Xr6t

[Guest DZ.]

We're not talking about an increase in power though, just maintaining power in heat. If 95RON is getting close to detonation in the heat, then the EMS will pull the timing back. However, 98RON is more resistant to detonation and therefore the timing may not be pulled back as much when it's hot.

I don't know too much about that side of things admittedly - chemistry was never my thing so I'd be interested to hear from someone who knows what they're talking about.

[Turbo6man]

Mondie,

That's cruel! Late March is only NINE weeks away!!!!!!!!!

On the fuel, I don't see that a turbo with moderate boost needs the added octane. A high compression motor sure but the XR6T??

Turbo = higher compression, so if you want the best performance you will use premium.

[Guest 56Mainline]

Performance ALWAYS comes at a cost....it's each to his own to decide if they think it is worth it....

Browsing through the NRMA's "The Open Road" magazine, Jan/Feb 2003, pgs 26~30, "Fuel Guide" article by Jack Haley, NRMA's Senior Environmental Advisor.

"ULP 91

PULP 95~96

LRP 95~96 (LRP is essentially PULP with additive to protect engine valve seats and valve faces)

UPULP 98

There is no advantage in using high octane fuel unless your vehicles engine management system is designed to adjust to take advantage of the higher octane.

Even if the engine does adjust for the higher octane, the maximum advantage is generally around 1% increase in engine power (or reduction in fuel consumption) per octane number.  Unless the price of the higher octane fuel is less in cents per litre than the difference between the fuels in octane numbers, it is probably not economically worth your while using the higher octane.

From reading this forum & other literature, I understand that the knock sensor, VCT & EMS in the XR6T will manage whatever unleaded fuel you use (probably even a UPULP with additional octane booster to take it to 100 RON) to maximise power & economy (depending how you drive her) and inhibit detonation.

A question though.....I'm not aware that there are any improved additives going from ULP to PULP to UPULP where the additives aid in maintaining injectors, reducing carbon deposits, etc. I thought the only difference was the RON. Anyone know any different?

[Mondie]

l think the additive differences between ULP to PULP & UPULP come down to the source of the fuel, its not regulated by law as far as l know. A good reason to stick with Shell or Mobil fuel which utilise additives to promote cleaning, reduce deposits etc.

[tupperware]

The additives are only part of the fuel blend equation. The process in obtaining the individual octane in the different components of the final blend varies between ULP, PULP, UPULP. RVP (vapour pressure) and density also variy between the type of fuel.

The four majors (BP, Caltex, Mobile & Shell) all obtain the octane in roughly the same process, where as some import fuels use MTBE to dope the RON up a couple of points.

Personally I stick with fuel from the majors. It's worth checking the guarantee they provide with their fuel. What happens if you get a gut load of water with a fill? How about if a ULP tank has been contaminated with LRP or diesel. Some will cover all costs of repairs where as other might not. Let's face it it's only a couple of bucks a tank. I see it as an easy decision.

My 2 cents

[Turbo6man]

Performance ALWAYS comes at a cost....it's each to his own to decide if they think it is worth it....

Browsing through the NRMA's "The Open Road" magazine, Jan/Feb 2003, pgs 26~30, "Fuel Guide" article by Jack Haley, NRMA's Senior Environmental Advisor.

"ULP 91

PULP 95~96

LRP 95~96 (LRP is essentially PULP with additive to protect engine valve seats and valve faces)

UPULP 98

There is no advantage in using high octane fuel unless your vehicles engine management system is designed to adjust to take advantage of the higher octane.

Even if the engine does adjust for the higher octane, the maximum advantage is generally around 1% increase in engine power (or reduction in fuel consumption) per octane number.  Unless the price of the higher octane fuel is less in cents per litre than the difference between the fuels in octane numbers, it is probably not economically worth your while using the higher octane.

From reading this forum & other literature, I understand that the knock sensor, VCT & EMS in the XR6T will manage whatever unleaded fuel you use (probably even a UPULP with additional octane booster to take it to 100 RON) to maximise power & economy (depending how you drive her) and inhibit detonation.

A question though.....I'm not aware that there are any improved additives going from ULP to PULP to UPULP where the additives aid in maintaining injectors, reducing carbon deposits, etc. I thought the only difference was the RON. Anyone know any different?

My experience is different to what the NRMA expert is trying to sell - ALL engines will run better on higher octane fuel. Some of course will benefit more than others. Even engines with lower compression ratios will run cooler and also achieve slightly better economy. If you have an engine with non-ECU timing control you can advance your initial static timing by a few degrees to achieve better performance. It is true in some cases the cost benefit may be zero or less. ECU controlled engines with an agressive timing curve and equipped with knock sensors will benefit most. Work out for yourself if the XR6T fits this category. If I owned one it would certainly be running Optimax.

[Guest DZ.]

My experience is different to what the NRMA expert is trying to sell - ALL engines will run better on higher octane fuel. Some of course will benefit more than others. Even engines with lower compression ratios will run cooler and also achieve slightly better economy.

The Late model camira Ecotech V6 and the Magna 3.0L V6 don't have a change in economy with higher octane fuel - I've tested them.

[F6 RAPID]

The Late model camira Ecotech V6 and the Magna 3.0L V6 don't have a change in economy with higher octane fuel - I've tested them.

DZ, you have hit the nail on the head. If the car is designed and the ecu is programmed to run on normal ulp, you will not get any better performance from using pulp. It will just be a more expensive exercise.

Most cars these days that are designed to run on pulp have knock sensors on the motors and the ability to retard timing if necessary if you have to use normal ulp. Contrary to common belief, no car has the ability to "sense" what sort of fuel you are using, that is impossible. What the car does in fact do is try to run its normal program continuously and if it senses detonation or the like for example from using ulp instead of pulp, it then retards the ignition timing. A lot of factors come into play here, for example, a car using ulp over pulp will be more likely to have the ignition timing retarded in hot weather while under load and probably less so in very cool weather. Just an example for you.

[Ninka]

I have used std ULP on a couple of occations where PULP has been unavailable, and to be honest, the difference is only ever so slight at full throttle, and not noticable at all during normal driving on both city or country roads.

Sure PULP will probably perform better if you floor your car constantly, but for normal driving, I don't think you will notice the difference!

This may be unique the us here in the west as our fuels are not blended with ethanol, and I think we have slightly different standards for our petrol.