octane levels/detonation

im planning on swapping the rb25det in my 240. I heard a little bit about the need for higher octane or the use of race fuel, otherwise detonation will ocur with this engine (its always the important stuff everyone doesnt keep talking about). When you guys purchase skylines from motorex, do they fix this shit or are u guys paying for racing fuel all the time, lol. Can someone please explain this a little bit more before i make a mistake. thank you

Race fuel for a rb25. If you run 93oct you should be fine. Take the car to get it tuned, they can adjust the timing, and you will be good to go.

you know this for sure?

some smart ass was saying like he knew it for sure, detonation or w/e will occur if your not using like 110 or something...and THATS BAD! lol

are u in japan?

you know this for sure?

some smart ass was saying like he knew it for sure, detonation or w/e will occur if your not using like 110 or something...and THATS BAD! lol

Thats complete cow dodo. 110, thats some funny stuff.

Yes, 93 will be fine with an rb25 on stock boost. If you increase your boost, now then you need to get that sucker tuned.

Thats complete cow dodo. 110, thats some funny stuff.

Yes, 93 will be fine with an rb25 on stock boost. If you increase your boost, now then you need to get that sucker tuned.


Our BP 98 here in New Zealand is equivelant or slightly less than American 93 in quality and equal rating. It is more than fine for factory or even mild mods. Make sure your timing is set to no less than 17 degs at idle. Standard I believe they were 13-15 degs. You will be or should be more than ok up to about 12psi providing you have a good fuel pump. The factory is fine if it is working properly. If it isn't get a Bosch 044 Motorsports pump fitted but RETAIN the non-return check valve!

I'm running standard pumped gas (98) here in New Zealand with my GTR and pushing 17psi of boost with 18degs timing. No detination at all.
I would however still suggest getting your Air Fuel (A/F) checked to see what level it is. It should be no higher than 11.8 under boost anywhere in the rev range. Off boost lean is ok providing it isn't higher than 15.1 ! That would be simular to cruising.

Agreed :D

Where would you be able to get race fuel anyway ???

Also, can your engine take prolonged use of race fuel ???

We tend to use Optimax from Shell... it's also 98 octane and is the best fuel to use with the japanese imports... just a bit more expensive too...

Where would you be able to get race fuel anyway ???

Also, can your engine take prolonged use of race fuel ???

We tend to use Optimax from Shell... it's also 98 octane and is the best fuel to use with the japanese imports... just a bit more expensive too...

Your in England, Santa Pod should have it. Race fuel is pointless unless the car is tuned for it. You can run all day long, if you have the money.

I run Optimax in mine, but I also run 91oct(American), but I do not boost when its in the tank, for long trip I use that.

Most race fuel is old leaded aviation gas that has aged to much to be safe in aircraft.

There is a growing number of people who believe that leaded fuel will over time clog and ruin O2 sensors.
I peronsaly have yet to see any proof of it, and I even know of O2 sensor equiped cars that run perfectly fine on it, however I do some respested people who cliam to have problems.
If you do plan on running on race gas be warned, that if its leaded (it will be labled as such) you may damage your O2 sensors.
And of course you need to check on your local laws regarding the use of leaded fuel on the road, here in NZ for example it is illegal, and special unleaded high octane race gas has to be used. (again, its old unleaded aviation fuel, relabled, but its rare and so more expensive).

Most race fuel is old leaded aviation gas that has aged to much to be safe in aircraft.

There is a growing number of people who believe that leaded fuel will over time clog and ruin O2 sensors.
I peronsaly have yet to see any proof of it, and I even know of O2 sensor equiped cars that run perfectly fine on it, however I do some respested people who cliam to have problems.
If you do plan on running on race gas be warned, that if its leaded (it will be labled as such) you may damage your O2 sensors.
And of course you need to check on your local laws regarding the use of leaded fuel on the road, here in NZ for example it is illegal, and special unleaded high octane race gas has to be used. (again, its old unleaded aviation fuel, relabled, but its rare and so more expensive).


Actually it is fact that it stuffs O2 Sensors. I know of quite a few cases. Also Torque performance's A/F sensor, which is a wide band O2 sensor only last 4 hrs with leaded race fuel while standard fuels it averages 200 hrs. At $800 each he's not keen to have to keep buying new one's, so he charges accordingly extra with tuning on leaded race fuels.

....thanx a lot guys... :smile:

I run Optimax in mine, but I also run 91oct(American), but I do not boost when its in the tank, for long trip I use that.

You dont boost at all...im planning on taking it on a trip too...

Smokeurass define "boost". You can't and shouldn't simply wind the boost up to get more power without supporting. Not to mention the R33 has a factory boost cut of around 14psi. I honestly can't remember the cut. It is controlled by a boost control solinoid which makes trying to get around it a bit of a mission and if not done properly it WILL over boost.

Another quick fact the R33 GTS25t's have a two stage boost setup factory. It will boost to about 6 psi until around 4700 rpms then go up to about 7.5-8 psi after.

Another quick fact the R33 GTS25t's have a two stage boost setup factory. It will boost to about 6 psi until around 4700 rpms then go up to about 7.5-8 psi after.

you sure about that Vince because my 25T seems to have quite a smooth boost curve with very little step at all

you sure about that Vince because my 25T seems to have quite a smooth boost curve with very little step at all
Yep everyone and even your's has a movement, some seem to be more pronounced than others.

guess you should know with all the work you do for Robin

Apparently removing the restrictor from the input hose to the solenoid will allow for a "very consistent 15psi". That was for a 33 GTR tho. Dont know how different it is for the GTS-t.

(Know a lot of you hate quotes, but this ones from HPI, Special GTR Ed. 2, pg 33)
[Referencing like a good Uni squeezer ;oP]

Use the higest octane level you can get at the gas station. It maybe a little expensive but you can cover more miles on a gallon/liter (assuming the engine has a knock sensor and it should...)

Or try to get toulene it rises the octan number.

Derby

It maybe a little expensive but you can cover more miles on a gallon/liter (assuming the engine has a knock sensor and it should...)

Is this your only reason? If 93 is ok....then good,,,

No off course it is not the only reason. But why take the risk of a detonation engine.

If you can't afford to pay for the highest octane you should take in to consideration if you can pay for the car. And believe me buying new engine parts because of using low octane fuel is always gonna cost more.

Derby

the reason i asked is becuase several other guys said they dont get detonation, they also own and/or understand these cars well...back yourself up with your info plz...thanks

I don't doubt the knowledge of those guys. But high speed knock is inaudibel. And why take the risk. Boost is tricky.

When it is cold, an intercooler works better. so more atoms enter the cilinder. when they are heated up the expand more then a hot volume of air. the pressure rises, heat is rising and the chance of knock rises also.

So why using 93 octane in stead of 98. Only because of the costs? Why don't use oil from k-mart home brand, the engine works fine with it. Saving money on the fluids of your car is the worst way of saving. (look for fluids the live bloods of our car in this forum (nissan-skyline-maintenance)

Look if the car has a octane detection (BMW M3 has one) there is no problem with getting the lowest octane gas. But you have to give up some power...Just what you like.

What i said here is not intended to be taking to hard, it is just what i learned and saw during my life, it is not the only way, do what you want to do with it.

I was looking to build LPG(105) or CNG(114) into my car. only cause of the high octane levels, this not anymore against detonation but to increase power safely

Derby

thanks for the info... :)