atikovi
New Member
I just got this '91 and put some regular in it and can't hear any knocking or other issues although I haven't really put my foot in it yet. Do you have to use premium?
Any problem using regular gas?
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jelloslug
Digital
The car has a knock sensor so if there is a detonation issue it will retard the timing on it's own. Long story short, you won't damage anything.
kevinspann
Don't take my advice.
That's all I've ever run...
JRA2000TL
The Complainer
I now use regular too, although this week I did an experiment in my 89. I found some 88 octane 100% pure (no ethanol) gasoline. I filled up with that and added Chevron Techron fuel system cleaner because it was on sale. I want to see the difference in mpg.
I'm thinking even though non-ethanol gas is better than the blended gas, paying $4.29 for pure gas vs. $3.60 for blended, won't end up saving me in the long run with better fuel economy anyway.
All that said, 87 is fine like everyone else noted.
I'm thinking even though non-ethanol gas is better than the blended gas, paying $4.29 for pure gas vs. $3.60 for blended, won't end up saving me in the long run with better fuel economy anyway.
All that said, 87 is fine like everyone else noted.
RonPorter
SHO Club of America
Across 6 SHOs, on with full Bolt-On stage mods, 87 all the time.
Well, except during Convention time. Usually 90F - 100F+ temps, so I run 91-93 just during that period.
This was determined almost 23 years ago:
Well, except during Convention time. Usually 90F - 100F+ temps, so I run 91-93 just during that period.
This was determined almost 23 years ago:
Lorenr
Member
High Compression Motors
Higher compression motors make more power, are more efficient and that means greater fuel economy. More power can be made all the way up to 19 to 1, but the big gains stop at about 14:1. NASCAR has a limit in order to keep teams out of the very high ratios.
Some engines tolerate high compression better than others. I've seen Ford FE's burn holes in their pistons at 9:1 on premium with 32 degrees total advance. Hemi style combustion chambers (Chrysler, Toyota, Yamaha, etc) do much better. Fuel injection helps. Most modern engines would destroy themselves without "knock sensors". "Direct injection" where the injector is located in the combustion chamber tolerates a lot of compression and ignition advance. Leaky piston rings and valves allow oil into the combustion chambers increasing pre-ignition.
The SHO engine will probably do better with premium fuel under most conditions such as around town, short bursts, stop and go driving. It might do ok on regular fuel under "no load" continuous driving on the freeway. The SHO motors' knock sensor will detect pre-ignition and automatically retard timing thus decreasing efficiency, power and economy. I also suspect that at a true 10:1 the SHO motor will not see any pre-ignition on premium fuel.
Gasoline is made a number of ways at the refinery and some batches tolerate pre-ignition much better than others, even with the same octane rating. Most states test for posted octane and I've learned that it rarely varies more than a tenth of a point. Refiners would pay a public relations nightmare if it wasn't.
I use premium 92 octane because I believe I get better average fuel economy and probably more average power. Probably.
Higher compression motors make more power, are more efficient and that means greater fuel economy. More power can be made all the way up to 19 to 1, but the big gains stop at about 14:1. NASCAR has a limit in order to keep teams out of the very high ratios.
Some engines tolerate high compression better than others. I've seen Ford FE's burn holes in their pistons at 9:1 on premium with 32 degrees total advance. Hemi style combustion chambers (Chrysler, Toyota, Yamaha, etc) do much better. Fuel injection helps. Most modern engines would destroy themselves without "knock sensors". "Direct injection" where the injector is located in the combustion chamber tolerates a lot of compression and ignition advance. Leaky piston rings and valves allow oil into the combustion chambers increasing pre-ignition.
The SHO engine will probably do better with premium fuel under most conditions such as around town, short bursts, stop and go driving. It might do ok on regular fuel under "no load" continuous driving on the freeway. The SHO motors' knock sensor will detect pre-ignition and automatically retard timing thus decreasing efficiency, power and economy. I also suspect that at a true 10:1 the SHO motor will not see any pre-ignition on premium fuel.
Gasoline is made a number of ways at the refinery and some batches tolerate pre-ignition much better than others, even with the same octane rating. Most states test for posted octane and I've learned that it rarely varies more than a tenth of a point. Refiners would pay a public relations nightmare if it wasn't.
I use premium 92 octane because I believe I get better average fuel economy and probably more average power. Probably.
RonPorter
SHO Club of America
Can't get you the model, but Hondas have 11:1 engines that run on 87.
The Gen 3 SHO is 10:1, and those of us who first got stock Gen 3s into the 14s ALL ran 87 (me, Ian, Nimz, Ryan Dudek).
Back in the dark ages of carbs & points, that mattered. Not today with modern EFI, ignitions, and CC design.
Did you read the Bedard article? It's from a Ford engineer on the SHO development.
RonPorter
SHO Club of America
The SHO engine will probably do better with premium fuel under most conditions such as around town, short bursts, stop and go driving. It might do ok on regular fuel under "no load" continuous driving on the freeway. The SHO motors' knock sensor will detect pre-ignition and automatically retard timing thus decreasing efficiency, power and economy. I also suspect that at a true 10:1 the SHO motor will not see any pre-ignition on premium fuel.
I use premium 92 octane because I believe I get better average fuel economy and probably more average power. Probably.
Read the Bedard article.
Back in the late 90s, my original '89 had the Bolt-on Stage. I lived in Louisville, which mandated RFG. Mileage & power sucked, regardless of octane.
I was gas up with "pure" 87 gas when I left town. Mileage & power immediately improved (MANY tests proving this on the Louisville - Detroit run).
