My friend both brought a July, 2002 built SE-R (they arrived at the dealership in August for pickup).
My friend wants to save money and also read the posts here and decided to use regular. He now has 12,000k and the engine is making a slight clanking noises. like it needs valve adjustment or something. The dealer said it`s due to the gasoline that he uses. they will not look at the issue based on that fact.
My friend was being honest with the dealership because he did not think this was such a big deal and it was all performance related with the gas types. The knock sensors should do it`s job, rightÉ
I`ve been using 91 octane since new. I have not a problem.
If you are using regular gas, let me know how long you been using it and are there any side effects. Also, do you use it for all condition drivings, like city and highways, etc.
bring it to another dealer and don't bring up the gasoline. whether that is the cause or not is not the issue, you tell them something like that they will blame that one on you anyways so just don't volunteer any info to them!
I can tell you from a mechanical standpoint that you are slowly killing your engine. It was designed with specs centered around the burn speed of the gasoline and the compression was set accordingly. There is a misconception that the ECU will simply reset the timing ad you will be okay with 87 or 91 octain, but i can assure you that if your car is designed for 92+ then you need to use 92+ (or if it is designed for 91, use 91). If you take a few chemestry classes or better yet a few mechanical engineering courses you will start to understand that retarting the timing is not enough, the engine needs the slower or faster burning octaine, thus the minimum octaine requirement on your car.
Originally posted by BlackoutSpecV I can tell you from a mechanical standpoint that you are slowly killing your engine. It was designed with specs centered around the burn speed of the gasoline and the compression was set accordingly. There is a misconception that the ECU will simply reset the timing ad you will be okay with 87 or 91 octain, but i can assure you that if your car is designed for 92+ then you need to use 92+ (or if it is designed for 91, use 91). If you take a few chemestry classes or better yet a few mechanical engineering courses you will start to understand that retarting the timing is not enough, the engine needs the slower or faster burning octaine, thus the minimum octaine requirement on your car.
Best of luck.
maybe I'm missing the point but I don't understand what you're saying. higher octane gas is to help reduce pinging and detonation. so if you use lower octane and retard the timing, reducing combustion pressure, then you are basiclally doing the same thing. so I might be just ignorant, 90% probable, but is there some other function to higher octane gas that you know about?
Yes, octaine determines burn speeds of the gasoline in the combustion chamber. The entire engine is setup around this burn speed, not just the ignition timing. The lift and duration of the cam is setup around the burn speed, amoung other things. I do realize that with a computer controled cam this is less of an issue, but it is still an issue.
You are correct in that octaine is also a factor in pining and detonation... Detonation based on the burn speed of the fuel in relation to the sprak (solved by the ECU adjusting the timing). As for pings, that is because the valves are operating at a speed and timing for which they were not designed (because the timing has been retarted). the long term effect is extreamly high wear on the motor.
The cam timing contorol (CVCT or whatever Nissan calls it) certainly will help reduce the stress and strain on the motor, but the simple fact is that there is still a strain on the motor above and beyond that which it was designed for.
Originally posted by BlackoutSpecV Yes, octaine determines burn speeds of the gasoline in the combustion chamber. The entire engine is setup around this burn speed, not just the ignition timing. The lift and duration of the cam is setup around the burn speed, amoung other things. I do realize that with a computer controled cam this is less of an issue, but it is still an issue.
You are correct in that octaine is also a factor in pining and detonation... Detonation based on the burn speed of the fuel in relation to the sprak (solved by the ECU adjusting the timing). As for pings, that is because the valves are operating at a speed and timing for which they were not designed (because the timing has been retarted). the long term effect is extreamly high wear on the motor.
The cam timing contorol (CVCT or whatever Nissan calls it) certainly will help reduce the stress and strain on the motor, but the simple fact is that there is still a strain on the motor above and beyond that which it was designed for.
i'm sorry but I'm still not understanding... shouldn't the valve 'speed' be controlled by the camshafts? I know what detonation and pinging are but I just don't understand what you are saying about other 'extremely high wear' effects on the motor....
