Racing fuel in a Z
 

A station here is selling racing fuel. Say you 'accidentally' filled her up with racing fuel, what would happen?

This will happen

http://www.youtube.com/watch?v=FAQ5mRq9kes

Knock Sensors FTW.

Personally, I wouldn't "accidently" put anything other than 91-93 octane in my Z.

Anything above that is a waste, anything below that risks the engine.

Clearly anything above is not a waste as shown by the video above.

Shell claimed their V-power that sell worldwide is 99% same as the ones put into the Ferrari F-1 team...

1% can be a huge difference with fuel.

As the video shows, some amount of high octane is not a waste in this car - the timing adjusts and you get some of the benefit. I definitely notice the difference when I put in a few gallons at the track (of course, our maximum normally available octane here is 91).

I'm not saying to fill the tank with 107, but mixing in some 107 can have noticeable affect. My guess is the max usable octane is about 96 or so, at which point you stop getting any benefit with the stock motor.

My buddy and I go to the strip a lot. He drives the 370z. If anything you are advancing the timing due to the octane - it wouldn't hurt.

We basically coast our cars on empty then fill w/ around 3-4 gallons on VP109 (101 octane). BIG improvement.

Your ECU needs time to adapt. A couple WOT pulls should be good.

The engine's VVEL is pure awesomeness

As the video indicates, it's oxygenated fuel. Leans it way out and make it burn hotter.

:iagree: It's not the octane, it's the oxygen content. If you tried the same experiment with high-octane non-oxygenated fuel you would not gain any power, you might actually lose power.

Placebo

Do a few drag runs with 91, then do a few with 101.

VP109 is oxygenated and is 105 octane (R+M/2). Given that you can't advance the timing or increase compression most of the gain will be from the oxygen content.

It's amazing how much octane is thrown around as a way to increase HP.

The car is designed to run on 91. Running less than that trips the knock sensors to retard timing. It won't advance timing due to higher octane - in fact, the car won't even "know" that it's running on higher octane, it simply knows that the knock sensors aren't tripping.

In your original post you stated "someone is selling race fuel"?As to what grade race fuel he is selling I don't know nor do you probably.As to the dyno test shown with a gain that is with "oxgenated fuel" and I doubt your local station is selling that grade.Qxgenated race fuel is a whole different phase of race gas.It also is not your average race gas.
As to non oxgenated race fuel giving you anymore hp as this has been discussed before is a false belief.The need for race fuel is due to the high compression ratio that race cars or street cars that have been modified by raising the compression ratio.The higher octane race gas prevents the motor from detonation!Detonation will burn pistons and valves!The grade of fuel needed is determined by how high your compression ratio.A high compression ratio is determined by modifications mechanically or as a result of boost.To just run race gas will not give you anymore power.Just because it is labeled "race fuel" leads some to belief it will make there car make more power.Well those of you who believe that are clearly mislead due to the lack of knowledge when it comes to the combustion engine.Doesn't make you stupid or a bad person just not knoweldgable about engines.
I'am trying to explain this the best I can without confusing some who may not understand.Clearly there is more to this and truly a science.
So all here on this site are clearly on computers so do your homework and research and you will possibly have a better understanding of what I'am trying to say in simple language.

Exactly, sometimes it pays a lot to read a little, rather than repeat what someone else said, who was under/misinformed.



But hey, I'm just as guilty of it too.

From my understanding you want to run as low as possible of octane fuel you can with out knocking. Lower octane burns hotter and faster, hence the reason it can create detonation in high compression engines or those that have been force inducted. To run a high octane fuel in an engine not designed for it can lead to carbon build up on the pistons and valves.

Higher octanage will not hurt your motor...it will not make more power... its just going to be safer. If you are driving on the street, you are wasting money. I run 50/50 mix of 93oct and 98oct (at least) on the track for that extra safety margin...specially on our motor that likes to run hot..

What mods have you made for the need of the "extra safe margin"?

To the OP's origianl question: Nothing will happen. Although I can't see anyone "accidentally" putting something other than what they intend to into the tank.

