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What is the point of 180 degree headers? They seem to me to be a way to use your engine bay as a heat exchanger, basically you use your engine and bay as a giant heat sink, attempting to prevent all possible heat loss to the outside world. Is the 180 degree part the temperature of everything under the rear lid when they are installed?


Anyway, what is the advantage, I gather there is a performance advantage but I'm not sure what the "180" part gets you. Isn't running the exhaust down and out with large-bore long-tube headers with minimally restrictive mufflers accomplishing the same thing?

Educate me.

As an aside, I have just had my original ANSA units blasted and coated so they are going to be around for awhile. Is there a header upgrade I can use with my original heads and exhaust? Thanks.
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I'm sure there is a connection to the Ford GT40 program with the 180 degree headers. If the winning LeMans cars have it, then what would it do to a road car --- I guess that is the best answer that I can give. I do not know of any dyno testing to support the hypothesis that it gives sufficiently more power -- so there you have it.
If I recall correctly the 180's optimize the exhaust pulse from the cylinders. The 180's allow you to match to an exhaust port that is in a better position of the power/exhaust cycle to help "scavenge", meaning to help pull forward the exhaust gasses from the opposing cylinder which in turn creates a cleaner, more HP producing combustion in the next cycle.

The game is to get as much "dirty" atmosphere out of the cylinder and get more fresh air in as possible, the 180's are a tool to do so. It was by coincidence that physics gave us a bitch'in looking exhaust sytem with a distinctive tone.
The "throws" of V8 crankshafts can be configured in either a "cross plane" design or a "flat plane" design. The configuration of the crankshaft is what gives certain V8's a burbling exhaust tone, while others (like the Ferrari V8's) produce a smoother exhaust tone that has a "whine" to it. A "cross plane" crankshaft produces an exhaust tone that burbles, a "flat plane" crankshaft produces an exhaust tone that has a smooth whine.

The firing order of the 4 cylinders in each bank of V8 engines with a "cross plane" crankshaft are not evenly spaced, so when the exhaust of all 4 cylinders in the common banks are connected in a common collector or header, the result is that uneven exhaust "burble" we all love so well.

However, that unevenly spaced firing order per bank results in uneven "pulses" within the exhaust system for each bank. That robs power. How much power you ask? About 30 to 40 bhp, depending upon the state of tune of the motor. That's too much bhp for a racer to give up.

The purpose of the "bundle of snakes" is to even out the spacing of the firing order in each side of the two exhaust systems, evening out the pulses, and gaining that 30 to 40 bhp that would have otherwise been lost.

cowboy from hell
Last edited by George P
Ok, cool. What that tells me is that there is an optimum length and obviously order of the pipes that cross over. I would be wary of making my own setup (not that I could anyway, I am speaking theoretically) but would want one that someone with an engineering degree had figured out. Are there setups that are considered historically correct when compared with the factory race cars? Anyone that knows also don't forget to chime in with answers to my more personally practical question above as well. Thanks.
The correct grouping of the exhaust primaries depends upon the firing order of the engine in question. The Cleveland firing order is:


To evenly space the exhaust pulses in each side of the bundle of snakes, you'll group the primaries so that every other cylinder in the firing order is in the same grouping.

Collector A: 1-7-6-4

Collector B: 3-2-5-8
72 Red,
Your question is why I posted the links at the beginning of my header build segment.
They include the theory of the principles behind the 180 degree design.

Here is where it has been discussed on the PIBB before.Lots of pics of installations here.

In conventional cars most people use a X pipe to accomplish the same thing. Even out the pulses from bank to bank. George explained it well.

There are "Historically" correct designs as applied to the GT40 because the GT40 "Historically" used them. This involves making them correct in the materials used and the routing as based on the original race cars.

I imagine that there is a magic number that would be your engines optimim primary length but I know of no way to determine this other than Dyno testing different lengths.

As a rule longer pipes boost mid range and shorter ones boost top end.

The typical Pantera header is very short. 180's allow the ability to use a longer pipe.

I am going to push that limit when I build my under car set and see how long I can make them.

I am building both the 180 and undercar systems for my car and I will chassis dyno both to compare them but that is a long way off.

