Waldo5.0

Ok so.. I have an STOCK 03 Cobra. Been thinking about changing my s/c pulley. I've read that billetflow is a really good company to buy s/c pulleys.

I've read numorus thread about s/c pulleys.. from them creating too much heat.. to creating too much boost that they would be unhealth for the stock s/c..

So.. here is my question...
Can I order just the upper 2.76 pulley and the DiabloSport Predator tuner and be OK?????

Thanks in advance for your guys inputs

antiv6

not exactly,you will need the following
2.76 w/ hub (150 billetflow)
at least 1 100mm snub idler (130 billetflow)
new belt(40 gates or goodyear gatorback)
ngk-tr6 spark plugs(25 bucks gap at .35)
1.Predator/2.sct xcal/3.chip with a dyno tune for correct a/f (380/380/150 tune 400ish)

using a predator tune wont give you the perfect a/f
also may want to look into a larger heat exchanger and a head cooling mod
you can buy all the stuff at lethalperformance.com

xxkazp3rxx

If you put a smaller pulley on your car - you really want the heat exchanger/head cooling mod combo...

I might also suggest backing off the 2.76 to a 2.81, won't lose much boost.. but you won't see as much slip either... even with the idlers, lol.. my 2.81 doesn't slip on my stock idlers.

CobraBob

A larger heat exchanger is not really necessary with a smaller upper pulley unless you intend to do some racing (especially open circuit). I had both a 2.90 and 2.80 upper (504rwhp) with the stock HE and never had a problem. Heat was not an issue for me. I would agree that it is recommended, but it isn't a necessity in most cases. As far as the head cooling mod, doing it has nothing at all to do with the size of the pulley or any other motor mods. The purpose of the cooling mod is to reroute coolant to overcome the potential development of the tick issue in the driver's side head.

Belt slippage with a 2.81 will not be much different than a 2.76. Drive RPM @ redline for the stock 3.65 pulley is 13,534. With a 2.76 pulleythat increases to17,899. For the 2.81 it would be approx. 17,600. Not enough difference to really affect potential belt slippage. On the other hand, a 2.93 upper would be 16,860. A reduction of around 1,000 rpms over the 2.76. The truth is that any pulley under a 3.10 can produce belt slip with other contributing factors such as the condition of the tensioner, belt size and whether or not you have any auxiliary idlers. It is recommended that if you use an upper that is 3.00 or smaller that you use at least one auxiliary (100mm) idler. I chose to go with a 30-piece Billetflow idler set. All that said, I have seen on rare occasion little or no belt slippage with an upper as small as a 2.76. But that is not the norm. It is best to be safe and increase belt wrap (with auxiliary idlers) to reduce the chance of belt slip. One thing that will help eliminate belt slip is that Billetflow pullies are an anti-slip design. But that doesn't mean you WON'T see belt slip. Even Doug (at Billetflow) recommended auxiliary idlers with smaller pullies.

Another excellent way to minimize belt slippage is to go with an upper/lower combo. Lower crank pullies are much more difficult and time consuming to change, but it allows you to use a larger upper vs. going with a 2.76. A 3.10 upper with a 4 lb. lower. will get you the same max boost as a 2.76 upper. A very popular combo is a 2.93 upper with the 4 lb. lower.