darksider

are all gas the same? like from am/pm, 7/11, etc. are there any performace benefits?
ive been pumping from different stations but i think my car just drinks gas.
also i read you should always rev your engine before you turn it off. like rev it and while its revving down turn it off and let it die. my car idles perfect, runs perfect, no flooding issues, and so on. do i benefit from doing this? or is this whats killing my gas? thanks and sorry for the noob questions.

jeff_man

turbo or n/a?

i've learned from my fellow flamers that mazda saids n/a runs 87 and turbo runs 91. but lots of turbo owners sware by running 87. some people run premix, i know i run 2 stroke additive at 91oc on my turbo. as for cleaner gas i don't know. i've been told some pleaces have cleaner gas but it comes down to where there getting there gas from and who's refining it from them.

idsigloo

the rotary was ment to run on 87 octane whether its na or turbo. if its bone stock then just run 87. any mods at all on a turbo start running 89 or 91 and you'll be fine. get ur fuel at shell, get the shell gas card so you get 5% rebates

darksider

why shell? because of the 5% rebates?
what about revving my engine before turning it off? do i benefit form this?

idsigloo

Shell just has good gas from the consensus. Also because of the 5% rebate. I'm not sure about the revving the engine thing. I guess there is a possibility it could help clear the engine out of any excess fuel before turning it off. Our cars do run richer at idle.

t-von

iTrader: (8)

No they are not the same. I know for a fact that the 7-11 gas burns more black than the higher quality Texaco w/Techron. Every time I got on it with the 7-11 gas in the tank, all I would see is black smoke come out the tail pipe. It doesn't burn that clean. When I switched over to the newer Texaco blend, now the smoke is a whitish grey color. Truthfully I can't tell a performance difference between the two grades however, my gut feeling tells me the Texaco brand is much better because of the way it burns. I can't comment on the Shell brand as I have yet to use it.

There's my 2 cents!

t-von

iTrader: (8)

Excessive fuel will burn automatically when the engine is hot after shutdown. I've never revved my engine like that before shutdown. I think it's unnecessary. I got over 103k on my original Fd engine to prove it. The key is keeping the carbon build-up down as much as possible. You do this by not idling for long periods of time, running the engine hard on occasion, and performing carbon cleanings ( I use the water steam clean method 3 times a year ). All these things also help prevent flooding since this style of maintenance keeps the internal seals from carbon sticking. Also run a good grade of gas. I run 89 octane in my stock Fd because it burns a little faster. More burn means less carbon deposits left behind.

RETed

That's a really STUPID thing to do, especially with a rotary.
All that fuel washes everything inside the engine, and it accelerates premature wear&tear.
No fuel injected car should do this.
Owners of carbed engines used to do this just to keep gas in the bowls, which make it easier to start the next time.


-Ted

'89Vert

I only use Chevron/Texaco or Shell. Too many rumors about excess water in the gas or other harmful **** from places like ARCO or CITGO...just mo though...

jeff_man

where you get a shell card? just ask the dude working there? =P

Edit
Found it, don't see anything about 5% off shell gas

1noblerider

Iseen the 5% ... I buy gas from texaco. If i have a fuel issue I know who to go to. I am thinking about switching to shell

reatrdedspleen

Actuly most t2 owners, infact most owners of cars that are turbo run 91 octane or whatever is highest, reduces ping. For a NA, just run the cheapest they got (i think 87 is as low as it goes) any higher shouldnt make much difference. Although i swear i have slightly better power, and smoother running with higher octane. could just be all in my head, who knows.

Dont rev it up before turning it off, thats a bad idea.. This is what some people with carbed motors do. Makes it easier to start the car next time (kinda like spraying starter fluid in the intake.

classicauto

iTrader: (3)

Ok, I don't know if this is a Canadian only type of thing but I would imagine not. Gas stations all buy their gas from diffrerent outlets that sell to numerous lines of gas stations.........I believe shell is the only brand of gasoline that is actually acquired solely by that gas company.

Again, Im not sure if its the same with american gas companies, but you will buy gas from a Pioneer gas station one day, and that EXACT same gas will be in your local paki-mart pumps as well.

I think that the cases of contamination of gas (watering down) and things like that are too few and far between to make a claim of one stations gas getting better mileage then another's. I can see if personal experience has led you to believe this, but even if it has I would still bet that it was a one time occurance.

