Effective NA Power Mods

[86Boyz]

Originally Posted by nikitopo

I don't think you'll notice anything with a drop in filter. A real waste of money. Personally, I didn't notice any improvement.

If anyone buys a drop in air filter looking for gains then they are looking in all the wrong places. I only bought so I don't have to spend money replacing the filter over and over again. Saves money in the long run.

[Tcoat]

Originally Posted by nikitopo

I am preparing now for a bigger TB. I hope I'll not regret it

Originally Posted by DSLeach

I don't think you will get much from a larger TB except a lighter wallet.

Agreed. If you have a fully built, turboed engine then a TB may be one of the last finishing touches. A mildly modded NA engine is not even coming close to maxing out the airflow on the stock TB. There are a couple of long threads on the subject.

[Tcoat]

Originally Posted by 86Boyz

If anyone buys a drop in air filter looking for gains then they are looking in all the wrong places. I only bought so I don't have to spend money replacing the filter over and over again. Saves money in the long run.

There are lots of gains claimed by the manufacturers and backed by dynos.
But.
Most of those gains are so small that they fall within the margin of error of the dyno so...

[DSLeach]

Originally Posted by justatroll

I was reading along thinking that the world has come to it's senses because nobody has suggested LWCP or LWFW, and there you go ruining it.

It is NOT POSSIBLE to get "more hp" by reducing the rotating mass of the engine or drivetrain.
It does not Make more HP or "free up" more HP.
Removing weight from the rotating mass will give you the exact same benefits as removing that same weight from anywhere else on the car.
Except by focusing your efforts on reducing rotating mass you will certainly see a huge decrease in the weight of your wallet.

The only noticeable change in "responsiveness" is throttle response when the car is out of gear.

Actually, less rotating mass (crank, flywheel, clutch, drive shaft, wheels, tires) or moving the mass inwards towards the center of rotation will free up HP parasitic losses. Here is a thought experiment for you.

Take one straight shaft and put a heavy truck wheel/tire on it. Lets say it is 300 lbs. Stand that axle straight up on with the wheel/tire on the top. Now imagine using your hands to spin that axle with the wheel/tire on the top. Its going to pretty hard because of the mass you are attempting to accelerate.

Try the same thought experiment with a little 12" trailer wheel/tire combination on the axle. Spinning that little wheel/tire combo is a lot easier because the mass is lower and because that small mass is concentrated closer to the center of rotation.

Remember the force required to accelerate a mass is governed by the equation F=ma. As the mass you are accelerating increases, so does the required force. This equation also applies to to rotational mass. Its just simple physics.

By the way, where did you get your engineering degree?

If you want some further education on the effective of rotating mass, there is a pretty good discussion of it in the suspension forum.

Cheers!

[Tcoat]

Originally Posted by DSLeach

Actually, less rotating mass (crank, flywheel, clutch, drive shaft, wheels, tires) or moving the mass inwards towards the center of rotation will free up HP parasitic losses. Here is a thought experiment for you.

Take one straight shaft and put a heavy truck wheel/tire on it. Lets say it is 300 lbs. Stand that axle straight up on with the wheel/tire on the top. Now imagine using your hands to spin that axle with the wheel/tire on the top. Its going to pretty hard because of the mass you are attempting to accelerate.

Try the same thought experiment with a little 12" trailer wheel/tire combination on the axle. Spinning that little wheel/tire combo is a lot easier because the mass is lower and because that small mass is concentrated closer to the center of rotation.

Remember the force required to accelerate a mass is governed by the equation F=ma. As the mass you are accelerating increases, so does the required force. This equation also applies to to rotational mass. Its just simple physics.

By the way, where did you get your engineering degree?

If you want some further education on the effective of rotating mass, there is a pretty good discussion of it in the suspension forum.

Cheers!

Oh oh!

[brzd]

Originally Posted by DSLeach

The new 2017 does have a higher ratio final drive. If I'm not mistaken it is a 4.30 vs 4.10 in the old car. MT of course.

Yeah i saw that and I was thinking of swapping in 2017 pumpkin when they start going to the salvage yard but I'm afraid 5% increase wouldn't be that noticeable...

Heard great things about 4.556 and 4.67 for the MT and 4.88 for the AT

Looking at getting the FD from Cusco but OEM parts are so pricey. Might go with weir but I heard they whine. Decisions decisions...

But so far UEL and OFT keeps me content. I recommend this to everyone who says the car is slow. It gives it a little umph at a low cost

Sent from my SM-G920W8 using Tapatalk

[Captain Snooze]

WARNING
Thread Derail Imminent.

[nikitopo]

Originally Posted by Tcoat

Oh oh!

He is trying to wake him up ...

[Ultramaroon]

[DSLeach]

Originally Posted by Tcoat

Oh oh!

Why "Oh oh!"?

Do we have some non-believers in Newtonian Physics on this forum? Flat Earth Society folks?

[DSLeach]

Originally Posted by justatroll

I was reading along thinking that the world has come to it's senses because nobody has suggested LWCP or LWFW, and there you go ruining it.

It is NOT POSSIBLE to get "more hp" by reducing the rotating mass of the engine or drivetrain.
It does not Make more HP or "free up" more HP.
Removing weight from the rotating mass will give you the exact same benefits as removing that same weight from anywhere else on the car.
Except by focusing your efforts on reducing rotating mass you will certainly see a huge decrease in the weight of your wallet.

