Reflash Soon - 95 or 98 Octane ??

[Heylin]

Booking the car in at PBMS soon for a reflash.

Specs (2004 GT-B Sedan, Tiptronic, Subtech Front Pipe, High Flow Filter).

Recently switched to 95 to see how it would run and actually got good economy and no noticeable drop in power at top end. (no shuddering or hesitation)

Question....will these cars safely put out the 220-230kw (at engine) anticipated from the these mods running 95 ?? or is 98 a must ??.

Every little bit helps, but for the sake of $6 extra per tank, mabey 98 is in fact worth it for some more power ? how much would 3 extra octane points net at the dyno ?

[Joker]

I am biased and propose a false economy : how far are you actually travelling and cost per km

not $/litre

98 ftw

[xsvpwr]

where did you get the 220kw-230kw estimation from?

What turbo do those legacys run?

edit: didnt read properly I see you said at the engine not wheels

[newsuba]

Another important consideration - do you have a source of 98 nearby ?

[Wiretap]

My advice would be NOT to go with ECUTek as these do not have Subaru's sophisticated knock-protection system in play. Many tuners can work with the stock ROMs these days without issue.

My recommendation would be to tune for 95 as this is the highest fuel grade that is available throughout the country.

If your tuner knows what he is doing he'll be able to set it up to advance the timing up when you run 98 for more power.

[Heylin]

 Wiretap said:

My advice would be NOT to go with ECUTek as these do not have Subaru's sophisticated knock-protection system in play. Many tuners can work with the stock ROMs these days without issue.

My recommendation would be to tune for 95 as this is the highest fuel grade that is available throughout the country.

If your tuner knows what he is doing he'll be able to set it up to advance the timing up when you run 98 for more power.

Is that possible on factory ecu reflash ? I thought you tune for one grade only ? unless you have say a link which supports dual maps.

[Heylin]

 newsuba said:

Another important consideration - do you have a source of 98 nearby ?

Lots, and always the places we travel to as well (Auckland and Tauranga mainly).

[Wiretap]

The factory ECU has a whole bunch of maps but that's not the way I'm talking about.

The tuner tunes the car for 95, however Subaru's knock-correction system will progressively start trying to advance the timing up to the value in the Maximum Timing table. It learns where the limit is and holds that. If you run a better fuel you simply reset your ECU and go for a half-hour drive (covering all the load regions) and it will advance up, probably reaching the limits in the Maximum Timing table. (It's a lot more complicated than this, but essentially, your ECU ain't stupid and can learn )

Tuning these is a bit of an involved process, but having worked with both Factory engine management and Link engine management..... I can assure you Subaru really do know what they're doing and their product is massively more capable than the Link is.

[pl0x]

ask PBMS... your paying for a service which includes there advice imo. Tell them your mods, goals and ask what petrol do they recommend to get to those goals.

interesting 95 vs 98 dyno plots -> http://www.jzx100.com/forum/topic/10762-95-vs-98-octane-dyno-results/

I always go with 98

you don't spend $$$$ on mods to get more power then save $6 a tank & get less power

[chappell943]

I'd say if you have 98 available wherever you go then go with that as it is a better octane fuel which has 0 downsides apart form the extra $6 a tank. I choose 95 for mine as if I go to Hokitika which I do occasionally there is only 95. In saying that though if you tune for 98 and run 95 for a tank the ecu Should be able to compensate by pulling timing in relation the the load and rpm in which the car is seeing detonation.

[Guest]

98 is quite abit lower than they say it is

[madmike]

 4U2Envy said:

98 is quite abit lower than they say it is

Pretty big claim there...

Did a mate of a mate tell ya??

[Kiwi_Fozze]

get tune for 98. stock ecu DOES have MULTIPLE maps, and will adjust its timing based on knock detection within it's preset limits. link will costyou ~2k plus a tune for exactally the same flexibility that the stock ecu has. tune for 98. stay with standard ecu.

[lunchie]

 pl0x said:

ask PBMS... your paying for a service which includes there advice imo. Tell them your mods, goals and ask what petrol do they recommend to get to those goals.

interesting 95 vs 98 dyno plots -> http://www.jzx100.com/forum/topic/10762-95-vs-98-octane-dyno-results/

I always go with 98

you don't spend $$$$ on mods to get more power then save $6 a tank & get less power

+ 1 to PBMS they will actually listen to what you want, STM is also good to deal with

[Swindog]

We did comparision for the karts between which fuel company was better too. All runs tested on 95 and Shell V power was the best. Gave the best engine temps, best start up, best mix with the 2 stroke etc. So if you HAVE to run 95 go with the v-power.

Also using that and the castrol ttr oil i had no carbon deposits on my piston or chamber unlike some guys who ran castor based oil who had carbon build up. Engine was clean as a whistle even after 8 hours racing.

[Guest]

no a mate of a mate didn't tell me, it's common knowledge to some that octane ratings are often even 2 - 3 points lower than they are advertised at.

[newsuba]

"Common knowledge" is usually baseless speculation.

If there is such a variation why isn't there widespread outcry by consumers and investigations by the Ministry of Consumer Affairs etc. ?

:

http://www.consumeraffairs.govt.nz/for-consumers/goods/fuel-quality-1/fuel-quality

[Bugle]

Perhaps its a reference to high octane petrol going 'off' vs lower octane than claimed?

My BG runs like a bag of butt on 95, a thirsty bag of butt. 98 ftw

[Heylin]

 newsuba said:

"Common knowledge" is usually baseless speculation.

If there is such a variation why isn't there widespread outcry by consumers and investigations by the Ministry of Consumer Affairs etc. ?

:

http://www.consumeraffairs.govt.nz/for-consumers/goods/fuel-quality-1/fuel-quality

Mabey because 99% of cars are owned by non ethusiasts who wouldnt notice or care.

[twinturboboy]

Actually - I've just bought a 2001 GTB E-tune - I live in Nelson and the car used to run on 98 but Iam only able to run it on 95 because we don't have 98 in Nelson at all ever since I ran it on 95 it's been a bit funny it sometimes pinks and the boost will cut back - I cjanged the oil and that helped very much - if i reset the ecu - would it fix it? - it hardly ever pinks now and will sit on 14 pound 95% of the time

[Wiretap]

 twinturboboy said:

Actually - I've just bought a 2001 GTB E-tune - I live in Nelson and the car used to run on 98 but Iam only able to run it on 95 because we don't have 98 in Nelson at all ever since I ran it on 95 it's been a bit funny it sometimes pinks and the boost will cut back - I cjanged the oil and that helped very much - if i reset the ecu - would it fix it? - it hardly ever pinks now and will sit on 14 pound 95% of the time

That would be the bad thing to do. You should really get your car re-tuned for the fuel to avoid blowing it up. 95 is not good fuel for these.

Resetting your ECU will re-advance the timing to 50% of the maximum timing advance and cause it to un-learn all the knock-correction retarding that it already has.