There are far too many factors in the equation of mileage to say that buying X over Y will get you more mileage.

classicauto

iTrader: (3)

The factory Turbo car was designed to run on 87, if it pings on 87 - you have something wrong......or its not stock.

darksider

that revvigng thing, ive been doing it for a while now... this cant be good. i also leave my engine to idle if im making a quick stop in and out of a store.

RETed, can you give me more information on how revving the motor before turning it off accelerates premature wear&tear. does it just build but carbon faster? or is damage on the internals itself? i assume it was ok since its recommended that we redline every now and then to keep carbon away. daym i hate hearing news like this.

Icemark

just to clarify what a couple people have posted.

Use the lowest octane that the car will run on.

Octane ratings have absolutly nothing to do with power output (BTU) of the gas. If your FC runs fine on 86-87 octane, it will never ever ever make any more power using 89 or 91 or 93 octane.

The octane rating is simply the rating of how much the gas can be compressed before igniting by itself. Pre-ignition or igniting by itself is also known as pinging or detonation.

On the US spec FC, the stock engines (both non-turbo and Turbo) are designed and tuned to run on 87 octane gas. This allows all the gas to be ignited by the spark. Using a higher octane, can actually result in lower HP in a rotary motor because of the bath tub design on the rotor face where because the octane is higher, not enough of the fuel is ignited by the spark plugs. This leads to increased emissions, and increased build up in the rotors.

Now this should not be confused with cars designed to run on higher octanes with higher compression and leaner mixtures that are designed to run on 91 or premium octanes. Then using a lower octane can result in less power as many of those cars will have the ECU crank back the timing if it "sees" detonation or pre-ignition of the fuel mixture. Our cars do not have that ability however and again are not tuned or set up for a higher octane than 87.

RxRolla

iTrader: (1)

Ok I own a 90 gtu with a rebuild engine with probably around 40k on it since I got it I was told by my family to use 93 octane, is this bad? I have 100psi of compression on both rotors.

-=Lil Red=-

iTrader: (24)

how would u know if its pinging with 87octane on a modified t2?

darksider

anyone is welcome to speak on this.

RxRolla

iTrader: (1)

I used to do that alot back when I had an s4 if I didnt rev it it would flud when I would go to start it again so I had to do all the flooding procedures, but with my s5 now I never do it (dont need to) it doesnt get flooded as much only like once every like 3 months. my s4 had a injector leaking problem dough.

Icemark

Its pretty easy to hear detonation under 3000 RPM.

If you are using a stock Turbo ECU, then there is some minor protection there as well

Icemark

But you were asking Ted...

A couple of reasons:
#1 you spike the engine and oil temp up right before shutdown (effectivly cutting oil life down- as well as generting additional heat in the engine compartment).
#2 usually the car has already slowed, and under no load so now you increase bearing wear just spiking the RPMs up.
#3 if you have a turbo, you load the fuel rail dumping extra fuel in- leading to further flooding if flooding is an issue.

That is just off the top of my head, I am sure that Ted has a couple other ideas as well.

darksider

man that doesnt sound good at all... i usually only rev up to 4-5ks when shutting it off. at those rpm ranges, do those defects still apply?

thanks ICE

synesthete

I heard the big difference in different brands of gas is the additives. Some gas has additives to keep the injection system from gunking up and whatnot, at least thats what they claim. I just get whatevers convenient and run some injector cleaner every other month or so since im premixing.

RETed

Like I said in my reply, all that gas ends up inside the engine, and it's not a very good idea especially in a rotary engine.

The rotary engine uses engine oil (for stock systems still using the oil injection) to help seal the internals.
Revving the engine like that and shutting it off allows excess gasoline to wash the internals.
This, in turn, washes all that precious oil away.
This does two bad things:
1) Decrease compression cause the oil is now washed away, and this hurts starting.
2) Increase wear, cause the oil helps lubricate the internals surfaces - with the oil washed away from the extra gas, there is more metal-to-metal contact, and this prematurely wears seals and mating surfaces.

As a side, piston engines wear piston rings premature when you do this - bad bad bad.

NO FUEL INJECTED ENGINE SHOULD BE DOING THIS.
The computer is programmed to inject more fuel at cranking, and this should be enough to start the engine.

This blasted rev-before-you-shut-the-car-off is something that was left over from carberator days.
You do not have a carb on your FC!
STOP DOING IT!


-Ted