Pulley & Throttle Body Spacer

[punk2m1d]

So I was pokin around online and found this Scion 2AZFE Lightweight Crank Pulley & Throttle Body Spacer Combo

I'm not smart enough to understand what the throttle body spacer does, if anything. All comments welcome.

[navylife59]

The LW crank pulley looks OK but I would purchase from a proven company like NST, Agency Power, or Unorthodox racing with preference in that order but all 3 are good. As for the performance gains on a LW crank pulley, it is explained in the links below.

http://www.club-tc.com/forums/engine...ht-pulley.html

http://www.club-tc.com/forums/engine...s-more-hp.html

Now for the TB Spacer. They have been around since the earliest days of racing. They would space the carburetor up from intake manifold which would increase the plenum (the area where the fuel and air mixed). This would provide a greater are for the air/fuel to mix which, in turns creates more power in the mid to upper powerband. If the spacer was made from phenolic or other non-heat transferring material, it would help stop the dreaded vapor-lock that can plaque carburetors. It ideal of creating vorticies within the plenum to increase atomization has some merits, but only in carburetion and only with large fuel droplets. Swirling the already atomized (fine mist) can have an inverse affect by causing the fine mist droplets to combine into larger droplets within the slower flowing boundary layer of air surrounding the swirling effect. This boundary layer is caused by friction with the walls of the plenum chamber and intake runners. Puddling of fuel in the intake runners causes quenching of the ignition flame which can rob HP. This can also be engineered to the advantage in "hot" running engines to lower cylinder pressure (pre-ignition) and EGT's.

So how does this relate to EFI engines you are asking? First, OEM EFI engines inject fuel in one of 3 ways; at the TB (TBI), in the intake runner (manifold/head), or Direct -Injection into the cylinder. The 2AZ-FE utilizes the intake runner injection schema. Fuel injectors spray atomized fuel in a defined pattern directly into the intake port of the head. Swirling the air in the intake plenum really serves no purpose in this configuration. It may have benefits in the TBI setups but not here or Direct-Injection. In fact, swirling the air only serves to cause turbulence from friction and that friction will only slow down the velocity of the air. Not exactly what you want in WOT conditions. As for the ability to block heat transfered from the cylinder head thru the intake manifold, nothing to gain here. The fuel is injected at the cylinder head so no cause for vapor-lock. Also, the intake manifold itself is made out of high-temp ABS so no heat is even transfered to the TB.

To sum it up, these TB spacers are not designed for the 2AZ-FE. These companies take a general idea that is not universal and apply it to the 2AZ-FE to sell product. A respected tuner shop in Puerto Rico has done extensive testing on these units and discovered performs losses as proven on a dyno.

[punk2m1d]

As always, you give a full blown explaination to a simple question. Thank you, I appreciate all the new info I've learned here.

The guy that runs the shop I go to here in Eugene, suggested against pullies. Said they weren't worth the money. I've read the threads on this site about pros and cons and weather or not they kill the engine's life span, and still haven't made my mind up.

[navylife59]

Not one person has stated any issues, but all have been impressed at the butt dyno. The engine is internally balanced. If you look at the size of the counter-balance and you will notice that it is not much compared to older 4-cylinder engines. Now, if you were to do this on other engines, you might have a different outcome with balancing but not on the 2AZ-FE. Trust me, I would not have one on my motor if I thought it would damage my motor. Now, if you are going to run an all-out motor with LW pistons/rods at high RPM then you will want to run an external dampener.

[punk2m1d]

For sure. Alright, well now I'm gonna go back through those threads and read up as to which pully system I want. No underdrives, I know that much. Then it's off to google to find the pullies for the best price.

[punk2m1d]

Scion tC Alternator & Water Pump Pulley KIT for $168 incl. shipping. Should I keep looking? Or is this a good price?

[navylife59]

Whose pullies? I have the NST pullies and they work great. I think $168 is a bit much.