anyone try 87 octane in their gt?

I am on my second tank with regular fuel and it seems to be running perfect.anyone else trying it?

Are you boosting w/the low octane fuel? For boosted applications, there is a reason that higher octane fuel is required (ok - recommended).

 

View octane as a burn inhibitor. More octane gives your fuel a higher flashpoint, which defends against detonation/preignition/knock. Detonation happens when the in-cylinder temperature is hot enough (due to compression, hot spots on the head, etc) to ignite the air/fuel mixture before the spark plug fires. Less octane makes your motor much more prone to detonation.

 

This is why the guys running big turbos/big boost use race gas. More boost == more air forced into the cylinders == more pressure(heat) during compression == much larger chance of detionation. If the motor knocks bad enough, it will 'eat itself'.

 

Even though knock may not be audible, it is happening nonetheless. The ECU uses the knock sensor(s) to listen for knock, and when it hears knock it will start taking 'self preservation' measures - pulling timing and pulling boost.

 

When the ECU pulls timing & boost, it does so in small steps, so you may not even notice, esp if the car is new to you. Do you have any way to monitor timing & boost?

 

Just don't do it. Your motor (most likely) will knock unless you don't get into boost. After spending the amount of money for such a kickass car, why even play games with lower than recommended octane fuel?

 

IMNSHO, as always.

A good primer on octane can be found at howstuffworks.

Do some logging and post results.

Not I- I'd rather pay 5 bucks more for a tank of gas than buy a new engine- particularly in modded cars, it's cheap insurance.

Even with a full tank, it's only $3 more.

Bad idea

My fiance put "regular" in my car last week and I noticed a sluggish,boggy feeling.

I've run regular in my car 87 octane, and the mid grade 89 octane. Under normal circumstances 87/89 octane won't hurt your car. The knock sensor will detect most pre-detonation and pull timing / reduce boost to correct the issue. It will take you down on power and you may notice it more with humid weather/people in the car. Also under high load, as in large amounts of throttle at low RPM's could cause harmful knocking. With all of the sound deading in the car its hard to hear knocking unless its really bad, which maybe too late.

 

My experience with 87, I notice the car seems (of course this could all be in my head) more sluggish on 87 octane. I don't recommend 87 octane as it will reduce performance/and possibly fuel economy, and potentially lead to engine damage.

I'm sure I'd never run anything but SUL (91 Octane or better) as there are too many variables (temp, humidity, on/off boost, load carrying, etc.) that all contribute to engine heat under load. Even if the ECU can pull timing to inhibit knock, it typically does it after the fact. Over time, that all adds up and your engine is suffering. Think of it as mini-tremors before the big quake, sort-of loosening up everything. And, once the big one happens, there's no going back to normal, the fracture is permanent.

That's essentially what's happening to your engine. Every ping and knock, whether you hear it or not, is damaging your engine and compromising its structural integrity.

For $3-4 more a tank/week, I just can't see causing irreparable harm to your engine.

Just my .02

SBT

including 6 vettes 3 mustang cobras, 5 turbo awd eclipse,5 transams,a camaro ss, a wrx,an outback ....luxury cars,tons of trucks and sport utes.i think i ran every car on regular without a problem exept for possibly my '80 and '70 vette.i think i may stick with premium but i needed to know.thanks for everones input..much appreciated!

Good decision.

Good decision.

 

i agree... it's worth it for the peace of mind.

including 6 vettes 3 mustang cobras, 5 turbo awd eclipse,5 transams,a camaro ss, a wrx,an outback ....luxury cars,tons of trucks and sport utes.i think i ran every car on regular without a problem exept for possibly my '80 and '70 vette.i think i may stick with premium but i needed to know.thanks for everones input..much appreciated!

My H6 runs perfectly on 87, but I'd be reluctant to use low octane fuel in any turbo if I planned to use the available boost.

Can someone please just make a sticky somewhere that says:

Don't be CHEAP, give her the good stuff.

including 6 vettes 3 mustang cobras, 5 turbo awd eclipse,5 transams,a camaro ss, a wrx,an outback ....luxury cars,tons of trucks and sport utes.i think i ran every car on regular without a problem exept for possibly my '80 and '70 vette.i think i may stick with premium but i needed to know.thanks for everones input..much appreciated!

 

Soliciting stories and experiences i can understand... but it boggles the mind how someone could have 25+ autos and not be able to make their own decision on something like this...

So I accidentally put a lower octane gas in my car and I definitly felt the power loss. It still feels slightly sluggish a tank or 2 later. Im guessing because the ECU detected knock etc. Will it learn back to the way it was or should I reset the ECU and do the "Hold the break while giving a little boost in 2nd gear" trick to get things back up to par?

 

Thanks

It is right to be concerned under load and low RPM as some have mentioned. If you drive in Florida (or any other flat state) and are just going to put it on cruise control for a long highway drive, you won't be under load and you can save yourself 5$ on your trip. HOWEVER, I would truly answer the question this way... if you are on year 2 of a 3 year lease (and you are just going to turn the car in), go ahead, save a couple of bucks. If you bought the car, brew your own cup in the morning, skip Starbucks, fill it with the good stuff, and you will be even. As an added bonus, your motor will still be running in four years.

including 6 vettes 3 mustang cobras, 5 turbo awd eclipse,5 transams,a camaro ss, a wrx,an outback ....luxury cars,tons of trucks and sport utes.i think i ran every car on regular without a problem exept for possibly my '80 and '70 vette.i think i may stick with premium but i needed to know.thanks for everones input..much appreciated!

 

Think how well all of your previous vehicles may have run if you had used the correct octane.

So I accidentally put a lower octane gas in my car and I definitly felt the power loss. It still feels slightly sluggish a tank or 2 later. Im guessing because the ECU detected knock etc.

Granted it's not a turbo but we have a Nissan Quest with 3.5l V6 and they publish the hp rating for 91 and 87 octane.

 

For 91, it's 242. For 87, it's 237. So you have one sesnitive butt.

heh maybe but I definitly felt it ..... so should I reset the ECU anyone?

I've only run 92+ in all of my cars for years now. High compression and forced induction applications usually require premium pump fuel. How many of you out there have actually scaned the LGT to see if the ECU pulls timing or detects knock on lower octanes? Just curious, every car will be different, consider thousands roll off the production line. There will be some that run stronger and might run just as well on 87 octane while others will still pull timing even with the good stuff...as with my cars in the past, I'd say it's a case by case basis but spend $3 extra per tank if you want to play it safe.

Knocking is not your friend. However i doubt that it will cause as much problems as everyone speaks of now a days because of modern technology. The ecu will be able to detect if you put in 87octane gas.. but play it safe put in the right gas and enjoy detonation free, higher boosting fun .

I used 87 a couple of times last year when gas was over $3/gal. I stayed fairly light on the loud pedal and it ran fine. Doesn't regular actually have more energy in it than premium? I'd like to try running water injection with a custom tune for it and see if I could make more power than stock using premium.

///How many of you out there have actually scaned the LGT to see if the ECU pulls timing or detects knock on lower octanes? Just curious, every car will be different, consider thousands roll off the production line.////

Good point.