Posted: 7/15/2010 1:33:34 PM EDT
| OK. I can't afford to run premium in my car anymore, but my GF refuses to run anything less than premium out of her 350Z. Theother day while filling it up I started thinking " What about the gas that's leftover in the hose coming from the pump?" Do you get regular gas that's in the hose until the premium kicks in? Are there three hoses inside the one big hose to insure against this? How does it work? |
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The little squirt that comes out of the hose isn't going to have a measurable effect on 15+ gallons of gas. What does the owner's manual for your GFs car recommend? I only run premium in vehicles that require it (unfortunately my car is turbocharged, and it does). |
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This can be a problem if you're a motorcycle rider. That shot of low grade in the hose before you hit the good stuff has more of an effect since you only do about 3 to 4 gallons to top her off.
I also knew somebody who would raise the hose all the way over his head after the pump stopped at his amount, in order to get that last swig in the hose |
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Quoted: I have wondered this. I believe the pumps pull-back the gas left once you're finished. That's why it takes a few seconds for the gas to start to flow once you begin pumping. No, the handles have a pop-off valve, keeping a bit of pressure in the hose even when the handle is pulled. This pressure the pop-off maintains removes the "spring" from the hose for accurate volumetric measurement. |
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Tell your GF she's wasting money if her manual doesn't specifically recommend 'Premium Only.' Higher octane numbers do nothing for power - unless the engine is tuned for it. On the other hand, if the manufacturer says "Premium Only' then you'd best use it, as engine damage can result from using gas with a lower octane number. If you need it, use it. If you don't need it, there's no benefit in using it. It's really that simple.
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You can get away with running regular or mid-grade in the Z - the computer will compensate. However, you will lose power and fuel economy.
I only did it once in my G35 and never did any calculations, but the savings you get would at least be partially offset by using more gas. |
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Quoted: Quoted: I have wondered this. I believe the pumps pull-back the gas left once you're finished. That's why it takes a few seconds for the gas to start to flow once you begin pumping. Back when hi-test was red, you could see the color change. Single hose delivery only started when leaded gasoline was stopped. Putting a hose full of leaded into an unleaded car would ruin the O2 sensor. When leaded gasoline burns, it releases metallic lead vapor. To prevent this from clogging the exhaust system, a compound containing bromine was added, forming lead bromide which has higher vapor pressure. Lead is still deposited, only in controllable amounts. The catalytic nature of the O2 sensor reduces lead bromide to lead which shorts out the element. |
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What is the purpose of mid grade gas? I can see the need for high grade and regular. Sam's Club here doesn't even sell the mid grade. Im not sure but my suzuki DR650 likes mid it seems. The IROC has to have premium though. It also likes lead substitute when on the bottle as well. And yes i do have to change the 02 sensor more frequently. Good thing its only like 20 bucks. |
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This can be a problem if you're a motorcycle rider. That shot of low grade in the hose before you hit the good stuff has more of an effect since you only do about 3 to 4 gallons to top her off. I also knew somebody who would raise the hose all the way over his head after the pump stopped at his amount, in order to get that last swig in the hose My bike has a small tank, I usually use two 5 gal. stored in the garage for it. When filling up the gas cans, I usually top off the truck before pumping the cans. I don't think there would be a difference with a car though. |
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Quoted: What is the purpose of mid grade gas? I can see the need for high grade and regular. Sam's Club here doesn't even sell the mid grade. Cost savings. The refineries produce 2 grades. They are splash mixed at the pipeline end terminal rack for mid grade. No joke. |
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Quoted: You can get away with running regular or mid-grade in the Z - the computer will compensate. However, you will lose power and fuel economy. I only did it once in my G35 and never did any calculations, but the savings you get would at least be partially offset by using more gas. No you won't. I love that the American public is nearly completely ignorant of what octane rating is. Higher octane fuel is more resistant to detonation, and will not burn as completely as lower octane fuel unless it is used in a high compression engine. In 99% of cases fuel mileage will be better with 87 octane than with 92. The only thing you're getting for your extra money is a higher resistance to detonation (important in turbocharged or very high compression ratio engines) and a better additive package. |
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Technically unless your car is knocking or adjusts it's timing according to octane you will actually make LESS power with higher octane gas because of how they raise the octane (single hydrocarbon fuels vs 2 hydrocarbon fuels)
Just like how with E85 you need so much more fuel to make the same amount of power, but with lots of boost you can make a LOT more power. T |