On a side note, I have 5 gallons of 100 octane oxygenated fuel in my car right now (topped up with pump 91) and it seems to be running just fine. :tiphat:

Anytime you are running at the track your engine experiences more stress than usual. More stress and higher revs over an extended period of time lead to higher cylinder temps. Sometimes hotspots are created within the cylinders which can ignite the fuel mix pre-tdc. , aka detonation, pinging, knock, whatever you want to call it.

I have intakes and a full exhaust, which can lean the car out a little bit. I am tuned so I know where my AFR is so that's not that big of an issue. Either way its always safer to run higher octane when your are putting your engine under that much load. This engine normally runs really hot, I would even think about running some meth or WI later on for extended sessions. Specially if I am going to eventually run a supercharger.

Its funny, but I think you were expecting me to not know what Im talking about. Knocking isnt only caused by higher compression and boost like you said. If you are near the knock threshold because of your AF mix, simply filling a bad batch of gas can cause knocking. Bad batch of gas being something with lower octanage than what is advertised. It happens...

Did I mention I live in Florida and sometimes I track the car in 100+ degree weather.

We would like to make sure that the video's results are not misinterpreted. Higher octane fuel (or "race fuel" as a broad term) will not always increase power. Rather, the amount of oxygen contained by the fuel can make a bigger difference than the octane rating. We do not endorse using fuel such as the XXX oxygenated blend on the average street car as a means of increasing power. For that, we offer plenty of bolt-on power adders that you could combine with a reflash tune or AccessPort :)

Whats funny is that you believe I was questioning you because" I didn't think you new what you were talking about"?Not at all because I noticed you tracked your car and actually assumed you had the knowledge but was curious as to any mods you may have had?
As for a bad batch of gas possibly with a lower octane rating causing detnation is quite obvious but thanks for informing me that you was aware of the that.
As for me saying that detonation is caused by high compression and boost it is a fact! If you read correctly you will now see that I never used the word "only" in that statement to simplify matters for readers not familiar with the science involved.I also stated there is a science to this but didn't get in dept because I wanted to make it very simple to be understood without to many variables and confusing for any readers that want to learn.
So thanks for informing me that you understand what I'am talking about.Its always good to know that someone picked up on some good info.
My post was to try and help understand the needs for race fuel with simplicity for anyone that doesn't understand.

I understand the benefits of oxygenation as well as energy density. However, it is not uncommon for modern high performance moderate-high compression motors (like ours) to have small amounts of detonation with 91 octane gas, especially when the motor is hot and/or the air is hot and dry. Likewise, they can adjust the timing to can take advantage of moderately higher octane fuel (94-96) when conditions warrant - like being on a dyno or on a race track.

Edit - sorry - missed the second page. RCZ is exactly right.

Oops *104-105

I cannot comment on his car as I do not own a 370z. I've not ridden in it w/ fuel nor seen it run at the track w/o fuel. It just seemed quicker, but you are right.. could be a placebo effect.

I've never run fuel in a NA engine before. Admittedly, I know little about it other than it's improving my cars performance.

My AFR's are fine. Stock compression ratios are already high. I may make a switch from fuel to meth though as fuel is just getting way to expensive. I am consistently trapping higher on fuel - 109mph vs. 112.9mph over nearly 30 runs. I am tuned though, but none of my logs have shown me knocking on 93oct. I'm actually riding the factory knock sensor - the tune is not adjusting timing at all.

I need to go back and review the logs, maybe try different parameters, and see if I can see anything.

I think that the Z is built on spec for 91 octane to run properly under all conditions, and as a safety will retard the timing if it detects a knock.

Gas that is delivered to the gas stations are "more or less" 91 - so some days you might be pumping in better than 91, other days less than 91. Depends on what gets delivered from the supplier.

If you doubt it, look at the sticker on the pump where it was tested.

Soemthing also to consider for those who top-off often. There's fuel in that hose all they way from the pump - that's about 1-3 gallons worth of whatever was put in there by the last customer. So, the first 2-6 gallons you put in are more than likely "mid grade" - 89 octane...even if the gas in the tank is on-spec, you won't reach a perfect 91 octane even if you fill up...

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