Your pump-gas octane usage and MPG!!

[slipnfall]

Poll it up, I want to see how many of you folks really run factory recommended octane. Please post MPG and any other factors that may contribute.

Figured this was as good a time as any, since gas prices spiked today(again).

Thanks!

[slipnfall]

18.9MPG on '87

Rebuilt DE, new O2, coolant temp sensor, cleaned MAF, stock stock stock.

-Slip

[hannibal]

On a 600mile road trip back in Feb, I averaged 29mpg (with avg speed of 75mph).

87 Octane! I read an article in Car and Driver on whether you HAD to use the recommend fuel. Their conclusion was that you should for best performance, but the ECU will adjust for lower octane. They tested a BMW, but I think this applies to other cars as well.I'll save the premium stuff for when I have a turbo. It'll probably be $3/gal by then...

[skatanic28]

93 always for me.

28-30 mpg highway22-25 mpg daily

[slipnfall]

Well yeah that's half the story... I'v never experianced knock/pinging on '87. S13/S14 ECU's will pull back the timing if it detects knock, but will always begin at the base timing. Other vehicles such as Mitsubishi(likely BMW too), start advancing the timing untill it detects a knock, then backs off. So for our cars running super-octane does nill unless the distributor base timing is advanced. This is what I gather.

Now what that threshold is I don't know: between keeping the ECU from pulling back timing, and wasting money on high octane. I guess you'd need a CONSULT or knock meter to really tell.

I don't think '87 will really do any harm 'per se, but I'm no mechanic either. It would seem to me that running a super-hi octane could be just as bad, if not worse(harder to ignite?).

I know this topic has been covered 398234029309324 times, so I don't want to really re-hash it. Just curious about 'real world' results.

Thanks for the response!

Oh and I wish I could get close to 30...phew...my next tank will be of 92-93 just as a test.

[Arrow]

Right around 20mpg (city/hwy - mostly city) on '89!!! And I still need to run some seafoam through it and replace my O2 sensor... BTW, my '90 says that what's recommended is '87. But once again it is a '90.

[slipnfall]

Hmm, interesting. I'v never been able to find the actually octane *number* in the FSM, my gas door just says 'premium'. I guess that's a big objective. I'd consider 89+ premium. :-)

[hannibal]

I think my owners manual says 'premium 91+ octane'.I dont think the 87 will do any harm. They have to make the car for cheap idiots (like me ). I assume theres some 'safe' room built in to their recommendation for premium.

From my undersatnding of octane rating, 93 is just more potent. It has more power in it than 87 octane (Kind of like Bicardi 151 vs Corona). All things being equal, 93 would just run slightly richer than 87. I think the ECU can make this tiny adjustment.

[corn322]

Incorrect. Octane rating is resistance to knock. has nothing to do with gas being more potent.

But as knock resistance goes up, you can add higher compression/higher boost, so you make more power.

[slipnfall]

Right. '87 has the same, dare-I-say, energy potential, as anything higher.

[ArticDragon192]

87 octane. 22-25 mpg.

[slipnfall]

Man I really should be getting better than 19MPG...I really hate Sheetz gas(I'v been told it's comparable to Wawaa's gas on west coast). Cheap stuff. I seem to get a *way* better feel and tank longevity off Texico or Shell gas. Too bad Sheetz is a monopoly around here.

I'm waiting to get Nissan to do an A/F test for me, hopefull it turns up something.

-Jamie

[mackdaddy240]

18-20 in town, with rough 4 puck act clutch. 28-30 on highway 75-80mph. octane........ somewhere between 95-98 mix 91 with airplane fuel. 11-1 compression 5 degree advanced timeing and a lil 50 shot every once in a while. gas is KILLING ME about $2.60 per gal.

[nissandrift]

I get about 23-24mpg daily driving and 28-30 on the HWY with 93 octane and my timing has been bumped 4 degrees.

[BII]

So is it just S14s that premium is recommended for, or the S13s too? Sorry, I'm new to the glorious 240SX.

[im two techno]

I run 93 allways unless i use the sunoco 100 and i must say the KA likes cam2 gas.

[CDE]

GAS IS A RIPOFF IN CANADA!

Where I live here on the west coast, gas prices change about 3 times EVERY DAY. And then stupidest thing is that they tax the gas on top of all the other taxes. RETARDED! Gas hit $1.03 A LITRE here which equates to about $3.90 a gallon. I would take that $2.60 anyday :P Of course there are dollar differences so that $3.90 would be around $3.20 US. OUCH!!!!!! Alberta has a HUGE oil production yet it is still so expensive.

