87 vs 93 octane

[DerekH]

yes.

but also, flashing the ECU does more than just adjust timing. it actually changes a lot of the drivebility, optiomizes AFR, etc.

the ecu can only adjust so much... so you will see a bennefit with 93, but to get 100 of the bennefit you will need the sw flash

And that being said you will need a sw flash to get the full benefits of whatever fuel you are using in a 2.5. Not just 93oct.

[Zoolook_]

You're right...I know nothing and have zero experience within the automotive performance aftermarket or this VAG space ...especially because I used LOL and emoticons.

I know how you feel... I also know nothing because I have a low post-count. If this thread goes on for much longer though, I'll be an expert and be able to build my own dragster from a potato and a piece of string.

[thygreyt]

I know how you feel... I also know nothing because I have a low post-count. If this thread goes on for much longer though, I'll be an expert and be able to build my own dragster from a potato and a piece of string.

the thing isnt post count or anything else.

again, it was the comments, assumptions and knowledge what made some people look bad.

[TylerO28]

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...

[Zoolook_]

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...

No worries.

[thygreyt]

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

Sent from my HTC Sensation using Tapatalk

[Zoolook_]

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

I'm heading right there... although I have a MKVI, so they might not like that!

[jaja123]

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.

[Jefnes3]

Can you explain, mechanically, how an engine not designed or tuned to take advantage of what is effectively knock resistance, can magically get more power from fuel that has no more power?

Easy.

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:
Get vag-com
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.


-Jeffrey Atwood

[thygreyt]

Easy.

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:
Get vag-com
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.


-Jeffrey Atwood

[GTIarist]

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.

[A1an]

Glad to see this old thread was bumped. Interesting information.

[Gunbu]

I don't think Ive ever seen 93 octane before. Only 87,89,91. What sort of special gas station carries such a thing?

[02Jetta]

East coast gas stations, from what I see carries 87 89 93 octanes. We dont have 91 octanes in NJ/NY area

[Gunbu]

Gotcha. Yeah I just googled it too, doesn't look like its available at all in California.

[GTIarist]

Yeah, I will not go back to 87. I've been running 91 and 93 ever since I found the change in performance, and I'm happier with the acceleration across the board.

And in Pittsburgh we have 87 89 91 92 (sometimes) and 93.

[iamgap]

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.


gap

[rabbitlvr]

[PhAyzoN]

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.


gap

Gas around my way has been "up to 15%" since before I started driving. My quarter million mile 30V V6 and my 2.5 have never complained.

[phrog23]

Gotcha. Yeah I just googled it too, doesn't look like its available at all in California.

I'm in Lancaster and I know of 2 stations out here that have 93, and I know of one in I think either Burbank, or N.Hollywood that has one( don't remember exactly where).

[thygreyt]

most stations on florida are up to 10% ethanol.

[stef 4x4]

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.

[Gunbu]

I'm in Lancaster and I know of 2 stations out here that have 93, and I know of one in I think either Burbank, or N.Hollywood that has one( don't remember exactly where).

Oh really? I work up in Burbank I'll have to keep an eye out.

[06jettaSEL]

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.

[Zoolook_]

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.

The "shyt" you mention comes equally from both side, on the internet as a whole (not necessarily this forum). Additionally, people who buy 87 octane are not necessarily "cheapskates" trying to justify being "cheap", they just don't necessarily see a benefit from going with a higher octane and thus higher cost. Generally, when you pay more for something, you want to know you're getting something for that extra money. Besides, there is more fluctuation day to day and brand to brand with gas prices, than there is between 87, 89 and 91.

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!

[bobsuncle]

I get horrible mileage with 93, but it's because the car becomes more fun thereby activating my heavy right foot and slowing the occurrence of my right hand twitch until higher RPMs.

[stef 4x4]

The "shyt" you mention comes equally from both side, on the internet as a whole (not necessarily this forum). Additionally, people who buy 87 octane are not necessarily "cheapskates" trying to justify being "cheap", they just don't necessarily see a benefit from going with a higher octane and thus higher cost. Generally, when you pay more for something, you want to know you're getting something for that extra money. Besides, there is more fluctuation day to day and brand to brand with gas prices, than there is between 87, 89 and 91.

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!

I am not sure but I think ethanol has a lower energy capacity than petrol.
If I am right it means with more ethanol in the fuel mile average will go down.

[bobsuncle]

I am not sure but I think ethanol has a lower energy capacity than petrol.
If I am right it means with more ethanol in the fuel mile average will go down.

Ethanol is 80% or so the energy density of petroleum. That's exactly why its a better fuel for high boost situations.

[KDM1116]

Definitely gonna fill up with 89 next time and try it out myself. If it rides smoother and all ill try 93. Glad I found this forum.


2011 Jetta SE w/out convienence 2.5L 5 Speed Manual

[bobsuncle]

Definitely gonna fill up with 89 next time and try it out myself. If it rides smoother and all ill try 93. Glad I found this forum.


2011 Jetta SE w/out convienence 2.5L 5 Speed Manual

It takes two tanks for the ECU to adjust fully. You'll notice the difference --I guarantee it. The ECU on these cars is pretty high quality so it can basically adjust on the fly.

[KDM1116]

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

[bobsuncle]

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 ram air intake will get you a slight bump in mileage as well.

That said, upgrades and fuel only get you an increase in mileage if you can keep you foot off the throttle. Every mod I do seems to motivate me to push the car harder

[KDM1116]

A ram air intake will get you a slight bump in mileage as well.

That said, upgrades and fuel only get you an increase in mileage if you can keep you foot off the throttle. Every mod I do seems to motivate me to push the car harder

I've been looking to get the SRI. What's this I hear about an ecu flash after you run higher octane though?


2011 Jetta SE w/out convienence 2.5L 5 Speed Manual

[bobsuncle]

I've been looking to get the SRI. What's this I hear about an ecu flash after you run higher octane though?


2011 Jetta SE w/out convienence 2.5L 5 Speed Manual

"The SRI" isn't a ram air. Its a short runner, and that one won't help your mileage at all because all the 2.5L tuners err on the side of safety with SRI tunes. Your car will run slightly rich afterwards.

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.

[KDM1116]

"The SRI" isn't a ram air. Its a short runner, and that one won't help your mileage at all because all the 2.5L tuners err on the side of safety with SRI tunes. Your car will run slightly rich afterwards.

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.

Ohhhh I gotcha. I'm gonna drop my jetta in a few months so I'm kinda turning away from the cold air intake, could you possibly post a link to a website selling a ram intake? Do I have to order a heat shield separately?