loudazzrx7

Motor is rebuilt --not ported

1Revvin7

I'm thinking 25hp, since you are adding a header, getting rid of parasitic drag, and the compression s/b better. All those other things listed do not add hp...

RX7Aggie

but they do add effective hp by reducing drag on the engine.

1Revvin7

Adding a lightweight flywheel/better clutch will not gain ANY hp.

pengaru

Actually, making the transmission of force from the engine to the rear wheels more efficient, will have an increase of power available at the rear wheels, which is where it really matters. So, in my opinion, the aggie is technically right, but only with regard to RWHP, the engine is not gaining horsepower, but more of the available horsepower is reachign the rear wheels. Like he said, effective horsepower.



In the case of a lightweight flywheel, the most significant gains are in the lower gears, where the engine accelerates through it's rev range most quickly, after 2nd-3rd ish the weight of the flywheel becomes pretty insignificant.





1revvin7, think of it this way, does your car accelerate quicker especially in 1st and 2nd gear after you put on a lightweight flywheel? Obviously yes. What accelerates your vehicle? Torque. What is horsepower? A product of torque, applied over time. Or, more appropriately, lbs-ft * rpm / 5252. It MUST increase the RWHP if the car goes faster afterwards, unless something else has changed, like the aerodynamics or gross weight of the vehicle... and losing 10lbs off the car or whatever the flywheel weight difference is, is definitely not responsible for the increase you get.



I think thats pertty clear, though I've been up all night working on a car, so I might be talking jibberish, feel free to correct me if I'm off.

roadkill669

I read an article in some domestic magazine that had a really good right up on this flywheel subject. I'll try to find it tonight. It deals with the inertia of the ecentric shaft. I could try to write about it, but I would probally be totally wrong. The article was awesome.

1Revvin7

I never said anything about rhwp

Streetrally

Modified Mag had a really good article on rotational mass on cars (e.g. lightweight pullies and flywheels etc) I'm at school right now so I'll post it up when I get home.

vosko

lwfw is not good for drag racing. its hard to launch

roadkill669

I couldn't find the article, but my friend (v8 engineer guy ) told me how it is:



An engine spins (duh). While it is spinning, it also has to spin a number of other parts (power steering, AC, water pump, gears, drive shaft, and in this case, a flywheel). All of these things weigh something. The faster they spin, the "heavier" they get to the engine due to rotational inertia. They also require more torque to keep them spinning. So changing the weight on them (lightining) allows the motor not to use more torque. You can put light weight everything on an engine and dyno it next to a stock one and you usually will get the same numbers out of them. But put them in a car, the one that has the lighter components on them will produce more to the ground. you change the ratio of hp and torque lost in the drivetrain. Thats why when you build a rae car (not drag), you use light weight engine components. Thats why when you take power steering off, or your AC off. When you turn your AC on, it adds ALOT of weight to the engine, thats why our cars bog down so much, we don't have the low end torque to begin with. You take a big V8, it doesn't do a thing. Every little bit helps in a way, when you start adding it all up, it does ALOT.



So you technically don't make horse power or torque, you just allow the engine to use it better.