ron 95 or ron 97

[ALBundy]

10.2:1 is actually quite a high compression ratio for an engine. For comparison purposes, the Golf GTi running the EA888 TSFI turbocharged engine, runs a compression ratio of just 10.3:1. As you can see, BMW's M52/M54 engines all run near-turbo levels of compression, between 10.2:1 (M52) and 10.5:1 (M54).

Mazda's SkyActivG engines hold the record for compression ratios though. They run a compression of 14.0:1 without the aid of a turbo.

Actually there is more to it.

What you have just describe is the static compression ratio. However in an operating engine, static compression is no longer the measuring yardstick. For normally aspirated engines, it's the dynamic compression ratio. Dynamic compression ratio differs from the static compression ratio due to the lift and duration of the camshafts.

As for forced induction engines, the measuring yardstick is effective compression ratio. This is due to the additional boost pressure from the turbine. The philosophy of the European manufacturers differ from the Jap where European forced induction engines have a relatively higher static compression but lower boost. This help to improve torque at the lower rpm range and more fuel efficient where as the japs have lower static compression but higher boost.

There are various sites that can calculate the effective compression if you decide to change your pistons and turbine.

So in a nutshell, turbo cars are running higher effective compression than the dynamic compression of the NA engines. As for 10.2:1 static compression ratio, as of today's standard it is no longer considered high as plenty of normally jap engines are running 10.0:1 and some even higher.

 

[rpmnut]

Actually there is more to it.

What you have just describe is the static compression ratio. However in an operating engine, static compression is no longer the measuring yardstick. For normally aspirated engines, it's the dynamic compression ratio. Dynamic compression ratio differs from the static compression ratio due to the lift and duration of the camshafts.

As for forced induction engines, the measuring yardstick is effective compression ratio. This is due to the additional boost pressure from the turbine. The philosophy of the European manufacturers differ from the Jap where European forced induction engines have a relatively higher static compression but lower boost. This help to improve torque at the lower rpm range and more fuel efficient where as the japs have lower static compression but higher boost.

There are various sites that can calculate the effective compression if you decide to change your pistons and turbine.

So in a nutshell, turbo cars are running higher effective compression than the dynamic compression of the NA engines. As for 10.2:1 static compression ratio, as of today's standard it is no longer considered high as plenty of normally jap engines are running 10.0:1 and some even higher.

Of course. An engine's theoretical calculated compression ratio, assumes two things:

(1) that the cylinder is sealed at the bottom of the stroke (bottom dead centre - BDC), and
(2) that the volume compressed is the actual volume.

However, operational issues such as intake valve closure and intake port scavenging may also allow a lower or greater mass of charge to be trapped in the cylinder than the static volume.

Nonetheless, 10.2:1, while not being on the upper ends of the compression ratio scale, is certainly not considered "low" by modern standards.

 

[ALBundy]

Of course. An engine's theoretical calculated compression ratio, assumes two things:

(1) that the cylinder is sealed at the bottom of the stroke (bottom dead centre - BDC), and
(2) that the volume compressed is the actual volume.

However, operational issues such as intake valve closure and intake port scavenging may also allow a lower or greater mass of charge to be trapped in the cylinder than the static volume.

Nonetheless, 10.2:1, while not being on the upper ends of the compression ratio scale, is certainly not considered "low" by modern standards.

So what's your point le?

My point is,

1) you can't simply compares static compression of na and forced induction engines as I have explained why earlier

2) 10.2 is not considered high and neither have I said is low. It was you that implied it is high since the tfsi engine also has similar static compression. Again for forced induction cars, the yardstick is effective compression ratio which is a combination of static compression and boost pressure. A turbo car with high boost pressure can easily have a higher effective compression than the Mazda ActiveG you mentioned.
For NA engines, anything above 11 is considered high and below 10 is low nowadays. In between is pretty much what you have in most cars on the road.

It will be good for everyone to read more on the various compression ratios before modding their engines.

 

[rpmnut]

Lower octane does not necessarily means lower engine power.

If it's a low compression engine (relatively speaking say for example the M52B28 which has a 10.2:1 compression)........

Cheers

Actually you did say it's low. Hence my response to correct the statement.....

 

[ALBundy]

Actually you did say it's low. Hence my response to correct the statement.....

Relatively low when compared to other engines in the m5x category. The M50 itself has a static compression ratio of 10.5:1. That was what I meant. You have to understand the context of the discussion which is with regards to octane level to engine Hp/torque. My point is a m52b28 which has relatively lower static compression when compared to the M50b25, m52b25, m54b25 and even the N52 engines which all have a higher static compression won't be able to fully utilise the higher octane petrol compared to those that have a 10.5:1 compression ratio.

