My mechanic tells me that unless I plan on installing a supercharger on my 06 GT (which I do not plan on doing), it is really not worth the expense of installing Long Tube Headers. He says that Long Tube headers on a naturally-asperated car actually slow it down? He recommends that I install FRPP shorties. Now correct me if I'm wrong, but I thought that on the new mustang GT (05-07) shorties really weren't much more effective than the stock manifold. My mechanic claims that shorties are good for an additional 8-10 horsepower. I asked him about mid-length headers which he advised me not to get. Can anyone confirm or deny my mechanics claims?

 

From what I heard, shorties aren't worth it. That's why I got Long Tubes. I'm not supercharged neither. I do not think the shorties gain 8-10.

 

That "mechanic" has NO CLUE.

He actually has it backwards.

Longtube headers make the most HP, especially on a naturally aspirated motor. First you have to understand why headers make HP. First off, both shorties and longtubes are designed to provide smooth passageways which the exhaust gases can flow through. They have gentle curves and smooth shapes which provides as little restriction as possible to the exhaust. This is an improvement over cast iron manifolds, which have a rough finish from the casting process, and which usually have tight turns with little regard to smooth flow. (As a side note, the OEM manifolds are actually very good as far as manifolds go)

Second--and this applies only to Longtubes--the diameter and length of the primaries (the tube between the exhaust port and the header collector) are carefully chosen to match the operating RPM range of the engine. Also, all the tubes are made to the same length (which is why some header tubes snake back and forth) The idea is that the exhaust gas pulse from one cylinder can be timed (with the correct length of primary) to literally help SUCK the exhaust gas out of another cylinder later in the firing order. This is called scavenging. Scavenging gets rid of the exhaust gas from the cylinder faster, which in turn brings in a fuller, denser, intake charge.

Shorty headers don't scavenge becasue the primaries are too short and are usually not equal length. All shorties can do is smooth out the flow a little bit compared to stock. LT headers do this AND they scavenge. That's why shorties are worth between 3-5 HP, and longtubes are worth 15-25 RWHP.

On a supercharged car things are much less important. Because you've got pump literally FORCING air into the engine, scavenging is an insignificant detail. On a supercharged car you don't really care about exhaust tuning. You want the shortest, least restrictive, set of pipes you can get.

 

CrazyAl, thanks for the info and confirming what I thought all along! Any thoughts on midlength headers? I am wondering if I should consider these because I have a lowered car and I am concerned about bottoming out, and also longtube headers may not be legal in my state.

 

yea i was wondering the same thing i lowered my car with the eibach pro kit so its only lowered about 1 inch will i have to worry about bottoming out with the LTs? and let me get this straight if im planing on gettin a supercharger i should go with shortys?

 

post links to the mid length headers because most people haven't heard of them.

Also header whether shorties or not help the most on a supercharged car because they are much less restrictive than the stock, it's like blowing through a straw vs a straw full of grass. It still is important whether it's restrictive or not. you'll get a larger gain out of an SC car from longtube than from an NA car.

 

Find a new mechanic that guy is clueless. As CrazyAL explained if your going to stay N/A L/T's are the only way to go, shorties don't offer any improvement over stock manifolds. Stay with 1 5/8 in tubes on the L/T's also for N/A application you only need the 1 3/4 inch for FI. The Kooks are about the best L/T for a N/A setup as they are more 3/4 than full length like the American Racing and others. Those are the 2 brands I would recommend as they are both offer top notch quality and fitment. I had Kooks on mine when it was N/A and loved them.


Earl

 

bbk anyone? or would you recommend something else? i can get a pair of hooker headers ceramic coated for 500

 

I love my Bassani Mid-length headers! Shorties on a 4.6 are a waste of time, no real gains for the money. Long tube headers will make more torque than the mids (maybe 5ft lbs) and the horse power may be down 2-3 compared to long tubes but, YOU MUST REMOVE ONE LONG TUBE HEADER TO REMOVE THE TRANNY/CLUTCH. Mid length headers leave plenty of room, I even did a T56 swap with both headers on...piece of cake.

 

I'm lowered with Roush springs and have the Kook LT's and have no clearance issues. I don't think they are full length but the fit is awesome.