Carbureted LSX forum - 87 octane?

Fixing to take off in my car on a 4 hour trip each way and it would be nice to run some garbage 87 octane fuel like I do in my beater

Right now I'm running 34* from 800 rpm through 6800 with no advance from a map sensor and get no detonation. On 10% ethanol 93 octane

What is your guys opinions where to start for a 87 octane "curve" with using the map to add some vac advance for maximum fuel milage

Motor specs in signature

how much compression in it? judging off the specs on your sig, I'd say just run it, and leave the timing the way you have it. When you intend on beatin on it, then put in the 93.
Only if your comp is above 10.5:1 would I lower timing to 31-32* for 87.
JMO
Barrett

how much compression in it? judging off the specs on your sig, I'd say just run it, and leave the timing the way you have it. When you intend on beatin on it, then put in the 93.
Only if your comp is above 10.5:1 would I lower timing to 31-32* for 87.
JMO
Barrett

Its stock compression other then the intake, headers and cam its stock i

With no overdrive and 4.30 gears, I would NOT be looking forward to that trip! Guess I'm getting old... :nod:

No doubt be a loud slow trip, all we have local is 1/8th mile that's the reason for the gear lol


On a side note I pumped my 12 gallon cell with 87 tonight set the timing to 30* and added 15* via the map sensor copying your map russ, seemed to do ok on the 10 mile ride home, I put between 60-70 miles on it a day so shouldn't take long to see how it burns through

id never would have 32 timing anything below 2500 rpm.. ..sounds crazy to me.. maybe im just used to old school bbc.. my ly6 carbed i have 15 idle to 1000rpm then ramps up to 31* at 3000 rpm.. runs good to me.. use vacum curve to clean up down shifting etc. slowing down..

id never would have 32 timing anything below 2500 rpm.. ..sounds crazy to me.. maybe im just used to old school bbc.. my ly6 carbed i have 15 idle to 1000rpm then ramps up to 31* at 3000 rpm.. runs good to me.. use vacum curve to clean up down shifting etc. slowing down..

You are missing out on alot of throttle response, and crisp part throttle running if you dont add as much timing as it will take at the low end. With a converter that stalls at 3500, there is no worry of lugging the engine, therefore no worry about the amount of timing in it at lower revs.
You should try setting your timing up to give your max total timing just above idle speed, and you'll see how much happier it feels.
Yes definitely use the vacuum advance as well, to add in another 10-15* at part throttle /high vacuum

With no overdrive and 4.30 gears, I would NOT be looking forward to that trip! Guess I'm getting old... :nod:

^^^^ That's the truth! :judge:

I wouldn't worry about the map at all with this guys set-up. I would 0 out the whole map curve as his time below 3000 rpm's is non existent with 4.30 gears and a 3500 stall. I would probably go with 30 degrees total flatlined from 3000 RPM's on for your trip with 87.


Manual transmissions and lower stall speeds should use the map and a carefully configured curve.

I don't see a problem with 87. Thats all i run in mine. I have 9.4:1 compression.

Wish we still had 87 with no ethanol...:(

I run 36* with my LQ4 and it diesels down when i shut it off with 87 in the tank, otherwise, it doesnt clatter.

No doubt be a loud slow trip, all we have local is 1/8th mile that's the reason for the gear lol


On a side note I pumped my 12 gallon cell with 87 tonight set the timing to 30* and added 15* via the map sensor copying your map russ, seemed to do ok on the 10 mile ride home, I put between 60-70 miles on it a day so shouldn't take long to see how it burns through

Seems to run just fine on 87 with the timing and such doesn't seem to have lost any power either and has seemed to pick up right at 1mpg. Which isn't huge but not horrid for this setup so I Done my math and came up with 18.1 mpg was getting right at 17mpg before so I don't think its going to get better then that with this gear and converter. Going to fill it up again after work and see what happens on this tank.