Flywheel HP to wheel HP

[andries]

Can someone tell me what about the loss in power, in percent, is between the flywheel and the driven wheels from a Yaris?

Do this also depends on the weight of the powertrain?
If the answer is yes means this that a large car with big wheels and for example a shaft to the back wheel loses more?

Thanks

[cleong]

If we assume that the engine puts out its claimed horsepower, then its about a 15% loss through a manual transmission when you compare it against what is measured at the wheels. 106hp vs. 90whp.

[andries]

Originally Posted by cleong

If we assume that the engine puts out its claimed horsepower, then its about a 15% loss through a manual transmission when you compare it against what is measured at the wheels. 106hp vs. 90whp.

That sound nice. Today I measured with my ScanGauge 167 HP.
If the loss is 15% this means that I have 142 HP on the wheels.
I have the 1.8 2ZR-FE engine (stock 133 hp). The only engine mod is a K&N stock replacement air filter. (that's gain more power for less money)

Whether conditions, during the meeting, are optimal. Outside temperature was two degrees celsius what means the engine got optimal cold air.

[cleong]

I would not trust a ScanGauge for accurate horsepower measurements. The most accurate would be a rolling road, ie, chassis dyno.

It is highly unlikely that a K&N drop-in filter will give you 34hp more at the crank. That's gains that you'd need forced induction to achieve.

[andries]

Originally Posted by cleong

I would not trust a ScanGauge for accurate horsepower measurements. The most accurate would be a rolling road, ie, chassis dyno.

It is highly unlikely that a K&N drop-in filter will give you 34hp more at the crank. That's gains that you'd need forced induction to achieve.

I have stock about 133 hp on the wheels. 15% from 167 flywheel hp is 142 wheel HP.
That would mean that the K&N is give me about 9 HP more and not 34 HP you said.
Or will I now accounting wrong?

[cleong]

Your interpretation is wrong. I believe Toyota quotes 133hp for the 1.8 TS and that is a crank figure, not at the wheels.

[Tamago]

Originally Posted by cleong

Your interpretation is wrong. I believe Toyota quotes 133hp for the 1.8 TS and that is a crank figure, not at the wheels.

gotta remember that that 133hp is the "new" SAE rating.. which means it's actually more "old" SAE HP lol

[CASTREX]

Originally Posted by andries

That sound nice. Today I measured with my ScanGauge 167 HP.
If the loss is 15% this means that I have 142 HP on the wheels.
I have the 1.8 2ZR-FE engine (stock 133 hp). The only engine mod is a K&N stock replacement air filter. (that's gain more power for less money)

Whether conditions, during the meeting, are optimal. Outside temperature was two degrees celsius what means the engine got optimal cold air.

Those numbers are way off!!!

I've seen a few dyno charts of the 1.8 2ZR-FE

Stock this engine puts out between 118-120 WHP

A K&N drop in filter will net you 1-2 extra hp if anything at all...

[CASTREX]

Originally Posted by Tamago

gotta remember that that 133hp is the "new" SAE rating.. which means it's actually more "old" SAE HP lol

The same engine is rated differently depending on the car and the market is from.

Some places will advertise it as a 128 Hp other at 133hp and others in 136hp.

As explained above the HP measurement depends on they way it's measured.


What is true and should remain the same is the actual HP numbers to the wheels.

As I said before this engine will put down 120WHP at the most in stock form.

[andries]

Oke, thanks.

And numbers do not always say everything, he goes like the fire and that is the most important thing.

[LtNoogie]

Time to dyno it and post the chart with the rest of them.

[09TRD]

Originally Posted by andries

If the loss is 15%..

"15%" has no basis in fact.

Here, read this:

http://www.sportcompactcarweb.com/pr...t_4/index.html

"...Paulsen also believes that drivetrain losses are neither an absolute percentage nor a fixed number. Instead, he feels the crank-to-wheel relationship is far more beguiling. From his considerable experience, Paulsen suggests that low horsepower (100-200 hp) cars may suffer from as much as 15 to 20 percent of drivetrain loss at the rear wheels. For more powerful cars (200-400 hp), the figure is around 12 to 15 percent. And for mega-powered cars (above 400 hp), the drivetrain losses can reduce to 10 percent or less. What's going on? Getting into the physics behind this complex relationship is worthy of a project in itself. (Engineering editor, Dave Coleman says he's working on it.)"