 

[Eggie86]

Yup or if you go straight on on the overhead bridge heading to Sunway there's one there and there one in USJ ( USJ 12 if i'm not mistaken ) that i go often too.

got lah bro... next to BHP... near the inti college roundabout in ss14... at the famous car wash place.

Oooh, no wonder. Okok. :top:

On a side note, finally reverted back to RON95 after almost half a year of using Shell's VP97. Car had around 1/4 tank of 97 left when I pumped 95 to the brim. Cost me about RM 120.99 for 63.68 litres of filling up @ RM 1.90.

Not really feeling any noticeable drop in performance or knocking like previously, and managed to get a decent mileage out of it during my return leg from Senawang to Subang Jaya. Car was effortlessly cruising around 140km/hr throughout the journey. :top:

 

[pakupakis]

Hi Guys,

Thanks for all the advise and debates on this thread. I have been using RON97 since i got my e46 but the price is getting higher and higher (ridiculously), and I think I will have to give RON95 a try out....

I tried pumping RON95 for my e30 but the lag was very noticeable that's why afraid to try on my e46..

Will give it 2 weeks!!

 

[SMG330i]

I've been running 97 for my new E90 320I LCI, switch to 95 for almost 2 weeks now. Never notice any different for me. So i think it's a good switch after all. Save more money. Cheers!

 

[puginfo]

So what's your point le?

My point is,

1) you can't simply compares static compression of na and forced induction engines as I have explained why earlier

this is the key point AL has pointed out. there is no logic to compare CR between a NA engine and boosted engine for all the reasons given. as they work on opposite ways, to insist on a yardstick to compare only confirms that the topic of CR is not understood to start with.

 

[affan66]

used RON 95 during the recent Awana drive. I don't think I had issues catching up with the rest

 

[kayzhen911]

RON 97 is actually a placebo effect.

 

[AiRBooM]

I've been running 97 for my new E90 320I LCI, switch to 95 for almost 2 weeks now. Never notice any different for me. So i think it's a good switch after all. Save more money. Cheers!

could you tell us what brand you use on 97 and switched to what brand of 95 ? thankss

 

[kayzhen911]

for all your information....
Shell VPower97 is not the same formulation as VPower of the past.

 

[ALBundy]

Vpower 97 is just a rebranding exercise.

Given the recent price increase, one would be better off using v power racing, if the engine is designed and able to take advantage of higher octane fuel.

 

[B33mEr]

RON 97 is actually a placebo effect.

Really why do you say that?

 

[SMG330i]

could you tell us what brand you use on 97 and switched to what brand of 95 ? thankss

I'm always a shell guy. So V-power for 97 then i've swtich to BHP ron 95, Caltex ron 95.

 

[EEEE30]

This I found in the interwebz.
Couple of guys did a research on differences among different brands of RON 95.

http://kereta.info/differences-of-r...es-from-bhp-petronas-shell-caltex-esso-mobil/

FYI: this is not a test between RON 95 and RON 97, nevertheless it's a good read.

 

[kayzhen911]

well B33mEr, pple who r so into the consumption thingy will be very sensitive to everything that affects his car.
its just their mind playing tricks on them.
we gotta be subjective when testing for FC.
FC "koyak" only when we vrOOOOOmmmmm too much
hehehe....

 

[B33mEr]

well B33mEr, pple who r so into the consumption thingy will be very sensitive to everything that affects his car.
its just their mind playing tricks on them.
we gotta be subjective when testing for FC.
FC "koyak" only when we vrOOOOOmmmmm too much
hehehe....

Hahaha ... true about the placebo effect but M54 engine power output is based on RON98. Using lower octane will result in lower performance hence have to tekan more to get the same performance which will lead to higher fuel consumption ... that's my theory anyways :4:

 

[ALBundy]

This I found in the interwebz.
Couple of guys did a research on differences among different brands of RON 95.

http://kereta.info/differences-of-r...es-from-bhp-petronas-shell-caltex-esso-mobil/

FYI: this is not a test between RON 95 and RON 97, nevertheless it's a good read.

This test doesnt mean anything.

All brands of fuel whether it's Petronas, Shell, BHP, Caltex, Esso and Mobil, and irregardless of whether its RON 95 or 97 have the same calorific value. Meaning to say in lay man's term the amount of chemical energy is the same.

It is the design of the combustion engine, ie; compression ratio, ignition timing and etc, that determines how much of this chemical energy is converted into kinetic energy (which is what everyone is interested) and the rest into heat.

To check which fuel has the highest RON, one needs to get the proper measuring equipment. The machine/engine would be running with the ignition timing kept advancing till a knocking sound is pick up. Only petrol companies can afford these machines.