I have been seeing HP figures all over the place here and have a few questions. Please excuse my ignorance or lack of knowledge on this topic. Here goes...

When a car is sold with a HP rating of 100 HP, I know the actual HP will be less depending on the tranny, accesories and other drivetrain parts that rob power from the engine. I am confused as to whether there is a ratio or a straight forward increase in power when power adders are introduced such as turbo, nitrous, SC. What I mean is this...

If I have a car that is rated at 100 HP and the actual HP is 90, if I add a 50 HP shot of nitrous, does this mean my power is now 140 HP?

I am sure this is how it works, because I can't see how a tranny will rob more power when more power is added to the motor. Does this make sense or not? Can someone elaborate on whether my theory is right or wrong?

parrasitic drag loss i think its called that or some thing like that, thats in the auto transmission little less in the 5 spd

i'm not sure if its rated at net hp(with all the accesories attached on the engine) or gross hp (no accesories)

Could you explain what that is? I guess my question is if I add 50 HP, it should be 50 HP to the crank AND wheel, correct? I am asking as far as general autos are concerned, not just 1 particular car.

I think CHP would win because they have Frank "Ponch" Poncharello. Mark

ummm...uhhh....CHP=Crank HorsePower. But yeah, Ponch is my hero too! I'm saving up right now to buy a timeshare from him!

did a little research, that 50 shot is only to the crank, you'll lose about 10hp due to parrasitic loss from the accesories and the transmission

I don't doubt you, but how can the tranny and accesories take away 'more' power? I am not trying to argue with you, I just am confused on the subject. I guess the way I'm thinking is that let's say the tranny robs 10 HP without nitrous, can it rob more power? I am having a hard time seeing how this is possible. Please don't take this the wrong way, as I am not trying to be an a$$, I'm just trying to learn...

rotating mass... robs you of that power

getting a lightened crank pulley would help get a small percent of that power back

http://www.goingfaster.com/spo/parasitic_power_loss.html

But it's the same 'rotating mass' whether the HP is measured at the crank or at the wheels. I guess you don't see what I'm asking.

Generally speaking, the drivetrain loss will be roughly the same. But it also depends on quite a few things as far as dyno's go.

If you plan to put nitrous on the 1nz, please build prior to install of nit. because you will blow your motor in no time doing so.

So for instance, if you have a 1nz pushing 150hp (crank), you will have roughly 135whp. Of course, all this depends upon other situations but thats usually what happens.

I also might point out with the new SAE ratings its a 106hp, not 100hp. Without the SAE it was 108hp. Really not all that much of a difference but yeah, a little more than 10hp drivetrain loss.

Most stock manuals run around 88-93whp, most automatics run around 84-89whp. It really depends on conditions, if you were in high elevation, extremely hot out, with other things envolved you could only see 75whp for instance. So yeah.

I was just using the 100hp as a nice round number. I do not plan on putting nitrous on my car. This ws just a general automotive question. I think you answered my question and what you said is what I think too...that the loss doesn't increae as the power increases. I really don't see how it could, but I'm no rocket scientist and wasn't sure. THX.

I was just using the 100hp as a nice round number. I do not plan on putting nitrous on my car. This ws just a general automotive question. I think you answered my question and what you said is what I think too...that the loss doesn't increae as the power increases. I really don't see how it could, but I'm no rocket scientist and wasn't sure. THX.

Actually it can to some degree, it depends on too much to say it does or it doesn't. But, with the mods you can do to the xb, rather, what you can't do yet, you really wouldn't see more % in drivetrain loss.

Now, if you were to convert drivetrains to rwd or awd, you would see a huge difference. Night and day difference especially with awd. But, your welcome. :P

this is a good question and your point makes alot of sense. I totally follow.

If you have 100 crank HP and lose 10 hp through the car to the wheels you have 90 WHP.

The car stole 10 hp. thats all it takes for the car to spin turn whatever it may be.

Now if you increase the same car to 200 hp at the crank. and dont change drive train, clutch wheels or anything, you would have 190 WHP. IN theory of course the car shouldnt take more than the 10 hp originally to make the car turn spin and whatever.

Is this how it works? Or will the 200 hp car (same car as 100 hp) lose more than 10 HP?

