2.0L Crankshaft Pulley
#41
An important point about the stock pulley...
It has a center section (hub) that is isolated from the pulley itself, using an elastomeric damper. The elastometric damper is used to partially isolate any nasty resonance effects that may otherwise become apparent from directly coupling the accessories to the crank with a single piece pulley design.
Although the CNC machined aluminum pulley itself will very likely be better balanced, the loss of the elastomeric damper will result in other undesirable vibrational characteristics to become apparent. For most people interested in improved performance... they may not care about this.
As far as the horsepower debate goes... I think everyone is stuck on what constitutes the "engine" and what constitutes the accessories, drivetrain, other loads on the engine... etc.
From a thermodynamics standpoint, the engine will not make more power. However, reducing one of the loads on the engine will allow for more of the power (that the engine already makes) to be made available to the wheels.
I don't think anyone doubts that the lighter pulley will make an improvement to the available power to the wheels. This is no different than removing an accessory load altogether... like a power steering pump for example or an a/c compressor.
The only real question is how much of a noticeable difference it will make. That's the question that we'll keep debating until someone gets some real numbers to back it up
It has a center section (hub) that is isolated from the pulley itself, using an elastomeric damper. The elastometric damper is used to partially isolate any nasty resonance effects that may otherwise become apparent from directly coupling the accessories to the crank with a single piece pulley design.
Although the CNC machined aluminum pulley itself will very likely be better balanced, the loss of the elastomeric damper will result in other undesirable vibrational characteristics to become apparent. For most people interested in improved performance... they may not care about this.
As far as the horsepower debate goes... I think everyone is stuck on what constitutes the "engine" and what constitutes the accessories, drivetrain, other loads on the engine... etc.
From a thermodynamics standpoint, the engine will not make more power. However, reducing one of the loads on the engine will allow for more of the power (that the engine already makes) to be made available to the wheels.
I don't think anyone doubts that the lighter pulley will make an improvement to the available power to the wheels. This is no different than removing an accessory load altogether... like a power steering pump for example or an a/c compressor.
The only real question is how much of a noticeable difference it will make. That's the question that we'll keep debating until someone gets some real numbers to back it up
In my personal opinion you do not need the elastic ring. The ecotec has internal balance shafts, and the small bit of vibration caused by a billet pulley can not be even noticed. poly engine mounts will cause 1000% times the vibrations that the crank might make.
#42
~~Claps~~
In my personal opinion you do not need the elastic ring. The ecotec has internal balance shafts, and the small bit of vibration caused by a billet pulley can not be even noticed. poly engine mounts will cause 1000% times the vibrations that the crank might make.
In my personal opinion you do not need the elastic ring. The ecotec has internal balance shafts, and the small bit of vibration caused by a billet pulley can not be even noticed. poly engine mounts will cause 1000% times the vibrations that the crank might make.
#43
The elastomer isn't a question of balance, either static or dynamic. It's the method of damping torsional resonant modes in the crankshafts themselves. There are scores of internally balanced crankshafts, but you will almost never see a production engine without a damper. Virtually every NHRA and NASCAR team out there uses ATI elastomeric dampers on their engines. These things cost several hundred dollars, and ATI doesn't give them out for free. Some crankshaft manufacturers will not even warranty their products if the dampers used are not on their approved list. The effect of these dampers isn't subjective. It's well studied and understood phenomenon that's been part of every engine designers training for the last 50 years, and unchecked torsional modes can wipe out main bearings and crankshafts in short order.
Also, GM Performance Ecotec Billet L61/LE5 Crankshaft Pulley p/n 88958631 does not include any elastomer...vibration damping ring.
#44
As of a couple weeks ago, the current/stock crank pulley p/n used on the HHR LNF motor is: 90537704
This particular p/n does have an elastomeric ring, isolating the hub from the pulley itself.
I can't remember if the stock Solstice/Sky LNF has a pulley with the elastomeric ring... I will have to check tomorrow.
-md-HHR
Do you have a link to a picture of the GM Perf Parts pulley, for the L61/LE5? Would be neat to see what it looks like.
This particular p/n does have an elastomeric ring, isolating the hub from the pulley itself.
I can't remember if the stock Solstice/Sky LNF has a pulley with the elastomeric ring... I will have to check tomorrow.
-md-HHR
Do you have a link to a picture of the GM Perf Parts pulley, for the L61/LE5? Would be neat to see what it looks like.
#45
http://www.strippermotorsports.com/ecbicrpu88.html
The picture isn't the greatest... oh well.
#46
Interesting on the GM piece. ATI makes an Ecotec model that has damping, and comes in regular or underdrive sizes AFAIK.
#47
This one looks like the JBP CAD model on page one of the thread, with a secondary smaller pulley for the power steering pump.
The oem pulley is 3 pieces:
- hub
- elastomeric dampener
- outer pulleys
#48
I contacted the individual with the understanding it was free he wanted feedback from a person with the vehicle... when i contacted him he wanted meto pay so i said i dont think so and never replied....
#49
Horsepower is a measure of work, changing the pulley has no effect on the output of the engine, it may allow the work to be used more efficently or it may chage the feel of that work, but it doesn't change the HP of the engine.
And FWIW, the ony real way to get an accurate HP number on a typical automotive dyno is at a steady RPM, otherwise it's up to the software how it figures the inertia in it's calculation of the current torque output.
And for those only interested in drag racing, if you have traction, a lighter pulley should make you slower, if you don't have traction a lighter pulley will make you faster. Same as changing the flywheel weight. In a drag race heavier is better, on a road coarse, lighter is better.
And FWIW, the ony real way to get an accurate HP number on a typical automotive dyno is at a steady RPM, otherwise it's up to the software how it figures the inertia in it's calculation of the current torque output.
And for those only interested in drag racing, if you have traction, a lighter pulley should make you slower, if you don't have traction a lighter pulley will make you faster. Same as changing the flywheel weight. In a drag race heavier is better, on a road coarse, lighter is better.
As far as lightened flywheels-I have direct experience having used them in the past. The car revs much, much faster. The only drawback is that it is more difficult to launch the car, since too little throttle and the car stalls due to the decrease in rotating mass of the flywheel. Once you master this, however, the car will rev quicker which means it will be faster. My Datsun 280Z had minimal engine mods, weight reduction from fiberglass body parts, and a lighter flywheel and it turned mid 15's. Traction was the biggest problem, both at the start, and shifting to second gear.
#50
Guys, big sale on the LSJ crank pulley, which fits the L61 & LE5. CLICK HERE