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New 2011 LGT owner here. Was wondering what everyone's thoughts were on running 89 octane plus instead of the recommended premium fuel. I'm sure this is not the first time this has been asked but I really wanted to see how everyone feels on the subject. And is it true that you can tune it to run on lower octane fuel using a cobb access port. Like I said, completely new to the turbo world and I just want to make sure I am taking care of the car properly so any info is good info. Thanks in advance.
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You could probably get a custom tune for 89, but why? You won't be saving much if any money and you may be rebuilding the engine much sooner than you would have done otherwise. As far as Cobb offerings the lowest octane on the site is for an ACN 91.

 

If you are concerned about taking care of it properly, use the proper fuel end of story. 93 octane/ 91 if you live in an area where 93 isn't available.

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Welcome! Where are you located? What are your plans for the car? Do you want to modify it at all?

Yes you can use a Cobb Accessport [AP] to tune for different octane levels. Some people even tune for different fuels (e85) or different turbos. A custom tune typically runs around $500 from a reputable tuner, plus the cost of the AP. I just don't see much value in tuning for lower octane unless you can't get higher octane where you're at. This car is not made for high MPGs.

I would not run it on less than 91 octane without getting a custom tune for it. Even 91 is low, with my tune I can still see knock occasionally with the 91 it was tuned for, especially in hot weather.

Throwing in a tank of 87 is OK in a pinch, but you should take it VERY easy on lower octane fuel. Stay out of boost. If you build boost with lower octane, you could easily blow your motor.

For further research, look for threads on here or about WRXs or STIs on other forums using lower octane fuel. Their engines are pretty similar to our EJ255, so a lot of what goes for them on this subject applies to our cars as well.

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The reason to run higher octane to to prevent preignition under boost. Hot spots and higher dynamic compression start preignition (detonation). Too much preignition and you can damage the pistons, heads, melt spark plug tips, etc. Like Sarag said, if you have to run a lower octane, stay out of boost or keep it low.
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You could probably get a custom tune for 89, but why? You won't be saving much if any money and you may be rebuilding the engine much sooner than you would have done otherwise. As far as Cobb offerings the lowest octane on the site is for an ACN 91.

 

If you are concerned about taking care of it properly, use the proper fuel end of story. 93 octane/ 91 if you live in an area where 93 isn't available.

 

If hes in cali, their 91 might as well be 89..lol

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Thanks a lot guys I will definitely be sticking with 93 octane and now my fiance actually believes me that she has to listen to the manufacturers recommendations. Also I am in PA for anyone that was asking and for right now, I am using the car as a daily driver so no big plans as far as modifications go at this time.
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Thanks a lot guys I will definitely be sticking with 93 octane and now my fiance actually believes me that she has to listen to the manufacturers recommendations. Also I am in PA for anyone that was asking and for right now, I am using the car as a daily driver so no big plans as far as modifications go at this time.

 

This debate has been raging in my household for some time now, apparently my ME degree is no match for "its all the same stuff"..... enablement incoming....you gotta do the clutch damper delete... the shifter mods are a must too... and I'm really enjoying my EBC USR rotors and red stuff pads... maybe just do a little tune, Accessport and a custom tune are more than worth the cost to really liven up the car.

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I wish I could buy 93 around here... premium is 91 in NM (and in some regions of the state, it's 90!) There used to be a few stations where you could get race gas (Trick 100 or 107 - I forget which it was) - did a mixed tank in my old WRX taking the average for the tank to 95 and the difference was noticeable...
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This debate has been raging in my household for some time now, apparently my ME degree is no match for "its all the same stuff"..... enablement incoming....you gotta do the clutch damper delete... the shifter mods are a must too... and I'm really enjoying my EBC USR rotors and red stuff pads... maybe just do a little tune, Accessport and a custom tune are more than worth the cost to really liven up the car.
What is the going rate for the accessport and a tune? Are we in the $1000 range? Is a completely stock car worth that, as in how much will it wake it up? Can you actually achieve a few more mpg's with a tune? Sorry, new guy taking in info.

 

Sent from my moto z3 using Tapatalk

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The off the shelf stage 1 tune for the AccessPort makes a very noticeable difference in the car - it's definitely worth it. The version 3 accessport is $675, but you can pick one up used for much less than that - $450-500. Just make sure it's not married to a car already - they need to uninstall it from their car (and show you the screen indicating it has been uninstalled) before you buy it, otherwise you have a brick. You need an AP3-SUB-003 (doesn't matter which maps are installed on it - you can download and install what you want - that version is also used for the WRX and FXT - if the last owner had one of those, just remove the maps, download the ones for the Legacy, and you are good to go)

 

A pro-tune generally nets you more power - there are a number of shops that do an e-tune for the car, where they will send you custom maps for your vehicle and fine tune it by having you send them logs from the vehicle as it runs.

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A stage 1 tune makes stepping on the throttle feel like a field goal winning kick in the pants compare to stock. But, a custom tune smooths out the power delivery, dials in more timing ( or less depending on the situation), optimizes the fuel curves, and should make the car more enjoyable to drive and more efficient. If you have a local tuner with a good reputation I would go that route, if not then there are a few really good ones that frequent these forums I wouldn't hesitate to trust with my vehicle.

 

Brentuning, Cryotuning, XRT are the ones I can recall of the top of my head.

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What is the going rate for the accessport and a tune? Are we in the $1000 range? Is a completely stock car worth that, as in how much will it wake it up? Can you actually achieve a few more mpg's with a tune? Sorry, new guy taking in info.

 

Sent from my moto z3 using Tapatalk

 

you could go with a used V2 and get it for $300 or less, there are always a bunch on ebay and the only thing you lose is the ability to watch multiple gauges over the V3. and that will get you the cobb OTS tunes which are a big improvement from stock but rich for safety. another $300ish and you could get a custom tune from cryo and a bunch of other people by doing the pulls yourself (its basically the going rate) and that will let you get rid of the leaky BPV and replace it with a turbosmart kompact plumb back ($130 and you could install yourself with any as sort of confidence level) . if you can get yourself to a dyno the cost is going to be a little higher to much higher depending on the tuner. the cobb OTS tunes are the best bang for your buck, the e-tune will give you a better driving car and the ability to put some small mods and have them properly integrated, and the dyno more so plus you get to say my car put down X ridiculous amounts of extra torque.

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You should be able to find a V2 for cheap, but Cobb is no longer supporting it (on their website, Cobb states "Starting on 1/1/19, all further support of any kind for the V2 Accessport will cease."). Probably not a huge issue for the LGT since they haven't updated the maps in a while, and though they indicate it might happen, I would guess accessport manager will still run the V2 for the foreseeable future.

 

That being said, if you are just going to flash and forget, toss the AP into a drawer, etc., there is no real advantage to getting the V3.

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