Long Tube “Hedder” Tech on SRT8

Out with the Bad Air

Words and photos by Richard Kratz

In our 2012 October issue we covered the installation and dyno tested the power improvement of short tube headers on a 5.7L late model Hemi Challenger. When we tuned the motor with Diablosports software on the dyno the results were startling—up to 50 lb. ft. more torque in the low range and an average of about 30 more horsepower everywhere.

But the 5.7L has fairly restrictive iron “log” style exhaust manifolds from the factory and was thus a prime candidate for just about anything that offered less resistance. The 6.1L engine, as found in SRT models, actually comes from the factory with individual runner short tube headers. It may not be obvious from the outside because the factory manifold/header has a second layer of stainless steel encasing the exhaust tubes to reduce exhaust noise. Experience has shown that upgrading to aftermarket short tube headers on these 6.1L engines just doesn’t produce enough improvement to be worth the cost and installation hassle.

 

But what of long tube headers? Is the potential for increased power and torque from long tube headers worth the cost and labor on an SRT vehicle? We had a feeling that the answer was yes, especially for our Magnuson supercharged project Maulin’ Magnum street/strip car, so we decided to find out. We connected with Hedman Hedders, one of the original performance exhaust companies founded by Bob Hedman back in 1954. They hooked us up with a set of their HTC Coated Stainless Steel Street Headers long tubes made for our car. HTC stands for High Temperature Ceramic, this ceramic-metallic coating is much more than a cosmetic touch. It is extremely durable and provides heat insulation, keeping more exhaust heat in the exhaust gases and letting less into the engine compartment. And on late model Hemis, that’s sorely needed, our engine bay gets seriously heat soaked in hot weather racing or driving around in traffic. Hedman still uses the full aviation grade coating process, not a modified process that some companies use that while it reduces cost may also reduce durability.

It is important to note that we installed these headers on a well optimized supercharged engine. Our car has over 500 quarter mile passes on it and has been dyno tuned as various upgrades were undertaken. As far as the tune and setup goes, we weren’t leaving much, if any, horsepower on the table.

We got to do the installation on a lift with an experienced header installer leading the job. Having recently done a short tube header install on jack stands in a garage, this long tube job is quite possible to do at home, but it will be difficult to get to some of the bolts.

 

Removing the old manifolds is a lot harder then installing the new ones, with one bolt on the driver’s side being particularly difficult to remove (thank goodness contributing editor Alex Rogeo has small hands, she saved the day on this bolt). If you’re hesitant to do the install at home you should probably listen to your instincts and find an installer.

A note on gaskets: There’s nothing wrong with the gaskets that aftermarket exhaust companies include with their kits, they work. The factory gaskets however, are extremely well designed and work even better. The multiple-layer Mopar exhaust manifold gaskets may cost nearly $30 each, but remember that the factory designed them to last virtually forever. They don’t leak and they don’t blow out, so considering how much work it is to replace them, we’d advise you buy them ahead of time and use them on your car like we did.
Hedman Hedder compared to stock SRT8 manifold. You can’t tell from the photo, but inside the stock manifold are separate short tube exhaust pipes for each cylinder, it’s virtually a short tube header from the factory. Note the three slotted bolt holes in the Hedman Hedder flange, this makes installation a lot easier.
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