SC300/400 owners ... are you still buying premium gas for your car?
#17
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From: DE
This to me, is wrong (sort of anyways) because people will not understand it. Yes, your motor will pull timing (to a certain extent) when knocking occurs but there are many more variables that happen for a car that is designed, from the factory, to run higher octane gas.
AIT, etc all play a role in the octane of gas (or pre-detonation), if it's hot outside and you run a lower grade gasoline that has more chance of pre-detonation you'll just enable it to do so, lowering power, gas mileage, and throttle response and potentially flooding your intake path and head with carbon (dumping fuel is a no-no).
EGT's can also go up when running a lower grade octane gas that's on the verge of detonating, but you won't hear anything, and when your EGR recycles hotter-than-normal gas/carbon guess what happens? Carbon Soot Yay!
You never, ever, ever want to depend on your car pulling timing as a sign of oops I should have put what octane gas my car was made for in there.
Both the 1UZ and 2JZ are high compression motors in N/A form, and are advanced ignition timing wise, from the factory.
If you're running an aftermarket ECU, have a EGT probe on each cylinder, and the ability modify all sensor (AIT, etc) then sure, you can toy with that, but until then is the $0.20 a gallon really worth the long term ability of your motor and components inside it?
And for the people that are worried about price, stop buying cigarettes once a week, or stop drinking that beer once a week. There are plenty of areas you could cut down to make sure your mode of transportation and fun stays on the road longer.
AIT, etc all play a role in the octane of gas (or pre-detonation), if it's hot outside and you run a lower grade gasoline that has more chance of pre-detonation you'll just enable it to do so, lowering power, gas mileage, and throttle response and potentially flooding your intake path and head with carbon (dumping fuel is a no-no).
EGT's can also go up when running a lower grade octane gas that's on the verge of detonating, but you won't hear anything, and when your EGR recycles hotter-than-normal gas/carbon guess what happens? Carbon Soot Yay!
You never, ever, ever want to depend on your car pulling timing as a sign of oops I should have put what octane gas my car was made for in there.
Both the 1UZ and 2JZ are high compression motors in N/A form, and are advanced ignition timing wise, from the factory.
If you're running an aftermarket ECU, have a EGT probe on each cylinder, and the ability modify all sensor (AIT, etc) then sure, you can toy with that, but until then is the $0.20 a gallon really worth the long term ability of your motor and components inside it?
And for the people that are worried about price, stop buying cigarettes once a week, or stop drinking that beer once a week. There are plenty of areas you could cut down to make sure your mode of transportation and fun stays on the road longer.
On N/A cars (especially older, low compression designs) there is no discernible difference between high vs low octane. If an ECU doesn't detect enough knock to pull timing, there will be NO effect on power.
In modern high compression motors it can and DOES make a difference (I personally spent some time back in 2009 in a pre-production Corvette ZR1 that was being low octane tested) Many ECU's will pull significant timing in response to knock.
That being said, on my stock NA 2JZ I ran both. No difference that I noticed. My motor didn't blow up. Passing power was not affected. Ran nearly 220,000 miles without problems before the motor got swapped.
On my 1JZ? I'll only run premium
In modern high compression motors it can and DOES make a difference (I personally spent some time back in 2009 in a pre-production Corvette ZR1 that was being low octane tested) Many ECU's will pull significant timing in response to knock.
That being said, on my stock NA 2JZ I ran both. No difference that I noticed. My motor didn't blow up. Passing power was not affected. Ran nearly 220,000 miles without problems before the motor got swapped.
On my 1JZ? I'll only run premium
#23
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It comes down to weather or not you car is vvti or not since vvti is aggressive in the timing map and high compression to boot and the worse it will do is get slightly less mpg's and have slightly less power however non vvti its just a waste of money.
If you believe your car gets better power on 93 the perhaps you should also invest in a tornado fuel saver or purchase some swamp land here in Florida.
If you believe your car gets better power on 93 the perhaps you should also invest in a tornado fuel saver or purchase some swamp land here in Florida.
Last edited by xspsi6; 08-19-11 at 09:20 PM.
#24
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From: DE
Says the guy who started a thread asking the same question a little bit back Do you honestly think the less power and worse gas mileage is just the ECU saying hey you can run cheaper gas? If so I've got a set of plastic rods that will decrease the rotating mass of your engine too!
Let me just specify since people seem to think I'm pointing at it will give you more power, it won't.
Your ECU will never advance your ignition timing for you if you use higher octane (say like the idiots that like to try and run race gas in a stock car). You will never make any MORE power than STOCK.
Let me just specify since people seem to think I'm pointing at it will give you more power, it won't.
Your ECU will never advance your ignition timing for you if you use higher octane (say like the idiots that like to try and run race gas in a stock car). You will never make any MORE power than STOCK.
#26
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Yes I did start a thread asking if the sc400 guys only were running premium still and I did hook up a Vi-pec knock amp to see if there was any audible detonation which only in the worst of conditions there was such as up a hill in od on a 100 degree day which was on 87 and on 89 there was 0 preignition so as I said anything more than 89 is a waste of money as it does not affect the engine opperation.
My thread was more to see if people were running 87 and for how long etc etc
My thread was more to see if people were running 87 and for how long etc etc
#27
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Yes I did start a thread asking if the sc400 guys only were running premium still and I did hook up a Vi-pec knock amp to see if there was any audible detonation which only in the worst of conditions there was such as up a hill in od on a 100 degree day which was on 87 and on 89 there was 0 preignition so as I said anything more than 89 is a waste of money as it affects the engine opperation.
My thread was more to see if people were running 87 and for how long etc etc
My thread was more to see if people were running 87 and for how long etc etc
How would anything MORE effect engine operation?
#28
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Yes I did start a thread asking if the sc400 guys only were running premium still and I did hook up a Vi-pec knock amp to see if there was any audible detonation which only in the worst of conditions there was such as up a hill in od on a 100 degree day which was on 87 and on 89 there was 0 preignition so as I said anything more than 89 is a waste of money as it does not affect the engine opperation.
My thread was more to see if people were running 87 and for how long etc etc
My thread was more to see if people were running 87 and for how long etc etc
#29
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Anything more will cause unburnt fuel to allow the engine to run dirty and these cars run mega rich from the factory 12.4-12.8 afr under WOT which is just a factory failsafe built in to the ecu as if you were to build your own timing and afr map I would be willing to bet you could pick up 25-30 whp on the non vvti v8.
#30
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From: DE
What do you think happens when you run 87? Do you think the ECU just happily pulls timing and does nothing else? No, it will dump fuel to compensate for the increase in EGT, etc.
And no, the stock sensor is garbage, and the stock location is not exactly the best regardless. Unless you're monitoring all 8 cylinders you can never give any conclusive evidence as to what was going on, only a general blanket statement.
And no, the stock sensor is garbage, and the stock location is not exactly the best regardless. Unless you're monitoring all 8 cylinders you can never give any conclusive evidence as to what was going on, only a general blanket statement.