I have been hooking up powerful audio systems in all types of cars and almost every time I put the system in, I get asked by the customer if their gas mileage will go down because of the power drain. The only answer I can give them is that if your gas mileage goes down, its because of the added weight. I would think though, that the added strain on the battery and the alternator would drain the gas a little more. Does anybody know of any clear data related to this?
I'd have to say no. The only way it would reduce milage would be like if it was slowing down the speed the alternator spins at, in turn increasing your RPM's on your engine. Which, I'm pretty sure that doesnt make sense at all and would never happen so no, i dont think the drain effects ur milage.
Yes, it will affect your gas mileage to a degree. An alternator imposes a load upon the engine, just think of it in horsepower. 1hp-746W, which if the alternator were 100% efficient that would be a little over a 50A draw. Usually it isn't large enough to worry about, but once you factor that in with the added weight to the vehicle, your gas mileage will drop-perhaps to a noticeable degree. It will be about the same difference as turning the A/C on.
The reason I ask is because I noticed an immediate drop in mileage after I completed the system and it always had me thinking if it was due to the extra draw in power or just simply the added weight. Thanx for the help guys.
not accounting for losses due to efficiency, one horsepower is equal to 746 watts.
Technically, yes there is some minor parasitic loss of power, and increased drag on the motor causing a decrease in fuel economy, since the alternator works off of the engine's crank pulley, and the more current draw, the more drag. Now will it be a measueable loss? Not really, no. I ran a 150A alternator with 820 watts of class AB amps in a festiva with the stock motor and never noticed a difference. Yes the weight will hurt, too since you're talking an average of a couple hundred pounds in audio gear with amps, speakers, MDF, etc.. and that's like driving around with a fat guy in the passenger seat all the time. That's more drag on the motor to haul the added weight.
In the end, no it won't make any significant difference, but physics dictates that indeed there will be a loss in fuel economy. It's just a matter of if it's enough to notice.
Thanks wolf. As always, you always come through with the best answer. Heres an off-topic question. At what amount of posts does your membership status change? I didnt even know there was a platinum level until wolf came along.
I have mentioned this before because I think B has the same engine and he is always driving on E. I have an economy computer and have noticed when I bump on my way home on the e-way there has been a .5 mpg loss. I have tried it on and off and the result has been the same with the same volume level and same music played int the same order (i-pod), lol..Polo..
well, if you figure a fair amount of loss to heat etc, say 500 watts per HP, so a 2Kw system is going to lose ya about the equivelant of 4BHP in drag on the engine. Still not as bad as an AC condenser/compressor, but it is a loss.
platinum is at 10K, gold is at 1K, silver @ 500, bronze @ 50, if I recall. may be off a bit.
it does uses more gas with a system, especially if you have a HO alternator!! Like GW stated above, its a extra load on the accessory/serpentine belt!! Its almost as bad as your AC compressor, if you have a big sized HO alternator!!
My alternator however, can increase my engine RPMs when its demanded from!!! All of this is at idle!! Is it noticeable at the pump?? I dont know.. However you can notice a diffrence when runing the AC.. doing both AC and system will draw alot more gas...
Now you still have to account for the added weight you are hauling around in the trunk or cargo area! I know my box, subs, and big @ss amps weigh alot~~!!! I ride solo to begin with, so its ok for me...
