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Unread 06-11-2015, 03:51 PM   #1
Web Wheeler
hutch1200's Avatar
1979 CJ7 
Join Date: Feb 2007
Location: Clarks Summit, Pa
Posts: 3,155
What to use for Octane boost. Your thoughts?

I sure hope this is the correct place to post this. If not let me know.
My question is, what do you guys use for an octane boost for your weekend jeeps. I'm putting out at tad over 400 HP (on the engine dyno during cam break-in)from my 360. I was gonna build a street rod, but I had my High School CJ7 in my barn since late 99 when the frame rotted out. It has an AJ's Kevlar/Glass body & 1piece Kentrol front that tilts either way. It needed a frame, so this is a nut & bolt resto from a late '86 WT frame (hence the D-44). My 4' Roughest country lift turned out to be closer to 6"s & called for the 35's to get the proportion back. My 33 looked like donut spares!
Engine specs=
1)10.75 Bulltear forged, pop-up pistons
2)40+ hours of porting & port mating the Pacesetter headers, and Edelbrock Air gap w/670 Holley Truck Avenger

2.5) Pacestter headers are 1-5/8 tubes into 3" collector. Planning on 2.5 pipes into 3" Flowmonster turbo style mufflers, & 2.5's out the back corner. Open headers for now, but advice on that is welcome as well..
4) Comp 292 (Hydra, 2500-6500 RANGE, Duration=292, 244@.050,518 LIFT, SEPERATION=110, CENTERLINE106, p/n 10-210-4)
roller lifters & rockers
5) Stock bore & deck
6 Forged bottom end, wish I had the coin for a bigger oil pan at this time.
7 T-18 (6.32 granny low for off road use)
8) D-44, 4.10 w/Tru-Trac & 35 BFG a/T's
SOooo, my question is this. What do you guys use to prevent Pre-ignition. I'm at about 1500-2k feet above the sea.
I've been told to use 93 octane, cheap gas+ octane booster (Nobody gave me a brand!) or AV gas, which I have access to, but the price I imagine is astronomical!).
SO, what do you all do? I don't want to back the timing off, or add 6" head gaskets to lose all the power I tried so hard to make.
Basically it's a street machine that I trail ride & hit mud with! Even w/the stock 304 & 2.5" Rancho lift I could put the speedo into the fuel gauge. I've only driven it 1 mile & w/open headers couldn't hear detonation if it was a hand genade!
It will stand straight up w/the x-case in low & the hubs unlocked, so a Tatton's shaft is on the way!
I'm open to all suggestions and critisisms
Thanks in advance for any help.

I've also learned that sometimes... when people don't agree with you .... its best to hold them down and kidney punch them till they agree with you

Last edited by hutch1200; 06-11-2015 at 04:02 PM..
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Unread 06-17-2015, 04:15 PM   #2
Web Wheeler
222Doc's Avatar
2012 JK Wrangler 
Join Date: Sep 2011
Location: Lake Havasu City, AZ
Posts: 5,234
I have used xylene no more than 10%. start low. I use that in a 454 that is running 11:1 Or buy race fuel. All the shelf stuff you will find on shelfs is all BS. It takes a lot more than a pint bottle to move the gas from 93 to say 105. Google it

Here in our town race gas is at about any pump in town. I was running the sunoco 100 no lead in a Solsitce that was a bit over boosted, 4 banger.
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Unread 06-18-2015, 10:41 AM   #3
Registered User
1976 CJ5 
Join Date: Jan 2011
Location: Carson City, Michigan
Posts: 827
I keep saying... E85
'76 CJ5
434 pump gas SBC with an NX/HVH plate system
th350/Coan 5,000 converter/Dana 300 tcase
Dana 30 front with 4.56's/Dana 44 rear with 4.88's
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