I have a 4.8 and trying to get out as much power as I can out of the engine. I already have a airaid jr. and aftermarket exhaust installed and will be ordering LPP longtube headers and a BB tune. Will getting a crankshaft underdrive pulley and throttle body spacer be worth installing?
is underdrive pulleys and throttle body spacer worth it?
- Thread starter Nosho47
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Yukon Lover
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Most people on here will tell you that a spacer is a waste and does nothing for the vortec engines but i have one and i think it gives it a little more go power especially with an air intake. As for just a crank pully im not sure. I had a set of pulleys (crank, alt, water pump)on another truck and it had quite a bit of power but also had other upgrades. I did notice though i had varying voltages on my dash gauge after so i took them back off.
Companies make them because people are gullible and will fork over money for them. Plain and simple. Think about how a throttle body spacer works...it's supposed to swirl the air going into the intake manifold. What benefit would that have for us? None. Any spin imparted on the intake charge would be broken up by the intake runners before it reaches the cylinders. Now, they DO work to some small degree on older carbed engines, and engines with TBI/single point injection "wet manifold" systems, because the fuel/air mixture is mixed a little bit more thoroughly before passing through the intake runners and reaching the cylinders.
On a modern engine that has multi-point direct injection, where the fuel is injected directly into the cylinders before combustion (ie, our trucks), there is ZERO benefit to adding a throttle body spacer. Since there isn't any fuel to be mixed in the intake manifold, imparting any kind of spin on the incoming air is useless. The spin is defeated before it can be of any benefit.
As for the underdrive pully...it might free up a few hp, but nothing all that noticeable. I'd rather have my accessories and AC working at max potential.
On a modern engine that has multi-point direct injection, where the fuel is injected directly into the cylinders before combustion (ie, our trucks), there is ZERO benefit to adding a throttle body spacer. Since there isn't any fuel to be mixed in the intake manifold, imparting any kind of spin on the incoming air is useless. The spin is defeated before it can be of any benefit.
As for the underdrive pully...it might free up a few hp, but nothing all that noticeable. I'd rather have my accessories and AC working at max potential.
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