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YACT: do electronic systems in a car reduce torque/hp

I

iwantanewcomputer

Diamond Member
also, does having a rear spoiler on a FWD car help? (because it's forcing the back wheels down, not the front wheels that need traction)

just some unresolved car facts i've heard thrown around recently
 
your altenator charges your batt which powers the electronics in the car. a higher alt might help, dont quote me on that though. also, a spoiler on a fwd car doesn't help much, unless you are dragging and you take the weight out of the rear of the car
 
ac radio and lights should have little to nothing to do with hp/tq, what retards are you talking to?

spoilers on the back of a FWD car don't do sh1t either way, useless

could cause drag but they aren't "pushing down on the back wheels"
 
They don't reduce power, but the more electronic load in your car, the harder the motor has to work to turn the alternator (and compressor, if you have A/C on).

So they don't reduce power, but they use some of it that might otherwise go to the wheels.

You headlights, stuff like that, use very very little power, but if you turn them off the alternator will be just a little bit easier to turn and more power would be available for the wheels. This is a basically zero amount, though. If you have 15 1000W amps and the like in your car, you'll notice . . . or if you are running a window A/C unit off of an inverter in the bed of your truck, you'd probably notice that, too.
 
The more load that is put on the alternator the harder it becomes to turn.

So yes. If you hook up an alternator to an arc welder and strike an arc, it will stall a 5hp motor.
 
There's too much confusion about electrical accessories and car engines. It's really not that hard, as all the power units translate.

1 hp = 746 watts.

And no alternator is 100% efficient. So if your accessories are using 746 watts, your alternator is sapping a little more than 1 hp from your engine. So yes, it reduces the power to your wheels.

Likewise, there is no such thing as free energy! I've seen people pulling off mechanical accessories from their car and replacing them with electrical accessories. They think they are freeing up HP because electricity is free. It's not. It's just moving the load from that accessory to the alternator.

 
Originally posted by: CRXican
ac radio and lights should have little to nothing to do with hp/tq, what retards are you talking to?

spoilers on the back of a FWD car don't do sh1t either way, useless

could cause drag but they aren't "pushing down on the back wheels"
Click to expand...

I have to agree, fwd with a rear spoiler is f-ing nuts. unless the car is well past 130mph. buy a front spoiler if you want a spoiler for a fwd....but whytf would you want that kind of car to go that fast? control sucks at those speeds
 
this reminds me of the guy at work who is CONVINCED his G35 has like 10-20% more HP when he turns off his AC...

too bad its a black , with black leather interior, and he lives in phoenix 😛 thus when i can keep up with him going uphill in my dakota he blames that...
 
Originally posted by: Drakkon
this reminds me of the guy at work who is CONVINCED his G35 has like 10-20% more HP when he turns off his AC...

too bad its a black , with black leather interior, and he lives in phoenix 😛
Click to expand...

heh, thats sad if his a/c saps that much power from his engine. but turning stuff off doesnt give your engine more power, it just allows the power the engine has to go to the wheels
 
Originally posted by: Drakkon
this reminds me of the guy at work who is CONVINCED his G35 has like 10-20% more HP when he turns off his AC...
Click to expand...

The AC compressor does sap power from your crank, although not 10% of a G35's full power.
 
Originally posted by: 91TTZ
Originally posted by: Drakkon
this reminds me of the guy at work who is CONVINCED his G35 has like 10-20% more HP when he turns off his AC...
Click to expand...

The AC compressor does sap power from your crank, although not 10% of a G35's full power.
Click to expand...

it must be a placebo effect on said idiot
 
Originally posted by: 91TTZ
Originally posted by: Drakkon
this reminds me of the guy at work who is CONVINCED his G35 has like 10-20% more HP when he turns off his AC...
Click to expand...

The AC compressor does sap power from your crank, although not 10% of a G35's full power.
Click to expand...

I'd guess he is afraid to make it downshift.
 
Likewise, there is no such thing as free energy! I've seen people pulling off mechanical accessories from their car and replacing them with electrical accessories. They think they are freeing up HP because electricity is free. It's not. It's just moving the load from that accessory to the alternator.
Click to expand...

True, but there is a small amount of saving to be had by moving belt driven accessories to electric.

Many manufacturers are now switching to electric AC and power steering. The problem with a mechanical drive is that there is always friction from each pulley regardless of whether the device is engaged or not. Additionally, each accessory has an angular momentum, which must change with the speed of the engine - so acceleration is reduced, although brake torque/power isn't.

Using electrical accesories means that each accessory offers no resistance when switched off. Also the accessories can be more reliable - electric AC should never need recharging, because they don't inherently leak.
 
