A friend who ran low 14's in a 55 Ford with a 272 Y block motor claims that 89 or 91 octane gas slowed him down. It has to do with the slower burn of the higher octane gas. Has anybody tried a lower octane gas and alcohol with any good results? I know that the lower octane gas will only support lower boost levels, but will the faster burning lower octane gas make up for the lower boost levels? I also know that that alcohol increases the octane level of the fuel. So would it be to much to expect lower octane gas and lower boost with alcohol to at least equal the performance level of higher octane gas with boost at say ........ 15#'s? Comments anyone?????
87 or 89 Octane and alcohol
- Thread starter Jeasen
- Start date
Welcome!
By registering with us, you'll be able to discuss, share and private message with other members of our community.
Why would you want to try and save a few dollars and risk costing you many many hundreds or thousands? 
There is about 20 cents per gal difference in cost between 93 & 87.
20 X17 gal (max if tank is empty) is $3.40 per tank full.
one tank per week for one year 52 x $3.40= $176.80 Max saving a year.
One blown head gasket will cost you a bunch ($500 to $1000 or more).
Back to your original question. Yes you could lower the boost and have the chip timing reduced any you could run the cheaper 87 octane fuel with alchy injection.
IMHO, the car probaby won't run as strong as 93 with regular timing and NO alchy.
You could also buy an import or a high gas mileage American car if your intend is to save fuel money.
Gary
There is about 20 cents per gal difference in cost between 93 & 87.
20 X17 gal (max if tank is empty) is $3.40 per tank full.
one tank per week for one year 52 x $3.40= $176.80 Max saving a year.
One blown head gasket will cost you a bunch ($500 to $1000 or more).
Back to your original question. Yes you could lower the boost and have the chip timing reduced any you could run the cheaper 87 octane fuel with alchy injection.
IMHO, the car probaby won't run as strong as 93 with regular timing and NO alchy.
You could also buy an import or a high gas mileage American car if your intend is to save fuel money.
Gary
I experimented with lower octane fuels including a few 93 octane ones that are available here in New Jersey. I was having a problem with transitional knock at part throttle. I switched to Sunoco 94 and have had no problems.
I am presently tuning the new combo (TE45A,55lb injectors, new exhaust, etc) and am presently running 23° in low gear and 21° in high with 23lbs of boost and have experienced absolutely no knock and O2's are still in the 790 to low 810's range. I am going to try tuning up the boost a little more and see what I get. I also want to try the lower boost and higher timing and see how she feels. Stick with the good gas and alky. Better to be safe than sorry.
I am presently tuning the new combo (TE45A,55lb injectors, new exhaust, etc) and am presently running 23° in low gear and 21° in high with 23lbs of boost and have experienced absolutely no knock and O2's are still in the 790 to low 810's range. I am going to try tuning up the boost a little more and see what I get. I also want to try the lower boost and higher timing and see how she feels. Stick with the good gas and alky. Better to be safe than sorry.
I've gotta agree with the others. Running alky defeats the purpose of wanting to go with low octane fuel. An alky kit is like $300, and the alky costs money to refill. The two (alky and 87 octane) seem to counter one another.
As for low octane fuel burning faster, that is true. If your friend was faster on low octane it was because his timing wasn't set up for the slower burn of higher octane gas. A lot of timing ensures max pressure at Top Dead Center, with high octane fuel. And more octane = more boost = more power.
As for low octane fuel burning faster, that is true. If your friend was faster on low octane it was because his timing wasn't set up for the slower burn of higher octane gas. A lot of timing ensures max pressure at Top Dead Center, with high octane fuel. And more octane = more boost = more power.
Mr URL
Member
- Joined
- May 24, 2001
- Messages
- 674
I've done a lot of experimenting with 91 octane and alchy. Works pretty well. That's the common gas around here. I won't try 90 or 87 cause I don't think it's worth it for many reasons. My 60ft time, E.T., and mph picked up over race gas if you can believe it. You won't get the transitional knock problem and be able to take advantage of higher timing with the alchy on if the timing tables are setup properly in the chip.
Similar threads
- Sticky
