Crank pulley questions
01-27-2009, 03:42 AM
#32
Senior Member
Join Date: 01-13-2008
Location: Washington State, where it rains
Posts: 4,708
Hmm...chevy sells em for this motor..and I bet somewhere on that package it says for offroad/racing use only.Yes drag cars use them..But then drag cars usually see lightening of the cranks rods pistons and just about everything rotational AND they usually see scheduled tear downs to inspect things.And they are infinitly balanced!Now, does the stock motor come under of any ot these catagories?Ive run drags and circle track and would never ever consider not having a damper..Ive seen what happens when dampers fail!If they weren't needed then why do they fail?Would it be because they move around?And is that because its absorbing crank harmonics?Gratnted,theres a counter shaft there,but just how finely balanced is the whole assembly? For offroad/racing use only.
01-27-2009, 03:55 AM
#33
Senior Member
Join Date: 01-13-2008
Location: Washington State, where it rains
Posts: 4,708
Heres an off topic question..why is it a lot of people say they are not building race cars yet want to put every race car part they can find on their car? But then only go half way. so now they have a vehicle that can pass everything but a gas station,but run a stock, waiting to explode clutch..or waiting to fade away brakes...or dying to break a valve spring thats only designed to run 6.5 k but is run up to 8 k.( this are just examples..don't bash the numbers).Or..this is a good one..playing lets twist the half shaft!!Some parts are good for the street..other parts are best left to the pro's who know how to compliment those with other parts.You can't mod one end without modding the other without having something pushed beyond its intended limits. Simple example..headers..on a motor with a stock air filter...now wheres the restriction?What have you really gained?
01-28-2009, 08:09 AM
#34
Senior Member
Thread Starter
Join Date: 03-08-2008
Location: United States of Texas
Posts: 505
I am building mine for mileage
I am building my car for mileage and so far it appears to be working but the results are not as consistant as I want. When I am done I may put it back to stock and do some tests to verify it.
My thinking is to open up the intake and exhaust to free the factory restrictive system, taller tires to lower RPM a little, lower it to help aero, air dam in front, and a Trifecta tune to bring it all together.
My choice in parts was:
1. Airiad intake filter
2. 2.4 intake manifold
3. 2.4 exhaust system with Cherry Bomb Vortex muffler
4. Goldline lowering springs
5. Home depot home made air dam.
6. 225.45.18 tires on Soltice wheels (I think a narrower tire would have been a much better choice) Taller tire is good wider is not.
I have not done the Trifecta tune yet which I think will be a big help. (I want to do it very last)
Right now my city mileage has went from 20-21 stock to 25-26 that is until it got cold and I think most everyone went to Winter blend fuel. It dropped back some. My highway mileage at 70 has went from 30 to 35-36.4.
Those numbers are significant and an improvent with out sacrificing any durability, ride comfort or anything.
Performance is just a little better than stock, the taller tires help the mileage but hurt the acceleration about the same. The intake and exhaust helped a little so right now my car in a race with a stock 2.2 is about dead even at the start and at higher speeds it starts to run better.
To be realistic my car is not making much more HP than a stock 2.2 and maybe not even as much as the 2.4 but it should be more effecient. Believe me it is getting a little better gas mileage but she does not make enough horsepower to break any parts!
When I do the Trifecta tune I fully expect 2 MPG in the city and 4 on the highway at 70. Plus it should perform a little better to. I am not building the car for performance although I believe it is a benificial side effect of opening it up to breathe.
One other thing I am hoping for is for the highway "Sweet Spot" to move up from 55 to maybe 65 or 70.
We will soon see how everything comes together but right now I can say one thing is it has helped mileage some but I am a little dissapointed in the consistancy. Even when it was completly stock, now it is better but not as predictable as I think it should be and I really do not know why.
My thinking is to open up the intake and exhaust to free the factory restrictive system, taller tires to lower RPM a little, lower it to help aero, air dam in front, and a Trifecta tune to bring it all together.
My choice in parts was:
1. Airiad intake filter
2. 2.4 intake manifold
3. 2.4 exhaust system with Cherry Bomb Vortex muffler
4. Goldline lowering springs
5. Home depot home made air dam.
6. 225.45.18 tires on Soltice wheels (I think a narrower tire would have been a much better choice) Taller tire is good wider is not.
I have not done the Trifecta tune yet which I think will be a big help. (I want to do it very last)
Right now my city mileage has went from 20-21 stock to 25-26 that is until it got cold and I think most everyone went to Winter blend fuel. It dropped back some. My highway mileage at 70 has went from 30 to 35-36.4.
Those numbers are significant and an improvent with out sacrificing any durability, ride comfort or anything.
Performance is just a little better than stock, the taller tires help the mileage but hurt the acceleration about the same. The intake and exhaust helped a little so right now my car in a race with a stock 2.2 is about dead even at the start and at higher speeds it starts to run better.
To be realistic my car is not making much more HP than a stock 2.2 and maybe not even as much as the 2.4 but it should be more effecient. Believe me it is getting a little better gas mileage but she does not make enough horsepower to break any parts!
