At what point are headers "worth it"?

people running headers also change from stock exhaust and mufflers to...bigger exhaust pipes and free flowing mufflers... so is it the headers giving the performace gain and sound or the pipes and mufflers...
anyone have any header only change numbers to prove or dissaprove this.

 

The Doug Thorley shorties were no problem to put on and no leaks or bolts coming loose. They fit with power steering with no drop bracket. There could have been a problem with the column shift linkage for the C4. Don't know about that since the bell crank was eliminated because the 5.0 block didn't have the mount for it.

Wasn't hard to install the headers but might require lifting one or both sides of the engine. Headers went on while engine was being installed so lifting the engine was no problem.

They don't interfer with the spark plugs and no problems with burned wires or boots. Obviously no road clearance issues.

I don't know how much better they flow than the stock manifolds but for sure they're lighter.

I would guess the stock manifolds would be OK with the stock '72 heads, stock intake, and 2 barrel carb but if a 4 barrel, aftermarket intake, and improved heads are in your future I'd think you'd want to replace the exhaust manifolds.

 

I have to disagree about people putting headers on and also putting bigger exhaust pipes on at the same.
I think most people already have dual exhaust and first put headers on. It's fairly easy and you don't have to break the bank to buy a complete exhaust which can cost some big bucks.
As I mentioned in my earlier post talking about my 97 Mustang Cobra, the results were done on a chassis dyno which measured rear wheel HP and did show a gain with both the "FMS Shorty Headers" and then when I replaced the complete system including the Cats I gained more.
So, I guess this question has as many answers are there are letters in alphabet, it really depends on the car, motor.................etc. Take the new Mustang GT500, put a set of long tube semi-tuned headers and get 35hp without changing anything else...................I'd say that's pretty impressive!
IMHO

 

Headers are just one component of the entire engine. To make power they have to match the carb, intake, heads, compression, and the rest of the exhaust system. Putting huge headers on a stock engine will hurt your performance more than putting small headers on a strip performance engine.
Making the best power requires careful selection of all the components you use.
Can headers improve the performance of a stock engine? Yes, but only if they are made to enhance the stock configuration. small primary tubes that are longer than most headers available with smaller but longer collectors and a properly sized "H" tube after the collector. Mufflers the same size as the collectors and then smallish exhaust pipes to finish it off. Keeping the velocity high, which keeps the temp up is the key to making it work best but tubing size and tuned lengths are also critical to get the real advantages from the header/exhaust system.
The advantages on a stock engine are a bit better mileage and a tiny increase in power when the engine is all tuned to make it work. It would only be worth "the hassle" if you get GOOD headers that last a long time and fit well but you are not likely to ever get the money out of the cost in benifits.

 

I've read negligible gain on hp for the installation effort, but nothing concerning trq; any comments pertaining to this?

 

Put very simply, you can relate torque to air velocity, and HP to the volume of
air flow. The faster the air enters and exists your motor the more torque you make, and the more volume of air you get through the motor, the more HP the engine will produce and what you want is a combination of both.
Personally I think one of our 302's that is makeing 300hp (which is not to hard to do) could probably use 1-1/2" primaries (long tube), now if you add a supercharger to that without any other mod's you would need to use 1-5/8 to 1-3/4" primary headers, for nothing else other than the volume increase.
But as was mentioned earlier, the complete motor needs to be built for a specific purpose and then the headers are designed with everything else taken into account. So off the shelf headers are usually just a compromise as no two motors are alike and header manufacturers couldn't afford to make 15 different types for one car.
Scavanging and velocity are the key players here, and on a street motor the whole system has to be considered, but in a race only motor you only need to worry about the primary tubes, headers flange, lenght of tubes, what type of merge collector to use, megaphone and cone type, like reverse cone, megaphone and length...............
Also one thing no one except Paul has mentioned is exhaust header temperature. If you can reduce the heat in the engine bay by 30% you can almost bet on a 5 to 6% increase in power output, and ceramic coating can do that and will help scavanging by keeping the heat in the header, not going into the engine bay..................IMHO

 

Ok - it sounds like the only thing we're gaining with headers on a fully stock 302 / 2V engine is (probably) improvement in exhaust tone. Which is good, I'm all for that - just not sure I'm willing to risk the hassles for better sound this early in the game.

 

I'm well aware of what's involved in FAST racing, I was just throwing it out there to say you can build power with manifolds and using FAST as an over the top example.

 

a fully stock engine (the topic of this thread) has single exhaust. if you just change to headers the sound will not change...JMO

 

In my own experience, even with a relatively stock motor, you should see a small gain in power, and a notable gain in gas mileage, especially if you play with carb tuning, you may need to rejet a size or two.

Historically, it is pretty well established that headers will provide a gain on even mild motors. Just stay modest on the pipe sizing. And the good news is that as you do other mods, they become more important.

If you take a good look at the manifolds that came on our cars, I can't see how anyone would call them good, especially the passenger side. It was a "log" that made the accountants happy. Keep in mind that exhaust gases are their hottest and most expanded straight out of the port. Some stock exhaust systems will step down in size slightly, the further you get from the motor, and this is OK, ... cooling gases don't take up as much space.

I would go with modest headers, 2.5 inch pipes and some tame performance mufflers ... room to grow, and the car will be more fun to drive right now.

 

modest headers, 2.5 inch pipes and some tame performance mufflers...

on a 2V stock 302, will make it a turd...JMO

 

but it will sound cool:bananaman
JMSAO

 

Appreciate the refresher on scientific theory; I should have posed my question differently. Has anyone experienced a difference in torque before/after installation via dyno?

Although I'd read years ago that the A/C will decrease overall hp up to 7%, how accurate is this?

I will always endure the pain of long-tube header installation because I believe in allowing the motor to "breath." I can build from there, no matter what direction I pursue.

Reduced temperature explains why performance is better at night.

 

OK, I am restoring my 73 Comet GT now. I am installing a 5.0 roller motor with a 5 speed manual out of a Cobra. The current motor has headers & I assumed I would re-install them with the new motor. I want to put on side pipes. So the question is: headers or no headers?

 

Obviously I'm no expert - heck, I started the thread LOL - but wouldn't dropping in a completely new motor tranny combo with the stock 5.0 shorty headers would make life easier - assuming the shorties themselves don't bonk into anything to start with.

Either way, it seems like stock manifolds or shorty headers would make hooking up sidepipes much easier because you have a greater net distance to work with for the connector pipes (from header collector to sidepipe inlet.) Getting to the sidepipe inlets from the collectors of long-tube headers would require some fairly abrupt bends wouldn't it ???

I understand the tongue-in-cheek response, but on a serious note are you saying this will actually hurt the cars performance?