Fabricating Turbo Headers and Exhaust Systems with Eimer Engineering and Burns Stainless

Fabricating Turbo Headers and Exhaust Systems with Eimer Engineering and Burns Stainless

by Mike Kojima

How do you make a good turbo system even better?  We did it by enlisting the help of Burns Stainless. Our subject car had a turbo LS engine.  Although the car made lots of power, it had issues with late turbo response, a drop in top end power, a ton of weight in the nose that negatively impacted handling and a propensity to burn up everything under the hood.

The existing turbo system had a lot of items mounted way up front where they were vulnerable to crash damage.  A final issue was that the turbo system got in the way of many maintenance items and made mechanical work on nearly everything in the engine compartment difficult. It was a pity to ditch a beautifully crafted system but function is more important than just looks, especially on a race car.

 

The original turbo system was good looking and exquisitely made but had some issues with practicality that we had to address.  In order to get a perfectly symmetrical exhaust, the heavy Garrett GTX50R turbo was mounted way in front of the the engine.  This pushed a heavy bar and plate intercooler to the very edge of the bumper skin.  In fact the intercooler overhung the lower part of the bumper making everything very vulnerable to any sort of contact.

With the turbo and the intercooler being mounted forward and high meant that nearly 100 lbs of metal were pushed as far forwards and as high up as you could physically get in the nose of the car.  These pieces were doing there best to make the weight bias nose heavy and to raise the CG. The turbo header made a plug change an hour long process and doing a compression and leak down check a full day's work. Adjusting the valves was very labor intensive as well. 

Even though every non metal part in the engine bay was thermally wrapped, the car had an appetite for coils, plug wires, hoses, wires, sensors and injectors.  To keep the car reliable meant an elaborate PM schedule and the car still suffered from DNF's due to heat damaged underhood parts failing at the worst time.  This had to change.

 

To fabricate a new everything, we busted out the Burns Stainless catalog and ordered up a bunch of stuff.  This picture is only a small representation. We were changing everything from our headers and exhaust parts, to our charge piping and even our water pipes for the rear mounted radiator. We used a bunch of Burns 304 stainless U-Bends in many different diameters to build the headers, Y pipes and exhaust system. 

You might wonder what is the big deal about Burns stuff and why it costs more.  Burns uses ASTM certified tubing to make their bends.  The certification means you are getting consistent high quality aircraft grade materials vs melted down old Chinese woks and stuff. Chris Eimer, of Eimer Engineering, told us that he prefers Burns tubing because it actually welds better making his job easier.

Burns has a lot of experience in bending tubes with mandrels and bending thin walled stainless is pretty tricky.  What happens is that many cheap thin wall stainless U bends come out ovalized or misshapen in the tight parts of the bend.  When building headers or exhausts, if a cut section is ovalized it makes building the part really hard.  The fabricator has to waste a lot of time getting the section round again if it is even possible.  

Thinwall stainless requires tight mitering because it's TIG welded with a sharp tungsten and thin filler rods to control the heat being put in to the metal. Any weirdness in tubing cross section will drive a fabricator nuts and greatly increase expensive labor time. Burns' experience with metal forming means a consistently round cross section anywhere in the tube bend.

We also ordered up some aluminum bends.  Burns' aluminum bends are made of ASTM certified 6061 aluminum.  The bend tubing starts off in the annealed O condition and straight sections are heat treated to the T6 condition. Like the stainless bends, Burns aluminum bends are consistent in cross section.  Due to cold working the bends end up being in the F hardness condition once formed.

 

The most impressive part of a Burns fabricated system is the use of the famous Burns merged collector. Typically, most header collectors are just a terminus where the primary pipes dump into la large pipe, making the acoustic end of the primary, the Burns collector takes all of the primary tubes and gathers them into one aerodynamically smooth merge. 

In this cutaway of a Burns Collector you can see the exquisite construction and perfect mitering to make the ultimately smooth, non turbulent merge of exhaust gasses.  The smooth termination is one reason why Burns Collectors make such great power.

 

A look down the backside of the Burns Collector shows what a piece of metal artwork it is!

In our experience, the use of a Burns Collector allows for the use of a shorter and larger diameter primary tube than what the classic resonance calculations would give for primary diameter and length.  This has allowed us to make much more top end while not losing and sometimes even gaining top end power. 

Another big plus is that Burns will do a no cost header design consultation for you with the purchase of a Burns collector using their X-Design process. We have been using X-Design and found it to work so well that we have given up trying to calculate our headers' tuned dimensions ourselves! We have found that the Burns consultation is worth the price of the collectors due to their help in getting the headers right the first time.

 

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