Running Premium Fuel w/ N/T?

[DSMOCTANE]

-I am working with a 99' Eclipse with the 420a engine. I have bolt-on's including a short-ram cold air intake and a full header and catback exhaust system. On my rebuilt engine, is it truly beneficial to run premium 93 fuel? I know the fuel gauges in the gs-t and gsx insist on only premium, but will higher octane give me much more power for a n/t? I also heard fellow mechanics speaking of higher octane resulting in more efficient fuel economy and more mpg. What do you guys think?

 

[synthetek]

-I am working with a 99' Eclipse with the 420a engine. I have bolt-on's including a short-ram cold air intake and a full header and catback exhaust system. On my rebuilt engine, is it truly beneficial to run premium 93 fuel? I know the fuel gauges in the gs-t and gsx insist on only premium, but will higher octane give me much more power for a n/t? I also heard fellow mechanics speaking of higher octane resulting in more efficient fuel economy and more mpg. What do you guys think?

It wont do anything, your ECU is tuned for 87

 

[clipto]

So all octane does like oct 87, 89, and 92 is to help reduce knock, the higher the octane the less prone you are to see less knock in the motor like if it is turbo charged or high output motor it well keep the motor running smooth.As for your n/a car it will be fine with regular gas, plus it will save you alot of money becuase I know gas is not cheap .Pump gas is not all that of a power adder.

 

[buhay6]

I don't think it will give you much more power in a noticeable sense, but it will improve your mileage tho for sure over say mid grade and regular. If you were to run E85 you would notice an improvement in performance that and other higher grade fuels like av gas and alcohol, but how much more power you see will depend on mods and tuning for sure.

 

[clipto]

I don't think it will give you much more power in a noticeable sense, but it will improve your mileage tho for sure over say mid grade and regular. If you were to run E85 you would notice an improvement in performance that and other higher grade fuels like av gas and alcohol, but how much more power you see will depend on mods and tuning for sure.

It won't help any with his 420a n/a.

 

[synthetek]

I don't think it will give you much more power in a noticeable sense, but it will improve your mileage tho for sure over say mid grade and regular. If you were to run E85 you would notice an improvement in performance that and other higher grade fuels like av gas and alcohol, but how much more power you see will depend on mods and tuning for sure.

It will not improve mileage or do anything with a stock ECU, you would not get any performance gains for E85 or Race fuel either unless you had some other type of engine management to tune your car to utilize other types of fuel.

 

[buhay6]

It will not improve mileage or do anything with a stock ECU, you would not get any performance gains for E85 or Race fuel either unless you had some other type of engine management to tune your car to utilize other types of fuel.

Exactly why I said "but how much more power you see will depend on mods and tuning for sure." nuf said there.

I guess I should have typed that a different way, my bad.
No he shouldnt run e85 or race gas because he doesnt have enough mods/right tuning set up to run higher octane fuels.

But as for better mileage running say 93 octane fuel to 87 octane yes your mileage WILL be better not by much no but it will be better. I got 5 mpg increase in my mileage out of my 4g63 n/t when I ran 3 tanks through it for experimental purposes so see if it was worth while to switch fuel........ I found its not worth the switch because what I found is I spent all the money I "saved" filling the tank again.

my 2 cents!

 

[gusu]

Higher octane fuel has a longer more controlled burn that is also more resistant to preignition and detonation.

The higher octane's smoother burn helps reduce knock.

The reason you get more from higher octane is 100% a better tune. You can run different timings and more boost on a higher octane.

 

[josh1095]

the only thing u would get is more carbon deposits on your pistons and valves. plain and simple. zero power gain. now if u were running say a 13:1 N/A compression you would HAVE to run premium.
and a gst would run perfectly fine on 87 as long as you didnt boost it. just thought id mention that. octane and compression run hand in hand. octane is used to get a proper burn vs an explosion(dtonation/knock) in high compression applications.

 

[CanadianTalonTC]

the only thing u would get is more carbon deposits on your pistons and valves. plain and simple. zero power gain. now if u were running say a 13:1 N/A compression you would HAVE to run premium.
and a gst would run perfectly fine on 87 as long as you didnt boost it. just thought id mention that. octane and compression run hand in hand. octane is used to get a proper burn vs an explosion(dtonation/knock) in high compression applications.

Reasoning behind this statement please.

Joel

 

[Project91Tsi]

I'm not going to quote any 100% verified answers on the more carbon buildup for high octane fuels, but I have seen many many people debate over it. Stating the slower burn time causes more deposits or more time for the fuel to soak into deposits causing more buildup.

Not saying I agree with any. Octane rating is simply a point at which a fuel will start to ignite, so it is understandable in some situations that taking to long to ignite would result in more unburnt fuel as the piston descents while the combustion cycle happens. Possibly to the point where the flame goes out and leaves unburnt fuel behind. Especially with the addition of cams which could increase valve overlap.

So in the long run I think it simply comes down to whether or not your engine is actually knocking, if it is, then yes, increase your octane. If it isn't knocking, chances are, you aren't going to see a gain at all and there is the possibility of causing more long term effects than without.

Please don't flame me for this response, it's just a logical conclusion.

 

[TSi Kid]

-I am working with a 99' Eclipse with the 420a engine. I have bolt-on's including a short-ram cold air intake and a full header and catback exhaust system. On my rebuilt engine, is it truly beneficial to run premium 93 fuel? I know the fuel gauges in the gs-t and gsx insist on only premium, but will higher octane give me much more power for a n/t? I also heard fellow mechanics speaking of higher octane resulting in more efficient fuel economy and more mpg. What do you guys think?

