Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 24, 2012 19:45:55 GMT -5
This thread is from 2009.
|
|
dogoman
A Boxer engine will fit in a Justy, its called a WRX
Posts: 445
|
Post by dogoman on Mar 24, 2012 22:54:11 GMT -5
Lack of traction because the engine is not as smooth as with a heavy crankwheel causing shuddering at the wheels down the drivetrain like a drag car without drag bars on the rear axle with soft springs hopping up the strip. I call bullshit.... lightening the flywheel has minimal effect on smoothness in most instances, EXCEPT with some odd clyindered engines, if that was the case as you are seeming to say, you couldn't take a flywheel off an engine and fit a flexiplate and expect it to hang together. If what you say is true, explain why my race car has a flexi plate that does nothing but hold the ring gear for the starter motor to drive on, and the gearbox (well, its sort of a gearbox, it contains 2 dogs and is direct drive) has minimal rotating mass, and I have no issues with handling or traction on the race track. As for the drag engines, I have a customer making over 2000 hp out of 550 cubic inches and he has no flywheel at all, just a direct drive to a modified automatic trans with no torque converter. Shuddering or axle tramp as its known is actually due to the tyres gripping and releasing then gripping again, and is adjusted out by clutch adjustment, tyre pressures, suspension settings etc, and can occurr any time depending on the day. Drag bars are only there to prevent excessive wheelstanding if you get the settings wrong and get too much grip, they are not used to prevent axle tramp, and actually assist in making the rear wheels skip if you get on the wrong side of the grip vs power line. I think you are confused between rotating mass, and engine / drivetrain balance. 2 totally different things entirely. Lightening the flywheel on a justy can be done, but since the weight of the flywheel is being used as a harmonic damper, you will notice an increase in vibration when lightening by simply removing metal. If you want to lighten a justy flywheel, do it properly and get the entire rotating mass (flywheel, pistons, crank rods and balance shaft) balanced properly.
|
|
dogoman
A Boxer engine will fit in a Justy, its called a WRX
Posts: 445
|
Post by dogoman on Mar 24, 2012 22:54:41 GMT -5
This thread is from 2009. so it is, who dredged this up?
|
|
|
Post by Captain Nemo on Mar 24, 2012 23:00:41 GMT -5
Yeah, and it's still true that the lack of traction is brought on in LOWER gears by the ability of the engine to put more power to the wheels, rather than to accelerating the fly wheel. My 300zx revved the same speed in 1st and 2nd gears as it did out of gear, because the flywheel was so heavy. Also a lighter flywheel improves throttle response, since it soaks up less power/feeds back less inertia. The flywheel on a Justy is very heavy for the size engine, mainly because of the diameter, smaller meaning less inertia so need more weight, but also the energy soaking ability of the weight smooths the pulsing of the odd cylanders at lower engine speeds. By all means, strip the weight. Just be aware that large decreases in the weight will allow the engine to creep it's speed up or down to some degree, when cruising.
|
|
|
Post by doctormcgoveran on Mar 25, 2012 0:02:57 GMT -5
I suspect dogoman has a black and white view of the world. The fly wheel weight does contribute to smoothness, and traction. The fly wheel averages out the pulsations from the crankshaft, by absorbing the energy when the piston is accelerated by the power stroke and releasing the energy as the piston moves during the other three strokes. The greater the rotating mass at a given rpm the less velocity change required to absorb and release the same energy. The less the velocity change the smoother the system. The greater the rotating mass, the less velocity change with each pulsation and the less velocity change available to break loose the tires the greater the traction. Axle tramp is an undamped oscillation because the system is being driven at a natural resonance frequency. Adjusting the clutch or the tire pressure, or suspension setting changes the natural resonance frequency of the system. The grip and release of the tires is a symptom of resonance in the system, not the cause. These principles apply to many systems from electrical generators, tractors in fields, and even subaru justys!!
|
|
dogoman
A Boxer engine will fit in a Justy, its called a WRX
Posts: 445
|
Post by dogoman on Mar 25, 2012 1:37:51 GMT -5
I never said it didn't contribute to the smoothness, its the interrelation between weight, or lack of it affecting traction that i'm disputing. Lightening the flywheel allows the engine to accelerate or decellerate faster, but traction is due to friction between the parts in contact with the ground, not the speed things are rotating at. Simply stating that lightening a flywheel will give you less traction is not correct. Getting the revs up faster will not result in less traction, it will result in greater acelleration, assuming friction remains the same. Its when you have enough power available to overcome the friction between the (on average) A4 sheet of paper sized contact area and the ground that you get wheel spin. Lightening the flywheel can cause engines to produce more power, sometimes it actually reduces the power output, it all depends on the engine. This is why a difference of less than 1/4 psi on a drag car means a blistering 1/4 mile run with the tyres just on the edge of breaking their grip, meaning all the powers going to the ground, and simply frying the tyres in wheel spin due to loss of traction. Nothings been changed in the engine, its still got the same rotating mass.
|
|
|
Post by =Justyless= on Aug 2, 2013 22:15:57 GMT -5
Lol wow haven't been in this forum in forever just to find out there was an argument here 2 years after it died lol. Justys here in Cali are only getting harder and harder to find. I've had a 1990 civic for a while, my build has changed a lot since my very sad attempt to build my justy lol. This was a good read though, brings back memory's. My civic build www.ef-honda.com/main/viewtopic.php?f=2&t=44677
|
|