I could care less about post count. Ours just frustrating to see the only safe haven in vortex (2.5 forum) get new people asking the same questions over and over.it want ra knock on you by any means. We all get along in here. Its just when someone newer comes along and argues with us about something we've all tested on our own... You're totally welcome to be a part of our group.its just the argumentative replies...
god i love my car. it may not be fast, but it's crazy fun!
C2 stage 2 TURBO!!! ACHTUNG!!! 2.5liter 5cylinder contents under pressure!!!
Most of the time we are all properly behaved people... When we feel the need to rant and internet argue, we venture onto the mkv forums!! Lol
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Im pretty sure the manual recommends premium. I run 93 all the time and I do notice a difference going to 87. I also put down 163whp with just carbonio and 2.25 inch magnaflow and of course 93 octane fuel. And remember the premium fuel has more additives which is what you want(helps clean out injectors etc.
Last edited by jaja123; 03-22-2012 at 08:38 PM.
5 cylinder FTW
The 2.5L engine as setup in stock form is knock limited.
I.e. even the stock ignition maps could be considered 'aggressive' when using 87 octane.
So: how is more power made running 93?
(Log this with vag-com and you will see)
on 87 knock control will pull timing.
on 93 knock control will pull less/none.
How to test this yourself:
log blocks 010, 020
do a 'street dyno' run: ~under 2000 to redline run
compare the data between the two fuels.
If you see ZERO knock retard on 87 for the entire run, then going to 93 will gain near nothing.
I put 93 in my car yesterday for the first time, and indeed there is a noticeable change in acceleration. I don't really know a whole lot about mechanical numbers or anything, but I do know my stock 2.5L Jetta does run differently in 93 also.
Last edited by GTIarist; 07-11-2012 at 07:51 AM.
I am glad I found this thread, and I am going to give it another bump.
I don't know if I am just now noticing it, or they are just now (past month or so) bringing it to my area, but all the pumps have a sticker that says contains up to 10% ethynol. Since I have read in several places that VW highly recommends non-ethynol gas, I started looking for non-ethynol stations. Only one in my area (GOGAS) is listed as non-ethynol, so I go to fill up, and it also has a contains up to 10% ethynol sticker. I then notice that the 93 octane button has a "no ethynol" sticker on it. Not know whether I should use that high of an octane, I relented and used the 87 octane.
Thanks to what I have read here, my next fillup will be GOGAS 93 Octane. (sorry, guys, I just increased fuel prices 10% by saying that)
I am pretty anal about logging fuel economy (between the cold temps, increased traffic, and ethynol, I have dropped about 4 MPG), so I should be able to tell if there has been a difference. My next fillup should be after the T-Day weekend.
UM Stage 1 Tune | APR Carbonio Intake | BFI Stage 1 Mounts | ECS Lightweight Underdrive Pulley | NLS Short Shifter | 42DD Bushings | Beetle Engine Cover
APR'91/Carbonio/magnaflow catback/BSH dogbone/ clear corners/ de-badged/ Eibach sportlines/ spherical drivers mirror/ kenwood 1200W/ Vag'd/ mesh grille/
most stations on florida are up to 10% ethanol.
The amount of octane a engine needs depends on: compression ratio, lay out of the combustion chaimber and engine (air) temperature in the combustion chaimber.
Compression ratio is not only a static thing but should also be considered dynamic. That means the more air is coming in the combustion chaimber the higher the dynamic compression ratio will be.
That's the reason why turbo engines normally have a lower static compession ratio than engines without turbo that have the same construction because their dynamic compression ratio is higher.
Good intercooling lowers air intake temperature and means more cooling (and also more oxygen!) in the combustion chaimber and less change on detonation.
Cams, valve timing and intake- and exhaust construction have also big influence on the amount of air the engine gets.
It's already sayd: the energy amount of perol does not depend on the octane number.
The highest petrol efficienty is only possible with the best front ignition curve.
Under normal circumstances the petrol recommanded by the factory will do but I can imagine a car driven in the mountaines with high outside temperatures runs a bit better on petrol with higher octane.
Detonation will occure later or not at all and the is engine working with optimum front ignition.
this thread brings the lulz
kid with golf (presumably leased for $179/mo) is trying to justify being cheap on gas by citing stupid random internet articles written by other stupid kids trying to justify being cheap on gas.
i'm glad i always use 93 octane even though everyone on the jettav forums says to use regular (more cheapskates trying to justify being cheap) saying there is no added benefits to 93 vs 87.
i'm glad the 2.5 forum has more knowledgeable peeps who are more legit than the jetta golf v forums which is just a bunch of kids with gtis talking a lot of shyt.
My own personal experience has changed my mind on this subject somewhat. On a flat road, cruising at 70mph, usually I get 34 - 36mpg (that's the reading I get) on 87 octane. 36 is pretty much the max on average. On 89 octane, that shoots up to 38.9, over the same conditions. It's always a little higher cruising at high speed, although my average around town doesn't seem to change. I can't explain this, but it has been consistent. If I go up to 91 octane, and I only did this for 2 full tanks as part of a really long road trip (more than 5,000 miles in total - 2 full tanks will get me about 950 miles on the highway) it dropped right down to 32 mpg. What does this mean? Nothing, its not scientific and was just my experience, but I stick to 89 octane now (2011 2,5l Golf).
What I would say though is that the fuel 'quality' is more determined by the brand, than the octane - especially at 91+. Higher octane fuel usually has more ethanol, which means it needs more additives to keep the same 'power' - the quality of those additives can vary from pump to pump and certainly from brand to brand. At 87 octane, the quality of probably the same regardless of brand, although personally I'd rather pump in Shell 87 or BP 87 than some no-name 89 brand elsewhere. That's probably irrational!
Last edited by Zoolook_; 11-23-2012 at 02:24 PM.
I haven't owned my first VW for more then a week(I know nothing about these cars). I've owned crown Vic's my whole life lol ill fill up twice with 89 and see how she rides!! I used to get 12-15 mpg with my v8. I already see HUGE savings with this jetta.
2011 Jetta SE w/out convienence 2.5L 5 Speed Manual
A short ram like the pflow won't require a tune, and it WILL improve your mileage if you back up off the throttle. I however lack the ability to back up off said throttle.