Well i guess this is why i do not have a pHD!, i cant teach.
Ask your mechanic if he would run a lower grade gas in his car, and maybe he can explain to you why not. All i can tell you is that on the 3 race motors we built (all be it they were ford 302's) our techs told us race fuel only becasue we had to have 101+ (or 104, i cant remember). I know that i have been taught, and read that the speed at which gasoline burns in the combustion chamber is based on spark timing in relation to the octaine of the fuel. and that the cams have to be timed with the combustion so as to make power... the cylander can not be being forced up when its suposed to be down and vice versa...
more importantly the people who designed these cars know more than you or I will ever know and they said run 91 or 92 or whatever, and thus I will do that. I know one person who blew a QR25 and he was running a simular setup as me, only diffrence was he used 91 and sometimes 87, I alway use 93.
Originally posted by James well on my I35 it says *recomended* 91 octane, it even says in the manual, using lower octane will cause power loss.
well go with the manual, maybe it does not effect that motor in any way other than power loss. However to me power loss equates to strain on the motor, which causes faster damage and failure of the motor. Like i said, the engineeres who design these cars know more than me, go with what they tell you, in that case it sounds like less than 91 will only effect perfomance. But note that every motor is diffrent, especialy open deck motors like the QR25.
My owner's manual states you should use gas with an octane rating of at least 87. This is for an '03 Spec V. Doesn't say anything about requiring or recommending 91.
Originally posted by JMF My owner's manual states you should use gas with an octane rating of at least 87. This is for an '03 Spec V. Doesn't say anything about requiring or recommending 91.
if you read the manual under the QR25 motor you should see otherwise, at least all the se-r's iv'e seen (spec v or regualr) all require 91+
.:EDIT:.
found what i was looking for in pain english...
"A higher octane may be necessary to prevent pre-ignition and detonation in a high performance engine." ... "Octane is a rating of a fuels resistance to ignite." ... "Higher octane fuel will generally burn slightly slower than a lower octane fuel which could require a change in ignition timing."
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-- 2002 SE-R Spec V
Last edited by BlackoutSpecV : Jul 17th, 2003 at 10:15 AM.
It is my experience that the SE-R takes 87 Grade fuel, and the Spec V takes 91. This is one of the major reasons the spec catches 10 theoretical horsepower more than the se-r. Other reasons are supposibly specially tuned exhaust (although part numbers are the same) and different intake. I'd bet the only difference may be a more aggressive intake and a ecu mapped for the 91 octane fuel. That should be enough for 10 ponies, and makes sense.
Either way, never give the dealer a reason to turn you around and get his foot stuck in your colon. Don't volenteer info, and if asked, know the right answer and give it. I complained of a smell from the Vent, oil usage, and engine noise, and they said "that's normal". Now there's a recall for just these issues due to some goofy thing with the precatalyst.
They will take the easy way out, so by all means don't give them a door is what I'm saying. You should use the fuel recommended though for you're own sake and the sake of your sanity.
Your friend played a game, and will prob lose, unless he fibs about the gas octane he uses.
I have the SER and use 87 99% of the time, no probs. Edmunds.com used to list the octane numbers and that was one of the reasons I stayed away from the Spec V, with gas prices as they are.
BTW, my info is for 2002 models only, I have no idea if Nissan has had the desire to change this since then. Good luck and have fun!
Jey
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Happy I didn't waste 2 G on funky looking seats and a 6 spd that grinds from the factory.
i dont understand why you cheap asses are not driving geos if nissan says 91+ use it. im an electrician and if i reccomend a costumer to use a specific wire size to optimize the flow of electricity and they dont ill deny them any kind of service work. so i can understand nissans point of view. they built the car and they know best.
SER Versus Spec V
Linear Mode
