10 replies to this topic

[podmak]

With the Twin Turbo setup (EJ20HDWAJE), what's the reommended octane level in the fuel. (Owner's manual is a luxury I didn't receive with the car, and Japanese language is an enigma to me). 

 

I've ben using the 98 Octane ever since I got the car. But, I will be honest, I don't understand why is there such requirement on the engine, and while we're at it, I don't even know if there is such requirement. 

 

Is there anyone who could explain, in plain English, why does one stick to the 98 octane?

 

 

What are the perils of running a 95 octane, or even the 91 unleaded fuel types (NOT including the ethanol mixes). 

 

 

If there is a good read about this that you know of, please paste it in the comments; 

 

And as always, your constructve input is greatly appreciated. Thank you in advance. 

[Barbbachello]

98 Octane resists knock/detonation/pinging better than the others. This is essential on a turbo car and especially on the TTs as they do like to ping.

If you run 91 your engine will probably melt. 95 could be ok in an emergency if you stay off boost

Technically the required fuel would be 100 RON but (im assuming youre in australia) 98 will be ok

TL;DR it stops your engine melting when boost

[RecklessB4]

In NZ we have (mainly) 95 or 91. Some of our Bps have 98 but mostly 95 is the easiest option. I have put 91 in once (lawn mowers fuel and I was desperate) and it ran like a man the night after eating dodgy chicken curry. 

[duncanm]

 fuel.jpg   66.23KB   12 downloads

[Jimbo]

Spot on Nick.

We all run 98 as that's all we can get. United used to do 100 but not sure if they still do, far and few between anyway. These ECU's are designed for 100RON. 

You also shouldn't own a car like these if you're not prepared to use 98 as a minimum. Don't cheap out for the sake of saving a couple of bucks.

In a nutshell, the RON rating of a fuel is it's resistance to detonation. The higher the rating, the greater the resistance. Fuel is not only a magical combustible fluid but it also cools down the intake charge. In the specific application of turbocharging, compressing air causes it to heat up. This is why we have intercoolers and higher rated RON requirements. The lower the temperature of the intake charge, the more advanced timing the ECU can run which results in more efficient power.

[duncanm]

FSM also notes (I think, somewhere) that car will run in lo-boost 'safe mode' if it detects low (95 RON) fuel, by leaving the SPRV valve open.

 

 Presumably the detection of low-RON is from knock events - which are bad, mkay? (*)

 

 

(*) - look up busted ring lands, big end failures, etc

[podmak]

Thanks to all.

[CRUISN]

I always run e10 in mine....

[zahmad]

I always run e10 in mine....

Seriously Mark?

[Jimbo]

lol...

[Poony_Tunes]

Hi podmak

As everyone on this thread has said these engines were designed to run on 100 octane but in Aus models were tuned down to 98 (not to good of a tune I'll add) but it's because of the time when these cars were built there engines had a higher compression ratio (9:0:1) compared to a wrx (8:5:1)even more than a Sti (8:0:1 from memory) they did this to help primary to come on earlier and a the change happen quicker when secondary came on, they can be retuned for 95 octane but there can be power loss in doing so

Sam
Btw e10 in a B4.......well I wouldn't even put that in my lawn mower it's a very dirty fuel