Octane requirements

[sleepar]

Highway mostly and that's what it got... edelbrock carb

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Nevertheless you can't beat the original leadded 108 octaine.... you can run 50 octaine gas in a 1930 mopar because that's all they had then.... or kerosene in some turn of the century stuff made for that but our cars on here were made for regular gas and its more than just octane it's how pure the gas is and you have to pay $10+ a gallon for it and it's worth every penny.

 

[383man]

Sure they were built to run on 104 back then but you can build your eng today to run better on the crappy pump we have today. Quench , aluminum heads , the right cam and timing are just a few of the changes to help your eng run on pump. There is no way Sleepar I believe that you got 15 mpg on pump and 26 on race gas. Better come up with a better story. Ron

 

[coloradodave]

The cheaper the gas the more it cost in repairs later.... I run $12-$14 a gallon 100-108 octaine vintage leadded gas or the racing gas with no ethanol,mpbe, water etc I. It.... if you can't afford $14 per gallon explain how you can afford to fix all the problems associated with the cheap fuel.... cheap and old mopar don't work well together in every instance except maybe the air in the tires versus nitrogen....

Are you drinking when you write these goofy posts?

 

[coronet340]

At a few bucks a tank between the 93 and 87 I'd just run 93 in a car like yours. Plus you should get a couple more MPGs for the extra spent. So in the long run why not just what essentially is going to be the same price AND have piece of mind?

Or you can move to TX where our 93 is cheaper then your 87. lol

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Are you drinking when you write these goofy posts?

Isn't everyone? I thought this was For BEER Bodies Only??

 

[HT413]

Isn't everyone? I thought this was For BEER Bodies Only??

I'm guilty.

 

[747mopar]

Current pump gas is what we are stuck with and if we want to put some serious seat time in our cars, not building the engine for it is just insane. Sure, good gas is a good thing for our stuff but leaded gas is not legal to run anyway. What happens if you get busted? Probably the same as getting caught running red diesel in my new Dodge. What do you do on a road trip? I say build for and run pump gas and if you want to store the car fill with good stuff and get it mixed through the system before parking it.

Exactly.

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At a few bucks a tank between the 93 and 87 I'd just run 93 in a car like yours. Plus you should get a couple more MPGs for the extra spent. So in the long run why not just what essentially is going to be the same price AND have piece of mind?

Or you can move to TX where our 93 is cheaper then your 87. lol

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Isn't everyone? I thought this was For BEER Bodies Only??

You might be right but it's painful watching the gallons versus dollars as I fill it up, 93 is quite a bit more where I get it. I wouldn't mind moving down there to be honest, one of the few states that seam to get it right anymore.

 

[Cranky]

What makes today's fuels crappy is the lack of lead and the addition of ethanol but it's been proven that we don't really need leaded fuel. Lead was used to help boost octane and it was found to help lubricate the valve seats but lead also has it's down side in the fact it leaves deposits and it also somewhat corrosive. Ethanol is more corrosive to the fuel system and it deteriorates faster but what about the ones who use alcohol based fuels in drag racing? E85 increases octane a substantial amount and so even E10 increases it some. Drag racers who use alcohol based fuels (Methanol too) have to do more maintenance to their fuel system but it's also a much cooler running fuel. Nothing wrong with running a much higher octane AND cooler running fuel if you build your system for it. As for letting a car sit for a long period of time.....yeah, it may be true that a better fuel will last longer but there's no way I'm letting anything sit for a year or longer with any kind of fuel in the system. And anyone running 108 octane in a stock street engine is simply throwing their money away. Yeah, the better fuels are better because they already have the additives in them that helps extend their 'shelf life' but you're going to pay for it. I double dose my 'cheap' fuel with products like Sta-Bil for my small engines and it'll last for a pretty long time but once my home supply gets to be a few months old, it gets dumped into my beater pickup and burned off but I've had good results letting my small engines sit for a year without any side effects but I try not to do that....and any car that I know is going to sit for a long period gets drained of the fuel and the system flushed.

 

[coloradodave]

[QUOTE Isn't everyone? I thought this was For BEER Bodies Only??[/QUOTE]

That's pretty funny......and, some days you'd think so....lol

 

[747mopar]