You'll see as much of a gain as you did when you put those headers on
Keep on usuing 87 and save up for a gsx in the mean time.

 

[DSM1G90]

.and save your money... If that 420A was running 11.0:1 compression, or you turboed the thing, then you'd be using the higher octane stuff.

Actually higher octane fuels are a more contaminated fuel due to the tons of additives added to raise octane than 85 or 87, which these fuels burns cleaner and hotter due to less additives.

E85 is the cleanest due to the high alcohol content and has an octane rating over 100, but the BTU output for E85 is lower than regular 93 premimum, thus takes more E85 fuel to produce the same BTU output as 93 octane. You just suffer in mileage with E85...

Adding all that intake and exhaust stuff is only allowing air and exhaust to flow slightly better-you might get a very small bump up in torque output on the bottom end, but it's not going to justify the dollars spent on the stuff to gain that 1% increase..and to look cool..

 

[Cornfed4G64]

save your money and put in the cheap stuff! Is all that really needs to be said

 

[Skorcher]

Personally in my 95 RS I haven't really noticed a difference in running Premium or Unleaded

 

[Fotowntalon]

Totally running premium 93 octane. Then again, I have to because the timing is so far advanced. Now if I didn't have my timing advance, or any tuning, I'd be using 87.

 

[97gst_spyder]

Running 93 in almost any vehicle will help gas mileage, and performance. Also, the car will run smoother.

Now it might not be much fuel mileage, or performance but it will help. My Sentra (2006 1.8se gets about 50 more miles per tank with 93. Plus it has more pickup and idles smoother.).

 

[greene3543]

I've noticed a difference in my talon, my eclipse, and my jeep cherokee using 93 rather than 87, also if you can find it non-ethanol fuel makes a pretty big difference in fuel mileage, and i've noticed more pulling power on uphills in the cherokee.

 

[josh1095]

^^^^^
thats the truth. the ethanol part. ethanol blends will definitely get worse gas mileage.

 

[T is for TURBO]

Read this. It will explain it better than most people on this board. The part in bold is the intersting part.

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, methane, propane and butane are all hydrocarbons. Methane has a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

 

[skatershawn]

Read this. It will explain it better than most people on this board. The part in bold is the intersting part.

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, methane, propane and butane are all hydrocarbons. Methane has a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

Where is that sourced from? I like that bit of info!

 

[eclipse420ags]

I could feel a slight difference between 87 and 93. Then again it could just be in my head.

 

[gusu]

Read this. It will explain it better than most people on this board. The part in bold is the intersting part.

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, methane, propane and butane are all hydrocarbons. Methane has a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

Which is meaningless due to the fact that octane is rated differently in different countries. It is widely accepted that the US uses the most well rounded octane rating system as well.

There is RON, RdON, MON, and AKI.




In the US the highest ever recorded on 10% ethanol blend was a whole whopping 7% in a national survey. That was in 87 octane, 89 and premium gasoline was typically between 0-1% ethanol. Average 87 10% ethanol blend actually only uses 3-4% ethanol.

 

[DSM1G90]

I have to because the timing is so far advanced. Now if I didn't have my timing advance, or any tuning, I'd be using 87.

How's your spark plugs..all white, blistered and burnt to hell?

Didn't anybody tell you that anytime you advance timing to the extreme, that the temp of the plugs have been risen so high where they can actually weld themselves to the head, or even crack the head itself around the spark plug bores since they have almost reaching red hot melting temperatures - first by blistering the porcelain and then breaking the porcelain out of the middle of the plug.

No, problem that normally happens is that one will start with 87, but let carbon build up in the combustion chamber to where it's built up compression to cause knock. Thus the vehicle operator shoves in 93 to rid of knock, but not thinking of blowing out the carbon with sudden blasts of high speed runs in 2nd or 3rd gear almost up to red line on the tach.

pretty big difference in fuel mileage, and i've noticed more pulling power on uphills in the cherokee

...this is a good example of a carboned up motor where the use of 93 had to come into play....

Seen this many-a-times and a good hard run in a low gear cures the carbon build up issue.

 

[DSMOCTANE]

Thanks for all the feedback guys! And its still funny to me how all the 4G63 guys continue to hate on my poor 420a haha! Shes only a daily driver for Christ's sake! Now that I have two blocks, I plan on building a boosted 2.3 stroker overtime to run in the league with the 4g63's! Stay tuned for future news guys! Thanks for all the controversial advice. I suppose I will run regular from now on until internals are modified!

How's your spark plugs..all white, blistered and burnt to hell?

Didn't anybody tell you that anytime you advance timing to the extreme, that the temp of the plugs have been risen so high where they can actually weld themselves to the head, or even crack the head itself around the spark plug bores since they have almost reaching red hot melting temperatures - first by blistering the porcelain and then breaking the porcelain out of the middle of the plug.

No, problem that normally happens is that one will start with 87, but let carbon build up in the combustion chamber to where it's built up compression to cause knock. Thus the vehicle operator shoves in 93 to rid of knock, but not thinking of blowing out the carbon with sudden blasts of high speed runs in 2nd or 3rd gear almost up to red line on the tach. ...this is a good example of a carboned up motor where the use of 93 had to come into play....

Seen this many-a-times and a good hard run in a low gear cures the carbon build up issue.

Well what if you ran 93 from the get-go after the rebuild? Wouldn't that naturally reduce major carbon build up from the start?