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Underdrive Pulleys

  #1  
Old 01-28-2008, 11:56 PM
bcrichguitars's Avatar
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Default Underdrive Pulleys

I was reading a different thread and many people were saying uderdrive pulleys aren't a very good modification. I was thinking of getting one for my turbo civc, is it not a good idea? Whats so bad about them?
 
  #2  
Old 01-29-2008, 08:19 AM
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Default RE: Underdrive Pulleys

Inline-4 engines aren't naturally balanced. When they go through a full cycle, there's some slight vibration. At higher rpms this is a lot more noticeable. To offset this, most I-4 manufacturers add weight to certain areas of the crankshaft to balance it. The crankshaft pulley, attached to the end of the crankshaft, is probably included in the crankshaft balancing. Changing the weight would very likely change the crankshaft balance (and perhaps lower your actual max rpm).

Why wouldn't a car manufacturer make the pulley smaller if they could? It'd cost them less materials to make in the first place and they'd deliver a product with (1-2 hp) more power. There's a balancing reason behind this, and I wouldn't be one to question Honda on it.
 
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Old 01-29-2008, 08:41 AM
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Default RE: Underdrive Pulleys

Its not a good idea. Your going turbo anyway and going to make good power, do you really need to get 2 more hp from the pulleys?
 
  #4  
Old 01-29-2008, 09:09 AM
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Default RE: Underdrive Pulleys

If you want added performance, look into weight reduction. If you strip your car down of the soundproofing in the doors and remove carpet, you can lighten up your car by several 10's of lbs. This will improve acceleration, braking, and handling. It'll also cost you nothing more than some elbow grease It won't impact the durability of your car, though removing soundproofing might make it a little noisier to drive.
 
  #5  
Old 01-29-2008, 09:50 AM
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Default RE: Underdrive Pulleys

i had a light weight pulley on my car and the damn thing was a pain in my a$$. Had to use a chain wrench and 3 foot breaker bar with a 4 foot pipe attached to it. It helped a little but not the cost of a new oil pump that almost went out. Unless you get a fluidamper i wouldnt get one, they just spell bad news
 
  #6  
Old 01-29-2008, 10:20 AM
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Default RE: Underdrive Pulleys

the amount of acceleration you gain is pointless unless you are taking it to the strip. And its not going to be a bullet after weight reduction. unless you drag its a waste.
 
  #7  
Old 01-29-2008, 01:00 PM
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Default RE: Underdrive Pulleys

Onlly have 1/4 tank gas at all times, the weight you have just shaved off is going to net you free hp. Ever had to lift a gerry can with 35 litres in it? Its heavy as ****.
 
  #8  
Old 01-29-2008, 02:54 PM
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Default RE: Underdrive Pulleys

http://crx.honda-perf.org/articles/battrep/battrep.html

"If you consider that every six pounds of weight you save is equivalent to one horsepower, you can see where simply loosing some of that battery pork could help the performance of your Honda, whether you're driving on the street or the track. "

Using these numbers, stripping that interior could amount to between 6 and 12 lbs, which would be equivalent to the 1-2 hp that the underdrive pulley would give.
 
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