What makes today's fuels crappy is the lack of lead and the addition of ethanol but it's been proven that we don't really need leaded fuel. Lead was used to help boost octane and it was found to help lubricate the valve seats but lead also has it's down side in the fact it leaves deposits and it also somewhat corrosive. Ethanol is more corrosive to the fuel system and it deteriorates faster but what about the ones who use alcohol based fuels in drag racing? E85 increases octane a substantial amount and so even E10 increases it some. Drag racers who use alcohol based fuels (Methanol too) have to do more maintenance to their fuel system but it's also a much cooler running fuel. Nothing wrong with running a much higher octane AND cooler running fuel if you build your system for it. As for letting a car sit for a long period of time.....yeah, it may be true that a better fuel will last longer but there's no way I'm letting anything sit for a year or longer with any kind of fuel in the system. And anyone running 108 octane in a stock street engine is simply throwing their money away. Yeah, the better fuels are better because they already have the additives in them that helps extend their 'shelf life' but you're going to pay for it. I double dose my 'cheap' fuel with products like Sta-Bil for my small engines and it'll last for a pretty long time but once my home supply gets to be a few months old, it gets dumped into my beater pickup and burned off but I've had good results letting my small engines sit for a year without any side effects but I try not to do that....and any car that I know is going to sit for a long period gets drained of the fuel and the system flushed.

The problem here in Ohio is unless you drive in the snow you'll likely be parking them for at least 5 months. I've got more research to do bit my understanding is the pump gas has a very short shelf life, you may be right that I'd be better off running it empty and emptying everything but I'd think you'd want something in there to prevent corrosion. I've got an old tractor that gets all of my old gas haha, poor thing will run on anything.

 

[coronet340]

You might be right but it's painful watching the gallons versus dollars as I fill it up, 93 is quite a bit more where I get it. I wouldn't mind moving down there to be honest, one of the few states that seam to get it right anymore.

I hear you. Back in 08 in Reno 93 was $5.25 a gallon. My suv runs like crap on 87 so I had to buck up for whole tank as we were going camping. Almost $150 to fill it up. It hurt, it hurt real bad. But I still won't run lower octane in it because I can hear the pinging - that always makes me think long term.

We are always looking for more productive members of society down here!! lol. Everything is cheaper here. From gas to houses. Get you a lower mortgage payment and roll the savings into your tank!

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The problem here in Ohio is unless you drive in the snow you'll likely be parking them for at least 5 months. I've got more research to do bit my understanding is the pump gas has a very short shelf life, you may be right that I'd be better off running it empty and emptying everything but I'd think you'd want something in there to prevent corrosion. I've got an old tractor that gets all of my old gas haha, poor thing will run on anything.

Our roads are dry and warm 300 days a year. just sayin. lol

I thought with all of todays additives gas had a longer shelf life? I could be dead wrong though. I've let motorcycles sit for a year plus and didn't even add fresh gas, never noticed a difference.

 

[Garys1969RR]

I am getting cranking compression pressures of 210 to 220 PSI. A 451 cubic inch at 13 to 1 C/R. Last fuel mix was 3 gallons of 91 octane Premium, (all the premium is 91 octane in Denver, as opposed to 93 at lower elevations). 2 gal of E 85 which is 105 octane, and 1 gallon of 100 Sunoco race fuel. This mix should be about 97 octane. The only time it would ping, was at wide open throttle going up a steep hill at 70 MPH. The engine was fairly warm. Got it to the track, cooled it down to about 130 degrees coolant temp, and no ping! Engine temp plays a big part in this. Cooler=less tendency to ping. Ok I put in a 50/50 mix of E 85 and 91 octane premium. It ran great at the track Wed nite. Last run and best ET so far of 12.54@109. It was a little too lean and had a bad flat spot between idle and 1/4 throttle. So next day went from 82 main jet in primary to 84. And went from 84 to 86 in secondary. Also went to 40 degrees total ignition timing. This helped alot. Pretty much eliminated the flat spot, although it still has a little hesitation right off of idle.

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Now going 4 jet sizes larger than stock on an 850 CFM Holley double pumper. And with this carb jetted richer than stock, I will use a 50/50 mix of E 85 and 91 Premium with the 850 on the engine. That should work well, and give slightly higher octane numbers. This mix averages out to 98 octane. Bottom line is experiment until you find what works for your particular combination of cam, C/R, Altitude, and fuel choice.

Still experimenting

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Still experimenting

Went to a 50/50 mix of E 85 and 91 octane premium. Then it ran a best ET so far of 12.54@109.

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Running too lean, as it had a flat spot between idle and 1/4 throttle. And plugs were mostly white with a little tan. So went to 84 primary main jet and 86 secondary. Also went to 40 degrees total timing. This pretty much eliminated the flat spot, and it pulls like a freight train!

 

[sleepar]

Sure they were built to run on 104 back then but you can build your eng today to run better on the crappy pump we have today. Quench , aluminum heads , the right cam and timing are just a few of the changes to help your eng run on pump. There is no way Sleepar I believe that you got 15 mpg on pump and 26 on race gas. Better come up with a better story. Ron

Ok .. just gave me a big complement if the mileage seems UN believable..... I drove from Epping Nh to Virginia and that's what it got taking it easy and driving the speed limit....

 

[Garys1969RR]

Stock jetting on this 850 dbl pumper is 80 all around.

