Regular Gas?

Forrest · 06-01-2009, 10:49 PM

just keep adding premium into the tank every chance you can get. Im sure if you wanted to you could syphon alot out but idunno doesnt seeem like fun.

on after thought it might actualy be 91 octane but from the cheapest crappyes gas station they could find a discount at.

I had no idea what the dealer put into mine but i can only assume it was crap so i kept putting chevron in it every day hoping to mix the good stuff with what ever they put in.

Cjanik · 06-01-2009, 11:21 PM

dont worry about it.

when your car is new, you cant (shouldn't, unless you believe in breaking it in by the dyno) rev it above 4kRPM's or so.

the lower octane gas will not do anything to your motor, as a mater of fact, if you plan on keeping the engine below 4krpm for 500+ miles (break in period?), then you might as well use regular gas for the 500+ miles. (although I wouldn't, the price difference isn't much of anything)

the reason premium is required is because the 370z's engine has high compression which will make low octane gasoline detonate BEFORE it reaches the combustion stroke.
there is an exception to that - which is if the engine is not under stress to put out the power, then the gas will not misfire, thus making 87 octane perfectly fine to use. You just have to remember not to floor it.

on top of that, many new cars have smarter ECU's that will regulate the misfiring to prevent damage. (although not all cars have it, and not always successful)

g96818 · 06-03-2009, 01:43 AM

Quote:

Originally Posted by Cjanik

dont worry about it.

when your car is new, you cant (shouldn't, unless you believe in breaking it in by the dyno) rev it above 4kRPM's or so.

the lower octane gas will not do anything to your motor, as a mater of fact, if you plan on keeping the engine below 4krpm for 500+ miles (break in period?), then you might as well use regular gas for the 500+ miles. (although I wouldn't, the price difference isn't much of anything)

the reason premium is required is because the 370z's engine has high compression which will make low octane gasoline detonate BEFORE it reaches the combustion stroke.
there is an exception to that - which is if the engine is not under stress to put out the power, then the gas will not misfire, thus making 87 octane perfectly fine to use. You just have to remember not to floor it.

on top of that, many new cars have smarter ECU's that will regulate the misfiring to prevent damage. (although not all cars have it, and not always successful)

the cylinder volume does not change when you rev past 4k, the compression is the same at 1k or at 8k. it may not be as detrimental since it's not exploding 8k times per min, but it's still exploding prior to the piston reaching TDC which damages the piston, piston rings, cylinder walls, valves, spark plugs, injectors, if it's in there, it's damaged.

don't put regular in your car unless u have some kind of piggy back or stand alone ecu which will redo the timing.

rbratton · 06-03-2009, 02:35 PM

Quote:

Originally Posted by g96818

the cylinder volume does not change when you rev past 4k, the compression is the same at 1k or at 8k. it may not be as detrimental since it's not exploding 8k times per min, but it's still exploding prior to the piston reaching TDC which damages the piston, piston rings, cylinder walls, valves, spark plugs, injectors, if it's in there, it's damaged.

don't put regular in your car unless u have some kind of piggy back or stand alone ecu which will redo the timing.

Your volume statement is correct, but your conclusion about pre-detonation is incorrect. If the ECU detects pre-detonation, it will retard the timing to alleviate the knock. It's very unlikely to suffer any damage from low octane gas, your performance will just suffer.

lww · 06-03-2009, 06:04 PM

Quote:

Originally Posted by g96818

the cylinder volume does not change when you rev past 4k, the compression is the same at 1k or at 8k. it may not be as detrimental since it's not exploding 8k times per min, but it's still exploding prior to the piston reaching TDC which damages the piston, piston rings, cylinder walls, valves, spark plugs, injectors, if it's in there, it's damaged.

don't put regular in your car unless u have some kind of piggy back or stand alone ecu which will redo the timing.

All higher octane gas lets you do is advance the timing which can increase the torque generated by starting the combustion process earlier on the compression stroke without detonation.

Essentially, there's no additional energy available in the air/fuel mixture, it's simply how it's being used that results in the generation of more power.

