I have a 1995 4runner with a 3.0. My question is, that it seems to run alot better using high octain gass rather then regular gass. Will this harm the motor in any way? Thanks for your time.

 

No, it won't hurt a thing. It's just not a requirement. The computer will adjust the ignition timing to run with it, and the engine will run a little better. But it won't be able to adjust the base ignition timing beyond where it's been set, and therefor won't be able to take full advantage of the higher octane fuel untill that's been changed too.

I run 92 octane in mine with the base ignition timing advanced to ~23° BTDC. It runs WAY better than stock base igniton timing(10° BTDC)and 87 octane. You should try advancing yours a bit too. It'll make the extra $ more worth it.

*Results may vary.

 

on older motors with a lot of miles on them, they'll usually ping if you use low grade gas actually. I drove a 96 Ranger with a 4 banger that use to do it. Would run like junk and ping like crazy if I put 87 in it. step up to 89, and it was a night and day difference

it's because over the years, so much carbon builds up on top of the pistons and under the cylinder heads that it actually lowers the volume in the cylinder, and consequently raises the compression ratio

 

^^^
which is why you need to do an Italian tune-up

 

for those who dont know what it is haha

 

i had a friend back in high school that filled is Yamaha virago 250 up with c16 and actually ran a full second slower in the 1/4

 

Ummm..did he tune it for c16? Well then there's your answer to that!
Higher octane fuel in an engine with no ignition timing adjustments for it = less power. Same amount of fuel in, with less time for it to fully burn. Plain and simple.

Just an FYI, my 3VZE is freshly rebuilt(less than 4000 miles)and TOTALLY carbon build-up free. So that ain't why my engine runs better on 92 octane. It's because I want it to.

Oh, and also any engine built since around 1980, or so, can be easily tuned to run on any grade of gas/fuel below ~96 octane. That's why they have relatively higher compression ratios compared to ealier engines. Non-EFI engines will need timing adjustments, or a turn of the octane selector switch for best results. Most pre-95 EFI engines, OBDI, will do just fine letting the ECU take care of that. But like I said they can't adjust base ignition timing, so doing so manually will yield the best results. Any EFI 96 or later, OBDII, will need no adjustments to igniton timing for higher octane fuels. The ECM has full control on those, and you can't fool with the ignition timing without fooling with it's programming. Anything OBDII will ALWAYS run better on grades higher than 87 octane.

Lots of misconceptions around regarding this. First and foremost being that you have to have a "sports car with a high compression engine that's made for it" to run premium gas. Nope, you don't. 9:1 compression already is "high", "high" enough for premium gas anyway. Yet not "high" enough to cause issues running 87 octane either. When you start getting into the 10:1 and higher range, then running on 87 just isn't doable. That's when you really DO need higher octane fuel.

 

for the record, I wasn't saying that running higher octane fuel is going to turn your 3.0 into a fire breathing race engine. I was just saying that for some people noticing pinging or other odd running conditions on very high mileage motors, sometimes stepping up to the next rating octane can help out. SOMETIMES, not all the time

 

how about the g8 gt 10:4:1 compression and gm recommends 87 octane

 

You've got the carbon build-up part right. And that may have had something to do with it. But any 96 or later engine with an OBDII ECM is going to have the ingition timing adjustment, from base to maximum advance, required to run higher octane grades than 87 without power loss built in to the system. They'll all be able to adjust for whichever octane fuel you put in them. 87 octane or up to ~96 octane. This is what Toyota calls ESA(Electronic Spark advance) or VAST(Variable Advance Spark Timing). The ECM uses the knock sensor to sense "ping" and retards the ignition timing when it does. Up untill that point it will try and advance the ignition timing as far as it can. That's what the knock sensor is there for.

To read another explaination of what I'm speaking of, with visual representations, see the link below.
http://autoshop101.com/forms/h59.pdf

No it doesn't.

The Pontiac G8 GT has an L76 V8 with a 10.1:1 CR. The Holden version L76, which produces more power and is not available in a G8 GT, has as a 10.4:1 CR and is not recommended to be run on regular gas. The Holden version isn't even available in this country. Most countries in Europe(or Australia)don't even sell 87 octane fuel, or petrol as they call it.

BTW, I said "getting into the 10:1 and higher range". 10.1:1 is at the lower end of that range. Problems running 87 octane fuel generally start to arise around that compression range and higher. That's a fact.