Thanks for your opinion Zeus but I contributed to this thread since it seemed as if some folks were arguing that cast manifolds are inherently more durable than tubular manifolds. If you held retail price at $600, then yes, you will find a $600 cast unit to outlive a relatively cheap $600 tubular unit. But if price where less of an object (And I think it is for many EVO owners who, afterall, purchased a single-purpose $30k car and not a less expensive and more generic form of basic transportation), a well designed tubular manifold will meet all requirements. It will cost more, of course. Whether it is worth it or not will depend on the user and their needs/budget.

my 2c,
shiv

 

I guess we will not agree on this subject. You may very well be right when one considers the very top line tubular manifolds. However, a $30k car these days is a cheaper car in the grand scale of performance cars. The average (majority of) people who buy these cars will be less likely able (or want) to afford the highest end manifolds. Worst example is there are a lot of younger people eating a lot of Ramen just to make payments on their "dream car". I keep hearing why would you put this or that on a $30k car. Well, when you consider that your average full sized Texas pickup truck (your average transportation here ) costs more than an Evo, it kind of puts things in perspective on that matter. In short, there are a lot of people who have, and will throw down serious coin for the best of the best for their Evo. It is just that they are in the minority. Of course everyone will want the best, but most will end up compromising a little to stretch the almighty dollar. With that in mind, your $600 example tends to carry more weight to my point. It will be interesting to see how Buschur's "kit" does. Just think of all the DSMs running "big" power on OE manifolds.

 

My associate at Garret/Honeywell (the folks that make Garret turbos) just notified me that there is a tech article in Drag Sport magazine this month comparing a cast and tubular manifold set-up on a Neon SRT-4. I haven't read the story but he told me that, as expected, the tubular manifold offered an power advantage at every engine speed across the board. More importantly, the results were consistent and measurable which is often rare when comparing similiar aftermarket parts. They didn't test things like coolant, oil or underhood temps which, in my opinion, would have been more interesting. But the power argument was appearantly settled beyond a shadow of the doubt. Again, a lot has to do with the design of both the cast and tubular manifold but it's still worth checking out.

Regards,
Shiv

 

Here is a link to the article.

http://www.dragsport.com/issue/12/feat_article.shtml

This is the text without the pictures.

Cast vs. Tubular: More Sting or Just More Bling?
By Michael Ferrara
Dyno and Wrench by Kevin Wells



Ask a group of tuners and you'll get a host of different answers. No one seems to agree on the merits of tubular exhaust manifolds for turbo applications. Some believe they are the only way to go. Others believe that they work as long as they are a certain length. Still others believe there is not performance benefit compared to a good cast exhaust manifold. We plan to shed a little light on the subject by explaining the logic behind the arguments and then putting an actual vehicle to the test.

Totally Tubular

Proponents of tube headers believe performance can be gained on turbocharged applications by building a header of the proper shape, size and design. A tubular exhaust manifold or turbo header offers a host of advantages. Across the cylinders, equalization and optimization are two potential benefits of a tubular exhaust manifold.

On the equalization front, a turbo header can match the flow and pulse timing between each of the cylinders. If the port area of the tubes and the lengths of the tubes are of equal length with a like number of bends, each cylinder will have a port to expel its gases under that provides the same velocity, wave and pressure characteristics. As the piston rises on the exhaust stroke with the exhaust valve open, the same resistance from back pressure will be seen from cylinder to cylinder. The energy of work required by each piston to clear the spent gases from the cylinder will be the same. As witness by many dyno operators, engines that deliver equal power from each cylinder tend to run smoother, stronger and longer than engines with varied output per cylinder. Of course, engines need to be optimized on the intake side also to achieve these benefits.

As for the optimization of power, the designer of a tubular header can vary runner diameters, runner lengths, collector styles and even incorporate stepped designs to maximize the flow out exhaust gases through the turbo header.

Get SET (Short, Equal and Tubed)

There is one group of tuners that believes that turbo headers have merits but also believe that the shorter the runner, the better the performance. This argument is also supported by the "Go Fast with Cast" contingent of tuners. The Get SET camp believes that longer runners tend to lose too much energy through heat loss. Extremists of the Get SET camp may even place minimizing runner length ahead of equalizing tube length in some instances. This group finds itself sharing beliefs between the extremes of the "Totally Tubular" and "Go Fast with Cast" groups.

Go Fast with Cast

"Get it there and get it there quick" is the mantra of the Go Fast with Cast element. This group believes that the sooner the exhaust gases are channeled into the turbo the better. This group also believes that a cast manifold with its thicker walls keeps more of the heat that a tubular exhaust manifold.

The Test

We took our Project SSR1320 Nissan and strapped it to the dyno with the factory exhaust manifold in place. Following a set of three baseline runs, we quickly wrenched on the SR20 and swapped on a tubular exhaust manifold provided by Pro Speed Top 1. We then proceeded to run three more passes on the dyno with the turbo header in place.

Our Pre-test Theory

It was our belief going into the test that the tubular exhaust manifold would probably improve low-end and mid-range response. Since the Pro 1 header had equal length tubes, we believed this equalization would make the exhaust pulses more consistent going into the turbine. As for peak power increase, we didn't expect any major gains on the top end. Our rationale was that the primary exhaust restriction was more likely to be the T28 turbocharger (an upgraded Turbonetics T28 sport turbo) rather than the factory exhaust manifold.

