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My friend just bought a 94 G20 a couple of days ago. I have not yet had time to look under the hood for more that a minute.

My question is, what negative effects will installing an underdrive pulley have on the engine?

I am a member of newcelica.org. For our engines, the crank pulley serves also as a harmonic dampener. Replacing the OEM dampener with an aftermarket un-dampened pulley will result in probable oil pump failure due to the excess vibration. THIS IS A FACT for the 1zzfe and 2zzge engines. What about the infamous SR20DE? I'm assuming that it doesn't use balancer shafts, and also relies on the crank pulley to act as the dampener.

I have used the search function here, and found only questions about cost, and load put on the accessory components.

Thanks for any help.
 

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I can't really answer your question, but just FYI...a good example of a dampener is a spray bottle, it makes something damp...a damper is what you're talking about, it damps the vibration.
 

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The stock pulley is a damper. It is in two pieces bonded with rubber between them. It could cause problems, but not for a long time is the general consensus...

It will be more troublesome on RR cranks and non 20V SR20VE cranks due to the 4 cwt design.
 

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USDM 91-99 SR20DE 8 counter weights - underdrive crank pulley seemingly ok
USDM 00-02 SR20DE 4 counter weights - underdrive crank pulley (maybe) not ok.

The roller rocker USDM SR20DE engines USDM 00-02 should have problems using an underdrive pulley, however, in the last 6 years I have not heard of one having problems. Experts say they should not be used but... Most of the VEs are 4 countet weight, except the 20v.


[edit] Cross post with Mark...
 

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don't forget that when you use the underdrive pulley it also slows down your accessories and they won't put out as much. i.e., whater pump will flow less, alternator will not charge as efficaintly or put out as maky volts as it did before. things like that.
 

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SR20's have no issues with underdrive pulleys....so go get some and slap them on. 150K miles with mine on the engine and no problems to date.
 

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foreverzero89 said:
don't forget that when you use the underdrive pulley it also slows down your accessories and they won't put out as much. i.e., whater pump will flow less
Not necessarily a bad thing as the pulley will keep the pump from cavitation at high rpm.
 
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