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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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Old 01-29-2009
FireRanger's Avatar  
Join Date: May 2004
Location: CT
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Originally Posted by wydopnthrtl View Post
. And you Matt. You just flat out ignore science because it doesn't fit your paradigm. And you ask what I'm smoking?
No, I don't ignore science. The only one ignoring anything is you. Let me try one last time explain this in terms that might soak through your head.

I said "Using 93 in an engine tuned or 87 will degrade performance and MPG".

You claim I'm wrong. But since I'm not wrong, that would therefore make you wrong. And since this is perhaps the most hard and fast proven and obvious fact relating to fuel, I can only conclude you are on crack.
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Old 01-29-2009
IN2 FX4's Avatar
Join Date: Feb 2005
Location: Costa Mesa, CA
Posts: 855
Compression is the best way to take advantage of higher octane fuel but advancing the timing will also provide some extra power when using higher octane fuel. This is true for street engines that are running normal pump grade fuels. At this point it is not important to me why this is true and I don't want to research it to find out all the details.

I do know it is true because I have personally experienced it. I have a tuner that is programmed for two grades of fuels (87 and 91 octane) at different performance conditions. I have used an acceleration test that uses only 3rd gear at the same location to determine if this tuner works or not. I use an accurate stop watch to time acceleration from one speed to another about 40mph higher. The test has repeatedly shown the 91 octane program gives higher performance than the 87 octane program.

I did not program the tuner but I do know that it is using timing to obtain more power out of the higher octane fuel. Obviously it is not changing compression.

As an added benefit the higher octane program (with high octane fuel of course) also provides slightly better gas mileage when driven under comparable conditions but not enough to offset the higher cost.

This is in no way intended to disagree or support any of the other posts. It is provided as additional information.
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