Свещи за Королата ми.

[hyankov]

Мерси Xeku!

Ами то тогава на мен значи ми липсва половината връх laugh.gif Ще ги извадя и останалите 11 (шегувам се, 3) да видим как са.

[ALTEZZA]

na tez det im gori maslo obiknoveno pochvat ot cilindar #4, ili inache kazano sveshta na #4 poniakoga tolkova se omasliava che dori ne podava iskra, ta proveri ia i neia.
na men tez sveshti si mi izglejdat originalni

[hyankov]

10х ALTEZZA, задължително ще видя, не го знаех това. Иначе въха (или дъгата, както каза Хеки) наистина ли е изгоряля/стопена/изядена или просто така си е laugh.gif

[hyankov]

Аз че ще ги сменям свещите - ще ги сменям. А timing трябва ли да правя? Зареждам 91.

[ALTEZZA]

ti niamash distributor, kakav timing iskash da pravish? komputara vsichko sam si pravi.
a zashto zarejdash s 91? samo si davash parite na viatara, kolata ti e za 87 oktana. niamash koi znae kakva visoka kompresia che da ti triabva po visok oktan. po visok oktan = na poveche pari, pak pri teb faida ot tova nikakva.(i tuk sega ochakvam specialistite da se vkluchat da pochnat da me obejdavat kak kolata im harchi po malko s po visok oktan )

[hyankov]

I stand corrected laugh.gif

[ALTEZZA]

Effects of octane rating

Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).

Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally iginted mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics.

It might seem odd that fuels with higher octane ratings explode less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation as opposed to the ability of the fuel to burn (combustion). However, premium grades of petrol often contain more energy per litre due to the composition of the fuel as well as increased octane.

A simple explanation is that carbon-carbon bonds contain more energy than carbon-hydrogen bonds. Hence a fuel with a greater number of carbon bonds will carry more energy regardless of the octane rating. A premium motor fuel will often be formulated to have both higher octane as well as more energy. A counter example to this rule is that ethanol blend fuels have a higher octane rating, but carry a lower energy content on a volume basis (per litre or per gallon). The reason for this is that ethanol is a partially oxidized hydrocarbon which can be seen by noting the presence of oxygen in the chemical formula: C2H5OH. Note the substitution of the OH hydroxyl radical for a H hydrogen which transforms the gas ethane (C2H6) (which is an alkane) into ethanol (which is an alcohol). Note that to a certain extent a fuel with a higher carbon ratio will be more dense than a fuel with a lower carbon ratio. Thus it is possible to formulate high octane fuels that carry less energy per liter than lower octane fuels. This is certainly true of ethanol blend fuels (gasohol), however fuels with no ethanol and indeed no oxygen are also possible.

In the case of alcohol fuels, like Methanol and Ethanol, since they are partially oxidized fuels they need to be run at much richer mixtures than gasoline. As a consequence the total amount of fuel burned per cycle counter balances the lower energy per unit volume, and the net energy released per cycle is higher. If gasoline is run at its preferred max power air fuel mixture of 12.5:1, it will release approximately 19,000 BTU (about 20 MJ) of energy, where ethanol run at its preferred max power mixture of 6.5:1 will liberate approximately 24,400 BTU (25.7 MJ), and Methanol at a 4.5:1 AFR liberates about 27,650 BTU (29.1 MJ). [Can someone please determine the correct unit for this measurement? Does the gasoline release 19,000 BTU per cycle, per gallon, or what. It is tough to determine whether ethanol is actually being proven to be a better fuel in this article]

To account for these differences, a measure called the fuel's specific energy is sometimes used. It is defined as the energy released per air fuel ratio. For the case of gasoline compared to the alcohol fuels the specific energys are as follows:
Fuel Net energy Units
Gasoline 2.92 MJ/kg
Ethanol 3.00 MJ/kg
Methanol 3.08 MJ/kg

Using a fuel with a higher octane lets an engine run at a higher compression without having problems with knock. Actual compression in the combustion chamber is determined by the compression ratio as well as the amount of air restriction in the intake manifold (manifold vacuum) as well as the barometric pressure, which is a function of elevation and weather conditions.

Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more power. Engine power is a function of the fuel as well as the engine design and is related to octane ratings of the fuel... power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. At partial load, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than what is available. It is only when the throttle is opened fully and the manifold pressure increases to atmospheric (or higher in the case of supercharged or turbocharged engines) that the full octane requirement is achieved.

Many high-performance engines are designed to operate with a high maximum compression and thus need a high quality (high energy) fuel usually associated with high octane numbers and thus demand high-octane premium gasoline.

The power output of an engine depends on the energy content of its fuel, and this bears no simple relationship to the octane rating. A common myth amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this is false—engines perform best when using fuel with the octane rating they were designed for and any increase in performance by using a fuel with a different octane rating is minimal or even imaginary.

Using high octane fuel for an engine makes a difference when the engine is producing its maximum power. This will occur when the intake manifold has no air restriction and is running at minimum vacuum. Depending on the engine design, this particular circumstance can be anywhere along the RPM range, but is usually easy to pin-point if you can examine a print-out of the power-output (torque values) of an engine. On a typical high-rev'ving motorcycle engine, for example, the maximum power occurs at a point where the movements of the intake and exhaust valves are timed in such a way to maximize the compression loading of the cylinder; although the cylinder is already rising at the time the intake valve closes, the forward speed of the charge coming into the cylinder is high enough to continue to load the air-fuel mixture in.

When this occurs, if a fuel with below recommended octane is used, then the engine will knock. Modern engines have anti-knock provisions built into the control systems and this is usually achieved by dynamically de-tuning the engine while under load by increasing the fuel-air mixture and retarding the spark. Here is a white paper that gives an example: [4] . In this example the engine maximum power is reduced by about 4% with a fuel switch from 93 to 91 octane (11 hp, from 291 to 280 hp). If the engine is being run below maximum load then the difference in octane will have even less effect. The example cited does not indicate at what elevation the test is being conducted or what the barometric pressure is. For each 1000 feet of altitude the atmospheric pressure will drop by a little less than 1 inHg (11 kPa/km). An engine that might require 93 octane at sea level may perform at maximum on a fuel rated at 91 octane if the elevation is over, say, 1000 feet. See also the APC article.

The octane rating was developed by the chemist Russell Marker. The selection of n-heptane as the zero point of the scale was due to the availability of very high purity n-heptane, not mixed with other isomers of heptane or octane, distilled from the resin of the Jeffrey Pine. Other sources of heptane produced from crude oil contain a mixture of different isomers with greatly differing ratings, which would not give a precise zero point.

[hyankov]

^ Супер информативно, браво.

[Japanese_fever]

Az karam su6to s 91, za6toto s 87 mi 4uka avansa(ili tam kakvoto e) kogato nabiram na 1-va i 2-ra.
Su6to taka 91 mi dava 50 mili pove4e probeg na rezervoar ot 87. Tova sum go meril, no za da si go dokaja sledva6tiq put 6te sipq 87.

[hyankov]

Аз пък да проверя дали Алтезата (Сега known as STI) е прав ще сипя 87 да видя дали ще направя повече от 265 мили градско (колкото правя сега с 11 галона 91).

[hyankov]

Дано да е прав, защото тука бензина вече е 3.5/галон. В Сан Франциско е 4.0/галон ("скоро и във вашия град").

[ugabuga]

ba si cenite ... tuka premium-a e 2.50 i mi se struva MNOGO!

[ALTEZZA]

tuk e pochti $3, no problema e che prodaljava da raste, ta na po hubavo niama da otide

[hyankov]

Дамммм, много интересно.

С 87 правя 16.5 mpg, с 91 правя 23+ mpg, а колата ми е за 87

Отидох и си купих свещите, утре ще ги слагам. Дано е от това.

Алтеза, знаеш ли дали трябва да коригирам gap-а? До колкото разбирам и колко се завива е много важно, мога ли да го направя без torque wrench?

[jamie]

Gap от 1.2 да иде на 3.5мм не се коригира а се сменят свещи.
Ако верно са оригиналните от фабриката - мисля 100 000 мили им е предписания живот.