Saving Gas MOney!?!?!?

[93RPS13]

i had heard that the highest octane is cali is 91, In MA it is 93. Since the RB25DET will work with 91 will it work 90 octane. Can this work If i took 10 gallons of 93 plus 10 gallons of 87 mix them and work it in the RB25DET?

93 octane + 87 octane =180180/2= 90if it works then it is cheaper the 89 octane gas and has 1 octane more.

PLEASE dont flame me i was an idea that i was think in the middle of class:icesangel

[93semax]

My question is why? You buy a $3000 engine but are too cheap to spend $100 (if even that) extra a year on gas???

[93RPS13]

because after i buy the engine i would be broke

[mightymouse0x]

dont drive so much

[93RPS13]

i cant that my job, pizza delivery in the winter

[93RPS13]

can we please keep this on topic

[jacob360]

You cant mix two different ocatnes and average them out. It doesn't work like that. You'll suck up a pocket of low octane and get detonation, which will ruin the engine that you just spent all your money on. Doing a swap like this you have to look at the big picture. If you only have enough money to buy the engine, but you don't have enough to treat it the right way(Premium gas, high grade synthetic oil CHANGED REGULARLY), then you aren't ready to buy it. Either save more money, or find a new project.

[93RPS13]

i am most likely save up more money, thanks for the reply

[Nismo_Freak]

93 RPS13 the others brought up very important parts to a motor swap. It's hard to be patient but it more than pays off in the end. Sit back and save up some more. Even in swapping in the motor you will run into problems. Problems cost money.

We aren't trying to talk you out of it. Just telling you how it is.

[93RPS13]

Thanks Nismo Freak i am so impatient just becasue i love the engine so much

[Nismo_Freak]

Yep, we all are dude. Just don't be another statistic in the "I've blown my motor" catagory cause you couldn't afford proper gas. Plus the motor won't run well on the lower fuel octanes.

[Nismo241]

Thats the truth, here in the great state of Oregon, we are too incompetent to pump our own gas, as me being a forgetful person I forgot to tell the gas guy to put premium in my car. I have to say, it runs like absolute **** on regular gas. I finally got it all out, and running on better gas now, but the difference is night and day.

[Nismo_Freak]

Yeah motors don't run to well when timing is retarded to like 15 degrees advance.

[93RPS13]

The RB engines run just fine off of 91 octane gasoline. Don't run the 87 cheap gas...it's not going to ruin your engine, it just won't run to it's optimum potential. If you can, run some toulene through it every once in a while.

Night

what about 93 because in MA we dont have 91? The one we have are 87, 89, 93, 94, octane gas.

[Rockenreno]

I;d run it on the highest octane I can get at the pump. Go 93 or 94 (I didn't know they had 94 *shrug*), it will make a big difference and it is worth it to keep your expensive new engine in tip-top shape!

[93RPS13]

yea, the only station that i can get 94 octane is at this SHELL station near my house.

[eurosx]

Living it up here in England, I've been enjoying the 98 octane here but not the price. Ya'll havn't seen nothing till you pay $1.45 for one liter of gas.

[93RPS13]

93 is $1.89/gallon in MA

[93RPS13]

eurosx you are so lucky:D

[nlzmo400r]

well honestly, i would just splurge and get the best of the best, it only makes sense, i understand ur on a tight budget, as am i, but only 93 goes into my car, and i drive an altima!!, and also, no offnese, but ur gonna put a lot of miles on ur beloved rb25 if ur a pizza guy, id look into getting another job thta wouldnt put so much milage on ur car, then it would save gas money too!

[93RPS13]

yea i thought of that so am change perfesstion, but this summer i am going to a motel manager. that will keep those miles off for a month or two.

[spec-v5150]

This is the exact reason i got in the habit of using only the highest Octane a long time ago. Whe I had my 01 Altima I used 91 and now on my 240 I use 91. I budgeted and got my wallet accustomed to the price of high octane. You cant take the cheap route especially with a turboed engine

[roundrocktom]

Hmm... no chemist on the list, odd.

With the octane ratings, you can "blend" the fuel. A neat trick, YEARS AGO, was to mix leaded and unleaded. OK, most folks haven't seen leaded for 15 years... but the early unleaded fuel, when added to leaded, would give it a nice kick. So when "regular" was 91 octane, and "unleaded regular" was 91 octane... a blend of 70/30 gave a 96 octane! Way too cool for high compression carb'd engines back then.

Odd thing about fuel... same base is used. Fuel flame fronts will travel at the same speed for regular or premium. It is the additive package that changes the knock index.

