Fuel - brands & octane

[Kitty's VR4]

diesel has an octane rating of about 30.

Actually, the Octane rating of diesel ranges from 15-25, not 30 !!

Petrol engines compress the fuel-air mixture significantly higher than diesel engines, and so petrol needs to be able to withstand significantly higher compression than diesel.

Stephen, you have this all arse about. Diesel Engines have a much higher compression ratios than Petrol engine MUCH HIGHER.

Compression ratios for petrol engines start at about 7.5 : 1 and run through to 14 : 1.

Compression ratios for diesel engines start at about 14 : 1 and run through to 22 : 1.

Average compression ratios for petrol engines are somewhere in the area of 8.5 : 1 to 9.5 : 1

Average compression ratios for diesel engines are somewhere in the area of 16 : 1 to 18 : 1

Using any higher octane fuel than what you need, is not going to give you any increase in performance, no increase in power output, nothing...

This is also very misguided, there is a noticable difference running 98RON in a car designed to run 91RON in both terms of responsiveness, cleaner burning and more over you'd expect better economy.


Without trying to sound harsh, this discussion is about fuel/brand options that are being used in VR4's.

Your contribution is always welcomed, but please refrain from posting misleading or misguided statements thats are clearly not correct.

 

[king_panther]

Also, the compression ratio gets dropped when the engine gets turbocharged.

If the engine is designed to accept the higher grade fuel, then you'll get a increase in performance. Seems a lot of the current engines will do that.

Yes diesels don't need sparkplugs, but they do need glowplugs.

Kat, is the distance worth it? I get concerned with fuel losing octane, so as the Super only gets driven now & then, I will usually just fill up a quarter of a tank of whatever I can get.

 

[Kitty's VR4]

Good point Brad !! But I'd still drive to marulan to fill up, just because of the way the car responds to Ultimate.

 

[Gary31]

Also, the compression ratio gets dropped when the engine gets turbocharged.

Not true, turbo charging has no effect on the compression ratio, however turbo charging will increase the pressure in the cylinder, this has the effect of 'artificially' increases the the compression ratio. For this reason turbo engines are often designed with a low compression ratio.

 

[king_panther]

For this reason turbo engines are often designed with a low compression ratio.

That's the point I was trying to make.

 

[ed84]

Yes diesels don't need sparkplugs, but they do need glowplugs.

They don't need glow plugs like petrol engines need spark plugs, they just assist cold starts...

Well the v18 's i work on have no glow plugs anyway

I Definataly get an extra 20-30 k's out of BP ultimate.
& Definataly there is a trend forming here.
& i definately cannot spell

 

[cyber_scriber]

I've been using Shell 98, mainly due to the discount shopper dockets.

Given the positive experiences here, I might give BP a try.

 

[bradc]

A car that is designed for 91 octane will not suddenly make more power if you run it on 98 though. The only time you'll see more power with higher octane fuels is if the car detects knock when running on lower fuels.

 

[BuzzPuppy]

Here's the kicker for you.

Anyone tried running E85 on standard gear? One place I know of is at Southland on Nepean Hwy (Melbourne).

-No, I don't have bigger injectors/new fuel pump.
-No, I'm not expecting OMGWTFBBQ performance increase.
-Yes, I know that even though it's under $1 (98.5c/L last time I drove past), that you will burn more since there is less energy per mL.


The most recent article in Performance Imports as well as continuously seeing it as I drive to Southland every two weeks has piqued my interest.

 

[Merlin032]

Using any higher octane fuel than what you need, is not going to give you any increase in performance, no increase in power output, nothing...

actually, if you tune the car's ecu to run on 110 octane then you will get more power out of the car because you can tune it past where it would normally ping on 98 octane fuel.

Actually, I was told by someone that the petrol companies have a fuel exchange program to simply transport and logistics or something along those lines. so Shell will get fuel from BP or Mobil (or vice versa) depending on what is available at the location.

 

[twisted32]

E85 is a dry fuel like propane, so you should run an upper cylinder lubricant to protect the valves etc. If you stay on lower boost you should be able to make similar power to 98, but, having enough flow (injectors) will be an issue, ie doubt you will make 200kw on E85 without doing injectors.