i have shorty headers now..but im looking for more power..and i have a cam to install but just havent had the time yet but my question is...is it worth it to get long tube headers if i already have shortys?

 

Are you going for high RPM performance or low RPM performance??

And is this mass air flow or speed density??

 

If it's a 5.0 definitely get some LT's.. that motor needs all the torque help it can get.

 

Another vote for the longtubes. They are fairly cheap too. Don't waste your time on shortys

 

Correct me if I am wrong, but these headers don't do ya much good till after 4000RPM.

Unless you got heads, intake manifold+plenum, cam and throttle body + the proper fuel system that match that power range, you arn't doing yourself much good. You are just mismatching parts.

And this kind of high RPM powerband just aint that desirable in a truck.....

 

well im not looking for high rpm..i have the 4spd manual with the granny gear..its my daily driver and it just doesnt "get up and go" so to speak..i just would like to accellerate a little faster..

 

what motor are we talking about here?

 

That's complete nonsense... who has been feeding you BS?

 

I wouldn't consider that statement BS per say....

He's generally right....you're not taking full advantage of a header unless the rest of the engine is modified as well.

It would be a "mismatch" to throw long tubes and a full exhaust on one of these engines. But it would be a mismatch that doesn't produce a noticeable side effect.

We see this a lot when people put together a head, intake, cam, exhaust combo that is a mismatch and poor performance is a result. If the components chosen work together appropriately, than max performance is achieved.

In an ideal world, you'd put the long tubes on with a head/cam/intake system that cooperates perfectly with it for an ideal output.

This is why we see stock engines that have the size intake, throttle body, cam, etc that we see. They're all designed to match and work with eachother.

 

I'll agree you won't get full potential from headers with a stock motor, but if recent threads are any indication people here are building high output engines from scratch that are a mismatch of components and as a result are not seeing the motors full potential. Technically nothing short of a full race engine will take full advantage of tubular headers.. but how practical is that in a street driven truck?

In the case of long tubes and a full exhaust the low rpm gains are real and substantial on this vintage engine. Been there done that. The OP also has a cam to install which will provide another power boost over stock, and this afterall is the goal of these upgrades.

 

The OP also has a 1987 truck and unless he has a mass airflow conversion kit to go along with this cam and headers the computor will get it's panties in a bunch.

A true dual exhaust with headers (I am assuming he will do true dual) does not provide the ideal velocity of exhaust gas for good low rpm performance but at the same time helps high rpm performance. In a truck, high rpm performance just is not practical. It's all about the speed of the gases. I have yet to see a dyno test that proves otherwise. But if you (Conanski) have proof of the of the contrary, please share. I am always looking to learn more.

 

Evidence to the contrary...
My '89 F150 had the factory speed density system, ran just fine and performed much better than stock, with a full MAC exhaust that included longtube headers, high flow cat and single 2.5" cat back. There are plenty camshafts available that work just fine with speed density computers as well, including the one I have in my SEFI 5.8 at the moment. Don't forget, the 5.0HO mustangs only got mass air in '89. The '88 has the same cam, which is a lot more cam than the trucks ever got, and that motor works great and responds to many of the usual bolt-on goodies like high flowing exhaust. The stock SD system cannot handle as much hot rodding as the mass air system, but that's a limitation of the stock programming, not the system. With an the right programming tool you can make an SD system run a 500hp motor.

Low rpm torque production is all about increasing air flow into and out of the cylinders. This is a particular problem at low rpms because airflow is starting and stopping so cylinder filling is not at an optimal level, and some exhaust stays in the cylinder further diluting the mix. The air velocity in the longtube runners is maintained longer than it would be in the factory manifold and Y pipe assembly, thus creating a better vacuum for the next exhaust pulse. This helps empty the cylinders better at low rpms, which helps fill the cylinders, which builds more torque. In some header designs(tri Y), the exhaust pulse from one cylinder is used to create a vacuum for the next cylinder in the sequence. The benifit here is obvious.

My '89 F150 could not chirp a tire in stock trim, and it would loose speed on even the slightest grade at highway speeds. With the exhaust added to an otherwire factory motor, it could lay rubber from idle when you planted it,(with a tight LS diff) and had no trouble maintaining hwy speeds on all but the biggest hills where a downshift was needed.

P.S. 5.0 Mustang did a dyno test comparing short tube and long tube headers. The graphs clearly show the longtubes make more low rpm torque..
http://www.mustang50magazine.com/techarticles/29618/