The thing that still blows my mind is a perfect 14.7:1 a:f ratio (remember that stoic only applies to regular gasolene, alcohol, and other fuels have a different ratio)... the flame front is in the order of meter per second. So if you had a ROOM full of A:F in the proper mixture, and ignited it 30 ft away... you would have 10 SECONDS to leave the room (if you were at the far end by the exit door!). So if that is true, and I have a piston of 75mm bore... doesn't that mean it takes a long time for the mixture to burn? YES, catch is TURBULENCE. The more turbulence, the faster the mixture burns. Turbulence also will affect any "knock" issues to the motor.

Had some friends up in Ann Arbor who could mix up stuff and test it on the octane test engine. Pretty cool, but lots of the fuel boosters were plain ol' industrial toluene (janitor supply stuff for stripping floors). VERY NASTY chemical, but we could buy it in 5 gallon buckets cheap. Wouldn't mess with it these days.

With the modern EFI systems, there is a knock sensor -- or way of detecting knock via misfire (crank angle speed), so the timing is backed way off when that occurs. Stock engine doesn't blow up or melt down, just you can feel the power back off. Thankfully most of us keep our foot of the throttle when we feel that. Now if you are running 20 psi boost, horrible gas, things might go really bad in that short 1/4 run!

EuroSx -- I hear you! Lived in Germany, and paid about $4/gallon for my VW Golf Bistro (1600cc 8V, GTi interior & suspension). Loved living there... but blowing $50 to fill up once a week was a pain! :pface

Too much coffee this morning!

Tom

[SET240SX]

I have been wondering for awhile about octane numbers on these engines because i have a source for 110+ octane fuel. Actually you all have the same source i would think. Talk to some old muscle car guys and you may find it.

Not trying to steal thread but would this high of octane #,s run ok on a daily driver?

[93RPS13]

i would guess, but be pretty expensive

[SET240SX]

If i can confirm that 110 + octane will not hurt the engines then i will let everyone know where to get it.

Yes it is a little more expensive. But if your engine is set up for it you can produce alot better HP than running on 90 something octane.

I don't want to be responsible for some blown engines or wrecked turbo's until i find out how safe it is for these engines is why i want give up the source on the forum boards.

I can be e-mailed for serious inquiries:[email protected] or [email protected]

[Nismo241]

I ran a full tank and a half of 130 leaded through my SOHC. It made a difference, in fact, 4/10's difference, and 3 mph difference in the 1/4.

[roundrocktom]

I ran a full tank and a half of 130 leaded through my SOHC. It made a difference, in fact, 4/10's difference, and 3 mph difference in the 1/4.

Was it repeatable?

No, you will not "hurt" the engine buy running 110+ octane. Gasolene has a given "burning rate", and burns the same for regular or premium. The difference is the additive, which will increase the knock index.

If you had an engine tuned to run on 91 regular (compression ratio, ignition map, cam overlap, air temp, etc) and then dumped 103 octane in the tank... it should make NO DIFFERENCE.

However if that same engine had a more aggressive ignition map (to produce higher bmep), and a knock sensor, then you should most definitely see an improvement. With the higher octane, and no knock sensed, it will run the more aggressive ignition map.

GM had a really neat "tune as you drive" algorithm for their performance vehicles. Computer would adapt to the octane level by changing the ignition timing while on a flat road, cruising. No assumption, but advance timing by 1/4 degree... check for knock... advance, check. Problem... "old timers" would hear the knock and take the vehicle in for service "something is wrong, going down the road I could hear it knocking... " Well, they updated the flash routines to disable to predictive knock... cutting back on performance! Most folks never noticed a thing... so it reduced the service calls. Oh well.

Only disadvantage to "too high of an octane" is the additives. The computer and 02 sensor works fine on gasolene. Night... do you know the stoich ratio for toulene? Too many additives,and the engine really needs more fuel (i.e. alcohol runs around 10:1 stoich ratio, so at 14.7:1 it is really lean!).

Too much toluene... change all the rubber hoses more often. Not an issue with a race vehicle getting torn down all the time, but a pain on a street car when the inner lining of fuel hoses fail and gunk everything up (been there, done that... ).

Uh, as to 130 octane source... live near a GA (General Aviation) airport? Shell usually has it. Just siphon your Cessena!

Tom

[chachi longshot]

I suppose I could always just drive down to Infineon Raceway (Sears Point). I think they got up to 118 octane at some of the pumps. Not cheap though, Last time I saw it was like $10+ a gallon for that stuff.

[apex_7]

I know!

Get a new job!