Cylinder Deactivation & 93 Octane

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Interesting question for sure..... I would assume if 3 cylinders were keeping the vehicles speed up that they would run hotter than with all 6 cylinders moving the vehicle. I'm sure Honda thought of this though.

/flamesuit on: I put premium fuel in any car I drive. So for me it would be burning premium anyway.

/flamesuit off.
 
Originally Posted By: beast3300


/flamesuit on: I put premium fuel in any car I drive. So for me it would be burning premium anyway.

/flamesuit off.


Why?
 
Originally Posted By: RamFan
Originally Posted By: beast3300


/flamesuit on: I put premium fuel in any car I drive. So for me it would be burning premium anyway.

/flamesuit off.


Why?


+1

I even get in a German car and i ask myself "Do i need to put premium fuel in this."

Isnt it something that "10:1 or 11:1" compression ratio and higher gets 93?
 
Originally Posted By: 45ACP
Originally Posted By: RamFan
Originally Posted By: beast3300


/flamesuit on: I put premium fuel in any car I drive. So for me it would be burning premium anyway.

/flamesuit off.


Why?


+1

I even get in a German car and i ask myself "Do i need to put premium fuel in this."

Isnt it something that "10:1 or 11:1" compression ratio and higher gets 93?


My Charger is 10:1 and Chrysler recommends 89 but says 87 is suitable. I always use 89.
 
i can remember when the cost of gasoline was one third of the octane. and you could buy 110 octane all day long for that price.
 
Well, for example...the 3.5L v6 with cylinder deactivation in many hondas has a compression ratio of 11.0:1 iirc. It may be 10.5:1. But in any case, wouldn't that necessitate the use of 91(premium in Cali) to gain maximum smoothness, economy, and power?
 
Originally Posted By: RamFan
Originally Posted By: beast3300


/flamesuit on: I put premium fuel in any car I drive. So for me it would be burning premium anyway.

/flamesuit off.


Why?


I guess the simplest answer is that I like using premium fuel to get the most out of the engine. I don't drive anything light/easy.
 
There are several factors that relate to high compression and the need for hi octane fuel. The valve timing plays an important part in this and just because an engine has a static compression ratio of 10 or 11 to 1 does not mean it needs premium fuel. Your owners manual is the good read in this case. Ed
 
Multitude of factors influence octane requirements. Too many to list.

But without a detailed data log of the knock retard values you have no idea how much timing is being pulled. Most modern cars that specify premium can run on regular without the slightest complaint, but they are pulling timing like crazy to avoid knock.
 
Originally Posted By: SteveSRT8
Multitude of factors influence octane requirements. Too many to list.

But without a detailed data log of the knock retard values you have no idea how much timing is being pulled. Most modern cars that specify premium can run on regular without the slightest complaint, but they are pulling timing like crazy to avoid knock.


And thats what kills fuel economy and performance. The extra cost of premium fuel is worth it. My challenger gets alot better millage on premium fuel. It cost less per mile to drive challenger on 91 than 87.
 
Originally Posted By: Eddie
There are several factors that relate to high compression and the need for hi octane fuel. The valve timing plays an important part in this and just because an engine has a static compression ratio of 10 or 11 to 1 does not mean it needs premium fuel. Your owners manual is the good read in this case. Ed



Your right! For instance my Lexus manual states select 87 octane fuel, but Premium fuel is recommended for optimum performance etc. Let me tell you brother, their not kidding when they recommend Premium fuel! It runs like a wet dish rag on 87 octane. And even 89 isnt too much better. The best way I can describe it is; imagine driving an old Ford Elite with a 200cid under the hood using 87 fuel.
 
Interesting... My grandmother has the same Lexus as the one in your sig, and while I've never tried premium in it, I don't find it sluggish on 87.
 
Originally Posted By: rslifkin
Interesting... My grandmother has the same Lexus as the one in your sig, and while I've never tried premium in it, I don't find it sluggish on 87.



Once you would try premium, I doubt you would go back to 87 Octane. But, your Grandmother probably wont notice a difference..bless her heart.
grin.gif
 
The car's computer knows when cylinders are activated/deactivated. And the spark and fuel curves are pre programed for this.
We need not intervene with higher octane.

As to compression ratio, high compression can be used nowadays because of variable cam timing, which makes the effective net compression go up or down as needed.
In the old days, who would have heard of 10.5 compression with a turbo? but it can and is being done in factory cars.
 
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