Wither it's a car or a bike, they both use gas. I drive both, one being a gas hog, and the other not. I've asked this question many times in my head, each answer proving to some way be right, and others way wrong. It just doesn't make sense to me though. It's such a stupid question, that I can't even figure out the real answer.


Now, which action takes more gas?
-Driving in a high gear, but giving the engine full throttle?
-Driving in a low gear, but giving the engine little throttle, resulting in high RPM's.


So which burns more gas? Pedal to the floor, or high RPM's?

Which octane burns quicker? 87 or 93? I'm assuming it is 93 due to more combustion in the engine, but I have heard many times that you will get more gas milage out of 93, over 87..

 

Lower Rpms with more throttle, also lugs* the engine more and does more damage.

 

As far as Octane is concerned, 87 burns hotter than 93, hence less ping given compression, timming, and boost.

 

High RPM's burns more fuel. The injectors have to spray fuel everytime the piston comes up. So at 12,000rpm the injectors spray twice as often as at 6,000rpm (obviously). For the RPMs to raise the combustion needs to be greater and greater, forcing the pistons down faster and faster.

87 octane burns quicker and hotter there for giving you more HP.

 

So the lowest octane you can get away with, without damaging your engine, actually makes more hp? I don't get why people run 101 or 110 octane in their car? I'm assuming it depends on the engine, how big the whole fuel set up is, etc.


I run 93 in both my bike and my 5.0. What is the lowest octane I can get away with in my bike?


I was talking with Vince(Show5oh) about octane in motorcycles. He runs 89 I believe, maybe even 87. I remember him saying that it makes him look cheap because he buys the cheaper gas, but his bike is actually faster and runs better. I understood what he said, but I have always just thought that 93 was the best, no matter what. So I guess I was wrong.


Offtopic- DogBoneR1 are you going on the March 5th ride?

 

When I had my 600RR I made 2 more HP on 87 as opposed to 93. The bike was stock with a Jardine slip-on. It took the 87 fine. My R1 is mapped to make the most HP on 93. I have to run 93 in it because of the high compression. 13.5:1

 

My $0.02.

I've done a little bit of testing on this vein of thought with my commuter car. I find that if I keep the rpms down under 4K in each gear and don't acelerate too hard to 4K RPM I can get the most out of each gallon of gas. Of course, when I do that, I'm rolling around slower than your grandma everywhere I go.

On your typical fuel injection setup the throttle controls how much air gets into the intak manifold and the computer decides how much fuel it should inject to keep the AFR correct. Less air, less fuel. Less RPMs, less frequent delivery of fuel. If you were to plot fuel consumption by throttle position (% open) and fuel consumption by RPM, there's be an intersection of the two graphs at which point you'd have the optimum throttle position and RPM given the diameter of your throttle body.

 

Mine runs perfectly fine on 87, but I run 89 to give me a little cushion most of the time just in case there is detonation that I'm not hearing while running 87.

The reason some people run 100+ octane is because that is how there engine setup was designed... some engine setups make way too much cylinder pressure to be able to run 93, so they need a colder burning fuel (for instance, high boost/compression/nitrous). Run a tank of 89 through your bike Jeremy and see how it does. The best way to test if it's running fine will be to put it in high gear and romp it from a real low rpm to put the engine under a lot of load, you should hear any detonation... you'll know it when you hear it.

Btw, your car, same thing. Unless your timing has been advanced you should be able to run 87 all day... remember, i know a little bit about the 5.0s and how to make them fast.

 

There's not enough information to answer that question. If you're going any great distance, riding in low gear with high RPM is going to use more gas. More revolutions = more vacuum = more gas consumed. Running it in high geat at WOT is going to use unnecessary gas too, due to your accelerator pump/computer dumping more fuel to compensate for the influx of air and drop in vacuum pressure. Eventually the WOT in high gear will use less gas due to less vacuum and lower RPM not being able to pull enough fuel. Either way, you're not being fuel efficient, so I don't see the point in asking. Just ride/drive like a normal human being. Who WOT's in top gear unless you're nearing top speed anyway?

 

You're misunderstanding on why I am asking this question. It's not because I open up the throttle in 6th gear at 35mph, it's pointless. I was asking this question just for the sake of knowledge on how the computer, fuel, and air mixture work. I'm trying to understand fuel consumption a little better. That is all. This is also for other's benefit, who don't know much about fuel consumption and how things work, and what goes on in the engine.