Nick06tC...You see where i'm coming from! It may sound like a dumb question, but my initial question was whether the total parasitic loss stays the same, and frankly, I don't see how it would change, but I didn't know for sure. THX all!
I do understand slight differences here and there will affect the overall, but I was thinking if everything stayed exactly the same (air temp, humidity, tire pressure, etc.), the parasitic loss will not increase!

this is a good question and your point makes alot of sense. I totally follow.

If you have 100 crank HP and lose 10 hp through the car to the wheels you have 90 WHP.

The car stole 10 hp. thats all it takes for the car to spin turn whatever it may be.

Now if you increase the same car to 200 hp at the crank. and dont change drive train, clutch wheels or anything, you would have 190 WHP. IN theory of course the car shouldnt take more than the 10 hp originally to make the car turn spin and whatever.

Is this how it works? Or will the 200 hp car (same car as 100 hp) lose more than 10 HP?

200hp on a 1nz would require significant modification, in the end you would loose more than 10hp through drivetrain. 200hp would equal some where around 180whp. It would be anywhere from 10hp-30hp drivetrain loss. A good example of this is a 210whp echo i've seen dyno'd on echo forums. He is pushing 245hp, and has a drive train loss of 35hp.

There are different issues regarding different losses.

In an automatic (for example), the loss is not a set hp number. It is a percentage due to the torque converter "to keep it simple". For example, if you have 100 hp and loose 10 hp due to torque converter...it has a 10% loss. If you have 500 hp at the crank....I assure you that you will loose more than 10 hp.

By design, an automatic will never give you 100% power transfer unless it is a lock converter (the tC does lock in overdrive).

^ so does the xB. Now I'm really fricken confused...So you're saying that there IS a gradual loss?

^ so does the xB. Now I'm really fricken confused...So you're saying that there IS a gradual loss?

Well, there are specific issues when dealing with automatics, but for simple sake, it can be viewed as a percentage loss. For example, you will always loose 10% thru the drive train. 10 hp on a 100 hp and 50 hp on a 500 hp car. a simple rule of thumb to convert back and forth is usually, 21% on an automatic and 16% on manual transmission. Add another 5% loss with 4wd transfer case added.

But is it always a percentage? Or is it 10% of 100HP which is 10 HP...then when 400 HP is added, it's not 10 HP? but 50HP (or 10%)? I don't mean to be ignorant but I am having a hard time seeing it.

haha i just learned to live with some of most of the hard to believe things in life

Yeah doesnt make much sense to me. How could a drivetrain take 10 HP to turn one time then 50 HP another. As long as nothing but HP was changed with the engine, how could the same exact drivetrain require more power to move?

I didn't realize we were talking specifically for automatics.

We aren't As a matter of fact we are not talking about Scions specifically. I started this thread as a 'general automotive' question and thats why I put it in off topic and not a specific forum.

I guess I have to go with what Hornet_on_flower said and chalk this one up with the crop circles and alien abductions....LOL. I certainly don't understand it and maybe I need to leave it as one of the many mysteries of the world. Maybe 'Unsolved Mysteries' can do a segment on it? Surely SOMEONE knows, huh?

We aren't As a matter of fact we are not talking about Scions specifically. I started this thread as a 'general automotive' question and thats why I put it in off topic and not a specific forum.

I guess I have to go with what Hornet_on_flower said and chalk this one up with the crop circles and alien abductions....LOL. I certainly don't understand it and maybe I need to leave it as one of the many mysteries of the world. Maybe 'Unsolved Mysteries' can do a segment on it? Surely SOMEONE knows, huh?

lol..

automatics - usually 10% drivetrain loss on any given number, no matter if its 10hp or 600hp, its usually 10%, in some cases 15% but that just depends on other things envolved.

manuals- Usually can follow 5% drivetrain loss on any given number, but hp can also be gained back with modifications you can't do to an auto..for instance, a high performance clutch *complete kit* could help free up 1-3hp that wasn't there before. Doesn't really effect it much, but every hp counts in some cases.

We aren't As a matter of fact we are not talking about Scions specifically. I started this thread as a 'general automotive' question and thats why I put it in off topic and not a specific forum.

I guess I have to go with what Hornet_on_flower said and chalk this one up with the crop circles and alien abductions....LOL. I certainly don't understand it and maybe I need to leave it as one of the many mysteries of the world. Maybe 'Unsolved Mysteries' can do a segment on it? Surely SOMEONE knows, huh?

haha thank you

OK, let me explain this a little easier so as to understand why it is a set percentage and not a set HP loss. Look at it this way, if you had a 10 CHP car, We are all pretty confident the car will still move. Reason being is you are not loosing a set 10 horse power, you are loosing a percentage of horse power thru the drive train.

