10.3:1 is the compression on the 03-05 VQ35DE found in the 350Z (minus the 05 track and 35th anniversary). The engine doesn't exactly have "low" compression. In every thread you have come back saying you will have proof. The fact is you do not. You continue to post B.S. that could cause problems for other users. In fact thus far you have not posted one piece of useful information. So sit back for awhile and absorb some knowledge before you start posting. That way you won't post the wrong information.
I have noticed you know nothing about the engine managment on any car. And since you know NOTHING about Zs and especially the 350Z please stop trying to act like you know everything. The engine will pull timing and ALOT more then you are letting on. You act like it won't effect anything when in reality it DOES. Please you have NO experience with the car. I'm sick of telling you over and over again your wrong.
And 100 octane will help on the 350Z it cost to much to be practical, but dynos have shown a 7rwhp gain from running 100 octane gas. Also low octane has caused pinging in the Z33. Performance gains aren't exact, but people have slips showing a .3 second difference between 91 and 100 octane in the 1/4 mile.
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Zpooled Zo Zya
Last edited by JAMESZ : Mar 28th, 2005 at 09:53 PM.
This is true...I guess I worded that awkwardly. The car will not be making its full potential because of the knock sensor (I assume the Z has one) will retard timing. Dyno graphs will show this on Spec Vs which use 87 while dynoing. Their graphs look somewhat like a richtor scale.
not to mention what would happen if the knock sensor crapped put... major engine knock and leading to fuct pistons...
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Originally Posted by apachewoolf
pssst yo token . your not black any more...there is no man
not to mention what would happen if the knock sensor crapped put... major engine knock and leading to fuct pistons...
Blown head gaskets, too. Depends on the engine. Some engines, such as the 4G63, simply melt the pistons before the headgasket goes. I have personal experience with that.....
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1992 Yamaha FZR 1000. 145 Hp, all stock..
lol ok james here we go. read the posts i write(and i mean the whole thing not just parts you like to pick out)
ok perhaps if you dynod your car with 87 octane im sure you would see that 91 will surely put up better numbers. (not by a whole lot though)
now as far as your timing retarding, yes to some degree you will have some retarding but not to the extreme like your thinking and this is why.
lets assume for the sake of argument that our new 350z has a compression ratio of 9:1 putting in what the oem recommends which im sure is 91 is always the best solution. however its not a requirement.
o2 sensors senses the fuel mixture and tells the ecu to change the fuel mixure if need be. (via exhaust)
knock sensor senses the vibration in the antifreez in your block, which then controls the timing to stop a knock if one should come about before something bad should happen
it would take a really low octane fuel to cause an engine to knock and retard its timing. this is a brand new engine keep in mind. so its effeciency is gonna be way high unless there are other problems that we dont know about. (an old tired 10 year old engine would probably prover otherwise)
i will agree if a knock does occur there will be substantial power lose of course.
Higher Octane fuels in low compresson engines will not produce more power PERIOD!
im looking at all data as we speak and will post some more precise data as time permits.
Irei
We are talking about the Z33, right? The ECU from the factory is tuned to 91 octane and the Z33 compression is 10.3:1 (fact) not 9:1. Have you noticed that it is very hard to make power on these cars? The reason is that Nissan has tuned the Z33 to it's optimal and why it's important to put in high octane gas. Anything less will drop your HP considerably and I'm not talking 5 hps (there is a reason the variable timing is used in this car). You won't find a dyno comparisions of octane difference because it's a waste of money and know one in there right mind would subject a $30+K Z to that kind of abuse.
Originally Posted by IreiMember "Higher Octane fuels in low compresson engines will not produce more power PERIOD!"
I hate to say it but this statement puts you in the John.. A Z32 has a compression of 8.5:1 and when this car came out the octane rating in Cali was 92 and when they switched over to 91 octane people with JWT ECU's went into safety boost. What does that tell you?? If you have some knowledge of how a car works this is telling you octane does count.
If you do have data please post it I do have a open mind?
Blown head gaskets, too. Depends on the engine. Some engines, such as the 4G63, simply melt the pistons before the headgasket goes. I have personal experience with that.....