Did I mention that 180's look cool and I'm sure chics dig them. Big Grin
Last edited by pittcrew
Just to add you will find it's the two middle cylinders that are crossed over on each bank. This all balances out the firing order as the next cylinder to fire exits out the opposite header as this is not the case with regular headers. As mentioned this is eliminated with a cross over pipe yet it's not as efficient as a true cross over header. The back two cylinders get the extra pipe added to make all cylinders have an equal length tube. It's definitely a different sound. This discussion could be taken deeper as you could get into the intake side of the engine and find that independent runner system would be the ultimate as a 4bbl intake has two short runners in the center and longer ones to the outside cylinders. That's another story....
In the end you have a good pizza warmer.
I just wanted to add a couple of points I didn't mention earlier.

When I wrote earlier that a bundle of snakes exhaust system is worth 30 to 40 bhp, that's under racing conditions, i.e. unmuffled. Mufflers alter the dynamic of an exhaust system tremendously, there's no guarantee a bundle of snakes will add anything, I'm not inferring they don't make more bhp, but exhausting through mufflers the gains will be less than 30 bhp. But they do sound bitchen.

A well designed collector covers a multitude of sins in regards to tube length, so when long tubes are difficult to fit into a chassis, it becomes more important to provide a generous collector. This is where the majority of Pantera headers fail, in an effort to provide long primary tubes, they leave no room for a collector of any length at all. This is where Pat Mical's headers differ from the others, and why you've seen those headers recommended so many times here. His headers are also beautifully constructed, but all that craftsmanship comes at a price. Again, if your exhaust system has mufflers, its hard to predict just how much gain primaries of the right length, or a well designed collector will provide, if any at all.

In my opinion, chasing every last horsepower in a vehicle that is not raced regularly in amateur racing classes is a waste of money. I would rather see a Pantera with a relatively quiet exhaust system that is driven all over the place regularly, than a Pantera with a bitchen open exhaust system that is only driven to local car shows. I like driving my Pantera and I don't want to do anything that hurts its drivability, that's why I settled for the GTS exhaust system. But that's just me.

By my comments I do not intend to cast dispersions on your plans for your Panteras. However each of us decide to use our cars is a personal matter, and I support each of you in your passion for your Pantera.

I love the sound of a good set of 180's too. Smiler

cowboy from hell
Originally posted by PLT-1:
I am considering/planning on an entry level set of 180's for my car. Has there been a case where the 180's have damaged/cooked the deck lid/paint??...

Yes, you can damage the paint.
Most Pantera owners with 180's run a heat shield attached to the bottom of the trunk lid


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  • daleyaracingrsbc
CBFH mentioned the effect of mufflers on the 180's.
My opinion is that if the system is designed correctly, the muffler is complimentary to it.
You just can't arbitrarily pick a muffler to go on the end of the collectors.
Mine use a 24" glasspack. They really aren't much more then a resonator but they were designed with the headers.
In the Pantera the only time you really hear the exhaust is in an enclosed space like a garage or a tunnel.
The rest of the time there is just a pretty good rock band behind you. Geeze those guys sure can play. Big Grin
Also IR intakes were mentioned here. I've got Weber 48IDA's on the car too. That is an IR manifold.
Most people stay away. I suppose that the combined sound is reminiscent of the 'pipe organist in the Phantom of the Opera. Probably explains why I am so 'freakin' nuts? No wait. I was nuts first? I don't know? Which came first the chicken or the egg? roll on floor
Last edited by panteradoug
When runnin' the Pocono highways with some Vipers and Ferraris, Mark D and I had a little fun. He screamed past me a few times and when we got back to the hotel I asked him what kind of revs he was turning. I figured at least 2000 more than me. But it wasn't the higher revs that give it the whine, it was the smoothed firing order exiting the snakes.

Thanks for the explanation Cowboy.
On the subject of 180's here's a link to a 30 second clip I took today of Bob Benson running the practice for tomorow's Virginia City Ferrari Hillclimb.

Great to see Bob flying the flag amongst a sea of F-cars applause

Not great video quality from my digital camera, but you get the idea of what the 180's sound like.
So back to part 2 of the question. Is there a simple bolt-on option for headers that use the original ANSA exhaust and make some positive difference in HP over stock? or should I just stick with the surface rusted but solid stock headers? I like the sound of the 180s but I also like the idea of air-conditioning. It is an interesting topic and I have never seen 180s used in any other application.
So back to part 2 of the question. Is there a simple bolt-on option for headers that use the original ANSA exhaust and make some positive difference in HP over stock?

