What's Your Octane?

Hey Gang,

Now that gas prices are spiking around the country again I have been tempted to run 87 octane in my '66 289 'Stang instead of the usual 93. Have to retard the timing a little, but it's sure more affordable - at least for a while.

What are you all running now days in your mostly stock classics?  

My '66 is far from stock (internally) with roller cam conversion, roller rockers, ported heads, forged pistons, etc. but I only drive it once a month or so (unfortunately have limited free time these days) so I keep 93 in it for the few miles it sees a month, same with the Cobra.

Now my '90 Fox body is a 347 stroker with aluminum heads, custom burned chip, etc. and I have always run 93 in it. The last couple of fill ups I've downgraded to 89, which only really saves me about $2-3 a tank, with no performance impairment, pinging, etc. I don't think I'd drop all the way to 87 in it due to the performance build of the engine. I think I'd be getting quite a bit of spark knock.

The rest of the daily drivers all take 87 no issues. Though filling the 23 gallon tank in the wife's Sport Trac gets it close to $100 these days!

Mark  
Mark Houlahan
Technical Editor for:
-Modified Mustangs & Fords Magazine
-Mustang Monthly Magazine

1965 FFR Roadster 427W/TKO-600 5-speed
1966 Mustang 289-4V/C4 Auto
1968 Mustang 4.6L Three-Valve/5R55S Auto
1990 Mustang 306/AOD
2001 Ranger SuperCab 4x4 3.0L V-6/5R44E Auto
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto

Mark, I won't be doing it again for sure - I'm almost ready to siphon it out, luckly I only put in half a tank. Thought I could get away with it since it is mostly factory stock, nooooo. It not only detonated, it also huffed and puffed.  

Funny, I wouldn't even consider putting less than 93 in my built Pontiac 400's and 455, they would laugh at me and spit it back in my face. I did apologize to my wife's Mustang and promised never to do it again.    

Throw a bottle of octane booster in it and use it. OR fill the rest of the tank with 93 to mix it, you should be OK then...

Yeah, I wouldn't dare run any less than 93 in the 427W in the Cobra! LOL

Mark  
Mark Houlahan
Technical Editor for:
-Modified Mustangs & Fords Magazine
-Mustang Monthly Magazine

1965 FFR Roadster 427W/TKO-600 5-speed
1966 Mustang 289-4V/C4 Auto
1968 Mustang 4.6L Three-Valve/5R55S Auto
1990 Mustang 306/AOD
2001 Ranger SuperCab 4x4 3.0L V-6/5R44E Auto
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto

Hi Braz. Here in Arkansas we haven't seen 93 octane for several years, you are blessed to be in an area where it is still offered. I won't put 87 in anything, its total dishwater, as you have found. I have resorted to buying Sunoco 94 octane at $5/gal to keep my carbed 455 happy, and the daily car gets 89. These days, carrying half a bottle of octane booster in the trunk ain't a bad idea because MANY times the gas coming out the nozzle isn't what the octane sticker says ...  

Heeeey Bro-n-law, didn't expect to see you appear - what a welcome sight! Did you get your green card?  

No, y'all haven't seen 93 octane in Arkansas cause your busy pumping 98. Here look, I have a photographic memory!


See ya back at the Round Table.  

We have a few stations around here that pump non-ethanol gas. I'm going to start using them for my '66 and the Cobra. A few Sunoco stations too with high octane pumps as well.

True story- A pal of mine with a new Roush Stage 3 (supercharged), stopped at a small station to put 93 in it before a dyno tune session. The tuner tried making pulls and while watching the knock sensors and AFR (2012 Mustang 5.0L) it was apparent what he had in the tank was NOT 93. Pulled out his receipt and sure enough it said 93 octane at 4.23 a gallon. Nice!

Mark  
Mark Houlahan
Technical Editor for:
-Modified Mustangs & Fords Magazine
-Mustang Monthly Magazine

1965 FFR Roadster 427W/TKO-600 5-speed
1966 Mustang 289-4V/C4 Auto
1968 Mustang 4.6L Three-Valve/5R55S Auto
1990 Mustang 306/AOD
2001 Ranger SuperCab 4x4 3.0L V-6/5R44E Auto
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto

I can totally believe it dude. Down here in Texas (and probably all over) the stations are struggling too, and some go to some unscrulplous means to make up their costs. 87 octane labeled 89 or 93 (Houston Racing around the corner from me verified that once). And another annoying thing they do is advertise regular for a certain price like $3.85 a gallon, but if you look close at the little price window it says $4.32 a gallon. When you ask about it they refer you to a tiny post-it note on the side of the cash register that says "cash price only." Grrrrrr.

Speaking of ineptness - two things I saw recently at gas stations. First, an underground tank was being refilled in hard pouring rain with nothing covering the hole and water from the pavement pouring in it. Then a week ago, a guy took the cover off to fill it and started wiping all the dirt and crud off the cap into the tank.....I ask him what he was doing and he said "oh, it sinks to the bottom."
If he wasn't three times my size I would have kicked his butt.

Mark, I'm sure you've got pics of your cars posted somewhere, I sure would like to see them!  