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You can get away with running regular or mid-grade in the Z - the computer will compensate. However, you will lose power and fuel economy. I only did it once in my G35 and never did any calculations, but the savings you get would at least be partially offset by using more gas. No you won't. I love that the American public is nearly completely ignorant of what octane rating is. Higher octane fuel is more resistant to detonation, and will not burn as completely as lower octane fuel unless it is used in a high compression engine. In 99% of cases fuel mileage will be better with 87 octane than with 92. The only thing you're getting for your extra money is a higher resistance to detonation (important in turbocharged or very high compression ratio engines) and a better additive spackage. Oh yes it will. On a high compression/hi performance engine that is made for hi-test, if you give it low-test, the car's computer will retard the ignition timing, in order to prevent pinging/detonation. This lowers power output. With standard compression engines though, hi-test is indeed a waste of money unless you suffer from pinging and want to reduce it. |
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Quoted: I could have swore I mentioned that a time or two. Quoted: Quoted: You can get away with running regular or mid-grade in the Z - the computer will compensate. However, you will lose power and fuel economy. I only did it once in my G35 and never did any calculations, but the savings you get would at least be partially offset by using more gas. No you won't. I love that the American public is nearly completely ignorant of what octane rating is. Higher octane fuel is more resistant to detonation, and will not burn as completely as lower octane fuel unless it is used in a high compression engine. In 99% of cases fuel mileage will be better with 87 octane than with 92. The only thing you're getting for your extra money is a higher resistance to detonation (important in turbocharged or very high compression ratio engines) and a better additive spackage. Oh yes it will. On a high compression/hi performance engine that is made for hi-test, if you give it low-test, the car's computer will retard the ignition timing, in order to prevent pinging/detonation. This lowers power output. With standard compression engines though, hi-test is indeed a waste of money unless you suffer from pinging and want to reduce it.  |
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I could have swore I mentioned that a time or two. Quoted:
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You can get away with running regular or mid-grade in the Z - the computer will compensate. However, you will lose power and fuel economy. I only did it once in my G35 and never did any calculations, but the savings you get would at least be partially offset by using more gas. No you won't. I love that the American public is nearly completely ignorant of what octane rating is. Higher octane fuel is more resistant to detonation, and will not burn as completely as lower octane fuel unless it is used in a high compression engine. In 99% of cases fuel mileage will be better with 87 octane than with 92. The only thing you're getting for your extra money is a higher resistance to detonation (important in turbocharged or very high compression ratio engines) and a better additive spackage. Oh yes it will. On a high compression/hi performance engine that is made for hi-test, if you give it low-test, the car's computer will retard the ignition timing, in order to prevent pinging/detonation. This lowers power output. With standard compression engines though, hi-test is indeed a waste of money unless you suffer from pinging and want to reduce it.
Yes, but you said qcka was wrong in your first sentence. He's talking about a hi-compression engine (with advanced timing). What he said is correct. The computer will retard the timing when it senses pre-ignition (caused by low-test in the high-comp engine). This lowers power output vs. hi-test gas. |
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Some gas stations have only two fuel tanks and mix the mid-grade at the pump.
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What is the purpose of mid grade gas? I can see the need for high grade and regular. Sam's Club here doesn't even sell the mid grade. Cost savings. The refineries produce 2 grades. They are splash mixed at the pipeline end terminal rack for mid grade. No joke. |
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I have a Nissan 3.5 Liter, the same engine as in your 350z.
Your ICM computer will note the drop in octane and lower (retard) the ignition timing accordingly. It will run...although it will run sluggish...don't expect too much response from the accelerator. Be careful when you swing out to pass someone because it AINT gonna jump like it will with premium. It won't hurt it though. |
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I could have swore I mentioned that a time or two. Quoted:
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You can get away with running regular or mid-grade in the Z - the computer will compensate. However, you will lose power and fuel economy. I only did it once in my G35 and never did any calculations, but the savings you get would at least be partially offset by using more gas. No you won't. I love that the American public is nearly completely ignorant of what octane rating is. Higher octane fuel is more resistant to detonation, and will not burn as completely as lower octane fuel unless it is used in a high compression engine. In 99% of cases fuel mileage will be better with 87 octane than with 92. The only thing you're getting for your extra money is a higher resistance to detonation (important in turbocharged or very high compression ratio engines) and a better additive spackage. Oh yes it will. On a high compression/hi performance engine that is made for hi-test, if you give it low-test, the car's computer will retard the ignition timing, in order to prevent pinging/detonation. This lowers power output. With standard compression engines though, hi-test is indeed a waste of money unless you suffer from pinging and want to reduce it.
