more hp, more mpg?

Seems to me that we need fuel to create hp. It also seems to me that more hp with the same weight should get better mpg. If you are pushing the same car the same speed for the same amount of time, wouldn't more hp make the effort needed less, causing more mpg? Maybe I'm crazy, but it seems logical to me. I'm sure if the car was lighter then you'd definitely get better mpg, that's a given. I am curious about the weight being the same though. Any body have any info oe experiences with this idea? Thanks

Nobu

Horsepower = more fuel, to create more hp you need more fuel, more fuel being burned = less miles per gallon.

Good assumtion if we were going full throttle on our way to work. WRONG more potential hp doesn't mean you always use it in your econmy rpm. Just because an engine can make the hp doesn't mean it has to do it all the time. LOSSES in a system can be over come or decreased to make the system more efficient...flow, friction ect.

bbyvfr6,not sure about that last one. :screwy: I figure that the more hp, more gas or not, should move the same car more efficiently. jcrx, I see what you mean, but I still don't quite grasp this. Can someone help? Thanks

Nobu

In order to create an explosion with quicker cylinder displacement (HP), you need more fuel (and air). Perhaps some reading on the subject of super or turbochargers will clear this up for you.

Ok, imagine a dyno plot...

http://www.importreview.com/dyno/1.6/16jun341.jpg

now pick a point on it, we'll say 5000rpms, in order to make this amount of power, at this point, you need a certain amount of fuel/air in the cylinders, take away the fuel/air, and you have less power, because fuel/air is what makes power in an engine, take that away, or lessen it, and you have less power, add to it, and you make more (turbo anyone?), it's that simple. Of course this can all be tuned in different ways, you could raise the compression, which means you are cramming the same amount of air/fuel into a smaller space before detonation. Of course doing this will raise engine temps, thus requiring guess what, more fuel. That's where octane levels come into play, along with ignition tuning.

That was what I was trying to say. Huge difference in economy driving and flying in your car. Most of the time on the street in economy conditions your area under your HP curve plays a key roll...TORQUE Plus I don't see many people trying to get high MPG's at 5 grand. Cruise speed 2-3000. Freeing up hp does not hurt economy.

In older v8's newer cam profiles can actually increase econmy. Don't know about imports, but I doubt honda was messing.

I'm not trying to dissagree with more hp=more gas, but I am trying to argue that just because you increase a cars potential it doesn't decrease its economy. All with in moderation of course. Now high CR, big cams, Force Induction, rich tunning of the ecu...ect will make a difference. But simple free hp will benefit everything. Reduce friction, increase flow, ect.

I dont think that a generalization can be made about power adders raising or reducing gas mileage.

For example: When I added my AEM CAI, my gas mileage went up noticeably. I cant give any exact figures because I never sat down and really figured it out. All I know is that before cai, I could go about 240 miles before needing to fill up again (I usually fill at about 1/8 tank when funds are tight) Now I make it to about 270. Thats 30 more miles per TANK (please don't confuse this with per gallon and accuse me of wild fabrications later)

However, I would find it hard to believe that bolting on a huge turbo would have the same affect.

Mods such as I/H/E, fuel rails, etc I believe might free up some gas mileage as well as hp.

Mods like FI, aggressive cam/valve timings, and engine boring seem that they would only decrease ags mileage. just my :2cents:

Okay then. I think I got it. Fuel+air=hp. Period. So because you need more fuel to make more hp, it is inherently less fuel efficient to tune your car to go fast. I understand that exhaust, intake, etc. can increase hp, but not like a turbo or high compression engine. I do understand now. More hp=less mpg. Thanks jcrx,

Nobu

Good, good, I think we all agree now. Feeing up hp is different than forcing more hp. I think I missunderstood the first post in the begining. I need a spell and grammer check on my posts, that's for sure.

My addition again...that hp isn't everything. (TORQUE) is something that is crucial too oh my which hp is derived from...

Economy doesn't mean high rpms

I can't wait for the post about body kits and lowering for mpg's.

Why be a smart ass? I was asking about actually ADDING hp, not freeing up hidden horses. And WTF is the spell/grammar check have to do with this? Take your body kits/lowering for mpg comment, shine it up real nice, turn it sideways, and shove it staight up your candy as*. Douche. Holler back,
Nobu

Oh that's right you're the smart one... You can come try to shove it up my candy a##. I wanna see this better yet I'll tell you how to get here.

...by the way I've built several cars that could smoke yours with proprietary fuel injection on the car. I have been on a team that has completed 4 open wheeled cars 500lbs... 75 RWHP and thats with a 20mm restrictor, which all air must flow through. Did I mention it was an economy competition too... get off you high hp and figure out about torque. I guess my B.S.M.E. means absolutly nothing.

Another thing...I have a farm truck would smoke you little 4 banger honda even if you increase hp or what ever you think you might be talking about. You're the one with the dumbass post. Put a turbo on your car and I'll still smoke it because I have 408 ci of displacement.

OMG When/Why the hell did this thread turn so malicious? I never saw any insults thrown, but now arrangements are being made to shove body kits up asses? :confused:

"Why can't we al just get along? DAMN GINA!!!"

Upgrading, doesn't exactly = less gas milage, that is if you are increasing efficiency.

Ok so to answer your question. Not to piss you off more. Simple lesson... Lets say
W= Work; F= Force; D= Distance; P=Power; T=Time; V= Velocity
W=FxD
P=W/T or FxV

Ok so your car going down the road at any speed takes X amout of force to keep it going. This force comes from the engine to compensate for drag,friction, and all the other things that slow your car down. If the engines force is increase (in your terms "using more hp") you car will accelerate because you are no longer in equalibrium with in the system.

Now you going to ask about acceleration. If your accelerate at the same rate as you did before and accelerated smoothly as a daily driver would then you have not used anymore power than before because F=Ma. Your "constant acceleration" has remained the same. If you floor board it off every light your acceleration would increase thus increasing force needed from the engine. You are correct about decreaseing the weight as that can be seen using that same equation. M decrease which would mean that the force requird to accelerate at the same rate would be less.

I know this isn't that techinical and is a huge generalization, but after looking at your original post more hp wouldn't make moving the car down the road any easier, because it only requires X amount of force to move the car at that speed to begin with.

Now as far as efficiency with the engine is concerned. If the engine uses less effort to move air and fuel in and out, it will be more efficient in delivering the power you need to keep the car moving or accelerating. This is where you will see you increase in MPG from mods.

These were the most simple equations I could give you to help you with your question. Take your system draw a box i.e. control volume, around it an isolate the things going in and out of it. You can make your box big like the entire car or break it down to idividual cylinders, but lord help me with all those numbers.

The key is efficiency... making things have less friction or reducing the weight. Unless I am insulted again because of my lame humor I'm done.