Except for extreme conditions, a basically stock SHO V6 doesn't need more than 87 octane.
Chris Smith ran a comprehensive test years back, proving it on his own. A search should bring it up.
Lorenr
Member
Bedford Article
I read the Bedford Article many years ago. I know he was associated with Ford.
Problem was, no one else in the industry ever supported him. I never read anything that came out and agreed with or supported what he wrote. My experience did not agree with his.
Although I'm not a fuel and lubricants engineer, I graduated in chemistry and I've always found this subject interesting. The only rule that generally applies is "High compression internal combustion engines need high octane fuel to maximize efficiency".
Not to say that this 10:1 motor won't run on 87 octane, but the original Ford research says 91 or 92 octane. True or not, makes sense to me.
Next step is to run some valid tests. Good luck.
:wave:
I read the Bedford Article many years ago. I know he was associated with Ford.
Problem was, no one else in the industry ever supported him. I never read anything that came out and agreed with or supported what he wrote. My experience did not agree with his.
Although I'm not a fuel and lubricants engineer, I graduated in chemistry and I've always found this subject interesting. The only rule that generally applies is "High compression internal combustion engines need high octane fuel to maximize efficiency".
Not to say that this 10:1 motor won't run on 87 octane, but the original Ford research says 91 or 92 octane. True or not, makes sense to me.
Next step is to run some valid tests. Good luck.
:wave:
RonPorter
SHO Club of America
Time to be the cranky old guy.....
Tests have been run See my posts above.
And it's obvious you DID NOT READ THE BEDARD ARTICLE!!!
Who the **** is Bedford???????????????????
Your "Chemistry" degree was obviously a waste of $$$$. WTF did it have to do with octane?????
"High Compression" is a relative term. 9.8 is LOW compression nowadays.
Again, in NOT READING THE BEDARD ARTICLE, Ford showed that their original estimates were wrong.
And 23 years of SHO performance, plus having the FIRST Gen 3 SHO, with a 10:1 CR, into the 14s on 87 octane (and the folks that followed me doing the same) says that you are fulla shyte.
Get a basic understanding of what higher octane fuel means. Then learn about how 87 has more BTUs available, then get a clue...........
Sorry, this topic was dead & gone 20 years ago. Fvckin' newbies need to learn something.......
People seem to think that detonation is always audible. As a matter of fact, detonation is often not audible. Its an established fact that the best overall performance from the SHO is achieved with premium gasoline. The argument is from those who assert that you can get by with less most of the time. Fine, to each his own. Bedard never claims to be a Ford engineer and the article just relates hearsay he claims to have picked up from a Ford engineer. I do not view it as authoritative in the least.
When individuals become so frustrated that they begin making personal attacks on others who express opinions different from their own, the thread ceases to be enjoyable or informative. There should be plenty of room for health discourse and at a minimum respect for all.
When individuals become so frustrated that they begin making personal attacks on others who express opinions different from their own, the thread ceases to be enjoyable or informative. There should be plenty of room for health discourse and at a minimum respect for all.
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Frisbeeguy
Member
Ohhh snap, I've been pouring in premium for almost 20 years. sob
SHOclass
Conan has one
What about the "Premium Recommended" above our Tachs and on the fuel door 
??
??SHOtime2511
CGP
What about the "Premium Recommended" above our Tachs and on the fuel door
replace with only genuine motorcraft replacement parts.
+1 for 87 on N/A cars
I run premium now but only because the car is turbo.
I don't consider 9.8-1 compression "high"...
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zblackbeast
SHOtarded
I see no difference with the 87 to 91.. Maybe 2 mpg per tank MAYBE, but thats because the 89 I used in Omaha had E-10 in it, and iirc ethanol is less efficient, but a cleaner burn.
I've spun first, chirped second, had the car over 130 and beaten many cars on regular gas. ill throw a tank of 91 in every now and then because I get bored.. But as Ron stated above, with modern fuels and EFI the difference in a street car isn't with the .20-.30 cents more per gallon..
When/if I boost, ill run 91.. But N/A, no way..
Also, if 91 is so good for the SHO, why don't gas stations start offering race gas, thats a higher octane.. It must be better on a stock SHO..
I've spun first, chirped second, had the car over 130 and beaten many cars on regular gas. ill throw a tank of 91 in every now and then because I get bored.. But as Ron stated above, with modern fuels and EFI the difference in a street car isn't with the .20-.30 cents more per gallon..
When/if I boost, ill run 91.. But N/A, no way..
Also, if 91 is so good for the SHO, why don't gas stations start offering race gas, thats a higher octane.. It must be better on a stock SHO..
atikovi
New Member
So basically. If you use 87, the computer retards the timing when it hears knocking so gas mileage is less but the gas is cheaper. If you use 93, you get better mileage and a little more power but you pay more for the gas. OK if I’m going on a 1000 mile all highway road trip, taking it easy, I’d use regular. If I drove a lot in the mountains, or was pulling a trailer, I’d use premium. Just have to figure what’s the break-even point between gas mileage and price between 87 and 93 for everyday driving. Some places it’s just 15 cents difference when they have a special sale, other places it may be over 40 cents difference.
zblackbeast
SHOtarded
No, i feel/see no performance gains from 87 e-10 to 91.. I see a MPG improvement from the fact the 87 is 10% ethanol and the 91 isn't..
The ONLY time ill use premium for a reason is on a track, or if your towing a trailer.. where IAT's are high..
The ONLY time ill use premium for a reason is on a track, or if your towing a trailer.. where IAT's are high..
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