I try to normally use 91 just because it accel's smoother (seemingly) but lately it's been regular (87) because it is just so damn expensive. I also like to fill up at chevron because they have the cleanest gas. I'm not sure what I get MPG wise, because my dash was broke when I bought the car and I just fixed it today...so in about a week I shall have a good idea of what I get...

[petesleaf]

I'm suspicious of Seafoam and other engine cleaners. Damage to valve and other seals is probable. Replacing 16valve seals is a *****.

[petesleaf]

Time to get a bicycle!.

[justmerging]

22-25 mpg91 octane yak piss(highest we got at the pump in cali)

[Bronze MFP]

93 octane, bone stock ka24de, 22-30mpg depending on how much I floor it around town or cruise on the highway.

[CDE]

Time to get a bicycle!.

Motorcycle actually

I'm going to get an 80-84 Honda Magna V45 750CC. I can pick one up for about 1000 bux. I can ride it about 8-9 months out of the year and after 2 years it will pay for itself as it gets around 80 MPG.

[mackdaddy240]

93 octane, bone stock ka24de, 22-30mpg depending on how much I floor it around town or cruise on the highway.

bone stock as long as your timings not advanced you can run good old cheap $2.25 87 octane

[surfwax95]

Put in 87 get out around 25 mpg average.

My friend's CRX just came home pulling 35 mpg. wow.

[slipnfall]

Yeah I just filled up with '93 yesterday, so I'll post back with new MPG. I might advance my timing a bit to see if I can pick up a 'pony's tail' afterwards.

-Slip

[hannibal]

Incorrect. Octane rating is resistance to knock. has nothing to do with gas being more potent.

But as knock resistance goes up, you can add higher compression/higher boost, so you make more power.

School me...I understand youre saying higher octane gives you more resistance to knock. But why? Its not like it comes out the refinery, and they say "oh, this bucket is very knock resistant. Lets call it 93 octane." Some characteristic of the gas is different for them to give it a higher octane rating (implying a higher resistence to knock).

If 93 octane is in fact more potent than 87, this would explain why 93 has more knock resistence, since according to my theory, its running richer than the lower octane fuel (and richer AFR's are more resistant to detonation than leaner AFR's).

On the same token, as long as youre avoiding detonation, 87 or 93 octane should give you the same performance, right?

[Bronze MFP]

93 octane physically does not have more power than 87 octane. The difference is 93 is harder to ignite than 87. That is why it is less prone to detonation, Because it is less prone to detonate, thats why you can run high compression, advanced timing and all that other good tuning stuff to get you good HP numbers. From the refinery, they add certain chemicals to the gasoline to make it less flamable. I know one you can get at a painters supply shop and make your own 95+ octane gas. I wish i had the link to that still, but it went down with my old harddrive

[slipnfall]

This is just from memory, so my spelling might be off... Xylene is commonly is found in paint supply stores, but is a lower octane than the Toluene, another 'octane booster' additive.

There are plenty of threads on this, so let's try to keep from veering off this one. Thanks for all the responses, keep 'em coming. The more poll results, the more accurate!

-Slip

[hannibal]

Sorry for the threadjack, but thanks for clearing that up guys...

[351cka24de]

hello everyone, just wanted to toss in some information about octane and what it really means

as many people have suggested, octace is just a measurement for how slowly a gasoline burns. a higher octane gas will burn more slowly than a lower octane gas. this has the benefit of being knock (detonation) resistant.

the reason that people say that it makes more power is because it has the potential to. however, this is very different from actually making power. how much power you get out of your gasoline depends on how you set up your camshaft/distributor timing. with higher octane, you can advance the timing, setting the gasoline burning before you could start burning the lower octane. advancing the timing has the potential to up the power figures. that is, IF you have your engine tuned to take advantage of it. with lower octane, you can also advance the timing, but not as much as the higher octane.

the biggest question to higher octane is... is your ECU programmed to adjust the timing to match the octane? advancing or delaying the timing to best utilize your fuel? or does it just detect pinging and retard the timing (as my 95 s14s does)? also, is your compression and your timing advanced enough to make use of the higher octane? if not, then there is no benefit whatsoever in using a higher octane.

if your engine doesn't knock with low octane, and you're not going to bother tuning it to make use of higher octane... save your money, get lower octane... save that money for other things... like more gas ;p

hope this helps