you know that scene where wiley coyote puts up the little umbrella as the shadow from the anvil gets bigger???

put up your little umbrella, nj.


dan

 

If that's the case (I couldn't find anything online about the 3.0 spec.s... My 4.0 Explorer is 9.0:1) it's the exception not the rule where compression is over 9.5:1.

 

Houstondan,

What the hell is that supposed to mean? Excuse me, but was I rude to you?

 

Luckily she didn't put diesel in it.

They should make the gas nozles different size for premium and regular so that people don't make that mistake. They do it for diesel.

 

not at all...it was an attempt at humor in suggesting that your attitude toward women was going to be noticed. obviously, i was wrong.

dan

 

Wes,

I looked at some specs on other cars and there are more than I thought running 10:1 compression on regular unleaded fuel. Example: Honda Accord V-6 @ 10.0:1. I think the reason they are able to do this for ratios over 9.5:1 is by using aluminum heads.

 

I would think that aluminum heads would be more easily pitted by predetonating fuel. they must be using much richer fuel scheduling. If it ever gets lean they will have major problems..... I would think. The knowledge I have on the subject is old school but has been common knowledge about compression and fuel octane since I was a kid. Of course we didn't have computers checking things like the O2 level in the exhaust gases to make sure the engine doesn't run too lean. It may very well be possible, I guess, for the ECU to make running lower octane fuel in higher compression engines safe. By keeping the fuel mixture on the rich side and retarding the igition timing on the fly.

Rule of thumb is.... If it's not pinging, you're okay..... That's a rule that I don't think will ever change.

 

the aluminum heads allow for greater compression ratios because they are superior at dissipating heat. it's the lower temperature that prevents the fuel/air mixture from predetonating at up to 10.0:1.

 

That makes good sense.

 

This female knows the difference between those little numbers on the gas pump. I go with the Premium gas. Always will in the Crossfire. Geez guys, give us gals a break. LOL :shock:

I maybe blonde, but don't let it fool you. :wink:

 

I Use Shell optimax or BP ultra. Don't know what the ron is but would expect around 97-98. Someone told me that, after reading the shell web site, optimax was listed at 104 ron but can't confirm as I did not read myself.

 

On the inside of my filler cap (UK spec) it states use EN228 RON95. I intend to experiment with RON98 next month to see if it makes a difference to 1) Performance and 2) Economy. I need to justify the extra 7p per litre for the extra 3RON.

Nice to know that the UK and US specs for fuel are different. You would think that it was possible to have one rating across the world for international fuel and car companies.

 

shell Optimax is 98.3 - 98.6 RON

 

I wonder if "Optimax" is the same/similar as "V-Power" :?:

http://www.shell.com/home/Framework?...t_ga_1602.html

http://www.shellvpower.com/

 

I use either Shell or Marathon 93 Octane.

The price at my last fill up was $1.989 per gallon.

With the air conditioner running, I am getting about 21 mpg with an even city/highway mix. With the air off, it goes to about 23.5 mpg.

 

Sorry about the misunderstanding Dan. No problemo.

Anyway I try and always use BP because they claim to remove all the impurities most companies leave in, making their fuels cleaner and more efficient. Whether it really is all true or not, I dont know.

 

I use Shell 92 oct........... 8)