In 1998, I built a 347 stroker for my GT350 and running on pump gas was the target. I chose 9.9:1 pistons, .512 lift cam, trickflow heads, 6AL MSD, MSD Pro-billet electronic dist, 650cfm Holley and aprox. 375-400hp. It runs great on 87 oct. and I add fuel system cleaner and upper lube intermittently. It will idle in 4th gear with no accelerator at 16 mph. It WILL clatter if extremely lugged but not during normal hot foot driving. But, crappy gas works but I did have to replace valve guides and a valve or two at 25,000 miles, probably due to not enough additives in the cheapest gas but the lowered compression has been the trick to getting no clatter.

I don't guess this is helpful because of the "What are you all running now days in your mostly stock classics?"  

Hey Cush! Naw man, I was just throwing it out there for the whole gang. I just said mostly stock classics cause that's what ours is, I haven't done much too it cause it's my wife's Mustang and she's already been freaked out a few times when my Trans Am got away from her (many circles - many amused spectators) - ooops.

Yeah, any hi-per modifications pretty much changes the equation. What .510 lift cam are you using? how did you lower the comp with the trickflows? (not really familiar).  

COMP Cams 35-351-8 - COMP Cams Xtreme Energy Camshafts .512"lift

The 9.1:1 Probe pistons were used. They have a dish in the top to lower compression.
Trickflow Heads TFS-51400002-M61. Nothing was done to the heads to effect comp. ratio.  

yep braz thats my pet dinosaur's favorite buffet, in the pic. The 104 they just took away was same price as that 98!

I stopped in to check back on a bodywork thread here, and saw this one. 91 with ethanol is the best widely available gas in my area and it works OK on about 8.5:1 compression or lower, in most stock all-iron engines anyway. Does y'alls car have the hi-po 289 or plain? I don't recommend putting anything in the old horse except for the modern best pump gas you can find. Not only for octane but also for the better additive combo found in the higher priced gas.  

Yeah ID, Cil's is the 289 Hi-Po. When we bought it in '09 the owner had just rebuilt it and put in an unknown cam. I never have pulled it apart to investigate because it hauls azz better than my first car - a 1971 302 Boss.

I did as Mark suggested and poured in some octane booster and filled it the rest of the way with 93 - worked, she's happy.

My mission of the morning was to get new tires and an overdue inspection done. Got the tires, replaced a rotten dimmer switch, washed off bird doings smack in front of my view, and headed to the inspector. His computer print out thingy was down and being repaired. I went back home to find my electricity was off, the whole area was out. Well, figured I'd waste some time and remove the old inspection sticker, Windex off the gum and head back. I always have them give me the sticker to put on because they always put it on crookjawed - I hate that. Got back over to Mr. Inspector and they were all sitting outside their shop with no electricity either.

Taint one thing it's another.
 

Braz, the FFR and the '68 are/were projects with Modified Mustangs & Fords, which is another title I work on here and was editor of the past few years. You can find build info/photos on both cars at www.mustangandfords.com and just click on the project car link. The FFR is called Snake Charmer and the '68 is called Generation Gap.

The '66 hardtop I built many years ago and you can find stories on it here on this site under the project car link. We just called it "Project '66" at the time. I know, no creativity! LOL

The '90 is my daily driver and purchased new. I've got to dig up a photo of it when it looked better (needs paint these days), and the Sport Trac is the wife's daily driver. Fairly stock except for cold air induction, 75mm maf, and after-cat exhaust on it. She won't give that think up. She just loves it.

Mark  
Mark Houlahan
Technical Editor for:
-Modified Mustangs & Fords Magazine
-Mustang Monthly Magazine

1965 FFR Roadster 427W/TKO-600 5-speed
1966 Mustang 289-4V/C4 Auto
1968 Mustang 4.6L Three-Valve/5R55S Auto
1990 Mustang 306/AOD
2001 Ranger SuperCab 4x4 3.0L V-6/5R44E Auto
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto

Hey braz, and all you old car lovers- I found an interesting tidbit of info on the Sunoco station's FAQ under "why does your 87 octane cost more?". I cut and pasted the answer below and highlighted the important sentence. Good to be aware of this-

"Congress has been subsidizing ethanol since the early 1980's, so retailers who sold ethanol gasoline did so at a lower cost. The most common product sold was E-10 (10% ethanol) 87-octane gasoline, which is similar to 89-octane gasoline because of the octane boost from ethanol. Some retailers advertised E-10 87-octane gasoline as 89-octane gasoline while others kept the 87-octane sticker and added the E-10 label. Since the 30-year ethanol subsidy expiration in 2012, many retailers have switched to E-10 85-octane gasoline, which is advertised as 87-octane gasoline. In short, most retailers sell a mixture of 90% 85-octane gasoline and 10% ethanol that is rated as 87-octane. On the other hand, we sell 100% 87-octane petroleum gasoline. To make an fair comparison, purchasing one gallon of E-10 85-octane gasoline is equivalent to buying 0.90 gallons of 87-octane gasoline; the 10% of ethanol adds 2 octane points to the 85-octane gasoline. The price of E-10 85-octane gasoline is 11% more than advertised when compared to pure 87-octane gasoline. For example, if E-10 85-octane gasoline is priced at $3.69 per gallon, then the equivalent cost is $3.69 per 0.90 gallons of 87-octane gasoline, or $4.09 per gallon."

thats from this page:

http://www.hioctanefuel.com/faq.html