Dear Unregistered, the permission changes should be complete, if you notice any issues with your access on the site please let us know and we will check into it.
Hey Unregistered it seems that you haven't posted a message in our forums yet. Please join in on the fun and post a message!
Dear Unregistered,
We've noticed that you are not yet a member of our Cayman Insiders group. This group provides a number of additional value-add services via this website for a very low annual fee. You can find out more about this group here:
Insider Announcement
You can join the Cayman Insiders Group here:
Insider Enrollment Form
We hope to see you "Inside" soon!
Your Donation Will Be Used To Pay For our ever increasing bandwidth costs, our hosting Service, domain registration, software licensing fees, maintenance costs and product evaluations Only!
Please enter your donation amount above, and then click on the donate button below.
I've been reading the previous threads on 100 octane racing fuel. I get the impression that 91 octane is permissible but not ideal for the CS. While it seems that using an octane above 91 (California) has definite performance advantages, even for street/road driving, the cost at my pump last week ($8.40/gal) took my breath away, especially if I were to contemplate this a s a habitual fill-up ritual. If the cost/benefit ratio were considered, what would the appropriate 100 octane/91 octane mix be in order to bring the fuel quality up to octane Porsche originally intended for the CS 07 models?
356N - One of the previous threads has a table from the Union 76 Web site that shows the appropriate tank mixture figures to blend 91 octane and 96 or 100 octane gas to get 93 octane. Do a search, and you'll be sure to find it, I believe it was posted by zornet. For regular 'ol street driving, I doubt you would see a big difference, if any, so I just use the 91 pump octane and leave it at that.
Before a track event when I fill the tank, I usually put in about 13 gals. of 91, and then top it off with 100, which gets me about 93. For autocross events, where I usually run about half a tank of gas or less for weight savings, I usually put in about 6 gals. of 91 and 2 of 100.
Running more than 93 is a waste of money, pure and simple. In order to take advantage of higher than 93 octane you would have to extensively modify the motor for a higher compression ratio.
You have to look at the compression ratio which is 11 to 1. It is very high for a street car and requires a higher octane fuel. But with todays electronic controls you are able to adjust the spark timing and are able to run a lower fuel octane. You will not get all of the performance that the engine is able to give you if you run 91 but you will not hurt the engine either. You really only need 93 octane if you are drive the car to the max ie racing, auto-cross etc. Hope that helps you.
__________________
Is that 35mph corner 45, 55 or a ..... corner?
Don't know where the experts are who would usually answer this but I'll give it a simplified go.
The engine tune is optimized for a given octane fuel, based largely on compression ratio. Knock sensors detect incipient pinging (pre-detonation) which a lesser octane will cause. To prevent the pinging, the system adjusts ignition timing and (not sure) maybe mixture and in so doing reduces power output. But there is nothing equivalent to a knock sensor to detect that higher than optimum octane is present so no adjustment can happen to increase power for octanes above the optimized value.
Absolutely no increase in power output can be gained by increasing the octane above what is recommended in your owner's manual. That is true for ALL cars. The only time there is an exception is when you have modified something about the engine - most common is an increase in compression ratio or spark advance, or both. The guys who run high octane fuel (e.g., race fuel) do it because they need it for their modded engines to prevent detonation, not because it causes the engine to produce more power. Higher octane does not contain more BTUs than lower octane, it only burns slower.
Major misconceptions abound out there about this. Just Google the subject and you'll find everything you could want to know about octane ratings and what they do for you.
It takes all the restraint I have not to speak up when I hear someone at work SWEAR how he can feel more power from using the higher octane fuel...
...in his Tahoe.
And then there's the guys who can 'feel' the power from different brands of fuel.
I totally agree. I remember a guy telling me that he put Cam2 (100+ octane) into his 86 Camaro (2.8L V6) and it ran like a bat out of hell. The truth is, in theory, because the higher octane fuels actually burn slower, if you go way above the octane needed to prevent pre-ignition you may actually lose power.
I remember reading a really detailed article about this in the Panorama tech session way back in the day. What an eye opener. The gasoline companies have brainwashed everyone in to thinking that octane = power.
Panorama Magazine
Panorama Magazine from PCA is published monthly and sent to all PCA members. For examples of the magazine visit PCA Panorama
I also live in California with sucky 91 octane gas.
From my own research, 91 is okay to use, (not harmful) but the car's computer *may* retard the timing and reduce the performance of the engine to protect itself, especially if it detects knocking or pinging (pre-detonation). So using 93 octane will give you the engine's full potential. If you drive really hard, track the car or do autocross, then maybe an even higher octane would be helpful.
If I did my math correctly, in a 16.9 gallon tank, 3.76 gallons of 100 octane (and the rest 91) will give you a tank of 93 octane. Anyone care to validate this?