When I do the Trifecta tune I fully expect 2 MPG in the city and 4 on the highway at 70. Plus it should perform a little better to. I am not building the car for performance although I believe it is a benificial side effect of opening it up to breathe.
One other thing I am hoping for is for the highway "Sweet Spot" to move up from 55 to maybe 65 or 70.
We will soon see how everything comes together but right now I can say one thing is it has helped mileage some but I am a little dissapointed in the consistancy. Even when it was completly stock, now it is better but not as predictable as I think it should be and I really do not know why.
01-29-2009, 07:46 PM
#35
Member
Join Date: 11-16-2008
Location: NJ
Posts: 68
I agree that a lightweight pulley will NOT result in a smoother idle. However, I have not seen a more erratic idle, and never heard of anyone else I have came across.
Lightweight pulleys do help performance. Less rotational mass...is less rotational mass. It takes less energy to move something that is lighter. You can not argue physics. During acceleration less rotational mass helps you get down the track faster. Ever put lightweight racing rims and tires on the car and go down the 1/4 mile compared to heavy 17's or 18's. I guess lightweight flywheels and pressure plates do nothing either. 
Every little bits helps doesn't it.
Every little bits helps doesn't it.
Will a un-damped pulley add more stress to the motor. Yes, but I and others believe it is not enough to effect or cause major problems. Our stock crank pulleys are no where close to balanced. Most CNC machined pulleys are VERY balanced, and normally do not require any additional balancing. Have you ever spun a stock crank pulley at 7,000 RPMS it wobbles and vibrates like crazy. Where a balanced CNC pulley doesn't even quiver.
I highly recommend getting a new crank pulley bolt. Since the stock bolt is torqued to yield. Some ecotec owners, while installing new pulleys, are not doing this, and the crank pulleys are working there way loose. Cobalt addition just had this problem with a customer.
Also, the oil pump is driven off the flats on the crank pulley snout. Extreme care needs to be taking to ensure the pulley is properly aligned and seated properly inside the pump gear.
Also, GM wants the motors to be as quite and have the least vibrations so Joe Smo has a nice quite comfy ride. While people doing performance mods normally do not care if comfort is lost in the pursuit of performance.
Heres an off topic question..why is it a lot of people say they are not building race cars yet want to put every race car part they can find on their car? But then only go half way. so now they have a vehicle that can pass everything but a gas station,but run a stock, waiting to explode clutch..or waiting to fade away brakes...or dying to break a valve spring thats only designed to run 6.5 k but is run up to 8 k.( this are just examples..don't bash the numbers).Or..this is a good one..playing lets twist the half shaft!!Some parts are good for the street..other parts are best left to the pro's who know how to compliment those with other parts.You can't mod one end without modding the other without having something pushed beyond its intended limits. Simple example..headers..on a motor with a stock air filter...now wheres the restriction?What have you really gained?
its funny cuz its true. Probably even more so with the Cobalt crowd since they are statistically younger i assume, but apparently its an issue here as well
02-02-2009, 09:32 AM
#36
Senior Member
Join Date: 06-23-2006
Location: Northeast Ohio in the Lake
Posts: 578
That is the pulley that GM used on early drag engines.....Its not recommended for street duty, and its never been used on any of the road racing cars(Time Attack, Koni Challenge) its also no longer used(not for some time either) on the drag engines either, they use aftermarket steel dampers, that are actually about the same weight as stock.
I said it wasnt really noticeable, but noticeable or not lightweight pulleys and flywheels/clutches degrade idle quality. As a matter of fact if you were to tear into a Koni Challenge car youd find they are running 100% stock clutches and flywheels. They ran Exedy Hypers for a while, but they were too light, the engine didnt like it. Will anyone who has one of these clutches acknowledge anything like this? Not likely as most people get a placebo effect from spending money. It doesn't matter what they bought you will find very few people who ever claim the product "X" doesn't work exactly as designed when it comes to bolt on mods of any kind.......
All very true, but you're talking about a 3lb 6.5" diameter pulley and reducing its weight by 40-65%, sounds impressive, but go to the other end of the engine now you've got a 10.2" clutch that weighs twice as much, losing weight their should be much more beneficial, and it is, but youre still not likely to ge true tangible gains from these things, wheels on the other hand is a much larger item, youre talking about four 18" wheels on an SS, that way about 24lbs each! You get even ONE moderately light wheel(say 20lbs) and youve already shed the weight of the ENTIRE stock damper. you replace all 4 wheels with true lightweight wheels and your easily shaving 32lbs of rotational weight, and as an added bonus its also un-sprung weight! There is no debating this makes a difference, the same cant be said for changing over to a 1.5lb 6" pulley. This of course doesn't even touch on the fact that I doubt you would ever find a single non-damped endurance engine.
Id go beyond and say its required. the bolt is torque to yeild, it MUST be replaced. The fact that people install a pulley and dont install the $9 bolt it needs is just indicative of the half assed mentality that was mentioned, I want a race car, but i dont wanna pay for **** or do it right.
Indeed it is, and this is actually why the GMPP unit was billet steel, to keep it from over expanding or deforming under stress and causing damage to the oil pump. Just another reason why nearly all of the pulleys(not just the MD :) ) on the market are a really bad idea.....they are aluminum.
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