The Actual Results

Our pre-dyno theory was half right and half wrong. The turbo header did pick up on the low end and midrange portion of the powerband. However, the header also made significant power increased on the top end. We picked up an honest 20 horsepower and 15lb-ft of torque on an engine that we assumed was maxed out in power production due to the relatively small turbocharger size.

For more on this article and more grab a copy of DRAG Sport at newsstands and tuning shops nationwide.

 

Dale_K-- Thanks for finding that article. So it was a Nissan and not a Neon.. I must have had a bad cell phone connection The results do support the testing we've done in-house here on other inline 4 motors (B16, BP18 and BP16) that we turbocharged.

One thing that the article didn't touch upon that was mentioned by the engineer at Garret is that long-runner tubular headers are, in fact, desireable in high output drag racing conditions. While the extra runner volume and associated heat loss with the long tube header will hinder boost response, the mid to top end gains provided by carefull exhaust tuning (kinda like a naturally aspirated car) will be the plus side. But for street cars where boost response is just as important as peak power, it makes more sense to keep runner length shorter and close as possible to being equal with smooth bend radius.

my 2c,
Shiv

 

You're right. It does get stronger as its heat cycled. It doesn't get stronger, however, when it is heated up and cooled down super-fast.

 

Seems like some more fuel for the Shiv / Buschur mutual admiration society.

I can't wait till Dave Buschur reads this newest insult to his products.

BTW - the most powerful DSM's I have seen so far all run cast manifolds and FP turbos. My money is on the Buschur kit - I am dyning to try that one out.

 

The other big stress is vibration. It's here where cast manifolds have the advantage since they have more vibration damping abilities due to their far greater mass. For lighter tubular headers, it's important achor it firmly to the block while still allowing for runner expansion and contraction. This is why many turbo header designs fail. They account for one and not the other.

my 2c,
shiv

 

have u heard of it happening alot

 

In turbo Miatas, yes. Both turbular and cast manifolds, for a long time, failed to exhibit long-term durability. One problem was the inherent imbalance/thrashiness/roughness of the venerable B18 engine. No balance shafts and lots of heavy recipricating mass. The motor wasn't transverse mounted like it is in the EVO so the engine would torque in a way that put a lot of stress on the downpipe which would tranfer that stress to the turbo/manifold. Packaging was also a pain which necessitated a whole bunch of design compromises. It, IMHO, was perhaps the worst foundation to build a durable turbo kit upon. Eventually, the design of the manifolds changed and things worked out. But it took time and lots of trial and error. Our manifold design for the EVO is a bit different than any other one I've seen. It holds the turbo in a very different position than most other headers I've seen. This, along with a few other features, greatly minimizes the stresses the header would otherwise be subject to. There is little doubt in my mind that this tubular header will last as long as a good cast unit.

Shiv

 

If you expect your EVO to get a lot of hang time in the air or hit a few trees on the way to work, then yes, you might want to stay away from a tubular header. Cast headers can take that kind of punishment far better than tubular units.

Also remember that WRC rally cars are inlet restricted and don't exactly fall into the mold of an efficiently running engine model. Lots of engine tuning compromise has been made made to work optimally within the rules. But it's not something you'd necessarily want to mimic on the road when the rules are open.

my 2c,
shiv

 

All I am trying to say is that mitsubishi did not give us these Evo's with cast manifolds because of cost and their budget. They managed to put tubular manifolds on the 3000GT and a few of the eclipse's. The design of the car and its speed and rate of boost, which jerks the car back, should be used with a cast header. The engineers put the cast manifold on for a reason. And that reason was seen when these tubular manifolds cracked and nearly killed their drivers. Sure the quality of your tubular manifold may be engineered better, and it looks like it is, but still. The way the car is desgined it will stress that manifold a great deal. Quality cannot defeat the laws of physics no matter how much "better" it is. The design is flawed on this vehicle, we need to use cast manifolds. There was an article regarding this in a japanese magazine which was about why the engineers at mitsu had designed every lancer evolution with a cast manifold and why they were having problems with tubular manifolds. The engineers have proven this.

 

Also if any of you had a old Subaru Rs with the borla headers. EVERY one of the first three generations cracked due to improper design. I think they finally fixed the problem, but i went through three sets while NA then another few when i was turbo'd. the last set i silicone bronzed doublers over the tube ends and where the tubes ran paralell. much like the Vishnu Subaru Up pipe has the collars on the ends ALA Top Fuel cars.

Up pipe from Vishnu


fatigue plays a major part in designing a good tubular header. heck try hanging on to something that weighs 20 pounds for 20 min and see how your arm feels
tom

 

by the way, keep away from hks manifolds

their not worth the money and hks deny to their customers that has happened before

simon norris cracked his twice and had to build a bracket
keithp from the mlr cracked his , it was brand new didnt even do a single track day and alot of others, and the best story hks gave him was it hasnt hadnt before, my ****, liars, they said they will give him a replacement for 1100 pounds sterling. they should get sued, and they should change their ****ty design

 

glad to know your ok. are you fixing the headers or are you getting a new one? what kind?