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Ok .. just gave me a big complement if the mileage seems UN believable..... I drove from Epping Nh to Virginia and that's what it got taking it easy and driving the speed limit....

I suppose high gas mileage is obtainable with the right combination of cam, jetting, timing, C/R, and driving at moderate speeds. But if there is any doubt, its always good to double check the results by repeating the test.

 

[sleepar]

Are you drinking when you write these goofy posts?

No when you pull a motor appart form having say 100,000 miles with the cheap crap pump gas (97) though it... you practically have to shovel the carbon and residual junk out of it.... the race gas burns clean and doesn't contaminate the oil also.... you have more power and will get better economy because the motor doesn't have to struggle to do the same work.

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If you have a 850 double pumper.... and everything else under it... and cheap pump gas to save money... it's a waste.. run the good stuff @$10 a gallon and give that pig a double pump of that.. then compare the cheap stuff. For the first mile it will leave a black cloud behind you till it clears itself of carbon and slag....

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Stock jetting on this 850 dbl pumper is 80 all around.

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I suppose high gas mileage is obtainable with the right combination of cam, jetting, timing, C/R, and driving at moderate speeds. But if there is any doubt, its always good to double check the results by repeating the test.

And I have with that car.... as for mopar they never get as good a mileage as Gm ... I don't know why.... try it and see for you're self... most people who run race fuel are balls to the wall and only care about faster than economy..... your car will run better and you will probably get worse mileage on 108 because of the added power and how great it runs... but if you can be moderate you will notice a difference.... why doesn't nascar run 87 ? .... they could save billions... why run the good oil... why spare no expense look for parts for years and feed a car crap to be cheap on fuel...

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Still experimenting

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Went to a 50/50 mix of E 85 and 91 octane premium. Then it ran a best ET so far of 12.54@109.

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Running too lean, as it had a flat spot between idle and 1/4 throttle. And plugs were mostly white with a little tan. So went to 84 primary main jet and 86 secondary. Also went to 40 degrees total timing. This pretty much eliminated the flat spot, and it pulls like a freight train!

Use 108 and no other changes.... and do a run... see what happens.

 

[Garys1969RR]

I found out a long time ago that more expensive doesn't always mean better. I like to try various combinations to see what works, and what doesn't. I met a guy that has a 509 big block Chevy with 14 to 1 C/R, tunnel ram, 2-4 barrel Holleys on top. Plus a roller cam and nitrous. Runs 8.90s at Bandimere in a Camaro. Prob has over 20 grand in the motor. Guess what fuel he uses? E-85! This fuel has virtually no carbon build up in the motor as it burns very clean. So far I really like the stuff. Have had no probs with it.

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To do a run with race gas I would have to re jet the carb to smaller jets. I have used expensive race fuel a few times the past 2 seasons and found no difference in ET. Best ET on race gas was 12.69@109. Best on 50/50 mix has been 12.54@109.

 

[sleepar]

Ok maybe you're at the limit anyways.. the higher octane always gave me more room to play with or seemed more forgiving... $20,000 motor doesn't mean anything to me there's so mutch variables.... you can build a motor for one shot or for 250,000 miles. My use for leaded 108 is so the car can sit for months on end and jump in and not have to worry about sediment, water,etc in my fuel... I have cleans my last gas tank of crap. It's different if it was a daily driver... I respect what you are doing geting the most bang for the buck. My car will see less than a 1000 miles a year and some years under a hundred. With out the good gas it would be more money and time than the it's worth to save $4-5 a gallon.

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Ok maybe you're at the limit anyways.. the higher octane always gave me more room to play with or seemed more forgiving... $20,000 motor doesn't mean anything to me there's so mutch variables.... you can build a motor for one shot or for 250,000 miles. My use for leaded 108 is so the car can sit for months on end and jump in and not have to worry about sediment, water,etc in my fuel... I have cleans my last gas tank of crap. It's different if it was a daily driver... I respect what you are doing geting the most bang for the buck. My car will see less than a 1000 miles a year and some years under a hundred. With out the good gas it would be more money and time than the it's worth to save $4-5 a gallon.

Any one else on here wants to avoid the problems of old gas that sits around because you put you're car up for months run the vintage leadded fuel available for off.road.use only.

 

[Lionized]

I run 94 in mine and have had no problems.
I suspect I would have problems with anything less up here because any lower octane has ethanol added.

What the engine likes, the engine gets.

 

[747mopar]

Well she's running on 89 right now and so far so good.

 

[747mopar]

O.K maybe not. Started having vapor locking issues and seemed to resolve them by adding a heat dissipater to the carb and insulating the fuel lines. My last tank was 89 with a little 93 mixed in but I ran it out and put straight 89 in it yesterday, it dieseled twice on me when shutting it off today so I'm thinking maybe I should just go back to the 93 since it's less prone to vapor lock and diesel.