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.

 

[diablos991]

Why not just add in some octane booster from autozone....It says it will add 1-3 points, cant hurt right?

1 to 3 points meaning now you will have 85.1-85.3 octane. There is a thread explaining this if you use the search button.

 

[halik008]

meh you have nothing to worry about.....we have knock sensors for a reason......i'm putting 87 or 89 in my 2g turbo DD

 

[JayRolla]

meh you have nothing to worry about.....we have knock sensors for a reason......i'm putting 87 or 89 in my 2g turbo DD

Thats not a very good idea. Forced induction needs at least 91. Like I said earlier I had a turbo shadow I bought for $500 becuase it needed a new fuel pump they thought becuase the car had no power. Put 91 octane in and it fixed the problem.

 

[nightspeed87]

Thats not a very good idea. Forced induction needs at least 91. Like I said earlier I had a turbo shadow I bought for $500 becuase it needed a new fuel pump they thought becuase the car had no power. Put 91 octane in and it fixed the problem.

You mentioned about the turbo spooled up after you put it, I dont understand how a slight raise in octane will have anything to do with the turbo itself spooling, it just means the engine will be more prone to detonation, unless that shadow has some kind of smart wastegate system that makes the turbo not feed any air to the engine if the ecu detects knock or something? Besides if hes running stock boost, stock set up the cheap gas technically wont hurt him, and the worse that will happen it may get a few counts of knock here and there and pull back timing a little until he refils with premium, but its not like the end of the world if you forget to fill up with premuim, just wont run as good... ( Obviously talking about a lightly moded dsm, the 300+ whp guys is a whole nother story; could be more drastic an effect for them...)

 

[VicBoost]

Your fine just don't boost and get premium asap!!!!

 

[xveganxcowboyx]

A pump screwed up on me and gave me 85 instead of 91 once. A whole tank. I dumped in a couple bottles of octane booster and drove through the whole tank (pizza delivery back in the day). It got worse mileage and lacked a bit of power, but no other ill effects.

 

[mra4886]

Just fill up with 91-93 oct. Add a couple of bottles of octane booster. Run the fuel down to 1/4 tank and fill up and add one more bottle of octane booster. Stay off boost. Then fill reguarly with premium. Thats what i did when i put a 1/2 tank of 87 in my srt4, turned out to work just fine and had no problems.

 

[JayRolla]

You mentioned about the turbo spooled up after you put it, I dont understand how a slight raise in octane will have anything to do with the turbo itself spooling, it just means the engine will be more prone to detonation, unless that shadow has some kind of smart wastegate system that makes the turbo not feed any air to the engine if the ecu detects knock or something? Besides if hes running stock boost, stock set up the cheap gas technically wont hurt him, and the worse that will happen it may get a few counts of knock here and there and pull back timing a little until he refils with premium, but its not like the end of the world if you forget to fill up with premuim, just wont run as good... ( Obviously talking about a lightly moded dsm, the 300+ whp guys is a whole nother story; could be more drastic an effect for them...)

I thought it was crazy too. Im sorry I should have said the turbo spooled but had no power. It felt like a piece of shit. It bogged horribly. The lady owned it since new, built in 89, and she ran 85 octane, even though it said premium only on the gas cap, till I bought it about 2 years ago. She had the injectors replaced and fuel system fully cleaned. Was brought to 3 different places and they all said needed a new fuel pump and wanted to charge up the ass. Even when I got emissions the guy was like your injectors or pump is bad. So the first fill up was premium and about 5 miles later it worked great. Boosted hard, felt like a new car. Its a fun car, with the small mods I can take a FWD stock dsm all the way and usually an AWD off a role untill 4th gear. Once it hits 90 it gets real slow.

 

[spyder dst]

http://www.europeancarweb.com/tech/0503ec_octane_boosters_tested/index.html

octane booster's do work

 

[t-revor]

yeah some dude at chevron put in regular, I about killed him, I live in oregon, we cant pump our own gas here...

 

[mra4886]

yeah some dude at chevron put in regular, I about killed him, I live in oregon, we cant pump our own gas here...

Why? And that is kinda cool if you never have a problem like you had.

 

[JayRolla]

Yea we had a guy with a brand new diesel ford come in and fill about 1 gallon of gasoline in his truck. I told him he will be fine maybe smoke a little, but he had it towed and had the fuel pump replaced just in case. Dumb ass

 

[droppinbottom]

Why? And that is kinda cool if you never have a problem like you had.

State law prohibits pumping your own fuel unless it is a motorcycle.

And for the guys who keep preaching octane booster, instead of throwing your money out the window you can send it to me. Ever heard of adding moth balls to the tank? Same effect but a fraction of the cost.

 

[xveganxcowboyx]

State law prohibits pumping your own fuel unless it is a motorcycle.

And for the guys who keep preaching octane booster, instead of throwing your money out the window you can send it to me. Ever heard of adding moth balls to the tank? Same effect but a fraction of the cost.

Perhaps you should read the link above...

 

[droppinbottom]

Perhaps you should read the link above...

Sorry man but just type in octane booster in your favorite search browser and you will find many articles that will tell you that the bennefits are just not worth the cost of buying octane booster. In lower octane fuel (87) adding octane booster will help raise the octane more than it will in (91) octane fuel. Unfortunatly for us we should already be running 91 octane or higher.

