Will putting a lightened flywheel show up hp on the dyno?

 

Yes it will, You are not adding HP with a lightened flywheel but you will free up some previously wasted HP.

 

No, the only thing that will change is the RoA

 

An inertia type dyno might, but a real engine dyno will not.

 

inertia type is dynojet?

 

No, this does not mean its not an excellent mod though.

 

It will definitely make the car quicker in the same way lightening the car by removing the sound insulation would. There is less mass to spin up. But on a real dyno where you stabilize the engine speed at each RPM point for a moment while measuring the torque it will not show up. You will only see a gain when that mass is being accelerated, not when it is at a constant velocity. A dynojet is not a true dynomometer in that it does not use a brake to absorb power it instead calculates power based on how long it takes to spin up a certain amount of mass.

 

I picked up 6RWHP and 8RWTQ on a dynojet. I went from a 25 to a 14 lb flywheel.

This was on my 5.0 mustang. I changed the clutch as well so maybe the clutch was just holding better or something.

 

yes, it will to a small degree.

remember that when you spin a heavier flywheel up to speed, you are storing energy that you could otherwise use to accelerate the roller on the dyno.

 

Steady-state measurement = no gain
Transient measurement = gain

This is an example of how dyno measurements can be misinterpreted. As stated, the engine is not producing any more torque at any speed, but the its moment of inertia has decreased, so it will accelerate more quickly.

 

The more I think about it the more I dont see how it wouldnt show up. Anything that helps get more HP/TQ to the wheels would have to show up I would think.

 

"Getting more torque/power to the wheels" is sort of a vague statement. It could suggest that parasitic losses are reduced, frictional losses are reduced, or rotational inertia has decreased.

If the dyno is operating at steady-state, no energy is required to accelerate the flywheel, so there would be no difference in torque measurements after switching flywheel weight.

 

Are you talking about an engine or chasis dyno?

 

Either one if you do steady-state testing, not acceleration testing.

 

Well I learned something new today.

Thanks,

 

As stated previously it's the same as running on a dynojet with 15" wheels and then bolting on some heavy 17" wheels. The dyno's I have personally seen showed a 4-5 whp loss on a b16a. The more weight you have to spin up, the more energy consumed, which shows up on a dynojet, not an engine dyno.

 

It shows up on a Dynojet because it's an inertial dynomometer. It will show up on any brand of inertial dynomometer, but not on a brake type dyno. It doesn't matter if it's a chassis dyno or an engine dyno as long as it is a brake type dyno.

 

you didn't answer the guy's question. nobody wants to hear some nonsense that doesn't relate to the original question! I'm pretty sure most of us have taken high school physics, so you guys don't have to flex your highschool physics knowledge to us here.

YES, YOU WILL GET A HIGHER POWER READING ON A DYNO WHEN YOU MAKE A DYNO PULL WITH A LIGHTENED FLYWHEEL.

 

You obviously failed high school physics. Wrong!

 

I guess you are right and I know nothing. It appears that several in this very thread have already indicated real world results backing up my statement along with a few others agreeing with the theory, provided the car is accelerating on the dyno. So we are all wrong and you are right! Congratulations!

 

There are 2 correct answers
they are
YES and NO

 

On an inertia type dyno, or a dyno pull that covers the RPM band fairly quickly, yes.

 

I think the bottom line is that it is in fact a good modification and will make your car faster. And isn't that what everyone is really looking for? Or do people just look for higher numbers on the dyno? I think the latter prevails on this forum!

 

You even quoted it...

 

There is a lot of weight loss to an engine that is not seen on a dyno... But thats not to say that it doesnt help get down the track quicker. It just relieves stress on the engine, thus making it more efficient and reliable.