Pat Mical's headers are recognized as being some of the best available. Many aftermarket headers have too small a collector.

Don't let A/C alone put you off 180"s there are options like going to a front mounted condenser or others have mounted it in front of the right rear wheel (Hall used to ofer a kit for this)
Originally posted by 72red:
So back to part 2 of the question. Is there a simple bolt-on option for headers that use the original ANSA exhaust and make some positive difference in HP over stock? or should I just stick with the surface rusted but solid stock headers? I like the sound of the 180s but I also like the idea of air-conditioning. It is an interesting topic and I have never seen 180s used in any other application.

All of the venders sell a header that will replace the factory header and bolt to your original ANSA's. PI who sponsors this forum sells one that is a design that has been proven.
Hall, Pantera Parts Connection and pretty much everyone sells something that will work for you.
Ceramic coating is a popular choice then you won't have to worry about rust any more.
A popular choice is the GTS headers and Muffler combo. Great sound.
There are a number of mufflers available also to replace the ANSA's offered by the vendors.
Do some searching on the vendor sites and you will come up with something.
Originally posted by 72red:
So back to part 2 of the question. Is there a simple bolt-on option for headers that use the original ANSA exhaust and make some positive difference in HP over stock?

The stock tail pipes between the headers and the mufflers are too small. The GTS exhaust system increases the diameter of the tail pipe tubing to 2 3/8" or 2 1/2". The GTS exhaust uses ansa mufflers, looks stock, the headers have 2" primaries. Its a good bolt-on upgrade.

Originally posted by 72red:
I have never seen 180s used in any other application.

Now you have


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Last edited by George P
First let me say that the 180's that Brooke has been making in his thread are absolutly a work of art. Absolutly well done. Don't forget to check those out.

When some one says 180's gain 30-40hp the first thing I have to ask is how much of that comes from the fact that the exhaust is far larger then the typical exhaust you can get through the suspension. We put big headers and put them through a small pipe back through big mufflers.

I would love to see a dyno with headers and exhaust the same primaries and collectors as 180's and see if there is a detectectable difference.

Second we are really talking two effects here. One is balancing out the exhaust pressure AND the harmonics of the pulse itself (scavege). The larger the exhaust and the shorter the system the less influence either of these will have.

I personally believe the 30-40 hp comes from the size of the exhaust more then the cross over pipe in a system with adequate primaries AND adequate exhaust further down. The effect of a cross over pipe will have a minimal effect with adequate pipes. Second, we have a pretty short over all exhaust system for the scavage effects to play much of a role. The effects of the scavage pulse are so pinned on cam and RPM that the effect typically improves a little on one RPM and is worse at another. The only way to know one way or another would be to actually dyno the car and change the exhaust system.

Beyound that what we are doing is largelly guesing. Which is ok. It's why we bought cars, to play with them.

And Damn, the headers Brooke is building are HOT!


From my drag racing experience with headers the length of the primary tubesand the length of the collector both have impact on low end torque and top end speed. Adjusting these accordingly for your application will yield and increase in desired performance. Also the cross over tube ... which in 180's equalizes the back pressure and produces performance also .. basically one v8 in comparison to 2 I4's. The data I compiled was on my 428 CJ Comet I shortened the primarys running with no collector ..and putting a piece of tape along the side making one pass ..where the tape burned I cut them off ... the slipped on the collectors and repeaded ... then cut the collector. The perfromance was increased and picked up 4 tenths in the 1/4 ..not sure though technically .. what the reason was where the taped burned off ?

Later on I welded in a cross over tube and it added to my top end power and added mph in the 1/4 mile.... I didnt get to alter the location on the collector to see the difference.

Here are some pics of Mike Trusty's 6 Merge Headers in his Pantera.
This is one of the most unique designs I found while doing my research.
They appear to combine the principles of a Tri-Y and a 180 system. They use a single exit.
They appear to be made out of stainless.
I would have loved to know the thought process and techniques that went into this set.

Absolutely Beautiful.

Last edited by pittcrew
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