How much is the average bottle of octane booster? Anywhere from $2-10 per botte and one bottle is appromatly 16-24oz which makes it cheaper to buy a gallon of race fuel and more benneficial in the end.

I am not trying to start a flame war but there is a very large amount of information available and just one article does not make something a fact.

 

[xveganxcowboyx]

How much is the average bottle of octane booster? Anywhere from $2-10 per botte and one bottle is appromatly 16-24oz which makes it cheaper to buy a gallon of race fuel and more benneficial in the end.

True. If he has race fuel then I certainly recomend it. I also don't recomend running octane booster in every tank to try and gain octane rating. This is, however, a completely different situation. He has 1 tank of low octane gas. Given the availability of bottled octane boosters and his need to raise octane it makes perfect sense to dump in a bottle or two. Obviously they have some effect on octane rating as the link above shows through what appears to be pretty solid testing.

Long story short, the couple $ he'll spend on a bottle might help with the situation.

 

[Defiant]

Don't be concerned in the slightest. There is the possibility that a slight boost in octane may occur when mixing regular and high-octane gas.

 

[Samzer]

Hey im relatively new to the DSM hype. I dont even own one myself yet, but plan on doing so very soon. I just had a question that i know has been answered from different threads, but in pieces and is very difficult to find. I request that this information be all in one thread and all recent to make it easier to find.

First of all, i know that turbo engines in the DSMs are high compression, therefore they must use premium gas. I have, however, heard of people running unleaded pump gas and sometimes race gas. The race gas keeps knock down and has more octane, but would unleaded leave way too much knock to run?

Also i was curious to see what types of mileage people have been getting in their dsms? Please list model of car, modifications done to car, and list in MPG form. This information would be greatly appreciated. -Samzer

 

[Bmxr152]

i got like 25mpg heading down to RRE a couple weekends ago, I have a 1G Talon but Look at my Vehicle Profile if you want specifics.

 

[MrBoxx]

i know that turbo engines in the DSMs are high compression, therefore they must use premium gas.

Actually, turbo DSM engines run fairly low compression numbers. 7 bolt motors usually have 8.5:1 compression ratios and 6 bolt engines usually have 7.8:1 compression.

Using premium gas in a turbo DSM is almost a must. I would never try to run regular unleaded in my car. I've used mid-grade a few times when premium was unavailable, though. Use premium gas. It usually only turns out to be about $1.00 more per fill-up.

With a 95 GSX sporting a 14b at 16psi, I get roughly 22-24mpg, and that's with a dying O2 sensor. On one two hour trip, "drafting" behind a friend's Jeep, I got over 30mpg.

Edit: Just a thought, after reading your post in another thread, it seems as if you think that knock is a constant worry. If you get a logger/DSMLink/AEM and take a datalog of just driving around to the store and back, chances are you won't see a hint of knock. As long as the intercooler isn't getting heat soaked, the fuel delivery is okay, and you're not running crazy amounts of boost, knock shouldn't be an issue. If by any chance you're seeing lots of knock for no reason, your knock sensor may be failing.

 

[2gGSX]

First of all, i know that turbo engines in the DSMs are high compression, therefore they must use premium gas. I have, however, heard of people running unleaded pump gas and sometimes race gas. The race gas keeps knock down and has more octane, but would unleaded leave way too much knock to run?

They're low(er) compression motors actually; 8.5:1 and 7.8:1 for 2g's and 1g's respectively. The use of a turbocharger however increases effective compression, etc etc so we use the highest octane reasonably attainable. The unleaded (93, or 91 for those unfortunates in Cali) is ok to run but after modifications you will have to adjust your tune to compensate for the octane. This is standard procedure when tuning on any car really--different tunes for race gas and pump gas.

Also i was curious to see what types of mileage people have been getting in their dsms? Please list model of car, modifications done to car, and list in MPG form. This information would be greatly appreciated. -Samzer

22 mpg mixed, 25 mpg highway only. 95 GSX, mods in profile.

 

[GVR4592]

Hey im relatively new to the DSM hype. I dont even own one myself yet, but plan on doing so very soon. I just had a question that i know has been answered from different threads, but in pieces and is very difficult to find. I request that this information be all in one thread and all recent to make it easier to find.

First of all, i know that turbo engines in the DSMs are high compression, therefore they must use premium gas. I have, however, heard of people running unleaded pump gas and sometimes race gas. The race gas keeps knock down and has more octane, but would unleaded leave way too much knock to run?

Also i was curious to see what types of mileage people have been getting in their dsms? Please list model of car, modifications done to car, and list in MPG form. This information would be greatly appreciated. -Samzer

The 4g63T is low compression, not high compression. 7.8:1 for 1g cars and 8.5:1 for 2g cars.

I think you're confused about pump gas. It's all unleaded if you can pump it into your car at a gas station. Get whatever the highest available octane is, usually between 91 and 94. The higher the octane the more detonation(knock) resistant it is.

Gas mileage varies immensely depending on modifcations and your right foot. There is currently a gas mileage thread in the Tuning and Engine Management forum: http://www.dsmtuners.com/forums/showthread.php?t=11241&highlight=gas+mileage

 

[GVR4592]

You beat me, I guess that's what I get for proof reading 2 times.

 

[Samzer]

Sorry, i read somewhere that you have to use Premium because they are high compression. Thanks for clearing that up for me. Any more info on this subject would be appreciated as is all of the info already posted.

 

[GVR4592]

You do have to use premium, but not because of the static compression ratio.