Take an automatic for example. As a general rule, when given crank horse power, you can deduct 21% or so. For a manual tranny, deduct 16% or so. It's a loss that is not dependent on horse power, it is in the design of the hydrolics, clutch, gearing, drive train components, etc.

Just like manual transmission cars, cars with automatic transmissions need a way to let the engine turn while the wheels and gears in the transmission come to a stop. Manual transmission cars use a clutch, which completely disconnects the engine from the transmission. Automatic transmission cars use a torque converter.

The key difference between a manual and an automatic transmission is that the manual transmission locks and unlocks different sets of gears to the output shaft to achieve the various gear ratios, while in an automatic transmission, the same set of gears produces all of the different gear ratios. The planetary gearset is the device that makes this possible in an automatic transmission.

A torque converter is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission. If the engine is turning slowly, such as when the car is idling at a stoplight, the amount of torque passed through the torque converter is very small, so keeping the car still requires only a light pressure on the brake pedal.

If you were to step on the gas pedal while the car is stopped, you would have to press harder on the brake to keep the car from moving. This is because when you step on the gas, the engine speeds up and pumps more fluid into the torque converter, causing more torque to be transmitted to the wheels

In addition to the very important job of allowing your car come to a complete stop without stalling the engine, the torque converter actually gives your car more torque when you accelerate out of a stop. Modern torque converters can multiply the torque of the engine by two to three times. This effect only happens when the engine is turning much faster than the transmission.

At higher speeds, the transmission catches up to the engine, eventually moving at almost the same speed. Ideally, though, the transmission would move at exactly the same speed as the engine, because this difference in speed wastes power. This is part of the reason why cars with automatic transmissions get worse gas mileage than cars with manual transmissions.

To counter this effect, some cars have a torque converter with a lockup clutch. When the two halves of the torque converter get up to speed, this clutch locks them together, eliminating the slippage and improving efficiency.

Good info scion dad. But I dont see how this explains why the more power you have the more you lose. And why its a percentage and not a stagnant number.

I am going to chalk this up to the cop circles and aliens thing and say it is because it is.

But I will propose another question.
Lets use human power:
If I crank a handle that turns gears and turns a wheel, I encounter resistance in the meshing of the gears and the pivot points and what not. Lets say I use a certain amount of power to get it to turn. Now if some one stronger than me turns the same crank, wont it take the same amount of power to get it to turn?
Just because he is stronger than me, doesnt mean that the machine will lose more power through out it.

Or lets use Horses, the root of Horspower:
If one horse can pull a concrete slab across the floor, the resistance of friction is set. It ook 1 HP to move the concrete (yes I know this is not how HP is measured. Its actually how much one horse can move over a certain distance or something, but I am keeping it easy). Now if 2 horses pull that concrete slab, (2HP), it will still take the same amount of force to move that slab.
No more friction is created.





Maybe this is just jibber jabber, but kinda makes sense in my weird thinking.

^ you fail to see that by using 2 horses, you are adding weight from the extra harnesses and such. Also by having 2 horses, you have more vet bills and more feed will be used. HAHA...just kidding Nick06.

Anyway, I understand what ScionDad is saying to a point. Yes, the car would move with only having 10 HP, so it is a percentage...BUT I still do not believe it is a SET percentage. I am starting to beieve that it is a gradual percentage. Thank you ScionDad for shedding a little light on the subject.

^ you fail to see that by using 2 horses, you are adding weight from the extra harnesses and such. Also by having 2 horses, you have more vet bills and more feed will be used. HAHA...just kidding Nick06.

Anyway, I understand what ScionDad is saying to a point. Yes, the car would move with only having 10 HP, so it is a percentage...BUT I still do not believe it is a SET percentage. I am starting to beieve that it is a gradual percentage. Thank you ScionDad for shedding a little light on the subject.

You're correct, it is not a set percentage, but it usually is close enough to get an idea what your loss will be from crank to wheels.

But that 10% is only if we are at 100 HP correct? I mean, I fail to see how the drivetrain can miraculously cause the same 10% if 900 more HP were added (a total of 100 HP lost or 10%). So is it safe to say that the more power that is increased, the less percentage of power will be lost through parasiticity? <---Is thateven a word?LOL.