I've seen it!!! (crap, my buddy was pulling bad knock on his heavily modded 4G63 with 93 octane).
Ok show me the fact, I'm waiting? But if your word is fact then you really need to go to the 300zxclub because that kind of baby talk belongs there.
ok idiot, run 87 in your car, but dont tell other peole to, because you are too ignorant to realize IF THE KNOCK SENSOR FAILS A 350Z WILL BECOME SERIOUSLY FUCKED UP WITH 87 OCTANE GAS! and like i said, you lose power with lower octane BECAUSE of the sensor, is that what you are disputing? or are you disputing my statement you WILL NOT gain power from higher octane?
its a high performance car, use high performance gas... god i went through with this shit in the qr section with spec V's, some dumb ass is gonna have 100 people fuck up thier cars to save 30 cents at the pump...
in the end, if your car says 91, run 91, 87 will hurt it, 100 wont help it, use what is recomended...
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Quote:
Originally Posted by apachewoolf
pssst yo token . your not black any more...there is no man
ok idiot, run 87 in your car, but dont tell other peole to, because you are too ignorant to realize IF THE KNOCK SENSOR FAILS A 350Z WILL BECOME SERIOUSLY FUCKED UP WITH 87 OCTANE GAS! and like i said, you lose power with lower octane BECAUSE of the sensor, is that what you are disputing? or are you disputing my statement you WILL NOT gain power from higher octane?
its a high performance car, use high performance gas... god i went through with this shit in the qr section with spec V's, some dumb ass is gonna have 100 people fuck up thier cars to save 30 cents at the pump...
in the end, if your car says 91, run 91, 87 will hurt it, 100 wont help it, use what is recomended...
We've already shown that 100 octane will help it.....
You'd lose power in a car running 87 octane that should be running 91 octane, knock sensor or no. Why? Because the knock is incomplete combustion..... The typical engine only uses 33% of the energy contained in a given amount of fuel. When improper octane levels cause knock, that means far less is used.
Knock is improper flamefront propegation in the combustion chamber. Typical knock can be best explained as too fast of such propegation, instead of uniting as a single "wave" and creating the powerful push on the piston, it splits up, "echoing" off the walls of the combustion chamber and charging the middle, where one or more meet and cause a reverberation effect. All of this is supersonic and takes place in milliseconds, your brain registers it as a high frequncy tapping sound.......
Anyway, what I'm trying to say , is that you would lose power whether the knock sensor heard that noise or not. Knock sensors are designed to hear that certain frequency of where 90% of all knock occurs. However, it can happen at a much lower or higher frequency, especially if the car has any modifications that affect airflow. Air density affects knock frequency. It's possible to have knock the the sensor will not even notice, especially in older vehicles.
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1992 Yamaha FZR 1000. 145 Hp, all stock..
And I should perhaps point out that Irei is incorrect as to how the knock sensor hears the sound. It is not listening to the sound of the antifreeze. Not on gasoline cars anyway, that is reserved for the newer diesels. No, it is listening to the sound of the engine block itself. The metal is of a known composition and will conduct sound almost always in the same way. Composition of antifreeze can change, and could change how much or how little of that particular knocking sound is actually heard by the sensor. Go ahead, pull the knock sensor on any car, it is not in a water jacket...
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1992 Yamaha FZR 1000. 145 Hp, all stock..
We've already shown that 100 octane will help it.....
You'd lose power in a car running 87 octane that should be running 91 octane, knock sensor or no. Why? Because the knock is incomplete combustion..... The typical engine only uses 33% of the energy contained in a given amount of fuel. When improper octane levels cause knock, that means far less is used.
Knock is improper flamefront propegation in the combustion chamber. Typical knock can be best explained as too fast of such propegation, instead of uniting as a single "wave" and creating the powerful push on the piston, it splits up, "echoing" off the walls of the combustion chamber and charging the middle, where one or more meet and cause a reverberation effect. All of this is supersonic and takes place in milliseconds, your brain registers it as a high frequncy tapping sound.......
Anyway, what I'm trying to say , is that you would lose power whether the knock sensor heard that noise or not. Knock sensors are designed to hear that certain frequency of where 90% of all knock occurs. However, it can happen at a much lower or higher frequency, especially if the car has any modifications that affect airflow. Air density affects knock frequency. It's possible to have knock the the sensor will not even notice, especially in older vehicles.