U-NVmyZ? · 06-03-2009, 06:09 PM

when i had my 350 i 80% of all the fillups i used with unleaded... didnt feel any diverence. my dad who grew up with datsuns and had a 300Z for a long time always used the 'cheap' gas... idk the only gas u should b worried about NOT putting in ur ar is from "THRIFTY"..

g96818 · 06-04-2009, 04:18 AM

Quote:

Originally Posted by lww

All higher octane gas lets you do is advance the timing which can increase the torque generated by starting the combustion process earlier on the compression stroke without detonation.

are you high? if i'm reading this right, u're saying to ignite the fuel before TDC so that force will be applied to the piston head in the opposite direction of travel

if that's what u mean then just use low quality gas so the fuel mixture detonates prior to TDC. u want to ignite the fuel right after TDC as the piston moves back down to get the maximum amount of force applied, the high octane fuel allows you to achieve that high compression ratio at TDC without self detonation.

now idk how this new system works, but i'm figuring that if it does adjust then all it's doing is igniting the fuel mixture prior to detonation, since a control ignition is safer than a uncontroled explosion. since it ignites prior to TDC, the force is pushing against the piston, which would naturally decrease the output.

are u familiar with PV=nRT? V, n, and R are constants so as pressure increases in the cylinder, temp increases also. Low octane ignites at lower pressure/compression and high octane ignites at a higher pressure/compresion. actually V is a variable, but if we take it at TDC, it's a constant.

if i remember correctly, regular is used for compression < 8.5psi, 8.5 < plus < 10, 10 < premium < 12 or something like that.

Quote:

Originally Posted by lww

Essentially, there's no additional energy available in the air/fuel mixture, it's simply how it's being used that results in the generation of more power.

agreed

ChrisSlicks · 06-04-2009, 09:33 AM

Quote:

Originally Posted by g96818

are you high? if i'm reading this right, u're saying to ignite the fuel before TDC so that force will be applied to the piston head in the opposite direction of travel

Yes, you ignite the fuel before TDC. It takes time for the spark to ignite the fuel and complete the burn, so with a piston traveling at 150mph you must account for this delay and fire early. Obviously the goal is as you described, to have maximum gas expansion right after TDC, but to get there you have to start before.

Modshack · 06-04-2009, 03:04 PM

Quote:

Originally Posted by ChrisSlicks

Yes, you ignite the fuel before TDC. It takes time for the spark to ignite the fuel and complete the burn, so with a piston traveling at 150mph you must account for this delay and fire early. Obviously the goal is as you described, to have maximum gas expansion right after TDC, but to get there you have to start before.

Which is why Premium fuel has a slower burn rate. Allows for more timing advance..

lww · 06-05-2009, 02:29 AM

Quote:

Originally Posted by g96818

are you high?

Yes... yes I am.

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06-01-2009, 10:49 PM	#1 (permalink)
Forrest Track Member Join Date: Mar 2009 Location: california 707! Posts: 677 Drives: 09 370z Blk 6mt sprt Rep Power: 260	just keep adding premium into the tank every chance you can get. Im sure if you wanted to you could syphon alot out but idunno doesnt seeem like fun. on after thought it might actualy be 91 octane but from the cheapest crappyes gas station they could find a discount at. I had no idea what the dealer put into mine but i can only assume it was crap so i kept putting chevron in it every day hoping to mix the good stuff with what ever they put in.

06-01-2009, 11:21 PM	#2 (permalink)
Cjanik Track Member Join Date: May 2009 Location: Las Vegas Posts: 578 Drives: N/A Rep Power: 19	dont worry about it. when your car is new, you cant (shouldn't, unless you believe in breaking it in by the dyno) rev it above 4kRPM's or so. the lower octane gas will not do anything to your motor, as a mater of fact, if you plan on keeping the engine below 4krpm for 500+ miles (break in period?), then you might as well use regular gas for the 500+ miles. (although I wouldn't, the price difference isn't much of anything) the reason premium is required is because the 370z's engine has high compression which will make low octane gasoline detonate BEFORE it reaches the combustion stroke. there is an exception to that - which is if the engine is not under stress to put out the power, then the gas will not misfire, thus making 87 octane perfectly fine to use. You just have to remember not to floor it. on top of that, many new cars have smarter ECU's that will regulate the misfiring to prevent damage. (although not all cars have it, and not always successful)

06-03-2009, 06:09 PM	#6 (permalink)
U-NVmyZ? Base Member Join Date: Mar 2009 Location: Los Angeles Posts: 110 Drives: 18 370 Sprt 6 Wht Rep Power: 18	when i had my 350 i 80% of all the fillups i used with unleaded... didnt feel any diverence. my dad who grew up with datsuns and had a 300Z for a long time always used the 'cheap' gas... idk the only gas u should b worried about NOT putting in ur ar is from "THRIFTY"..