Okay, hit 100 replies! Should we go for time? Just five months to go to keeping this thread alive for a year.
On a forum for flatheads, all flatheads, not just Ford V8s, the question comes up often, which gas to use. Many people state premium,
those motors are well under 9 to 1 compression. Unless supercharged, absolutely no need for high octane.
Acura recommends 91 octane. Mid-grade is 89 octane. As long as it works for you, use it and save money. The car has some ability to tune the combustion cycle to accommodate slightly lower octane.
Yeah, thatās nuts. Bigger problem is the ethanol affecting the old rubber components on many of them.
I suppose they have to compare the cost of replacing the wetted rubber bits with the higher cost of E0 if itās available. There arenāt many ethanol-free stations near me. The closest is about 15 miles.
Octane in my area is 87-89-93
On an old iron block and heads V8 with a distributor, 9.5:1 is about as high as you can go on 93 octane while still running optimal ignition timing, add aluminum heads and you can raise it one point to around 10.5:1 and still run on pump gas, anything higher you have to run ocatane boost or100+ octaneā¦ E85 has been a game changer in the hot rod world with a compatible fuel system (E85 carburetors etc)ā¦
Now with todays engine (MDIS-COP, knock sensors with programming, cam designs etc), technology has changed and compressions are running wayyyy more, my Tacoma is running 11.8:1 on 87 octane with no issues, I put 93 in it once by mistake (had the fun car on my mind lol) and I didnāt notice any gains in performance or MPGā¦
MDIS = multiple distributorless ignition system, and does not have to be COPā¦ before anybody askedā¦ lol
Every pump Iāve seen shows the octane right on the button where you go to select the grade. Midgrade is almost always 89.
Well this is what I read in a very dense and long technical paper on emission controls. Sorry I donāt have a link.
I remember it well because I had never heard of that before. But this was an engineering paper. Not something someone just posted on the internet.
The paper was from some time ago so maybe things have changed especially with GDI where the fuel injection timing can be retarded to avoid pre-detonation but I was referring to spark retard.
Also the paper specifically mentioned deposits in the cylinders. I would assume a clean engine would not have that problem. Use top tier fuel I say.
Should fuel pumps and fuel hoses last 75 years? I hope the rubber parts have been replaced during the last 30 years, we have been using E10 since the 1980ās.
So would I, so itās a minor concern. Running regular in an engine with 6.5:1 to 7.5:1 compression ratio, like many of the stock flatheads. would seem to be zero concern. Hopped up? Then premium could be needed, of course.
Our safety officer had a habit of driving away with the hose still attached to her car, so that hose would be replaced anyway. 