Higher Octane Fuel = More popping and banging??

[matt_vtr_15]

Basically today I banged in some 99 RON fuel today instead of the normal 95 RON or whatever it is....

and my car is constantly popping when changing down gears...

I just find it strange as it barely popped before with normal fuel but now it does it on demand...

Anybody experienced this before? Should it happen?

I just have a piper backbox, otherwise a standard vtr exhaust however I have decatted it... so just surprised it actually pops...

[lee-watson-saxo]

yer have the same problem with myn m8t its jst coz there is more octain in the fuel and with it not having a cat the only way it gets out is bannnnnnnnnnnnnng haahh

[Matt_e]

high octane fuel wont make any difference on saxo

[gouldy87]

high octane fuel wont make any difference on saxo

explain?

[AXracing]

Higher octane fuel is more resistant to heat and pressure combustion. A engine intended to run on higher octane fuel will run higher compression and hotter to get as much energy in to the fuel air mix and in so get more power out of it. Engines intended to run on poor fuel cant do this and so cant get the extra power. You even find that most engines intended to run on lower octane fuel will be running at such low pressure that ignition timing will be close to optimal as retarding ignition looses you a lot more power and efficiency than lowering static compression. In so the engine is unable to do much if anything to gain advantage. This probably explains the popping as well because when you lift off there is less air and even harder for fuel to burn, in so your probably just pissing out unburned fuel and this is the popping.

Edit, I have seen tests on a Rover K series where higher octane fuel actually lost power and economy.

[starletcal]

Higher octane fuel is more resistant to heat and pressure combustion. A engine intended to run on higher octane fuel will run higher compression and hotter to get as much energy in to the fuel air mix and in so get more power out of it. Engines intended to run on poor fuel cant do this and so cant get the extra power. You even find that most engines intended to run on lower octane fuel will be running at such low pressure that ignition timing will be close to optimal as retarding ignition looses you a lot more power and efficiency than lowering static compression. In so the engine is unable to do much if anything to gain advantage. This probably explains the popping as well because when you lift off there is less air and even harder for fuel to burn, in so your probably just pissing out unburned fuel and this is the popping.

Edit, I have seen tests on a Rover K series where higher octane fuel actually lost power and economy.

INIT... BOOST FTW:afro:

[kenny]

explain?

Higher octane fuel is more resistant to heat and pressure combustion. A engine intended to run on higher octane fuel will run higher compression and hotter to get as much energy in to the fuel air mix and in so get more power out of it. Engines intended to run on poor fuel cant do this and so cant get the extra power. You even find that most engines intended to run on lower octane fuel will be running at such low pressure that ignition timing will be close to optimal as retarding ignition looses you a lot more power and efficiency than lowering static compression. In so the engine is unable to do much if anything to gain advantage. This probably explains the popping as well because when you lift off there is less air and even harder for fuel to burn, in so your probably just pissing out unburned fuel and this is the popping.

Edit, I have seen tests on a Rover K series where higher octane fuel actually lost power and economy.

sums it up basicly. saxos wont have any advantage to using higher octane fuel unless set up to run on it. eg my mr2 is set to run on high octane fuel and runs great. i put in normal unleaded and it runs like a bag of shit.

[Steve]

99 ron fuel made my saxo run like shit.

[Spanky]

99 ron just does nto apeal to me, especially when its 112.9p a litre!

My car runs perfectly fine on 95 ron, although i may try a tank of 99 when i get my turbo on...

[toms_vtr]

the only way to get something out of puttin super unleaded in a saxo is to get it remaped with super in.
even still it will make hardley any difference...

[rushy_23]

I know this is off topic. But when having engine work done, can the car be mapped to run on higher octane fuel.

Also, Ive been using High Octane since day one with my car. But reading some of the stuff above I feel like Ive wasted money doing this.

If I start running it on normal stuff, Im not making any sacrifices with the car am I? Basically I always thought along the lines of Higher Octane being 'better' for the car.

[toms_vtr]

I know this is off topic. But when having engine work done, can the car be mapped to run on higher octane fuel.

Also, Ive been using High Octane since day one with my car. But reading some of the stuff above I feel like Ive wasted money doing this.

If I start running it on normal stuff, Im not making any sacrifices with the car am I? Basically I always thought along the lines of Higher Octane being 'better' for the car.

read my post above,,
should answer the question

[Matt_e]

One of our users commented that using higher octane fuel than your engine requires actually gives no benefit and may be a waste of money. This is because virtually NO engines require 98 RON over 95, and the market for 'super' fuels seems to be based on people's misunderstanding of octane ratings and the placebo effect of filling up with 'more powerful' fuel - making motorists think their engine is running better in some way.



http://www.petrolprices.com/about-fuel.html

[iluminusbutterfly]

the only main advantage of 99octane fuel is to stop pinking on highly tuned cars, however the pinking sensor on saxos should stop this anyway, false economy on a saxo imo

[jamsey]

Yeh my saxo loves the shell v power lol but drinks it fast lol

[Mint-VTR]

i think my car defiantly runs better on 99!

[gouldy87]

the only main advantage of 99octane fuel is to stop pinking on highly tuned cars, however the pinking sensor on saxos should stop this anyway, false economy on a saxo imo

whats pinking?

do you mean knock by any chance?

[nickwillyhams]

ive never put anything but super unleaded in my vts, tbh i dont really no if it makes a difference but its a piece of mind thing i think, my point is can someone with a true understanding on the subject tell me if it really not worth it!? the difference in cost is minimal to me as petrol is a f-ing rip off anyway !!

[Jay_]

haha...sayin its expensive fuel....bog standard super unleaded is 115.9p a litre ova here...now THAT is expensive....

[Claki]

My R Deffinatly is more responsive with v power, because i tested it against premium unleaded at a Murco staition, the murco fuel feels numb and breathless and the v-power seems to always be ready to bite.

[col101]

whats pinking?

do you mean knock by any chance?

Similar things I think. The knock sensor eliminates pinking as a side effect.
If I understand correctly pinking is the cam knocking and knocking is the bottom end? So when the knock sensor adjusts tming or fueling or whatever it does, it gets rid of pinking at the same time..
I think

[webby]

pinking is pre ignition. caused by a number of reasons. crap fuel being one also a high compression ratio to name a couple.

[Cov_Rob]

I put super unleaded in my car for a 300 mile trip to cornwall hoping to get a few more miles to the gallon. I didnt see any difference in performance but i did get an extra 60 miles out of a full tank, not sure if that was just because it was all motorway and no town driving though, but in my opinion still not worth the extra 10/15p a litre.

[jpsaxo]

Always run mine on 98/99 as its running higher compression than standard!