Is an UR Ultra S underdrive crank pulley going to mess up the timing on my H22A? 'cause i bought one and my dad is convinced it is. Thanks alot.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NobodysHero &raquo;</TD></TR><TR><TD CLASS="quote">Is an UR Ultra S underdrive crank pulley going to mess up the timing on my H22A? 'cause i bought one and my dad is convinced it is. Thanks alot.</TD></TR></TABLE>

what timing?

you measure ignition timing on an H22a on the flywheel, not the crank pulley

 

you wont mess up the timing but it will gradually cause your crank to walk if its a daily driver. they're not really reccomended for daily driving because they are lighter and not balancrd w/ the crank.people do run thme on the street but most use them on a weekend/drag car

 

Alright thanks alot, i knew he was wrong, hes always wrong..........I love you guys.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95deckedlude &raquo;</TD></TR><TR><TD CLASS="quote">you wont mess up the timing but it will gradually cause your crank to walk if its a daily driver. they're not really reccomended for daily driving because they are lighter and not balancrd w/ the crank.people do run thme on the street but most use them on a weekend/drag car</TD></TR></TABLE>

your first statement is not proven whatsoever. lots of people use them but I wouldn't on my car personally

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by satan_srv &raquo;</TD></TR><TR><TD CLASS="quote">your first statement is not proven whatsoever. lots of people use them but I wouldn't on my car personally</TD></TR></TABLE>

i know its not proven, but it cant be good. if you wont, i wont and others wont it must mean something

 

A stock crank pulley is designed for the stock reciprocating mass of a stock motor. The OEM pulley is designed to remove the harmonics in relations to the OEM pistons and rods. Here is where problems with the UR comes into play. The pulley is designed to be lighter, and by reducing the reciprocating mass of the rotating assembly you are going to pick up power. The problem is that it is not specifically designed for each motor to tune out the harmonic vibrations, this is where engine damage can come into play.

If you are running a motor with aftermarket rods, pistons, flywheel, and a lightened crank pulley then you are further increasing the amount of harmonic vibrations that will be produced.

So what are harmonic vibrations?
Each time you combust a/f you get a torque spike, an extremely rapid rise in cylinder pressure. This pressure is then transfered to your piston, which is connected to your rod which will be then applied directly to your crankshaft through the rod. Not only does this force turn your crank, but it can also deflect/twist it. A "twisting action" and rebound is known as torsional harmonic vibration. As RPM's increase you will notice the amount of 'twist/deflect' will greatly increase. What do H series cranks tend to do again when reved up to 9k again? I know rod/stroke ratio has a factor in this as well, I am just simply pointing this out for the H series people that think running a lightened CP with a 9k redline equals safe power.

What do harmonic vibrations do?
A lot of bad things. They can very easily cause wear to your main bearings, main journals, kill oil pumps, and also lead to the crank breaking into pieces.

To counter this you can run a harmonic balancer/dampener. Not everybody runs these and you are not going to benifit from them if you have a simple bolt-on application, but if you have a fully built race motor then I highly recommend one.

Cliff notes: I wouldn't use a UR crank pulley on a daily driven car.

 

dang y0! you should write a book

my thoughts exactly