Originally posted by: Mark R
Likewise, there is no such thing as free energy! I've seen people pulling off mechanical accessories from their car and replacing them with electrical accessories. They think they are freeing up HP because electricity is free. It's not. It's just moving the load from that accessory to the alternator.
Click to expand...

True, but there is a small amount of saving to be had by moving belt driven accessories to electric.

Many manufacturers are now switching to electric AC and power steering. The problem with a mechanical drive is that there is always friction from each pulley regardless of whether the device is engaged or not. Additionally, each accessory has an angular momentum, which must change with the speed of the engine - so acceleration is reduced, although brake torque/power isn't.

Using electrical accesories means that each accessory offers no resistance when switched off. Also the accessories can be more reliable - electric AC should never need recharging, because they don't inherently leak.
Click to expand...



by electric ac you mean something like peltier? and not simply an electric driven compressor?
 
by electric ac you mean something like peltier? and not simply an electric driven compressor?
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I mean an electrically driven compressor.

Peltier is much, much less efficient than a compressor. The problem with a pulley driven compressor, is that it isn't possible to seal completely the gap around the pulley - so there will always be a tiny leak. With an electric compressor the system can be welded, or soldered, closed.
 
In my case, I have an alternator that pushes 136A, if you assume that is at 15V (a little high), and 70% efficency (a bit low), that means that the max my alternator and push is 2040W, and drag down 2914W. Going off the 1HP=746W conversion, that makes a max of around 4HP drag. Given the worst case scenario, (at idle), the max torque that it will take to drive it, is about 30LB/ft of torque. The engine makes about 100HP and 260LB/ft at 2000RPM, which is freeway cruising speed, and would only pull down 10LBft and the same 4HP. So not really a signifigant loss. Peak is 230 HP @ 4,600 rpm and 295 lb.-ft. @ 3,600 rpm.

I don't think I'll ever notice the alternator's draw.
 
Originally posted by: iwantanewcomputer
also, does having a rear spoiler on a FWD car help? (because it's forcing the back wheels down, not the front wheels that need traction)
Click to expand...
At low speeds where wheelspin might be an issue, aero does nothing. The purpose of a spoiler is to increase grip for cornering.

From what I've heard about race cars, you need to be near triple digit speeds before aero starts having much of an impact. So for a street car I'm guessing it's essentially useless no matter where you decide to stick the hideous wing.
 
Originally posted by: SludgeFactory
Originally posted by: iwantanewcomputer
also, does having a rear spoiler on a FWD car help? (because it's forcing the back wheels down, not the front wheels that need traction)
Click to expand...
At low speeds where wheelspin might be an issue, aero does nothing. The purpose of a spoiler is to increase grip for cornering.

From what I've heard about race cars, you need to be near triple digit speeds before aero starts having much of an impact. So for a street car I'm guessing it's essentially useless no matter where you decide to stick the hideous wing.
Click to expand...

this is true. the front spoiler does a little bit to help at lower speeds, but you still are looking at 70mph+
 
Yes, the alternator is a parasitic drag on the engine. Disconnecting it would increase hp slightly but then all your electronics would be running off the battery. This would only be useful on a drag strip and some guys do this for one run. You wouldn't want to do it on a street car for very long though. Especially since most belts also drive the water pump and power steering pump.

A spoiler on a FWD car, or any car for that matter, can only serve to help better stabilize a car on high speed corners. You would really have to play around with settings, tire compounds and suspension to set it up so that it provides any benefit though. Most likely you are just increasing drag and adding useless weight to your car. 99.9% of all ricers fall into this category I suspect.

Edit-Some production cars capable of mid to high triple digit speeds actually produce lift in the rear at high speeds so a spoiler helps to minimize that or counteract that. Trust me, you don't want lift in the front or rear of any car at 150mph.
 
Originally posted by: Mark R

Many manufacturers are now switching to electric AC and power steering. The problem with a mechanical drive is that there is always friction from each pulley regardless of whether the device is engaged or not. Additionally, each accessory has an angular momentum, which must change with the speed of the engine - so acceleration is reduced, although brake torque/power isn't.

Using electrical accesories means that each accessory offers no resistance when switched off. Also the accessories can be more reliable - electric AC should never need recharging, because they don't inherently leak.
Click to expand...

While it's true that they can save a tiny bit of performance by eliminating the other pullies, I think one of the main reasons for switching to electric accessories is for ease of mounting/space constraints. Sort of like how the MR2 had an electric PS pump. The reason for that is that the engine is in the back, and the rack is in the front. Also, everything being electric means you can monitor it better and start/stop it at will.
 
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