Yes, but you said qcka was wrong in your first sentence. He's talking about a hi-compression engine (with advanced timing). What he said is correct. The computer will retard the timing when it senses pre-ignition (caused by low-test in the high-comp engine). This lowers power output vs. hi-test gas. qcka said it would retard the timing to prevent detonation, which is inaccurate. The ECU will only alter timing if it's getting signalled from the knock sensor, which means detonation has already set in. There's no such thing as an octane sensor as far as I'm aware of. But this is assuming that using lower octane fuel than recommended will induce detonation, which often isn't the case. I don't know dick about 350Zs... maybe they're right on the edge of detonation (though I doubt it)... but I know bikes. And I know motorcycle manufacturers base their recommendations to assure there's NO CHANCE of you banging your engine to death w/ detonation. I'm sure most auto manufacturers are the same. So you usually have a bit of wiggle-room. I personally run lower-than-recommended octane levels in my bikes unless the engine has alot of time on it (as carbon buildup increases the compression ratio). Never had detonation set in once that I'm aware of, nor seen any signs during engine tear-downs. |
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Read the manual (or in some cases the gauge cluster), if it says regular..run regular. Anything more will do nothing at all for her car other than foul plugs and generally run like crap. i dunno man. ive filled my explorer up (4.6) several times with premium and kept track of the gas mileage. the engine seems peppier at low revs and i get 2 mpg better with premium on avg. how does a higher octane fuel foul the plugs more? i realize ive wasted money on this, but should i feel like a moron (or moran as many here say) otherwise? |
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What is the purpose of mid grade gas? I can see the need for high grade and regular. Sam's Club here doesn't even sell the mid grade. I have a '94 TBI 350 that needs mid grade as it knocks way too much with 87. (89 is mid grade around here BTW) I assume that chamber deposits have taken the compression ratio up a notch or two. |
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Read the manual (or in some cases the gauge cluster), if it says regular..run regular. Anything more will do nothing at all for her car other than foul plugs and generally run like crap. i dunno man. ive filled my explorer up (4.6) several times with premium and kept track of the gas mileage. the engine seems peppier at low revs and i get 2 mpg better with premium on avg. how does a higher octane fuel foul the plugs more? Refer a few posts up 
V-Power has additives to clean. Quoted:
I always put premium in for the cleaner, and since it burns slower it gets you a few more miles down the road.. |
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Read the manual (or in some cases the gauge cluster), if it says regular..run regular. Anything more will do nothing at all for her car other than foul plugs and generally run like crap. i dunno man. ive filled my explorer up (4.6) several times with premium and kept track of the gas mileage. the engine seems peppier at low revs and i get 2 mpg better with premium on avg. how does a higher octane fuel foul the plugs more? Refer a few posts up
V-Power has additives to clean. Quoted:
I always put premium in for the cleaner, and since it burns slower it gets you a few more miles down the road.. thats what i thought, but being merely a consumer and not very familiar with the differences, i figured more opinions would be helpful |
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i dunno man. ive filled my explorer up (4.6) several times with premium and kept track of the gas mileage. the engine seems peppier at low revs and i get 2 mpg better with premium on avg. how does a higher octane fuel foul the plugs more? i realize ive wasted money on this, but should i feel like a moron (or moran as many here say) otherwise? It is possible for a higher octane fuel to run better in an auto than a lower octane fuel, but it rarely has anything to do with the octane rating itself. Different formulations of fuel can have an impact on power output. Doubt it's something you feel, but anything's possible. If this was the case, it wouldn't be the octane rating itself, but rather the octane rating would be an unrelated side-effect of a different fuel formulation. It's also possible that a slower-burning high-octane fuel might produce a bit more power in an engine where the timing was advanced past optimum. slower burning & high octane are not necessarily linked (many high-octane racing fuels burn faster than lower-octane equivalents), but in pump gas... they often are. All this being said - it's most likely all in your head. |
