ARe you guys kidding me? This guy is about to be cam w/ nitrous and you guys are saying shorties will be just as good"?
Agreed that most of the time long tubes dont do much for the truck, but on your daily commute neither does a cam, or nitrous, or a stroker kit, or any of the mods really.
OP if your building a race truck, weather it be a serious ordeal or not, Your cam is going to shift your powerband north, which is where LTs shine. A good tuner that knows his stuff will make a truck with LTs drive like stock. Dont spend all this money on ACTUAL go fast mods then screw it all up now...
At the low to mid end, the best way to maximize your scavenging effect, thus helping to maximize your engine's V.E., Is to move the exhuast out of the engine as fast as possible, or with as much velocity as possible. Long tubes work best for this because of their length, and their width (well, lack of width). Thier length allows an elongated path for the gas to flow, thus allowing the gas to leave the cylinder with more speed because the gas has more time to gain velocity before it hits the collector.
Now, you've heard car enthusiasts state that ANY restriction is bad for a motor, no matter what. This is not completly true, in your exhaust, small, strategically placed, smooth mandrel restrictions can be a good thing due to the fact that well place, correct sized restrictions followed by larger openings actually speed up exhuast gas flow. So the smaller diameter tubes actually serve your scavenging better in the mid and low ranges.
Mid and low ranges dont produce alot of actual exhuast volume, so small tubes dont restrict or "back up" flow.
LARGE, SHORT TUBE HEADERS MAKE FOR "LAZY" EXHUAST GAS SPEED WHEN EXHUAST VOLUME IS LOW!! (as it is in the low and mid range).
However, if you dont even begin to tip into your power band untill about 3700, you may consider short tubes. High RPM operation in a big motor (not talking about 4 bangers here), yeild LARGE amounts of exhuast gas discharge. THIS is where you need the larger diameter tubes, to get more volume out of the cylinder. THIS is where you can loose power due to pumping losses on the exhuast stroke. In an ideal world, your exhuast system would be soooo effective, that by the time that pistion STARTS coming up on the exhuast stroke, your ports and headers will have scavenged all exhuast gas out of the cylinder during the duration of the exhuast pulse. If there's no sizable amount to push out, there in a low pressure area in the cylinder (also known as vacuum), almost causing a "pulling up" affect on the piston. So, your not loosing power by pushing, your gaining power by being pulled.
Hope this helped!
This is a quote from a physics site I use, just some of the research I've been up to. From the sounds of it LT's will help power from low-mid range (ie. situations like daily driving/towing), I however do not care about my power in these areas of the powerband. My intention is to take the truck to the track a few times this summer, on 20 inch general grabber UHP's and see what it can lay down, these will be the only times that the truck will be seeing the high rpms and from what I know shorties can be beneficial (maybe not as good as LT's but so marginally close that it wont matter) enough to make the $650 for coated JBA's worth it for me. Also I want to get coated headers as I intend to switch to the efan and want to try to keep the heat down a little.
Thoughts?
