Regular or Premium fuel? [merged]

[Eclipse_98_RS]

Hi guys, my car is an all-stock RS, but I'm going to start doing some mods to it. Right now I just use regular unleaded gas, but when should I start going up in the octane? After intake/exhaust, or beyond that? I don't want to screw up my engine but I don't want to have to shell out more cash on fuel than I do now. I know, I'm a cheap bastage.

 

[bjbaxter]

Regular gas = You got a turbo car for the performance so why would you sacrifice having problems that could cost you a decent amount of money, just to save a few pennies right now??? Stick with the high octane

 

[Splitpi]

If you stay off turbo, you will be fine. Especially with our low compression engines.

However, if you start using boost you run the risk of knock and in "severe" cases catastraphic failure... To counter this we use higher octane fuel. Either drive the car like an 80 year old blue hair granny or drive it like you stole it...

 

[ToDdErDoDdEr]

wait guys.. at the very beginning of this thread, the poster asked if he should run high octane in his 98 RS.. thats a non-turbo.. theres no reason at all to run premium fuel in a non-turbo... 0.o infact.. its just wasting money: burning hotter = worse gas mileage in a non-turbo... riight??

 

[turbosax2]

wait guys.. at the very beginning of this thread, the poster asked if he should run high octane in his 98 RS.. thats a non-turbo.. theres no reason at all to run premium fuel in a non-turbo... 0.o infact.. its just wasting money: burning hotter = worse gas mileage in a non-turbo... riight??

If you look at the title of this thread you will notice it says [merged]. That means this thread is a compilation of several threads that have been started on the same subject. The latest thread was started by a person with a turbo car.

 

[ToDdErDoDdEr]

oh, im sorry..

--newb--

*edit*

How do you tell where one thread starts and another ends?

 

[BoostFrenzy]

How do you tell where one thread starts and another ends?

Look at post #285 on this thread. The black bold letters at the top of that post signifies a new question (when merged).

 

[Locke]

wait guys.. at the very beginning of this thread, the poster asked if he should run high octane in his 98 RS.. thats a non-turbo.. theres no reason at all to run premium fuel in a non-turbo... 0.o infact.. its just wasting money: burning hotter = worse gas mileage in a non-turbo... riight??

You're mostly right about the non-turbo thing. There is absolutely no reason for a stock CR and factory tuned NT DSM to use anything other than low octane pump fuel.

High octane fuels don't burn hotter, and they don't lead to worsened fuel economy, regardless of induction type. The higher the octane rating a fuel has, the more resistant to ignition (detonation/knock) it is. I'm sure it has been mentioned somewhere in this thread previously.

 

[DSMunknown]

High octane fuels don't burn hotter, and they don't lead to worsened fuel economy, regardless of induction type. The higher the octane rating a fuel has, the more resistant to ignition (detonation/knock) it is. I'm sure it has been mentioned somewhere in this thread previously.

And yet, this thread keeps getting longer and longer.

 

[talonDSMerr]

So technically with a boost controller set at 0, 87 octane would be fine.. and with anything above 0 psi, 91 octane should be used?

 

[dylan702110988]

So technically with a boost controller set at 0, 87 octane would be fine.. and with anything above 0 psi, 91 octane should be used?

If the car is turboed then only use 91+, even if you set the MBC to 0 doesn't mean its going to have no boost, you will still be running the stock boost level.

 

[wildjoker81]

Only thing you can really do, to be good for lower octane, is just take the whole turbo system off... but then you have a whole other set of problems and what would really be the point right?

 

[gsxtasy]

Man, i wish premium still satisfied my boost cravings. Meth injection FTW!

edit: Or e-85 FTW

 

[wildjoker81]

Theres always race fuel, not sure where you can get that around here off of a pump. But it is there.

 

[Defiant]

It's not possible to "set the MBC to 0".

 

[Icarus]

It's not possible to "set the MBC to 0".

You could remove the spring

 

[turbobird14]

just take the compressor wheel out of the turbo......thats worth not paying 20 cents a gallon more for enjoyment!

but to add to this post like everone else has been refering to. the octane number is a burn rating. you want the peak combustion temperature to happen the millisecond bfore top dead center. increasing the octane will prolong the peak temperature... this is why timing becomes a huge factor for detonation. you could... i guess... tune a car to run lower octane if you really want to mess with the timing. but i have nowhere near the exparience to tell you where to start with that... and its just not worth it. the best thing you can do for your car is... turbo'd: run what manufacturer specs say or 1 grade higher(especially if you have knock)... N/T: unless you change compression and stroke which will mess with timing...YOUR DOING YOURELF A FAVOR BY NOT CHANGING ANYTHING...use what it tells you

 

[Splitpi]

You could remove the spring

Spring in the MBC? No that won't work. The waste gate will open at a certain pressure regardless of the MBC. I.e. 9.5 psi. With the MBC dialed in for 0 psi or even removed form the system and vacuum line attached to the wastegate, the waste gate will open at its prescribed value of 9.5 psi. An MBC only allows the user to increase or delay the pressure to the MBC, not decrease it.