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i dunno man. ive filled my explorer up (4.6) several times with premium and kept track of the gas mileage. the engine seems peppier at low revs and i get 2 mpg better with premium on avg. how does a higher octane fuel foul the plugs more? i realize ive wasted money on this, but should i feel like a moron (or moran as many here say) otherwise? It is possible for a higher octane fuel to run better in an auto than a lower octane fuel, but it rarely has anything to do with the octane rating itself. Different formulations of fuel can have an impact on power output. Doubt it's something you feel, but anything's possible. If this was the case, it wouldn't be the octane rating itself, but rather the octane rating would be an unrelated side-effect of a different fuel formulation. It's also possible that a slower-burning high-octane fuel might produce a bit more power in an engine where the timing was advanced past optimum. slower burning & high octane are not necessarily linked (many high-octane racing fuels burn faster than lower-octane equivalents), but in pump gas... they often are. All this being said - it's most likely all in your head. haha figured, thanks. |
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Technically unless your car is knocking or adjusts it's timing according to octane you will actually make LESS power with higher octane gas because of how they raise the octane (single hydrocarbon fuels vs 2 hydrocarbon fuels) T True, but for your daily driver commuter car not hooked up to a wide band and some computer monitoring software, you really have no clue if you are getting detonation under acceleration. On a 15 gallon fill up, it comes out to $3 more. Chump change, in the grand scheme of things. |
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Quoted: What is the purpose of mid grade gas? I can see the need for high grade and regular. Sam's Club here doesn't even sell the mid grade. Before cars were fitted with computers and knock sensors, spark advance generally followed a fairly simple pattern regulated by rpm and vacuum. As a car got older, carbon deposits would build up and promote pinging. You can hear pinging. Generally, your car isn't going to be harmed by a little pinging, but if hear constant pinging, it is time to go up a grade of gasoline. The mid grade was sufficient to stop pinging in my 1981 Camaro which I still had in the early 90's. Now, cars have knock sensors and sophisticated computer controlled spark advance. My Mustang will run fine on regular gas. If I put premium in it, the computer will advance the spark to take advantage of the extra octane available and will supposably produce 5 more hp. |
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Quoted: OK. I can't afford to run premium in my car anymore, but my GF refuses to run anything less than premium out of her 350Z. Theother day while filling it up I started thinking " What about the gas that's leftover in the hose coming from the pump?" Do you get regular gas that's in the hose until the premium kicks in? Are there three hoses inside the one big hose to insure against this? How does it work? She is wise not to run anything else in her Z. Like was mentioned above, the small quantity you get in your tank has no ill effect on your car. |
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My motorcycle has a compression ratio of 12.4:1. No knock sensor, no computer. Just electronic ignition timing. And it runs fine of most 87 AKI (R+M)/2 gasolines. I have had pinging on ONE tank. If you're riding a 250 Ninja,the flame front doesn't have very far to travel across those little pistons so they'll run just fine on 87.On larger motors with high compression,it's considerable more difficult to get away with using lower octane fuel without pinging. |
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Tell your GF she's wasting money if her manual doesn't specifically recommend 'Premium Only.' Higher octane numbers do nothing for power - unless the engine is tuned for it. On the other hand, if the manufacturer says "Premium Only' then you'd best use it, as engine damage can result from using gas with a lower octane number. If you need it, use it. If you don't need it, there's no benefit in using it. It's really that simple. I disagree, and most manuals specify 87 or HIGHER. 87 is the minimum that is safe to use, but you may (and I do) get better mileage and a smoother running engine by using 93. I have proof of this if needed, well, the mileage anyway. I also find that higher octane gas has an even bigger positive effect on small engines. YMMV. 
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I've got a 350Z as well, and the manufacturer recommends 91 octane. Around here we have 87, 89, and 93 to pick from. I always get 93 (premium)
Once or twice I got regular just to see if I could tell any difference, and I could. The engine bogged down at lower rpms and the car felt slower. I've got a lead foot, and like to autocross, so every extra bit of performance helps. Plus, you only end up spending like $2 or 3 extra vs regular when you fill up. Premium seems to make cars last longer and keep the engine clean as well. Just my experience. ETA: The 350Z has a 10.3:1 compression ratio |
So, I regularly ad octane boost and lead substitute additives. 