In the past, I have been somewhat critical of the power output of the Roadster Limited however as of late, I feel compelled to recant that criticism. i dont know if it was poor gas or what but my Roadster has all the power I need. And although I'll get beat up for this, I am burning 87 octane. At the equivallent of 4.80 for a US gallon I dont feel guilty either!

 

Been wondering about that octane stuff myself. Let us know if going to 87 octane has any detrimental effects on the valves. popeye

 

I know for a fact that this vehicl should use nothing other than premium. I work at a dealership and we have seen them come back with bad gas defects, and they are not covered unnder warrenty. I run 93 shell in it all day since day one. Prolly cuz I own a shell station. And you will be amazed what good gas will do for you enjine performence

 

So you work at a dealership and own a Shell station?

 

I should own a couple stations with what I've paid for gas the last few years.

Anyway, I use midrange (89 octane) pretty regularly with no problem. I've tried premium (91) and mpg and performance is almost the same. If I was running it hard, I would move up to premium to prevent knocking and engine damage. Generally I drive it pretty conservatively, when it comes to acceleration, but I do drive it fast on the highway.

 

The octane value of a fuel is an empirical measure of its ability to resist detonation (under compression) and, to a limited extent, preignition. Technically, octane ratings measure a fuel's ability to resist the spontaneous ignition of unburnt end-gases under controlled test conditions.

The need for premium gasoline is predicated in part by piston design and engine compression ratios.
It is my understanding that the 3.2 l Crossfire engine has only a 10:1 compression ratio. This relatively low ratio is not indicative of a high performance engine.

The Nissan 3.5 engine has a compression ration of 10.3:1 and high octane gas is not a requirement.

Burning low octane gasoline in higher compression ratio engines 12.5:1) will however subject the engine to knocking also known as detonation and this can reduce an engine's efficiency or even physically damage it.

I have listened for valve pinging while buring regular gas in my 3.2 L engine . and I am unable to detect any pinging which leads me to believe that the lower Octane gas is not causing a detronmental affect to my engine.

I do agree with using a good name brand regular gas that contains chemicals that keep your fuel system clean.

If someone can provide agood technical reasons why burning High octane gas in the Crossfire is a must then I'm listening......

 

Do you live in cold air temps area may help but,in the long run driving long distance or hard throttle will end up hurting the engine and be prepared for a big bill to do a burnt valve job, of course you can save the 15-20 cents per gallon for that !

 

What you are suggesting, is that the colder, denser, O2 rich) air is helping with combustion which may be temporarily offsetting the affects of the lower octane gas. I may notice more of a difference once the temperature warms up to 90 F + in July and August.

That's an interesting concept and good point to consider.

The warmest it's been so far is 73 degrees F (another measure I prefer vs Celcius ;-))

As far as the 20 cents /gallon savings, it's more like a 40 cents/US gallon (4L) difference here. (Pray your country doesnt switch to Metric measure! )

As long as there is no detectible pinging, I have my doubts that the engine will suffer any cummulative damage.

 

I don't see what the question is because unless I am just different than everyone else when I tried regular my performance went down along with the fuel milage so if its the same $'s in the end why not use the higher octane. JMHO

 

Most people say they calculate the gas mileage but few actually perform this function.

I'll tell you what...I'll compare the two.

 

I've always calculated gas mileage in my vehicles. Just a habit I got into 30 years ago when plugs used to foul quickly and mileage dropped as a result (I used to clean the plugs in my Triumph TR6 every ~2000 miles - we've come a long way, baby).

I never ran regular in either my Audi or Crossfire, but I did run about three consecutive tanks of premium through the Audi on one road trip. Maybe - just maybe - I saw 1 mpg better gas mileage. (I believe the Audi is running 9.5:1 compression + turbo.) But that is very easily impacted by the terrain and acceleration/speed.

So I've compromised on midrange in both vehicles since 2005. I do not accelerate hard although I run all of them at high speed. Sometimes real high speed - had the SRT6 to 150 last Wednesday. So I've never noticed any ping although I expect the ECU to compensate. My Audi had plugs changed at 40k and 107k. The regular interval was 80k but everytime I had my indie check they were good so I left them in. Even when they were replaced, the old ones were still clean and there was no improvement in mpg.

I would not run regular, but I have no problem running midrange especially in the winter. (PS - When I was looking at a BMW 330i before buying the Audi, the dealer told me it was better to run midrange over premium in the winter.)

 

Quote:

[/So I've compromised on midrange in both vehicles since 2005. I do not accelerate hard although I run all of them at high speed. Sometimes real high speed - had the SRT6 to 150 last Wednesday. So I've never noticed any ping although I expect the ECU to compensate. My Audi had plugs changed at 40k and 107k. The regular interval was 80k but everytime I had my indie check they were good so I left them in. Even when they were replaced, the old ones were still clean and there was no improvement in mpg.

The Mowhawk gas station in Canada is charging the same for 89 octane as they do for 87 octane gas, and they give points towards my BCAA roadside assitance. Needless to say i have switched to the mid octane gas.

FYI the gas here is now a wopping 5.28 per us gallon (4 liters)

I had the Crossfire out last weekend on West lake road on route to Fintry park here in the Okanagan. It's full of hairpins and S turns and long stretches are very narrow. i even got to test the brakes when a family of deer decided to cross the road. it was about 73 F so I had the top down. I had a blast taking 30 MPH corners at 60 MPH. The car handled like a dream. It's amazing how torsionally stiff it is especially for a convertable.

How would you rate Audi vs, Crossfire?