summer I need to find out the best fuel for the best price.

jeff
 

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Banned
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540 Posts
I don't have any problem with C-12 at that compression. I have also used Torco 110 and 112 with no problems. The engine lost power on the dyno with C-14, so 107-109 octane is fine with mine. Hope that helps. RR
 

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Cantard
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Not sure if you guys can get it but mark4 would be easier on your wallet and you would be fine with that.
 

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What is the minimum octane required for 14:1? I'm told 110 and typically C-14 but others have told me that Av gas at 104 with boost juice will be fine. I'm having a hard time with 600+ a barrel of C-12- C-14 compared to 350 for av gas. It's a true 14:1 motor that is going to get detuned this winter to run pump gas ..but for the summer I need to find out the best fuel for the best price.

jeff
what heads
cam size,duration lobe sep<ect.
all this things will play an affect on the octane required;)
hope this helps,oh yeah elevation also.good luck:)hand
 

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Resident Ford Nut
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10,075 Posts
Hooli,

I know a guy that runs on Av Gas with 12.5:1 with no problem's but 12.5 is not 14:1 that extra point and half might kill ya. With an engine that close to the borderline I'd run the known quanity of the C-12 vs Av gas.

Good luck with that baby. :)devil

Sleeper CP :D
 

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417 Posts
looks like you are the one that bought the alum boat with the lightning, that is a cool boat. i ran 12.5 to 1 with iron head with no problems on avgas
 

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Gone
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I don't have any problem with C-12 at that compression. I have also used Torco 110 and 112 with no problems. The engine lost power on the dyno with C-14, so 107-109 octane is fine with mine. Hope that helps. RR
I had the same results as others did in PGF. And we were above 14.1 compression.
 

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mo balls than $cents$
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11,734 Posts
Get 100LL from the airport. That's what most planes run on and it's 110 octane.
just left my local airport getting some 100ll, its definately 100 octane, or at least that's what the lil sticker on the pump said.
 

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Passin Glass
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2,825 Posts
Discussion Starter #10
This is all I have on the motor right now

Chevy Bowtie Block 468 CI, 14 -1 compression
Eagle Crank
BRC Rods
JE Pistons
Donavan Gear Drive
Brodix BB2xtra Heads
Manley Valves
Jesel valve train
Crower Cam and Lifters
Dart Tunnel Ram
Dual 850 cfm holleys
MSD ignition Marine 7AL

I'm not sure 600 ish a day to run it is gonna fly to far with the wife..:p
I'm waiting fo the build sheet from the last owner. As soon as I get my mits on it I'll post the info. Thanks for the replys.
Jeff
 

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mo balls than $cents$
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11,734 Posts
run alky and be done. :D
:)devil thinking about it myself, it'll be cheaper to run soon enough:)sphss


i've been wondering about busby's torco octane booster i've seen. has anyone used it yet? supposed boosts alot, but noone has stepped in to say how much or if it helps.
 

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B.A.M aka "Black Azz Mike
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2,925 Posts
<---- ran 12.5-1 on avgas all iron motor for 3 years and no problems. I was also locked out @ 38* of timing;) cylinder temp is the key)
 

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Where do you buy this thing you all call -alky-halll! Impatient1 your not talkin e85..?
 

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mo balls than $cents$
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Where do you buy this thing you all call -alky-halll! Impatient1 your not talkin e85..?
no, e85 is a pipe dream at this point. after all the political bs is said and done, e85 will go away just like ethanol did back in the early 1900's;) i've given up hope getting a e85 pump anywhere near me, and i've aquired all the necessary stuff to convert my fuel system over when it became available. even built a higher compression motor with the intent of burnin e85, but now i'm stuck buying high $$$ race fuel:mad: we were "supposed" to be getting a ethanol distillery in antlers okla. , but i've yet to hear them break ground on it, prob never will.

i can get methanol at almost 1/2 what my race fuel is costing me, therefore if my motor requires 75% more methanol than gas, well i'd still be better off runnin methanol for the added power, cheaper runnin cost, added power:D:)devil:)hand i change my oil so damn often anyways, it'd never have time to dillute the oil any. i would have to change rings and gap sizes.no biggie, just a sunday project:)bulb

now if i can get away with runnin avgas with higher jetting and the torco booster stuff, i'd go that direction but mum is the word on the stuff i guess, no info out there yet on if it works etc.
 

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I don't have any problem with C-12 at that compression. I have also used Torco 110 and 112 with no problems. The engine lost power on the dyno with C-14, so 107-109 octane is fine with mine. Hope that helps. RR
Hey, could you tell me more about losing power with C-14. We used C-12 in our car @ 14:1 (600 HP SBC) with no problems. We went with C-14 in our boat @ 14.5:1 (920 HP BBC), but thinking about going back to C-12 since we are not turning it very high RPM (7500 RPM).
My experience with C-14 has been good, but I've never heard of anyone actually losing power with it compared to C-12 or other similar fuels. Again, would appreciate any experince.
 

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Is methanol =alky?? I still have no idea where to get any around here(utah). David519 I think the reason a higher octaine(than you need) could cause power loss is just simply because higher octaine fuel burns slower. If thats not correct somebody please straighten me out.:)grn
 

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mo balls than $cents$
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Is methanol =alky?? I still have no idea where to get any around here(utah). David519 I think the reason a higher octaine(than you need) could cause power loss is just simply because higher octaine fuel burns slower. If thats not correct somebody please straighten me out.:)grn
yep, alky and methanol are 1 in the same;) some call it alky, some methanol.

the higher octane on a motor set-up to run a lower # octane, will flash later than the lower octane fuel will, or later on the down stroke than the c12.
 
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