The only noticeable change in "responsiveness" is throttle response when the car is out of gear.

Actually, I found a couple of good references for why rotating mass will affect your acceleration. The first a Tire Rack article on the benefits of lighter wheels and tires.

Link: http://www.tirerack.com/wheels/tech/...jsp?techid=108

You will want to scroll down to the 5th paragraph for the discussion on acceleration impact.

The second link gives a pretty detailed explanation of rotating mass and the power required to accelerate that mass applied to engine and drive train components. Its long but does a pretty good job of explaining the phenomena.

Link: http://www.w8ji.com/rotating_mass_acceleration.htm

[Tcoat]

Originally Posted by DSLeach

Why "Oh oh!"?

Do we have some non-believers in Newtonian Physics on this forum? Flat Earth Society folks?

This is debate #182,036 on this subject. And you rather rudely call out the leader of the opposition. He can out rude you though so this could be interesting.

[justatroll]

Originally Posted by DSLeach

Actually, less rotating mass (crank, flywheel, clutch, drive shaft, wheels, tires) or moving the mass inwards towards the center of rotation will free up HP parasitic losses. Here is a thought experiment for you.

Take one straight shaft and put a heavy truck wheel/tire on it. Lets say it is 300 lbs. Stand that axle straight up on with the wheel/tire on the top. Now imagine using your hands to spin that axle with the wheel/tire on the top. Its going to pretty hard because of the mass you are attempting to accelerate.

Try the same thought experiment with a little 12" trailer wheel/tire combination on the axle. Spinning that little wheel/tire combo is a lot easier because the mass is lower and because that small mass is concentrated closer to the center of rotation.

Remember the force required to accelerate a mass is governed by the equation F=ma. As the mass you are accelerating increases, so does the required force. This equation also applies to to rotational mass. Its just simple physics.

By the way, where did you get your engineering degree?
If you want some further education on the effective of rotating mass, there is a pretty good discussion of it in the suspension forum.

Cheers!

Actually you have it mostly right.
Horsepower measured by a Dyno is really measured at a lot of discrete points of constant RPM in the "curve" as the RPMs are raised.
When you look at "dyno pull results" (like this one from Vans 914 build


It looks like a constantly changing RPM and most people believe that you want to try to do the "pull" as fast as possible and that a faster pull means more HP.

That is not the case, in fact, the SAE requirements for dynamometer measurements are that the dyno is supposed to pause at each discrete measurement point for a specified duration before measuring torque & RPM.
In practice, dyno pulls are done in a dynamic sweep that seems to be one continuous pull, when they are really performing hundreds of discrete measurements.
The most accurate dyno measurements are done as slowly as possible.

What I am getting at is that each discrete measurement of torque is supposed to be done at constant RPM.

So how does the rotational inertia of the flywheel and crank affect the torque measurement at constant RPM (NOT accelerating)?

Answer: It doesn't.

So now lets hear where you got YOUR engineering degree.

my point again - it is NOT possible to get more horsepower by reducing rotating mass.
Will the car accelerate faster with a lighter rotating assembly - YES but NOT because the engine produces more HP. PERIOD

[DSLeach]

Originally Posted by justatroll

Actually you have it mostly right.
Horsepower measured by a Dyno is really measured at a lot of discrete points of constant RPM in the "curve" as the RPMs are raised.
When you look at "dyno pull results" (like this one from Vans 914 build


It looks like a constantly changing RPM and most people believe that you want to try to do the "pull" as fast as possible and that a faster pull means more HP.

That is not the case, in fact, the SAE requirements for dynamometer measurements are that the dyno is supposed to pause at each discrete measurement point for a specified duration before measuring torque & RPM.
In practice, dyno pulls are done in a dynamic sweep that seems to be one continuous pull, when they are really performing hundreds of discrete measurements.
The most accurate dyno measurements are done as slowly as possible.

What I am getting at is that each discrete measurement of torque is supposed to be done at constant RPM.

So how does the rotational inertia of the flywheel and crank affect the torque measurement at constant RPM (NOT accelerating)?

Answer: It doesn't.

So now lets hear where you got YOUR engineering degree.

my point again - it is NOT possible to get more horsepower by reducing rotating mass.
Will the car accelerate faster with a lighter rotating assembly - YES but NOT because the engine produces more HP. PERIOD

Actually, I have a couple. BS Nuclear Engineering from Univ of MI '81 and MS in Environmental Engineering from Univ of WA '97.

If what you are saying is that it is not possible get "additional" HP from the engine by reducing the mass of rotating assemblies, I completely agree.

However, if you were able to lower the mass of your rotating assemblies in the engine and drive train, you would free up power that was previously being used to accelerate the higher rotational mass. The power that is now freed up is available to provide linear acceleration for your car.

The simple way to say it is, lowering the rotational mass of the engine and drive train will result in faster linear acceleration, all else being equal.

I would also note that because a chassis dyno measures wheel horsepower, none of the parasitic losses in the engine and drive train (friction and losses to accelerate rotational mass) will show up on the dyno results. If you are able to reduce the rotational mass of the engine and drive train, you will get a higher HP reading on the chassis dyno. Less power used to accelerate rotating mass means more is available to spin the dyno drum.



Cheers!