I have some questions, I'm no engineer in mechanical field and I only have a general idea on how an engine works so correct me if I'm wrong

Question: does higher RON allows for higher performance in normal car? Eg myvi saga

Fact: A higher RON allows for a higher compression ratio without knocking

Doubt: to mechanical engineers, does a normal car engine adjust it's own compression ratio to the fuel octane ratio? If it's not variable then wouldn't it compress the fuel back to the same ratio? Then wouldn't the performance be the same between RON 95 and RON97 if the compression ratio is the same?



This post has been edited by destEX: Dec 4 2014, 08:45 AM

The compression ration between RON95 and RON97 is different. RON97 can hadle more pressure thus when combust release more energy, that's all about it. Most of the time you can't feel the difference, except when you paying for your fuel. Just use whatever fuel recommended for your particular car model.

inkambing ENGr. Uitm

This post has been edited by chokia: Dec 4 2014, 08:39 AM

Mahal = Bagus....

V-POWER Racing lagi mahal = lagi bagus

Yes ron97 can handle more pressure but who puts the pressuee? The engine right? Then the compression ratio is determined by the engine, so back to my main question, is the engine compression ratio variable for normal msia cars

Petrol halal > all

Inb4 minyak pelincir halal and minyak pelincir perisa babi

Eversince i used RON97 everyday i reach office early altho i go out late. RON97 can make your car reach places faster

100% success beating traffic light guranteed

Question: does higher RON allows for higher performance in normal car? Eg myvi saga

yes, if your saga got knock sensor, which is the sensor for detecting the fuel quality.

correct me if i'm wrong

The answer is yes, depends on the type of the engine. But i would not recommend to adjust the compression ratio though..

The difference in octane generally indicates the resistance to detonation. It has nothing to do with compression ratio. So throw the idea of the compression ratio out the window.

A car mostly cannot change its compression ratio, but it can advance or retard the ignition. It does this in concert with the O2 sensor for AFR and knock sensor.

eg; If a car senses it is using a lower RON than what is recommended due to the detection of knock and pinging via the knock sensor it starts to retard timing, which lowers the power. And if it detects that knock is 0 and AFR meets the target it gets more aggressive with the timing advance.

But, no. On normal cars, the car will go no more aggressive on the timing than it's stated RON target. If your car maker recommends a RON91 you gain nothing by going to 98 as the ECU will go no higher to preserve the engine from blowing holes in your piston.

Ron 97 less knocking tendency. Most modern engine can take advantage of that with more advanced timing hence producing more power.

This would be more accurate answer. So no need to get different RON for you car, just use whatever recommended by the manufacturer

konklusi disini.. ron 95 nor ron97. dua2 xde beza.

and myth pasal ron97 cuci enjin tu? owai. aku dengar pon dah topkek

Ayam chemical engr

Anyway just pass by

Good

If you own a performance car with a wide range of recommendations, then yes, you can try different fuels.

My Mitsu Evo in the manual says that it will run on 95 to 98, so maximum power is achieved at RON98.
My BMW says it will run on 91 to 98, so being a cheap bahgger I isi with cheapo petrol RON91 to jimat.

Under law, all fuel contains a certain amount of detergents. Some fuel sellers to increase sales put more additive in their premium RON97 petrols, but not all of them.

Also if you use a direct injection engine, all this cleaning shit is useless.

ouh wel.. now the price range not too far.. it should consider cheap.

How can I know my car sapot what petrol?

Proton information so limited on internet.

dont really care bout the more mileage or more power or more fast...
i using ron97 due to more safe for engine je...hopefully.

ingeniur here

still pumping ron95

ron97 more value for money? even for myvi/saga/wira? nah

high performance engines hav higher compression ratio, thus u need ron97 for dis kind of compression ratio

I heard on bfm last week or so some caller said she sometimes fill up with ron 97 to 'treat' her car.. Got such thing ah? Car will be happier if use expensive petrol?

Nope. car will be happier if use recommended petrol.

The higher the octane number, the more compression the fuel can withstand before igniting. For example my car using RON 95 the rate is about 16km/l while using RON 97 can go to 18km/l. #kthnxbai

This
+ if majority of the time driving in city, stuck in jam, what is the point even if the so call "improvment" on performance is true.

Compression ratio is fixed..where can suka suka change wan.hhahaa
U mean air fuel ratio?

97 on the A5, 95 on my C200. after all those bullshit, i just have to pay less. happy man ayam.

Can change ignition timing based on feedback from knock sensor

Yeah but the question was change compression ratio. That is fixed mechanically

Hope your 2.0t ea888 dun start eating oil..hehee

This post has been edited by ar188: Dec 4 2014, 09:47 AM

If timing is retarded, ignition happen faster. Therefore piston travel shorter distance before ignition hence lower compression ratio

if your car compression ratio is low no need so high ron.
go check your car manual or brochure.

