87 octane in 350z 6MT

[ManDogFish]

Hi,
please do not start with 'dont buy a 350z if you cant afford the fuel'. I am not asking for opinions, I am asking for knowledge....

and not everyone lives in the US where premium and regular gas prices are similar...so dont assume the prices for fuel (differences between 93 and 87 octane are the same everywhere)

I somewhat recently got a 2004 350z, 6MT...
I usually drive a minimum of 200km per day, which ends up costing me a minimum of $20 of premium a day

in Ontario, Canada... current premium gas prices are about 20-25% more than regular....

First when i got the car, i only used premium.... after researching and reading about all the people claiming that 87 octane would not work without knocking of heavy power loss (claiming without trying or first hand information), I stuck with premium 93 octane until this week, where I mixed 87 octane with premium...

can ran the same... accelerated the same, sounded the same...
so... when I ran out of gas, and the reserve light came on...
I put in $40 of regular 87 octane.... the car ran fine... I did not try flooring it all the way to the redline at first
did floor it once after the next 87 octane fill, redlining through first, second and third gear... The rear wheels normally chirp when rough shifting to 3rd but the didnt with 87 octane...

basically runs almost the same... and I have stuck with 87 octane since... my average is around 26-28.5 mpg when more highway driving... and around 23-24.5 with a bit more city driving mixed in...

I did reset the ecu when I was using 93 octane, and the car the currently running on the same tuning...
I also noticed a slight loss in torque when at low rpm in a high gear....say pulling from 1700rpm in 6th gear
and the car also smells like petrol when warming up a cold engine...which it did not do before but it might a dirty MAF, I overoiled the K&N rechargeable oil filter

My questions to those who have not tried 87 octane but are knowledge in the subject:
An altima 3.5 runs fine on 87 octane.... it does have a different ECU... shouldnt the 350z be fine aswell?? it has the same compression... a murano also has the same compression and runs fine on 87 octane... is it just the bias towards expensive car deeserving expensive fuel the reason why people are lead to believe a 350z can not live healthy with 87 octane
if my car currently runs fine on 87 octane, it should be fine right??
is pinging and knocking supposed to sound prominent on a vq35de?? I did not notice anything when switching over to 87 octane...

My questions are: (these only apply if you have tried 87 octane or have seen anyone try 87 octane on a vq35de 6mt ecu)
did you have any engine knocking...??
should i reset the ecu for using 87 octane?? i am avoiding it so that the engine does nothave to ping and readjust the timing, I did not notice any pinging or knocking the first place
did you notice power loss (significant to the point where you know its because of the fuel)??
do your exhaust fumes (when cold engine warming up) smell like unburnt fuel??

[jtk07]

I can understand your issue based on price - However I have been talking with a mechanic local to me (texas) about this same issue - and he stated to me that he has seen a few 350z's come in for knock sensors and things because of this issue. Also the owners manual says if premium is unavailable you can use cheap gas "Short Term".

If you want to run 87 grade I would suggest highly looking into a tuner - some tuners have a settings for cheap gas to change the detonation.

[ManDogFish]

what I meant by the bias was that...
if you google and read up on forums about if the g35 is able to safely run on 87 octane... most of the times the conclusion is that it cansafely do so but you will lost power... and according to US fuel prices, there would be no savings... there are many examples of 2004-2005 g35 coupes running on 87 octane for a long long time...

but if you google if a 350z can run on 87 octane... the threads are full of flamers.... most of the threads do not have a pointfull conlclusion and the ones that do, conclude that a 350z cannot safely run on 87 octane, some "experts" claim it will heavily knock or detonate... I will be driving another 200km today, and every working day...its running fine...
so how is a g35 coupe safe to run on 87 octane and a 350z not...??

wouldnt a tuner just change the timing the same way the stock ecu and knock sensor do??
I had to floor the car in 4th gear yesterday... a noticed slightly abnormal vibrations (proportional to the rpm) through the accelerator pedal and gear lever when over 4700rpm with the pedal fully pressed.... Im thinking there might have been slight knocking which was covered up by engine noise..


my fuel savings over like 2 years could pay for forged pistons and rods, I dont mind paying for the honing of cylinders and doing the rest myself

[ManDogFish]

in NorthA., 87AKI=91RON, 93AKI=97-98RON
is it possible that the 350z requires 91RON and not 91AKI?? and any less than 91 RON (bad batch of 87octane) may cause temporary knocking...

in Finland, Sweden, regular fuel is 95 RON, so a 350z will run perfect on regular fuel over there... premium there is 98 RON, kind of unnecessary for stock tuning

in some areas 89-90 octane is considered premium... while where I live, 93 octane if considered premium...

after all.... it is "recommened" fuel... recommended...not compulsory

you guys do realize that many of you spend more on fuel in a few years than the value of your 350z...why not try 87AKI

[ManDogFish]

to whoever claims 87 octane will damage the engine...
what damage can it do?? (except detonation...as its very unlikely due to knock sensor)


Im still running 87 oct... covered about 6-800kms by now

[jerryd1987]

your the same dude who had his thread locked in the other forums arnt you? you do realize that you have to hit 100 knock counts before the ecu retards timing right? you also know it has a set % it can retard right? also after 25 seconds without knock it starts to add timing back. it will destroy the engine from detonation, not unlikely it WILL happen, the ecu will bounce it back and fourth between knocking and no knock as it constantly retards the timing then adds it back. even if you dont manage to destroy a rod or piston you will spin a bearing, its number 3 in failures of bearings about 10% behind dirt on the bearing and 2% behind oil starvation keep going i cant wait to see your windowed pistons.

also remember that different areas of the world have different ecu's your car is still set up to run on your premium, and please use mon not aki because ron is a anti knock index as well its simply done under a different set of conditions, both represent the ability to resist ignition though.

[ManDogFish]

not disagreeing... I have been looking for that info for a while and havent been able to find it...
so how do you know the 25second timing return and the 100 knock counts?? I need the info to test some stuff

dude... some of ur info I can not agree with...we cant really say that it is the 3rd main cause of bearing failure for the vq35de when the survey/study is on engines in general and not just the VQ...

sure I will post up pics of windowed pistons if it happens but I still doubt it will...

I HAVE DRIVEN over 2500 miles SINCE!! on 87 octane... still running like new...it just doesnt screech tires when shifting to 3rd...might also be cuz the tires wore in by now...

why doesnt the g35 6MT suffer from any damage from 87 octane??

if you look it up on forums...where a lot lot of people running 87 octane... When I was looking into the market for a car... a lot of the g35 coupes 6MT were being run on 87 octane but the 350z on 91+ (owners claims)
never made sense to me...

Apparently...in some areas the fuel at times is soo bad (specially when the fuel station tank is being emptied) that the 350z knocks on 91 octane... read it up online...people are complaining about engine knock on premium gas...
some people have claimed the car knocking constantly on premium gas in their area but not on the premium gas is some other areas...

[Darkhorse]

I don't know about the 350Z, but I'm running 89 octane in my 370z with no problems.
My feeling is if the engine doesn't spark knock(ping)it will do no harm.
I've also talked to a few refinery workers that tell me the premium fuel at the pump my not always in fact be premium fuel.