And also, conversely, noise that the knock sensor recognizes as knock that is really harmless engine noise. Subaru's have huge problems with overzealous knock sensors.
I see what they were saying above though. Running C107 race fuel in a 350Z will not increase power, because all that a higher octane rating does is increase an engine's knock tolerance threshold. With a stock or even slightly modified VQ35DE, this isn't a consideration, because it doesn't knock with 91. 91 octane will deter 100% of knock just as well as 107 octane will. 87 octane however, might make the engine knock, which would activate the knock sensor, which triggers the ECU to retard the timing.
And also, conversely, noise that the knock sensor recognizes as knock that is really harmless engine noise. Subaru's have huge problems with overzealous knock sensors.
I see what they were saying above though. Running C107 race fuel in a 350Z will not increase power, because all that a higher octane rating does is increase an engine's knock tolerance threshold. With a stock or even slightly modified VQ35DE, this isn't a consideration, because it doesn't knock with 91. 91 octane will deter 100% of knock just as well as 107 octane will. 87 octane however, might make the engine knock, which would activate the knock sensor, which triggers the ECU to retard the timing.
Actually the Subarus (the STi) are having problems because the EJ25 was designed to run on 95+ octane gas.... The 91 octane salad oil we have completely freaks out the ECU. This problem is solved with an ECU reflash, but then the STi is not longer 300 Hp.... The 350Z, as JamesZ has already said, responds better to 100 octane fuel. Engines are specified to run the octane they are to balance fuel economy, Horsepower, and warranty. Also, cars that require higher octane can be offputting to potential buyers, especially with the prices we pay for gas these days. At 10.5:1 compression ratio, I would say that 91 octane was barely adequate to control knock in the 350Z. The 91 ZR1 Corvette, at a 10.1 ratio, specified 91 octane. Half a point higher, it makes sense that more octane would be required.
Something else you don't realize, almost all engines experience knock at some point. Could be one out of every 30 power cycles. Could be one out of 100. Knock sensors start to wake up when a threshold point is reached, which is about 1 out of every 10-20 power cycles. At 5000 rpm, you do the math. What higher octane does, is create smoother more useable power for the engine. Higher octane of itself is not more powerful, higher octane actually slows down combustion, makes it more useable by the engine. It lowers the chance of having knock in the threshold range of the sensor, and lowers knock in general, which means the engine can make power on every stroke, not just most of them......
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1992 Yamaha FZR 1000. 145 Hp, all stock..
I'll put this into perspective for some of you. What do a 79 308 GT Ferrari, an 86 Porsche 911 Turbo, a 94 ZR1 Corvette, and a 2004 350Z have in common? They all require 91 octane gas.... Even with such disparate power applications. What I'm trying to say is, factory octane requirement is a generalization. Especially for modified vehicles, factory octane requirement goes right out the window. Octane requirement is also specified the same for all altitudes, which is hugely incorrect in a place like Colorado.....
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1992 Yamaha FZR 1000. 145 Hp, all stock..
Might as well also add, when fuel is reformulated (oxygenated), I have always been told to consider bumping up octane as it can cause pinging or premature burn, especially vehicles with excess carbon build up. I know that MD is reforumlated in winter months, and PA is not. Premium is generally 93 here, and 94-98 is readily available. I would imagine Cali is oxygenated. The STi may simply not be able to take reformulated 91 octane without having a serious reduction in timing.
Might as well also add, when fuel is reformulated (oxygenated), I have always been told to consider bumping up octane as it can cause pinging or premature burn, especially vehicles with excess carbon build up. I know that MD is reforumlated in winter months, and PA is not. Premium is generally 93 here, and 94-98 is readily available. I would imagine Cali is oxygenated. The STi may simply not be able to take reformulated 91 octane without having a serious reduction in timing.
Aside from a few gas stations catering to the racers around here, the best we get is 91 octane. Kind of odd, since at higher altitude, we should get the higher octane stuff.
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1992 Yamaha FZR 1000. 145 Hp, all stock..
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