The type of dyno is also a factor. Two different types of dynos will likely yield two different results - even when all other variables are identical.

Chassis dynos are tuning tools; they do not nor were they ever intended to be used to somehow "calculate" flywheel power.

[cleong]

I explained that 15% is based on a comparison between quoted crank HP and recorded wheel HP. Yes, results vary according to type of dyno, even ambient weather conditions on the day.

It is my belief that flywheel HPs are quoted to eliminate the transmission from the equation and allow easy comparison to spec sheets as well as cars with AT or MT boxes.

[ddongbap]

Originally Posted by 09TRD

"15%" has no basis in fact.

Here, read this:

http://www.sportcompactcarweb.com/pr...t_4/index.html

"...Paulsen also believes that drivetrain losses are neither an absolute percentage nor a fixed number. Instead, he feels the crank-to-wheel relationship is far more beguiling. From his considerable experience, Paulsen suggests that low horsepower (100-200 hp) cars may suffer from as much as 15 to 20 percent of drivetrain loss at the rear wheels. For more powerful cars (200-400 hp), the figure is around 12 to 15 percent. And for mega-powered cars (above 400 hp), the drivetrain losses can reduce to 10 percent or less. What's going on? Getting into the physics behind this complex relationship is worthy of a project in itself. (Engineering editor, Dave Coleman says he's working on it.)"

The type of dyno is also a factor. Two different types of dynos will likely yield two different results - even when all other variables are identical.

Chassis dynos are tuning tools; they do not nor were they ever intended to be used to somehow "calculate" flywheel power.

The 15% is meant to be a guide. It isn't fact.

[eric81]

Here's a thought... There are two types of weight on a car: Dead and spun. Dead weight is engine block, frame, chassis, seats, and anything else that is not moving. Spun weight is all pulleys, crank, shafts, pistons, cams, transmission, flywheel, wheels, and so on. It is harder to spin weight than to pull weight. If you take off only 3 to 4 pounds of spun weight, you will see far more increase in end HP than if you lost 30 to 40 pounds of dead weight. This has a LOT to do with the intake and exhaust (follow me closely now.....). If you allow the engine to breathe easier, it is taking stress off of the pistons and valves, allowing for more spun weight items to move easier. It is not just how MUCH air you can pump in and out, it's how EASY the air can get in and out. Ask anyone who has bought the underdrive pulley. Or the NST lightweight pulley kit. They will tell you they saw a dramatic increase in engine response and a good increase in HP. There are several blogs and posts here to prove that. So, if you want to make the HP a better flow and lose less % at the tires, lighten the spun weight between the engine and the tires. Carbon shafts, light weight flywheel, stiffening off the engine to the chassis (for less engine movement that is another type of spun weight and lost spun drive), and lighter rims and tires will all help a lot. The 15% thing is not just some strange number someone thought up... it's the number that threatens cars like ours. The reason super cars have less % loss at the tires is because they use lighter stuff in the power train. If we did the same weight and strength to power ratio, we could easily be at less than 10% loss as well. I wish I was rich so I cold prove this to everyone on a dyno. For now, you'll just have to believe what I type.

[eric81]

Anyone have any comments at all?

[CASTREX]

Originally Posted by eric81

Anyone have any comments at all?

You are totally right.

A more efficient and lighter drive train will reduce the amount of power lost.

The problem is that other than flywheel / Pulleys and some other stuff there is not much you can do within a budget. The HP / $$$ ratio just doesn't justify those kind of mods. That's why people will try to make more power ( Forced induction) other than figure out ways to loose less power.

Is cheaper to make power than to avoid losses.

F1 and other race cars are exceptions....

[Tamago]

so i should take out one of my axles to save spun weight ;) fkin car is 1wheel drive anyway ;)