A5 eat more enjin oil, but then again, a visit to Autoreign solved everything.

p.s. firm got petrol subsidy and travel allowance. so, no pinch

My car stated the minimum RON is 97 and it is true that its deliver optimum performance than RON 95. how?

This post has been edited by merajey: Dec 4 2014, 09:54 AM

er.... u mechanical engineer? from where wan?

There is generally no significant benefit of pouring a higher rated petrol if your car does not take advantage of the increased compression ratio. People who claim that RON97 works wonders for their Wira/MyVi are probably trying to justify the extra cash they spent.

Wrong laaa... retarding ignition timing is not to lower compression ratio...
to lower the compression ratio the VVTi or iVtec or variable valve technology will keep the intake valve open much longer than its required so the mixture will reverse back into the fuel injector chamber thus lowering the compression ratio

this also works with retarding ignition timing to compensate for the low RON or premature ignition (Engine knock)...

but if your engine is design for Lower RON like RON91/2/5 no point pump 97 just waste of money only...

most of CKD cars are made for RON91 due to thailand fuel... (Thai sell RON91) so inorder for your car to travel to thailand and not dying there engine is made to lowes regional requirement hence in South east Asia is RON91... this is also why before RON95 petrol pump sell minyak merah (RON92)

Some europe car uses min 95 cause based on europe region where min RON is 95...

Japanese performance car usually go around RON97-RON100 eg. Type-R is RON98... but RON97 can laaa any below will kill your engine...

1. A higher RON that what the engine is designed for will NOT produce more power, the effects we feel is largely due to different additive packages for 95 and 97 at our pumps

2. No a car cannot adjust compression at all. Higher compression ratio requires higher RON because before the piston reaches top dead centre the air fuel mixture is already hotter than a lower compression engine. Take a very simplified example, two pistons traveling over the same distance 10cm in the cylinder. One has compression ratio of 10:1 and the other 14:1.

After 10cm travel the 10:1 compressed the air 8 times of nominal pressure, but the 14:1 would have compressed the mixture to 10 times of nominal pressure despite travelling same distance.

High compression = higher temperature = more likely to self ignite before spark from spark plug. Hence higher RON needed to withstand self ignition until the spark fires.

So why doesn't RON 97 give better performance in an engine requiring only RON 95?

simply because of the reason above, the engine needs to have the mixture NOT ignite BEFORE the spark, so 95 is enough to prevent that, putting 97 also achieves same results, hence 0 benefit.

Beep beep..fellow engineer passing through..just checking out how many mechanical engineers in /k..

Proton, probably 95 is fine.

Uni of Lolyat?

not exactly right

compression is completely fixed, it's the physical ratio of the bore of the cylinder and travel of the piston.

holding valves open will reduce the pressure build up BUT the compression ratio remains becuase the bore and piston travel does not physically change.

secondly , valve timing is not to change compression ratio, is to change the breathing of the engine, and VVTi only works when the piston is at TDC, the entire process of the mixture in and exhuast out is completey driven by the natural remaining pressure from combustion in the cylinder and scavenging of the exhaust system

the piston does nothing to change the suction, both valves MUST be fully closed once the compression stroke begins the upward stroke.

This post has been edited by rcracer: Dec 4 2014, 10:33 AM

I have to admit I'm an electrical and not a mech lol.

johnkia

I only know how to tuang Tecron Concentrate plus every 20K mileage to cuci engine, thats about it.

kalau pakai protong peroduak pakei 95 je laa

The difference of only 2 Octane numbers will not make a significant difference on the engine performance, kthxbye

just pun the magic ion sticker la. settle.

lol no worries..civil eng here..

one can always learn about engines and whatever there is to learn about the automotive things and give accurate explanations anyway

saya tidak pandai.

its more than that.
compression ratio
forced induction or NA
ignition timing.
rpm

Ron 95 or ron97

What more important is we still using euro2 fuel grade

Even thai, indon and singapore use euro 4 or 5 grade

well, we gotta check the definition of compression ratio.
opening the valve while compressing the mixture IS effectively reducing the compression ratio.

Ask johnkor, 1st class upper Lowyat uni phd in automobile

Doctorate of softmod

Vely powderful

while many mechanical theory stating this statement, many have fail to explain why they feel the extra power when driving around with a toyota VVTI with RON97, including me

#facts

Sadly this one doesnt help on Direct Injection engine..still have to manually cuci carbon.

From university of lowyat la...

the moving piston can change compression ratio wan

Tbh I had forgotten about thermodynamics and the operation of the four stroke engine combustion octo cycle
Lel...

tokok engineer can come in?

*Otto

oops

USA drag cars use RON 81 garbage fuel can make 1000HP. Its all about tuning la.

I can't even tell the difference between a stock GT-86 and one with a tuned Tomei exhaust in terms of performance. The general rule is that most people can't sense a difference in power till it hits the 10 percent power mark.

Your butt dyno must be incredibly sensitive.

US uses MON and not RON, 81 in US is the same as 92 with RON standard.